Looking for help. Does this mean I need cali compliant exhaust? 06 lc. I was getting p0430 and p0420. I can't clear the lights.started with 4 new denso O2 sensors, maf, had a shop replace cats, installed new fuel pump and filter, new plugs and coils, head gaskets, heater tees, hoses and thermostat. I'm not sure what else to do unless this is the problem. Hoping it's the wrong cats. Also can I tune around this?
Help p0430, p0420
- Thread starter Operationlc100
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holy crap you shot the parts cannon hard
- Thread starter
- #3
Everywhere I went told me something different. The dealership diagnosed most of it. Then I went to a reputable yota specialist. A lot of money gone and problem not fixed. I need help lol
hey at least you have new parts, I hope you get it sorted and someone with experience chimes in
The cats in these are not too advanced and unless they are 100 cell probably are not the issue, but without really knowing what they put in place of the oem units it can't be completely ruled out. An exhaust leak pre-cat/O2, even the smallest undetectable, can cause issues with the air-fuel ratio which van throw efficiency faults.
Stop throwing away good money and set yourself up with Techstream. Learn the functions, download the FSM from here, find the diagnostic charts that give you the required parameters, and observe the live data. In most cases you will find a direction from the live data. These trucks aren't advanced enough to keep an average diy'er from being more hands on. I'm a tech and don't want to take food off the plates of other techs, but bad diag is not acceptable.
Also, perform a smoke test. Again, air-fuel ratio has a big effect on cat efficiency and you may find a leak that is causing your fuel trims to swing enough to cause your problem. Typically, leaks will result in other faults as well, but it's an easy diag and can eliminate a lot of areas for failure.
Stop throwing away good money and set yourself up with Techstream. Learn the functions, download the FSM from here, find the diagnostic charts that give you the required parameters, and observe the live data. In most cases you will find a direction from the live data. These trucks aren't advanced enough to keep an average diy'er from being more hands on. I'm a tech and don't want to take food off the plates of other techs, but bad diag is not acceptable.
Also, perform a smoke test. Again, air-fuel ratio has a big effect on cat efficiency and you may find a leak that is causing your fuel trims to swing enough to cause your problem. Typically, leaks will result in other faults as well, but it's an easy diag and can eliminate a lot of areas for failure.
- Thread starter
- #6
The work was done at a local toyota dealership. The coils and plugs where due. When they pulled codes first time they assured me it was o2 sensors. When that called they said cats. Yes I'm going broke. I would assume toyota would have been able to properly diagnosed my issue. This is why I'm here now.
Most dealer techs these days are just parts changers. They pulled codes and ran with it. They most certainly did not put any real thought or diagnstic ability into the repairs. If you're limited in mechanical prowess then I can understand relying on the dealer. You can also post up in your regional clubhouse and I'm sure there will be more than one willing and capable member willing to lend a hand.
- Thread starter
- #8
I don't understand what you mean by regional clubhouse. Could you explain that please? I'm in Kansas city.
I'm in Olathe. Bring it by and we can smoke test it if you want? If you are interested PM me. I have TS as well.
2001LC
SILVER Star
Why head gaskets (HG)? Did tech find compression issue and or head gasket blown? Did HG R&R, correct compression, from what to what?
Head warpage due to overheating. Can result in coolant blowing into CATs. Coolant is a CAT killer as is excessive rich fuel mixture. Rich fuel condition to both CAT, is almost always MAF sensor issue.
Where, all issue found & corrected (parts). Before second CATs failed?
Has there been any S.A.I. DTC yet?
There was a few threads on these P0430 & P04290 DTC in 06-07, about 8 years age. I beat the drum, that those with. Needed of fix the upstream issues first. Or it would keep returning and kill new CATs. I beat on those with the issue, figuratively speaking. They'd "say" they did it all.
I became determined to find the main cause, of both CAT,s failing in a well turned 4.7L VVTi.
So I bought one with the issue about 6 years ago. _____________ Which I cured, my P0420 & P0430. They've not return in ~5 years.
________________
In 2019 I found a 2007 with the issue of P0420 & P0430. I found a number of minor upstream and a mid stream (O2 cross thread, resul in air leak BK2 only) issue, I corrected all.
But the final key, is a modification I created for the 4.7L VVti. I spent, a lot of time and money. To determine issue causing, create a mod to correct and test over last ~5yrs. It works!
