Help! - Rough Idle - LC100 Trouble codes P0300 + P0301-P0308...

[Rick Kane]

Looking for some assistance from the group! After recently fighting with my failing SAI system (installing all new, OEM parts including manifold gaskets, etc.) but failing to resolve those error codes I finally had to throw in the towel and go the bypass route.

Things went well for several months until recently, when I had to accelerate hard to merge onto the highway. Immediately thereafter I was greeted with the MIL and the VSC and TRAC OFF lights brightening my dash yet again.

Checking with the scanner shows a new set of error codes - P0300 (Random/Multiple Cylinder Misfire Detected) and P301 through P308 (Cylinder 1 Misfire Detected through Cylinder 8 Misfire Detected). Yes, ALL of them.

I subsequently pulled and cleaned my MAF sensor and cleared the error codes but they have returned. A new OEM air filter was installed with the SAI bypass project.

True to the error codes, the engine is idling very roughly, with the RPM initially bouncing pretty heavily (see video). A minute of so later the engine calms town to about 1K RPMs and then 700 RPMs or so, but the engine still accelerates roughly.

Anybody have an idea as to what might be going on?

LC100 Probs...

 

[Trunk Monkey]

Sounds like a coil pack, just figuring out which one.

 

[waitdrew]

Looking for some assistance from the group! After recently fighting with my failing SAI system (installing all new, OEM parts including manifold gaskets, etc.) but failing to resolve those error codes I finally had to throw in the towel and go the bypass route.

Things went well for several months until recently, when I had to accelerate hard to merge onto the highway. Immediately thereafter I was greeted with the MIL and the VSC and TRAC OFF lights brightening my dash yet again.

Checking with the scanner shows a new set of error codes - P0300 (Random/Multiple Cylinder Misfire Detected) and P301 through P308 (Cylinder 1 Misfire Detected through Cylinder 8 Misfire Detected). Yes, ALL of them.

I subsequently pulled and cleaned my MAF sensor and cleared the error codes but they have returned. A new OEM air filter was installed with the SAI bypass project.

True to the error codes, the engine is idling very roughly, with the RPM initially bouncing pretty heavily (see video). A minute of so later the engine calms town to about 1K RPMs and then 700 RPMs or so, but the engine still accelerates roughly.

Anybody have an idea as to what might be going on?

LC100 Probs...

I’ve got an 07… I was changing lanes and punched it… then the VSC lights came on. I’m not getting a rough idle. But I’m noticing some alternator issues maybe. Lights get brighter when I hit the gas, etc… gauge is sitting right at 14v. I haven’t checked the codes yet. I’ll keep posting as I get more details but would like to know more.

 

[Rick Kane]

Sounds like a coil pack, just figuring out which one.

Thanks Trunk Monkey. What made me think that it likely wasn't a single bad coil pack was that I'm getting "Cylinder Misfire Detected" error codes for all 8 cylinders (P0301 through P0308). The fact that the problem started right after I gunned the engine makes me think something broke, got clogged/dirty, or popped off. I can't find any broken or disconnected vac lines. Stumped for now.

 

[2001LC]

Not all 8 COP (coil on plug, AKA coils), as wouldn't have all 8 suddenly fail.
More likely crank sensor or it's wire.
Since you've installed a SAI bypass, I'll be of no further help. Sorry!

 

[Rick Kane]

Not all 8 COP, as wouldn't have all 8 suddenly fail.
More likely crank sensor or it's wire.
Since you've installed a SAI bypass, I'll be of no further help. Sorry!

Thanks 2001LC, really appreciate you chiming in! Wish I could have stayed SAI "faithful," but I ran out of time. Maybe I can play with it again now - I've got so many new OEM SAI parts in there now anyway!

 

[vipergrhd]

You didn't mention if you have replaced COP and sparkplugs, SAI should not cause a misfire but my experience with that system is minimal, it could derate the engine if the SAI is not repaired or corrected. Stretched timing belt could cause timing issues specially if tensioner is collapsing under load. I have over 320K on my 2UZ and cam and crank sensor is still original a good scope could check the sensors if they are going out.

 

[2001LC]

Thanks 2001LC, really appreciate you chiming in! Wish I could have stayed SAI "faithful," but I ran out of time. Maybe I can play with it again now - I've got so many new OEM SAI parts in there now anyway!

As stated above. First place to look as at crank sensor and its wire.

Okay, since you contact me in a DM: "Hey Brother, I really appreciate your chiming in on the other thread. As you might have seen in my original postings on the "I know a lot of '06-'07 owners bypass the SAI system when it starts to go bad, I'm going to try to fix it" thread, I spent a heck of a lot of time (months) and money (well over $1,000) trying to fix this the proper route. More importantly, as I just noted in my reply on the other thread, I'm not opposed to going back in now to try to do this the right way, and not only because I've already invested a heck of a lot into it in time and money. Please understand that I had some serious time constraint issues to deal ( redacted *****************) that necessitated having a car that could be driven and not towed. Again, I appreciate your time and generosity with the SAI expertise."

