Cylinder 1&3 Misfire - Coil packs replaced still CEL (1 Viewer)

[bajaphile]

Waiting to clean MAF and TB... However same codes came back... P0300, P0303, P0305... I'm very confused.

Spark plugs are new, swapped coils, etc. Old plugs looked used but not bad.

Also, the long term fuel trim is now reading +2.5 and +1 ... I think it was still too early to read fuel trims after I pulled the battery terminals off.

 

[Spike555]

You need to drive it for a few hundred miles after clearing the check engine light so the ECU and re-map to you and your engine, otherwise it's running the default "one size fits all" computer mapping.
Which might mean to rich of a fuel mixture for your plugs and wires, air filter, etc.

 

[bajaphile]

This weekend I cleaned the MAF with CRC MAF cleaner, and took some time and really cleaned the throttle body. TB wasn't that dirty really, and the MAF, well, the little wires in there didn't look black or dirty, but cleaned up everything anyways.

Decided to just clear the ECU again, start fresh. 2 days later, same misfire codes are back!

Started reading my OBD2 scanner manual, going to try and see if I can get any information from the freeze frame data.

Next ideas:
1) Compression test / Leak Down Test
2) Fuel pressure
3) Injector swap

Looks like removing the injectors aren't too bad, or am I wrong? I still am having a difficult time feeling a misfire. The idle is smooth in my opinion but maybe not as smooth as it should be.

 

[Spike555]

How far have you driven it?
I'd put at least 500 miles on it.
Have you tried changing brands of gas?
What grade of gas are you using?

 

[bajaphile]

Since the last reset, my wife has driven it 2hrs (says my OBD scanner) and approx 75 miles. I've checked the readiness of the systems and all are checked as "ready". The CEL just came on recently after several driving cycles.

Gas she uses is 91, even though I've read you can use 87. Probably a mix of Shell and Mobil.

 

[Spike555]

Ok. Just checking.
I'd still put more miles on it before doing anything else.
I feel your pain, nothing worse than chasing rabbits through the briars.

 

[bajaphile]

I've been researching this issue all over google for weeks now.

I'm trying to determine what could cause a misfire code without throwing another code. It is almost like the failing part isn't completely failing, and the ECM isn't realizing it is failing. I'm thinking those parts could be
- Injector
- A/F Sensor (Upstream O2 sensor) (Need to check if PO put a Bosch in or something).


I spent about 4 hours searching for my leak down manifold and couldn't find it, and my compression tester gauge is broken, so I have to go rent something I guess. I'm wondering if a valve issue, but I sure haven't seen much online about this type of issue.

 

[Julian Stead]

What are your fuel trims reading now?

 

[Julian Stead]

If it is still negative then you have a spark, it would read a positive number otherwise as you would have to much oxygen going to the 02 sensor. Swap the front 02 sensors over and check your air filter is clean as a start, then check for any air restrictions, intake or exhaust, see if you have damaged your exhaust anywhere. Then you do need a compression test if nothing is jumping out at you, then check fuel pressures and have your injectors checked.

 

[bajaphile]

Here's the latest...
Numbers don't look too bad, however I checked my dad's Tundra and his long term trims were both at 0.0.
Checked the upstream O2 sensors and they both have Toyota stamped on them and look great from the outside. Hmm.

Just to be on the same page...bank 1 is drivers side?

 

[Julian Stead]

Nothing alarming there, they are within tolerance, not as good as 0 but still ok.

 

[bajaphile]

Since I don't have time to work on my trucks until the weekends, I've still been reading through the FSM and googling issues on the 2UZ-FE.

The fact that the misfire is on 2 adjacent cylinders on the same "bank", has now brought me to the possibility that the timing belt jumping a tooth on the drivers side (LHS) cam gear.

After reading some threads, it appears that the timing belt jumping often happens shortly after replacement without replacement of the tensioner. The PO paid his "mechanic friend" to replace the belt shortly before I bought the truck. I'm assuming they didn't replace the tensioner and it may have allowed the belt to jump.

I'm planning on removing the LHS cam gear cover and checking. To remove this, do I need to remove the serpentine belt to gain access?

 

[bajaphile]

Tomorrow I am planning on checking to see if the belt indeed skipped a tooth. The idle is definitely rough... but still drives fine.

Can I remove the timing belt / cam cover #3 (drivers side) without removing anything else? (I guess I can just dive in and find out myself)

Can I check/change the tensioner by just removing the skid plate, or do I need to remove more things to gain access?

 

[bajaphile]

Well this weekend I was able to remove the timing covers on the LH/RH cams. The timing was dead on with the crank. No jumped teeth.

Using my OBD2 reader, I verified that the ECT and MAF were functioning correctly.

Kept going down the list in the FSM, and tested voltages at ECM (per ES-187). All read consistently at the supplied battery voltage.

While the engine was idling, I pulled the #3 injector harness and would hear a miss. Pulled #3 coil connector, and it would miss. Did the same for #5 injector and coil. Each one gave me a true miss, so that makes me think they are at least functioning somewhat correctly.

Inspected my AF sensors, they appear to be original Toyota/Denso. Are these known to fail after a certain time period? I'm going to try to find something in the FSM to test them, but I'm assuming it will be oscilloscope required.

Next up is compression test (been saying that for a while). Maybe weak valve springs. Other thoughts are:

1) Faulty/dirty injector
2) AF sensor not working correctly
3) Cam or crank position sensor?