Wherein, I replace the non replaceable S.A.I. pump filter, with an easily replaceable one. It's been running great ever since with aftermarket CAT. Now (Aug 2024), I installed new OEM CATs $$$. Just to make sure, mod corrected CAT issue and was not a VVT CAT defect or ECM coding issue. So far so good.
Note: 4.7L VVti 06-07 has 2 A/F (upstream) & 2 O2 (downstream). 98-05 have 4 O2's (no A/F)
S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert!
We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW! I've a very easy and cheap WORK AROUND. You are going to love this ;) This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the...
forum.ih8mud.com
My filter if pipe out from under intake manifold, for easy R&R. Take 3 seconds to replace filter.
I'm doing the S.A.I. filter mod now in my shop. On a 06 VVTi w/165K, and did another few months ago. I do about 1/2 dozen a year. In these last two. I learn a key of why the filter fails. They are shrinking and clogging with dust. The dust increases vacuum behind and on the filter, in S.A.I pump upper cavity cap area. By reduce air that can pass through filter. Humidity would reduce airflow even more. The filter (foam rubber) is also shrinkage, reduce hold within cavity of pump cap. The two combine (vacuum & shrinkage) conditions. Result in filter being sucked out of view, down into cavity. The impeller blades, then starts whittling down, eating the foam rubber filter. Then, foam rubber and dust/sand blow throughout the SAI system. Than dusty air, from under intake manifold. That's blown under, while driving and by radiator cooling fan. Then is pick up by filterless S.A.I pump during cold start up..
We now believe it's a factor of how much dust, heat, cold and humidity. As to if filter fails sooner rather than later. But they will all fail, in all models of Toyota. GX460 already had, a recall for these SAI filters. Recall TBS said they don't know why, but suspect humidity played a roll.
These days I actually inspect S.A.I. pump filter, with a borescope. If missing from view, I install the mod ASAP. If filter still there, I grade it and reinspect periodical depending on grading and where vehicle driven. I push off mod, until starter needed, if I can.
S.A.I. Filter seen in view, just inside S.A.I. pump cap.
Cap removed from S.A.I. pump. Filter in proper position.
This weeks SAI inspection with borescope. Filer was gone from view. Found 95% still deep inside cap. Second in a row caught just as filter failed.
The last two S.A.I filters, found near impeller (white blades in hole left of filter). These were first ever, I found more than a thumb nails wroth of foam rubber filter remaining.
Most times I find:
Last edited:
- Thread starter
- #11
Sent you my number. Gimme a text or call tomorrow. Thank you
- Thread starter
- #12
Thank you. Very informative. Would I need a code for this though? I'm only pulling the 0430 0420. If this is the issue how do you feel about the block off plate solution? My understanding was the head gaskets had a leak. I couldn't find one but many sources said itvwas a likely culprit.Why head gaskets (HG)? Did tech find compression issue and or head gasket blown? Did HG R&R, correct compression, from what to what?
Head warpage due to overheating. Can result in coolant blowing into CATs. Coolant is a CAT killer as is excessive rich fuel mixture. Rich fuel condition to both CAT, is almost always MAF sensor issue.
Where, all issue found & corrected (parts). Before second CATs failed?
Has there been any S.A.I. DTC yet?
There was a few threads on these P0430 & P04290 DTC in 06-07, about 8 years age. I beat the drum, that those with. Needed of fix the upstream issues first. Or it would keep returning and kill new CATs. I beat on those with the issue, figuratively speaking. They'd "say" they did it all.
I became determined to find the main cause, of both CAT,s failing in a well turned 4.7L VVTi.
So I bought one with the issue about 6 years ago. _____________ Which I cured, my P0420 & P0430. They not return in 5 years.
________________
In 2019 I found a 2007 with the issue of P0420 & P0430. I found a number of minor upstream and a mid stream (O2 cross thread, resul in air leak BK2 only) issue, I corrected all.
But the final key, is a modification I created for the 4.7L VVti. I spent, a lot of time and money. To determine issue causing, create a mod to correct and test over last ~5yrs. It works!
Wherein, I replace the non replaceable S.A.I. pump filter, with an easily replaceable one. It's been running great ever since with aftermarket CAT. Now (Aug 2024), I installed new OEM CATs $$$. Just to make sure, mod corrected CAT issue and was not a VVT CAT defect or ECM coding issue. So far so good.