But I'm a bit unclear. As the time to do a SAI filter MOD, was while intake off. It would have only add ~$100 and 1 hour while in there! If you spent over $1K and months. You must have replaced both the SAI Pump (Blower) and main switch. Which both are under the intake manifold. I give you the benefit of the doubt.

Let me ask. Was the SAI pump filter intact or was it gone?

Explain exactly, what was done for over a $1K and months to correct SAI DTC. Be detail and by whom worked perform?

"Things went well for several months until recently, when I had to accelerate hard to merge onto the highway. Immediately thereafter I was greeted with the MIL"
During hard acceleration. A few things happen. First G force moves components around, that are not firmly attached as designed to be.
A loose part like: wire housing block, damaged wire, lose vacuum lines, fuel pump not properly assemble/secured all move around.
It also loads the timing belt and it's components.

When was Time belt done and by whom?

Post a picture of the front LH of engine. So we can look at the wire routing.
Like this:

Some pictures of the top of engine on each side?

What else was done/service on engine and or fuel pump?

Did the SAI block off kit installed. Have any component's wired in. Like, to the MAF?

Was/Is coolant level (Look in radiator) low and did engine overheat?

Any sign of rodent in area or chew?

Any aftermarket toys wired in?

Any water entry into cabin?

Windshield factory install or a replacement?

Read the attached pdf. See is a "bells ring" in your head?

 

[2001LC]

BTW: About the only way all 8 Coils (PO301 thur 308) go bad at same time. Is if they'd been replaced with bootleg china junk.

 

[Rick Kane]

LC100 has been sitting while I search for a solution...

--

2001LC, I'm leaving your questions in in an attempt to make this easier to read:

Let me ask. Was the SAI pump filter intact or was it gone?

- SAI pump filter was entirely GONE.

Explain exactly, what was done for over a $1K and months to correct SAI DTC. Be detail and by whom worked perform?

- Work done by yours truly between January and June 2024 (see next).

- The following were replaced with all new Toyota OEM parts:

• Fuel Cap (77300-06040)
• Valve Assy, Air Switching, No.2 (25720-50020)
• Secondary Air Injection Pump Check Valve (25720-50011)
• Hose Assy, Air (17030-50070)
• Gasket, Air Tube, No.2 (x4) (17377-50010)
• Intake Manifold Gasket (x2) (17171-50030)
• Air Pump Assembly with Bracket (17600-0F010)
• Air Switching Valve Assembly (25710-50022)
• Air Hose #2 (17342-50180)
• Air Hose #1 (17341-50180)
• Vacuum Switching Valve Hose Assembly (17340-50030)
• Dust Starter Protector (28199-50040)
• Female Connector for Air Switching Valve (90980-10845)
• Air filter (17801-50040)
• Air Injection Control Driver (89581-34041)
• (Heater Ts and all related hoses also replaced while Intake Manifold off and access was easier.)
• PCV Valve (12204-50030)
• PCV Valve Ventilation Hose

"Things went well for several months until recently, when I had to accelerate hard to merge onto the highway. Immediately thereafter I was greeted with the MIL"
During hard acceleration. A few things happen. First G force moves components around, that are not firmly attached as designed to be.
A loose part like: wire housing block, damaged wire, lose vacuum lines, fuel pump not properly assemble/secured all move around.
It also loads the timing belt and it's components.

When was Time belt done and by whom?

- Alternator and "Serpentine Belt" replaced by “professional” auto shop in December 2017, which is probably when the crank sensor wire got routed wrong…see next.)

- Post a picture of the front LH of engine. So we can look at the wire routing.

- Wiring for crank sensor and oil sending unit wire housing DOES appear to have been routed wrong by someone, probably after earlier repair job. I don’t see wear on it, and I also don’t seem to be able to put it up and through to route it properly, as there appears to be another, flatter, wire split that branches off near the COP connector and current runs underneath the alternator. Very difficult to access this area with everything in place.

- Some pics of the current crank sensor after removal:

Some pictures of the top of engine on each side?

LEFT/Driver Side ((I replaced COP 4 with Denso when it failed back in 2020. I note now that the others don’t have labeling, which makes me wonder if they are generic, and have been since I bought this car. Still, would it make sense that all ignition coils, including #4, would fail at the exact same time? (As noted earlier, in addition to P0300, I’m getting failure codes for ALL of them individually too - P0301 through P0308). All spark plugs were replaced with Denso back in 2020 too.):

RIGHT/Passenger Side:

What else was done/service on engine and or fuel pump?