I've been researching non-stop and I'm almost about to take it to a mechanic. I'm 35 and have yet to take any vehicle to the mechanic in my LIFE and I'm trying to keep that trend going, but wow, I'm stumped!! Does anyone have a DLC3 tool??? Are they worth it? I'm almost thinking about buying one.

 

[Spike555]

Like I said in the very beginning, dirty injectors, you need to drive it for awhile with good Top Tier fuel to clean them out.
You're chasing rainbows and unicorn farts.

 

[bajaphile]

Like I said in the very beginning, dirty injectors, you need to drive it for awhile with good Top Tier fuel to clean them out.
You're chasing rainbows and unicorn farts.

Well our nearest and most used gas station is a Shell, which is in my opinion the highest quality here. I guess I can try some injector cleaner. I'm still not fully sold on that being the issue. I'm still having a hard time understanding why it would be on 2 cylinders.

 

[2001LC]

I'm sorry if this has been done and covered in thread.

Consider taking to Dealer and paying to have diagnostic. Meet with the mechanic as he does job. The masters have seen it all, they can spot stuff we'll miss.

Here a few more thoughts:

When getting codes on specific cylinders I look at all their workings i.e. , spark plugs, coils, fuel injectors & valve gap adjustment. Valve gap issue would be rare but not unheard of. Wires going to injectors & coils must also be tested.

Disconnecting battery for 30 minutes a good idea during any tune up, but normal not associate with specific cylinder codes. I hope that works.

Be careful not to get solvent where axle of butterfly goes into throttle body walls. Cleaner gets into inner workings, some have reported issue after this done.

I use 44k in the gas tank or simular. There are a number of different products that work well to clean fuel system & heads.

Sound is test for valve adjustment, takes a keen ear to hear them. I use a stethoscope. Again Master mechanic knows proper sounds.

I don't recall did you swap coils to see if issue moved! If not do before anything else. You can do same with spark plugs and fuel injectors.

These may not be your issue but worth it anyway:

I'm finding off vehicle fuel injector service a worthwhile endeavor. When to replace fuel injectors I use FIS in Denver. Inspecting and replacing vacuum lines while waiting on injector to come back is a very nice touch and a must. Look at all ends of lines, replace any that show cracks or have harden when squeezed. Start out with a compression check as you begin disassemble, make sure to inspect each spark plug. I like to line up spark plugs in order they came out. If any coils show signs of heat (running hot) consider replacing.

One more area @spressomon bought to my attention while working on getting his rig ready for sale For Sale - 1999 spressoWAGON UZJ100-Series Very Custom Build is the fuel pressure regulator. This is normally associated with varying MPG, again just worthwhile at your mileage.

I don't recall, is your engine a VVti. I'm seeing all (two out of two this year) intake manifold gasket leak on them. As I look through picture of VVti engine, I can see 2 out of 3 leaking. Even if is not a VVti check your gasket. Oil will be coming up side of intake plumes "a capillary action" from gasket, use a mirror to see underside also if going up & down from gasket. It's usually looks like gunk as dust is attracted to oil.

Depending on which engine you have you'll also have some vacuum diaphragm to test. Additionally the VVti has a row of butterfly's running along top inside of intake manifold. Look inside to see if and issue with them.

Once you've totally gone through air and fuel, spark if still present would leave electrical issue.

I don't usually just through parts at problem in hopes. But these things above I'm finding very worthwhile at 150K or more, especially on VVti engine.

If you look through my thread in signature you'll see much of this and how to. Good luck!

 

[Julian Stead]

Compression Test, you need to just prove either way if your engine is good or bad on these cylinders. A poor timing belt job can cause damage, it might of been corrected but the damage is still there. I don't think the fault is going to jump out at you, it might even be intermittent and you never get to see it happen, you just need to carry out tests and confirm they are good and move on. Saying your 02 sensors look good isn't really a test. Even getting techstream will help you more than your handheld scanner as it has more options available.

Agree with above, it can be more economical to take it to the dealership just for diagnosis. I used to repair cars with these faults at a dealership and most of the time you have good idea just from the job card what is wrong as you know the product so well, also all tests are carried out in a fraction of the time as all test equipment is to hand and it fits properly. A vacuum gauge was my favourite tool on petrol engines, also a cylinder leakage tester is handy, a oscilloscope is very good, fuel pressure gauge, just joe bloggs doesn't normally have them.

When does the light come on, instantly after you clear the codes, after driving x amount of miles, just after it warms up, when cold or just plain randomly. Just to know whether the engine is hot or cold or both helps a lot as some sensors are ignored when the vehicle is open loop.

 

[2001LC]

As usual @Julian Stead you bring good points to the table. Some of the tools you mentioned are on my wish list!

BTW @bajaphile it is very easy to pull and inspect the timing belt tensioner.

 

[Julian Stead]

Your on the right lines with your thoughts, just your testing ability or lack of test equipment is the thing that is stopping you going any further. If you suspect injectors, you test to confirm nothing else is giving you an issue, then either replace or have them tested, this how a dealer works, you sometimes need to spend money to rule things out. Swap your 02 sensors from one bank to another, it is free and is a lot more accurate than how much chrome is left on them. Swap your injectors around, again free, swap all of your coil packs around. Check fuel quality, take a sample in a jar. But all of this after a compression test, all of the cylinders, check all of the burn on every plug. Ignore cylinders 3 and 5 as your only fault as it could be a red herring or how your fault reader interprets your cylinder numbers, just test every cylinder the same.