Note: 4.7L VVti 06-07 has 2 A/F (upstream) & 2 O2 (downstream). 98-05 have 4 O2's (no A/F)
View attachment 3799292
S.A.I. Filter Modification, in VVT engines. To prevent its failure! Alert Alert!
We've a $2.00 part in the S.A.I. (secondary air injection) system of the VVT engine, that is taking-out ~$7,000.00 $15,000 $25,000 (inflation) in parts. WOW! I've a very easy and cheap WORK AROUND. You are going to love this ;) This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the...
My filter if pipe out from under intake manifold, for easy R&R. Take 3 seconds to replace filter.
View attachment 3799293
View attachment 3799297
View attachment 3799320
I'm doing the S.A.I. filter mod now in my shop. On a 06 VVTi w/165K, and did another few months ago. I do about 1/2 dozen a year. In these last two. I learn a key of why the filter fails. They are shrinking and clogging with dust. The dust increases vacuum behind and on the filter, in S.A.I pump upper cavity cap area. By reduce air that can pass through filter. Humidity would reduce airflow even more. The filter (foam rubber) is also shrinkage, reduce hold within cavity of pump cap. The two combine (vacuum & shrinkage) conditions. Result in filter being sucked out of view, down into cavity. The impeller blades, then starts whittling down, eating the foam rubber filter. Then, foam rubber and dust/sand blow throughout the SAI system. Than dusty air, from under intake manifold. That's blown under, while driving and by radiator cooling fan. Then is pick up by filterless S.A.I pump during cold start up..
We now believe it's a factor of how much dust, heat, cold and humidity. As to if filter fails sooner rather than later. But they will all fail, in all models of Toyota. GX460 already had, a recall for these SAI filters. Recall TBS said they don't know why, but suspect humidity played a roll.
These days I actually inspect S.A.I. pump filter, with a borescope. If missing from view, I install the mod ASAP. If filter still there, I grade it and reinspect periodical depending on grading and where vehicle driven. I push off mod, until starter needed, if I can.
S.A.I. Filter seen in view, just inside S.A.I. pump cap.
View attachment 3799295
Cap removed from S.A.I. pump. Filter in proper position.
View attachment 3799339
This weeks SAI inspection with borescope. Filer was gone from view. Found 95% still deep inside cap. Second in a row caught just as filter failed.
View attachment 3799283
The last two S.A.I filters, found near impeller (white blades in hole left of filter). These were first ever, I found more than a thumb nails wroth of foam rubber filter remaining.
View attachment 3799290View attachment 3799288
Most times I find:
View attachment 3799302
2001LC
SILVER Star
Not really! The S.A.I. filter failure, does not set off a DTC (code). At least not at first. But in time, as dust blows/accumulates into/in S.A.I. system. Then, you'd likely get S.A.I. DTC's. Toyota has a TSB out, on some of the S.A.I. DTC. Which requires all components of S.A.I. system, be replaced. What I found, is the dust, causes issues within SW and valves, and the tricky one is the air pressure sensor. Dust gets in it, yet it will test good.
Head gasket:
You should have been given some or all of: compression test, leak down test, coolant gas test, borescope pictures. Picture of coolant leak on outside of head.
If head gasket had a coolant leak. We typically see coolant on outside of heads. The compression test would fail, and they should have given you the reads for each cylinder.
If coolant entered cylinders, then blew into CAT. As I said, is a CAT killer if to much coolant.
Often head gasket leaks, blowing combustion gasses into coolant system. We test coolant for gases.
Other head gasket leak, may not leak coolant, just compression gases. But I've not seen that in the 4.7L, but can happen. Again compression test, would reveal cylinder(s) with the leak.
Once head gasket R&R, then CATs replaced after. CATs should not have failed again. Unless something else going on.
Trying to remotely diagnose, is very very difficult. Especially if one part or both aren't mechanics or mechanically inclined.
Detail of what was done, order done in and why done. Is very important.
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So this morning I was able to get some history on the vehicle and hook up Techstream. The owner is a very nice gentleman and it was great getting to know him. I hope we can have a beer sometime soon.
Just to update the forum on the history:
2006LC with 233K
Timing belt changed 50K ago. Valve cover gaskets and NOT head gaskets were replaced. (Owner misspoke)
Trouble started months back with a P0100 series code along with most likely some P0300 series and P0420/0430. Toyota dealership installed an owner provided Hitachi MAF and owner provided NGK coils (EBay), along with dealer OEM Denso plugs and all new 02 sensors.