- Nothing else in the last several years.

Did the SAI block off kit installed. Have any component's wired in. Like, to the MAF?

- Yes, MAF is wired in. I’ve also cleaned MAF with MAF sensor cleaner.

Was/Is coolant level (Look in radiator) low and did engine overheat?

- No, coolant level is good, and engine did not overheat.

Any sign of rodent in area or chew?

- No, none.

Any aftermarket toys wired in?

- No, other than SAI bypass.

Any water entry into cabin?

- No.

Windshield factory install or a replacement?

- Factory install.

Read the attached pdf. See is a "bells ring" in your head?

- Regarding the attachment, I’d say “rough idling” and “hesitation” apply.

Thanks much.

As stated above. First place to look as at crank sensor and its wire.

Okay, since you contact me in a DM: "Hey Brother, I really appreciate your chiming in on the other thread. As you might have seen in my original postings on the "I know a lot of '06-'07 owners bypass the SAI system when it starts to go bad, I'm going to try to fix it" thread, I spent a heck of a lot of time (months) and money (well over $1,000) trying to fix this the proper route. More importantly, as I just noted in my reply on the other thread, I'm not opposed to going back in now to try to do this the right way, and not only because I've already invested a heck of a lot into it in time and money. Please understand that I had some serious time constraint issues to deal ( redacted *****************) that necessitated having a car that could be driven and not towed. Again, I appreciate your time and generosity with the SAI expertise."

But I'm a bit unclear. As the time to do a SAI filter MOD, was while intake off. It would have only add ~$100 and 1 hour while in there! If you spent over $1K and months. You must have replaced both the SAI Pump (Blower) and main switch. Which both are under the intake manifold. I give you the benefit of the doubt.

Let me ask. Was the SAI pump filter intact or was it gone?

Explain exactly, what was done for over a $1K and months to correct SAI DTC. Be detail and by whom worked perform?

"Things went well for several months until recently, when I had to accelerate hard to merge onto the highway. Immediately thereafter I was greeted with the MIL"
During hard acceleration. A few things happen. First G force moves components around, that are not firmly attached as designed to be.
A loose part like: wire housing block, damaged wire, lose vacuum lines, fuel pump not properly assemble/secured all move around.
It also loads the timing belt and it's components.

When was Time belt done and by whom?

Post a picture of the front LH of engine. So we can look at the wire routing.
Like this:
View attachment 3708862View attachment 3708863

Some pictures of the top of engine on each side?

What else was done/service on engine and or fuel pump?

Did the SAI block off kit installed. Have any component's wired in. Like, to the MAF?

Was/Is coolant level (Look in radiator) low and did engine overheat?

Any sign of rodent in area or chew?

Any aftermarket toys wired in?

Any water entry into cabin?

Windshield factory install or a replacement?

Read the attached pdf. See is a "bells ring" in your head?

 

[2001LC]

LC100 has been sitting while I search for a solution...

--

2001LC, I'm leaving your questions in in an attempt to make this easier to read:

Let me ask. Was the SAI pump filter intact or was it gone?

- SAI pump filter was entirely GONE. Depending on how long SAI filter was gone (unknown assume long time) and what were driving condition (ie dusty or not) during that period of time/miles. I may do a compression test. But I'd first move coils (COP) from cylinders showing a DTC and swap with ones not. I'd check those spark plugs of cylinder with DTC while swapping also.

Explain exactly, what was done for over a $1K and months to correct SAI DTC. Be detail and by whom worked perform?

- Work done by yours truly between January and June 2024 (see next). Was all dust and sand cleaned from top of engine (intake manifold, heads, hoses, Sw and wires) before removing intake manifold. Were heads intake ports plugged/covered, to keep debris out, while intake manifold off. Were intake ports inspect for any debris and debris (sand, etc.) removed, prior to installing intake manifold. I ask, because I've seen more than one engine's compression damaged, due to sand falling in intake ports!