Owner picked up vehicle and run cycle tripped P0420/0430.
Owner took the vehicle to a “reputable” shop and they said it needed CATS. Shop installed aftermarket CATS.
Once again, first drive cycle tripped P0420/0430.
I hooked up Techstream to the warmed up truck and observed that the only codes present was P0420/0430. (Attached Techstream screenshots)
1. Intermittent misfires on 6 of 8 cylinders.
2. Idle fluctuating between 650 to 1000 rpm.
3. Turned my shop vac on exhaust and soaped both exhaust pipes. Found leaks on both CATS before upstream sensors due to poor welds. Slight leak on B2S2 sensor at the threads.
I have a 5 min recording on an old XP laptop that if anyone has any questions I can answer for the owner. Thanks for looking!
cold engine, or relatively cold.
cat temp typical lower than OEM running temp.
under 3.3V on bank one wideband washes with 12.5 short trim same bank.
lambda and voltages look within normal range, as does long and short trim.
AIR leaks are going to do what you think they are. (shown)
You can really hear air leaks on the SAI train part of the manifold.
Anything short of very monir leaks before the forward wideband sensors will give you 420&30
Increasing short term trim on bank one might be where I'd start replacing gaskets and such.
I have found it easier to get the exhaust train off the rubber hangers in the rear to easily get room when separating flanges at the front for gasket replacement.
I think you just need some exhaust work. Not cat replacement.
cat temp typical lower than OEM running temp.
under 3.3V on bank one wideband washes with 12.5 short trim same bank.
lambda and voltages look within normal range, as does long and short trim.
AIR leaks are going to do what you think they are. (shown)
You can really hear air leaks on the SAI train part of the manifold.
Anything short of very monir leaks before the forward wideband sensors will give you 420&30
Increasing short term trim on bank one might be where I'd start replacing gaskets and such.
I have found it easier to get the exhaust train off the rubber hangers in the rear to easily get room when separating flanges at the front for gasket replacement.
I think you just need some exhaust work. Not cat replacement.
Thanks Jerry. The leak before the CAT on bank 1 is a pinhole but the leak on bank 2 before the CAT is quite large. Owner stated exhaust smell in cabin at times.
2001LC
SILVER Star
My test vehicle, that I found issue and created S.A.I. mod . Had (while PO had) P0430, then BK2 CAT replaced with daivco by INDY shop. I found, 4 exhaust leaks: SAI pipe to exhaust man, exhaust man pipe to CAT, O2, rear CAT to muffler pipe. Tech caused leaks every point he touched. He also bent flange at rear of CAT to muffler joint and bent transmission crossmember. Apparently use a 20 pound pry bar, to pry off CAT from muffler joint. Instead of simple push back on muffler. Which rubber mounts of muffler allow for plenty of swing for. Guy was a gorilla, shop hired off the street, with zero mechanical skills.
Your exhaust leak, needs correcting. As does anything not to spec. So often, over the years. Many hand touch these 100 series, that just plain mess them up. Getting all system corrected is first order of business. Before replace CATs. Same is true for bad Charcoal canister. Or we risk damaging the new replacement.
The #5 misfire needs diagnosing. The ebay NGK coils are highly suspect. 90% chance they're bootlegs. Ebay is the worst place to buy coils.
Start by swap #5 with #3. See if misfire moves, and if it does. I'd get a whole new set of Denso coils, direct for a denso distributor. Since if one NGK coil already bad, likely all will follow soon.
If misfire doesn't move, check for spark. While plug out, check compression. A borescope is handy, to peak into cylinder. If all good, check fuel injector.
If, Hitachi MAF also ebay. I'd have concerns. A bad or wonky MAF, will take out CAT fast.
Once all tuned up. You may want to take a HWY high RPM run. Cooking off the A/Fs, O2s and cats. I find CAT temp max-out around 4,500 RPM. Hold there for ~10 minutes. Repeat maybe 3 runs, with 10 min normal HWY RPM cool downs.
Your exhaust leak, needs correcting. As does anything not to spec. So often, over the years. Many hand touch these 100 series, that just plain mess them up. Getting all system corrected is first order of business. Before replace CATs. Same is true for bad Charcoal canister. Or we risk damaging the new replacement.
The #5 misfire needs diagnosing. The ebay NGK coils are highly suspect. 90% chance they're bootlegs. Ebay is the worst place to buy coils.
Start by swap #5 with #3. See if misfire moves, and if it does. I'd get a whole new set of Denso coils, direct for a denso distributor. Since if one NGK coil already bad, likely all will follow soon.
If misfire doesn't move, check for spark. While plug out, check compression. A borescope is handy, to peak into cylinder. If all good, check fuel injector.
If, Hitachi MAF also ebay. I'd have concerns. A bad or wonky MAF, will take out CAT fast.
Once all tuned up. You may want to take a HWY high RPM run. Cooking off the A/Fs, O2s and cats. I find CAT temp max-out around 4,500 RPM. Hold there for ~10 minutes. Repeat maybe 3 runs, with 10 min normal HWY RPM cool downs.
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2001LC
SILVER Star
I'll push back a bit on exhaust leak. They need correcting. Factory Manual even states, can damage CATS. But I've seen many exhaust leak. Some very bad exhaust leaks go on for years, even ~100K miles. Fact is, a very high percentage of 4.7L 2UZ had/have crack exhaust manifold. Which is a pre CAT exhaust leak. That said. I've yet to see a CAT fail, on one with exhaust leak.
Going back over this thread. You noted misfire cylinder 6 & 8. Tech stream data show #3 misfire. We now know ebay NGK coils. Which I see intermittent misfires, often never set of a DTC. From weak or junky coils. It appears, the coils, spark plugs and MAF replaced, were in response to the P0430/P0420. Which were pre "known", exhaust leak.
Factory coils last a long time, even a milions miles or more. Unless subjected to excessive heat.
Spark plugs at ~180k miles, if first time replace. Would have walked out considerable. The hot combustion gases escaping past spark plug threads, cook the coils. Additional the spark plugs gaps may have been nearing or greater than max spec of 1.2mm.
Either or combination result in excessively hot coils.
forum.ih8mud.com
Also worth note is misfires and tech stream. We have a glitch, that hides them.
I'm seeing a lot of same history, as I did on my test 4.7L VVti. The one I bought with these symptoms and P0420 & P0430. Just so I could work to find why the VVTi CATs failing, being replaced and failing again. For one. Both had CAT DTC, before and known work on or reported exhaust leaks. Other than cracked exhaust manifold leaks. We don't see exhaust leaks on factory installed CATs, A/F or O2.
PO/mechican did what they should, in looking for and correct upstream issues, that result in CAT failure. We saw this time and time again with in 4.7l VVTi. But PO may have just been shooting for cause, not replace parts found as cause of issue. Also. PO did make what "may" have been, one mistake. He bought new name brand parts off ebay. Not to say also sellers on ebay, sell bootleg. As I once found a set of real Denso spark plugs there. But most, others and I found, have been bootleg.
So was the engine in badly in need of turn up with bad MAF, which caused first CAT failure. Or has cause yet, to be found, and now a repeat?
Here's what I'd do today, if in my shop.
Get out on HWY and run the piss out of it. I may put some Cataclean, Sledgehammer or paint thinner in gas, for a HWY run.
Also worth note: Prolonged idling is warned against in OM, as can damage CATS.
I also find lots cold starts with very short drives, without getting on HWY. Very hard on CATS, A/F and O2's. A sign of this, are holes in muffler. Difficulty to read those tea leaves. As age, miles and region diven in, also take a toll on muffler.
I'm thinking, CAt failure cause never found, also:
Coils are bootlegs, result in misfire.
We don't want to chance, a junk bootleg MAF.
Spark Plugs walked out, then replace. We want to make sure, no Time-sert or helicoils in heads and plugs tight.
S.A.I. filter are failing around 150K to 200K miles. Where driven, plays a big roll. At at when filter fails. This could yield, one more clue in the puzzle
We also need to make sure compression not compromised. We can have some loss, but below minimums or to wide spread between cylinder. Can result in fuel mixture issues. As can a wonky fuel pump, which 06-07 have a known bad one. Very hard to detect in the shop with test. It reveals itself, on hot summer days.
Going back over this thread. You noted misfire cylinder 6 & 8. Tech stream data show #3 misfire. We now know ebay NGK coils. Which I see intermittent misfires, often never set of a DTC. From weak or junky coils. It appears, the coils, spark plugs and MAF replaced, were in response to the P0430/P0420. Which were pre "known", exhaust leak.
Factory coils last a long time, even a milions miles or more. Unless subjected to excessive heat.