- The following were replaced with all new Toyota OEM parts:

• Fuel Cap (77300-06040)
• Valve Assy, Air Switching, No.2 (25720-50020)
• Secondary Air Injection Pump Check Valve (25720-50011)
• Hose Assy, Air (17030-50070)
• Gasket, Air Tube, No.2 (x4) (17377-50010)
• Intake Manifold Gasket (x2) (17171-50030)
• Air Pump Assembly with Bracket (17600-0F010)
• Air Switching Valve Assembly (25710-50022)
• Air Hose #2 (17342-50180)
• Air Hose #1 (17341-50180)
• Vacuum Switching Valve Hose Assembly (17340-50030)
• Dust Starter Protector (28199-50040)
• Female Connector for Air Switching Valve (90980-10845)
• Air filter (17801-50040)
• Air Injection Control Driver (89581-34041)
• (Heater Ts and all related hoses also replaced while Intake Manifold off and access was easier.)
• PCV Valve (12204-50030)
• PCV Valve Ventilation Hose

"Things went well for several months until recently, when I had to accelerate hard to merge onto the highway. Immediately thereafter I was greeted with the MIL"
During hard acceleration. A few things happen. First G force moves components around, that are not firmly attached as designed to be.
A loose part like: wire housing block, damaged wire, lose vacuum lines, fuel pump not properly assemble/secured all move around.
It also loads the timing belt and it's components.

When was Time belt done and by whom?

- Alternator and "Serpentine Belt" replaced by “professional” auto shop in December 2017, which is probably when the crank sensor wire got routed wrong…see next.) Crank sensor & oil sending unit wires. Are not touched, during Alt & serp belt service. These wire should be routed, behind fan bracket. Fan bracket is removed to replace it or during Timing belt service. Your wires are routed wrong. Wires seem to be, tuck-in away from belt or pulleys rubbing. I can't see any rub marks. So this not likely and issues at this time. You may want to strap wires in place, so they stay put, until day FB off. Where it is possible, to reroute correctly, with FB in place. But it's a PITA and they'll be fine, provided they don't rub.

- Post a picture of the front LH of engine. So we can look at the wire routing.

View attachment 3735942

- Wiring for crank sensor and oil sending unit wire housing DOES appear to have been routed wrong by someone, probably after earlier repair job. I don’t see wear on it, and I also don’t seem to be able to put it up and through to route it properly, as there appears to be another, flatter, wire split that branches off near the COP connector and current runs underneath the alternator. Very difficult to access this area with everything in place.

- Some pics of the current crank sensor after removal:

View attachment 3735944
View attachment 3735976

Some pictures of the top of engine on each side?

LEFT/Driver Side ((I replaced COP 4 with Denso when it failed back in 2020. I note now that the others don’t have labeling, which makes me wonder if they are generic, and have been since I bought this car. Still, would it make sense that all ignition coils, including #4, would fail at the exact same time? (As noted earlier, in addition to P0300, I’m getting failure codes for ALL of them individually too - P0301 through P0308). All spark plugs were replaced with Denso back in 2020 too.):

View attachment 3735946

RIGHT/Passenger Side:

View attachment 3735974


What else was done/service on engine and or fuel pump?

- Nothing else in the last several years.

Did the SAI block off kit installed. Have any component's wired in. Like, to the MAF?

- Yes, MAF is wired in. I’ve also cleaned MAF with MAF sensor cleaner. I've seen more than one now, with these S.A.I. Block off kits wired into MAF. That have damaged the MAF and or resulting in fuel mixture problems. Since you've replaced all the S.A.I. components, you have no need for this wired into MAF. I would get rid of it and replace the MAF with new OEM (disconnect battery (negative post) while doing so). Taking system back to factory stock. I'll also note: it is against federal law, to drive this vehicle on public roads, streets or HWY with S.A.I. disabled or any modification to pollution controls or equipment. Unless it improves (reduces pollution) or vehicle is strictly off road recreational use.

Was/Is coolant level (Look in radiator) low and did engine overheat?

- No, coolant level is good, and engine did not overheat.

Any sign of rodent in area or chew?

- No, none.

Any aftermarket toys wired in?

- No, other than SAI bypass.

Any water entry into cabin?

- No.

Windshield factory install or a replacement?

- Factory install.

Read the attached pdf. See is a "bells ring" in your head?

- Regarding the attachment, I’d say “rough idling” and “hesitation” apply.

Thanks much.

Open above, to see green lettered replies/notes.

Cylinder order.
BanK1: 1,3,5,7. That is from front of engine near radiator & battery to back of engine (Bk1, is left side of engine. Our left as we sit in driver seat. Or to say driver side, in left hand drive.

BK2: 2,4,6, 8.


With a P0301 & P0308 code, which is a fault (DTC) in cyl 1 & cyl 8. I'd remove the number 1 cylinder COP (AKA coil, AKA: coil on plug) Which is first COP on driver side at front of engine (nearest radiator & battery). Then swap with the next one (cylinder 3). Make sure to check spark plugs while COPs out. Also while there, check that fuel inject wire blocks, are connected (firmly pressed in until clicks).

Clear codes (DTC) and see if P0301 now moved to P0303.

You can do the same for COP cylinder 8 (PO308). Swap it with COP from cylinder #2 (first first BK2) or any you find easy to get to and swap. See if DTC move from P0308 to P0302 (or whichever cylinder you swap from).

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