Spark plugs at ~180k miles, if first time replace. Would have walked out considerable. The hot combustion gases escaping past spark plug threads, cook the coils. Additional the spark plugs gaps may have been nearing or greater than max spec of 1.2mm.
Either or combination result in excessively hot coils.
Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!
TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...
forum.ih8mud.com
Also worth note is misfires and tech stream. We have a glitch, that hides them.
I'm seeing a lot of same history, as I did on my test 4.7L VVti. The one I bought with these symptoms and P0420 & P0430. Just so I could work to find why the VVTi CATs failing, being replaced and failing again. For one. Both had CAT DTC, before and known work on or reported exhaust leaks. Other than cracked exhaust manifold leaks. We don't see exhaust leaks on factory installed CATs, A/F or O2.
PO/mechican did what they should, in looking for and correct upstream issues, that result in CAT failure. We saw this time and time again with in 4.7l VVTi. But PO may have just been shooting for cause, not replace parts found as cause of issue. Also. PO did make what "may" have been, one mistake. He bought new name brand parts off ebay. Not to say also sellers on ebay, sell bootleg. As I once found a set of real Denso spark plugs there. But most, others and I found, have been bootleg.
So was the engine in badly in need of turn up with bad MAF, which caused first CAT failure. Or has cause yet, to be found, and now a repeat?
Here's what I'd do today, if in my shop.
- I study history (even deeper than you have). i.e. Toyota service history, car fax, PO statement and work order receipt. May even, cal some shops and parts departments. To further drill down.
- Drive while monitoring & logging data. ECT, IAT, AT temps, FT, CAT, MAF, RPM, MPH.
- Check for misfires, with tech stream.
- Pull engine cover and look for vacuum leaks. Correct any.
- Check, air pipe fender to T-body for obstructions and condition of t-body (CLN).
- Pull spark plugs and run compression test, while engine hot.
- Borescope cylinders, also looking for time-sert.
- Borescope S.A.I. pump, checking its filter.
- I may run fuel pressure test.
- I'd have 8 spark plugs & coils and one MAF standing-by. Depending on results of above. I'd replace all, except possible spark plugs since they came Toyota.
- Correct exhaust leaks.
Get out on HWY and run the piss out of it. I may put some Cataclean, Sledgehammer or paint thinner in gas, for a HWY run.
Also worth note: Prolonged idling is warned against in OM, as can damage CATS.
I also find lots cold starts with very short drives, without getting on HWY. Very hard on CATS, A/F and O2's. A sign of this, are holes in muffler. Difficulty to read those tea leaves. As age, miles and region diven in, also take a toll on muffler.
I'm thinking, CAt failure cause never found, also:
Coils are bootlegs, result in misfire.
We don't want to chance, a junk bootleg MAF.
Spark Plugs walked out, then replace. We want to make sure, no Time-sert or helicoils in heads and plugs tight.
S.A.I. filter are failing around 150K to 200K miles. Where driven, plays a big roll. At at when filter fails. This could yield, one more clue in the puzzle
We also need to make sure compression not compromised. We can have some loss, but below minimums or to wide spread between cylinder. Can result in fuel mixture issues. As can a wonky fuel pump, which 06-07 have a known bad one. Very hard to detect in the shop with test. It reveals itself, on hot summer days.
Last edited:
I'll push back a bit on exhaust leak. They need correcting. Factory Manual even states, can damage CATS. But I've seen many. Some very bad exhaust leaks go on for years, even ~100K miles. Fact is, a very high percentage of 4.7L 2UZ had/have crack exhaust manifold. Which is a pre CAT exhaust leak. That said. I've yet to see a CAT fail, on one with exhaust leak.
Going back over this thread. You noted misfire cylinder 6 & 8. Tech stream data show #3 misfire. We now know ebay NGK coils. Which I see intermittent misfires, often never set of a DTC. From weak or junky coils. It appears, the coils, spark plugs and MAF replaced, were in response to the P0430/P0420. Which were pre "known", exhaust leak.
Factory coils last a long time, even a milions miles or more. Unless subjected to excessive heat.
Spark plugs at ~180k miles, if first time replace. Would have walked out considerable. The hot combustion gases escaping past spark plug threads, cook the coils. Additional the spark plugs gaps may have been nearing or greater than max spec of 1.2mm.
Either or combination result in excessively hot coils.
Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!
TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...
Also worth note is misfires and tech stream. We have a glitch, that hides them.
I'm seeing a lot of same history, as I did on my test 4.7L VVti. The one I bought with these symptoms and P0420 & P0430. Just so I could work to find why the VVTi CATs failing, being replaced and failing again. For one. Both had CAT DTC, before and known work on or reported exhaust leaks. Other than cracked exhaust manifold leaks. We don't see exhaust leaks on factory installed CATs, A/F or O2.
PO/mechican did what they should, in looking for and correct upstream issues, that result in CAT failure. We saw this time and time again with in 4.7l VVTi. But PO may have just been shooting for cause, not replace parts found as cause of issue. Also. PO did make what "may" have been, one mistake. He bought new name brand parts off ebay. Not to say also sellers on ebay, sell bootleg. As I once found a set of real Denso spark plugs there. But most, others and I found, have been bootleg.
So was the engine in badly in need of turn up with bad MAF, which caused first CAT failure. Or has cause yet, to be found, and now a repeat?
Here's what I'd do today, if in my shop.
- I study history (even deeper than you have). i.e. Toyota service history, car fax, PO statement and work order receipt. May even, cal some shops and parts departments. To further drill down.
- Drive while monitoring & logging data. ECT, IAT, AT temps, FT, CAT, MAF, RPM, MPH.
- Check for misfires, with tech stream.
- Pull engine cover and look for vacuum leaks. Correct any.
- Check, air pipe fender to T-body for obstructions and condition of t-body (CLN).
- Pull spark plugs and run compression test, while engine hot.
- Borescope cylinders, also looking for time-sert.
- Borescope S.A.I. pump, checking its filter.
- I may run fuel pressure test.
- I'd have 8 spark plugs & coils and one MAF standing-by. Depending on results of above. I'd replace all, except possible spark plugs since they came Toyota.
- Correct exhaust leaks.
Get out on HWY and run the piss out of it. I may put some Cataclean, Sledgehammer or paint thinner in gas, for a HWY run.
Also worth note: Prolonged idling is warned against in OM, as can damage CATS.
I also find lots cold starts with very short drives, without getting on HWY. Very hard on CATS, A/F and O2's. A sign of this, are holes in muffler. Difficulty to read those tea leaves. As age, miles and region diven in, also take a toll on muffler.
I'm thinking, CAt failure cause never found, also:
Coils are bootlegs, result in misfire.
We don't want to chance, a junk bootleg MAF.
Spark Plugs walked out, then replace. We want to make sure, no Time-sert or helicoils in heads and plugs tight.
S.A.I. filter are failing around 150K to 200K miles. Where driven, plays a big roll. At at when filter fails. This could yield, one more clue in the puzzle
We also need to make sure compression not compromised. We can have some loss, but below minimums or to wide spread between cylinder. Can result in fuel mixture issues. As can a wonky fuel pump, which 06-07 have a known bad one. Very hard to detect in the shop with test. It reveals itself, on hot summer days.
I really appreciate the detailed responses. FYI, the 5 min recording I took showed 6 of the 8 cylinders misfiring. The only cylinders that did not show a misfire was cylinder 1 and cylinder 6. 5 was by far the worst during the 5 min recording. The owner @Operationlc100 is a really nice guy and IMO really dedicated to correcting the issues. We talked after I had crawled under it and located the leaks and we both agreed that whatever you suggested should be his course of action moving forward.
I agree with the leaks not causing the 420/430. My 2001 had bad leaks on both manifolds and did not show 420/430. No codes at all actually. I also agree with purchasing Denso coils. I even have a couple old Toyota coils that were removed due them having splits in the shaft but were working perfectly if he wants to borrow some for testing.
According to owner the MAF sensor was purchased at NAPA. However the coils were purchased off of Ebay.
One other thing I noticed that was strange. Upper radiator hose (not OEM) was really bloated. Owner stated that it was only a year old.
I am going to step away from this thread and let the owner chime in from here on. If he needs to hook it up to my computer again I will gladly help. Thanks again!
- Thread starter
- #20
I'll push back a bit on exhaust leak. They need correcting. Factory Manual even states, can damage CATS. But I've seen many. Some very bad exhaust leaks go on for years, even ~100K miles. Fact is, a very high percentage of 4.7L 2UZ had/have crack exhaust manifold. Which is a pre CAT exhaust leak. That said. I've yet to see a CAT fail, on one with exhaust leak.
Going back over this thread. You noted misfire cylinder 6 & 8. Tech stream data show #3 misfire. We now know ebay NGK coils. Which I see intermittent misfires, often never set of a DTC. From weak or junky coils. It appears, the coils, spark plugs and MAF replaced, were in response to the P0430/P0420. Which were pre "known", exhaust leak.
Factory coils last a long time, even a milions miles or more. Unless subjected to excessive heat.
Spark plugs at ~180k miles, if first time replace. Would have walked out considerable. The hot combustion gases escaping past spark plug threads, cook the coils. Additional the spark plugs gaps may have been nearing or greater than max spec of 1.2mm.
Either or combination result in excessively hot coils.
Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!
TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...
Also worth note is misfires and tech stream. We have a glitch, that hides them.
I'm seeing a lot of same history, as I did on my test 4.7L VVti. The one I bought with these symptoms and P0420 & P0430. Just so I could work to find why the VVTi CATs failing, being replaced and failing again. For one. Both had CAT DTC, before and known work on or reported exhaust leaks. Other than cracked exhaust manifold leaks. We don't see exhaust leaks on factory installed CATs, A/F or O2.
PO/mechican did what they should, in looking for and correct upstream issues, that result in CAT failure. We saw this time and time again with in 4.7l VVTi. But PO may have just been shooting for cause, not replace parts found as cause of issue. Also. PO did make what "may" have been, one mistake. He bought new name brand parts off ebay. Not to say also sellers on ebay, sell bootleg. As I once found a set of real Denso spark plugs there. But most, others and I found, have been bootleg.
So was the engine in badly in need of turn up with bad MAF, which caused first CAT failure. Or has cause yet, to be found, and now a repeat?
Here's what I'd do today, if in my shop.
- I study history (even deeper than you have). i.e. Toyota service history, car fax, PO statement and work order receipt. May even, cal some shops and parts departments. To further drill down.
- Drive while monitoring & logging data. ECT, IAT, AT temps, FT, CAT, MAF, RPM, MPH.
- Check for misfires, with tech stream.
- Pull engine cover and look for vacuum leaks. Correct any.
- Check, air pipe fender to T-body for obstructions and condition of t-body (CLN).
- Pull spark plugs and run compression test, while engine hot.
- Borescope cylinders, also looking for time-sert.
- Borescope S.A.I. pump, checking its filter.
- I may run fuel pressure test.
- I'd have 8 spark plugs & coils and one MAF standing-by. Depending on results of above. I'd replace all, except possible spark plugs since they came Toyota.
- Correct exhaust leaks.
Get out on HWY and run the piss out of it. I may put some Cataclean, Sledgehammer or paint thinner in gas, for a HWY run.
Also worth note: Prolonged idling is warned against in OM, as can damage CATS.
I also find lots cold starts with very short drives, without getting on HWY. Very hard on CATS, A/F and O2's. A sign of this, are holes in muffler. Difficulty to read those tea leaves. As age, miles and region diven in, also take a toll on muffler.
I'm thinking, CAt failure cause never found, also:
Coils are bootlegs, result in misfire.
We don't want to chance, a junk bootleg MAF.
Spark Plugs walked out, then replace. We want to make sure, no Time-sert or helicoils in heads and plugs tight.
S.A.I. filter are failing around 150K to 200K miles. Where driven, plays a big roll. At at when filter fails. This could yield, one more clue in the puzzle
We also need to make sure compression not compromised. We can have some loss, but below minimums or to wide spread between cylinder. Can result in fuel mixture issues. As can a wonky fuel pump, which 06-07 have a known bad one. Very hard to detect in the shop with test. It reveals itself, on hot summer days.
Hi. First thank you to both of you. It's a lot to take in.
1. In following your steps starting with number 2 does it need to be techstream or could I use my autel scanner?
2. Could I buy cheap coils as temporary fix to see if it fixes the misfires?
3. Pretty confident I've fixed all vacuum leaks. I've replaced almost all hoses.
4. I've lost confidence in my dealership so is a. Compression test something I can do at home? Same with the borescope?
5 how can I check fuel pump to confirm/ eliminate it as issue? I saw where you said it can be wonky.
6. On the sai if it's the issue how do you feel about the blockout plate fix? I'm almost 5k into this fix and I don't have much room left to wiggle.
Once again thank you. I can't thank you enough.i assumed this was an easier issue to resolve and the dealership would be able to handle it. That was the beginning of my demise lol.
