98' 4runner timing issue

[sean.turner.1238]

I did head gaskets a bit ago and had symptoms very similar to yours. I had backfiring out the intake and it sounded like wrong timing. Try switching the front-most and middle coil pack plugs. The lengths of the wires are opposite of what you think they'd be logically, so it's easy to mix them up. If you have those mixed up, you'll have 4 plugs firing incorrectly.

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[Skulking]

I did head gaskets a bit ago and had symptoms very similar to yours. I had backfiring out the intake and it sounded like wrong timing. Try switching the front-most and middle coil pack plugs. The lengths of the wires are opposite of what you think they'd be logically, so it's easy to mix them up. If you have those mixed up, you'll have 4 plugs firing incorrectly.

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Just for reference in case the OP wants to check coil packs and spark plug wires.

 

[TravThePro]

I guess I can rule that out. It's on point every rotation

I might just be seeing some picture distortion with this crank timing gear, but it looks like one of the gear's teeth might be damaged. We chipped one of these teeth on the first engine build we did and the vehicle refused to run with several backfires taking place.

Turn it over and check the gear over 360 degrees to make sure it is absolutely flawless. I attached a picture from google because my build pictures are on an old phone.

If that all checks out with you having spark and fuel getting to the vehicle, constant backward blowby in the intake could suggest that your new head's valves are not sealing properly. Do a compression test in all of the cylinders just to help eliminate that possibility.

The last thing I could think of would be to get someone with an advanced scan tool that will show all sensors communicating with the ECU. If you see discrepancies with the frequencies/data or even a complete flatline, you know there is an issue.

Best of luck, you're welcome to PM me with any additional questions on this.

 

[ectech]

I have 180 across all cylinders in the compression test. I'm not getting backfire through the intake, only the exhaust. It happens when I give it gas, let off the gas and it may backfire when getting back to idle. It's not every time and there's no consistency to it.

 

[gamefreakgc]

I might just be seeing some picture distortion with this crank timing gear, but it looks like one of the gear's teeth might be damaged. We chipped one of these teeth on the first engine build we did and the vehicle refused to run with several backfires taking place.

Turn it over and check the gear over 360 degrees to make sure it is absolutely flawless. I attached a picture from google because my build pictures are on an old phone.

If that all checks out with you having spark and fuel getting to the vehicle, constant backward blowby in the intake could suggest that your new head's valves are not sealing properly. Do a compression test in all of the cylinders just to help eliminate that possibility.

The last thing I could think of would be to get someone with an advanced scan tool that will show all sensors communicating with the ECU. If you see discrepancies with the frequencies/data or even a complete flatline, you know there is an issue.

Best of luck, you're welcome to PM me with any additional questions on this.

Oh my gosh, you are right. It looks like one or more of the teeth is sheared right off. I was concentrated on the timing marks so didn't see it.

If you can, remove the upper timing belt cover and shine a light down on the crank gear. Should be obvious if they are all there. Just slowly turn the engine over with a breaker bar to see all the teeth.

 

[TravThePro]

I can confirm that your top end timing is all on point (I can also guess that your bottom end mechanical timing is also correct if the vehicle runs and revs as you say)

Could you possibly record a video of this taking place? I can't promise I will be able to diagnose anything without having the vehicle and my diagnostic tools there, but I think people on this forum could point you in the right direction if we get a little more detailed information.

Seeing how rough it idles, how hard it backfires, how quickly it revs, etc would be extremely helpful to narrow down the potential issues.

If you don't have an OBD II scan tool that shows running vehicle sensor data, I would strongly suggest you started with that before you go and waste money on parts.

 

[ectech]

Oh my gosh, you are right. It looks like one or more of the teeth is sheared right off. I was concentrated on the timing marks so didn't see it.

If you can, remove the upper timing belt cover and shine a light down on the crank gear. Should be obvious if they are all there. Just slowly turn the engine over with a breaker bar to see all the teeth.

I've turned the engine over and over looking at those teeth until I felt crazy at one point of trying to troubleshoot this... It's distortion in the picture if anything

 

[ectech]

Could you possibly record a video of this taking place? I can't promise I will be able to diagnose anything without having the vehicle and my diagnostic tools there, but I think people on this forum could point you in the right direction if we get a little more detailed information.

Seeing how rough it idles, how hard it backfires, how quickly it revs, etc would be extremely helpful to narrow down the potential issues.

I'll get a video. I had recorded one the other day but due to the lack of low frequency picked up by the phone it sounded much different. The weather has been nasty. I have the exhaust disconnected at the manifold so it sounds like my neighbors Harley.��

If you don't have an OBD II scan tool that shows running vehicle sensor data, I would strongly suggest you started with that before you go and waste money on parts.

I have a Scangauge II so technically I can search for and find the xgauge commands online and get some readings from what I understand.
Do you have a particular one that you would recommend or suggest? I would possibly be willing to put a few hundred into one. I do all of my own mechanic work and have no issue with remove and install when I already know the solution but eager to learn more about diagnosing issues.

 

[ectech]

I have the intake off right now so that I could tie in the fuel pressure gauge. I had originally ordered fuel injectors that weren't going to get here in time and I planned to install later. They'll be in early next week so I might as well wait for them at this point.

I'm not sure if this is logical or not but I'm going to put this out there. I bought my knock sensors last minute at the auto part store instead of ordering OEM. I was thinking about putting the originals back before I put it together again Just to rule it out. If the knock sensors are sending incorrect information would it mess with the ignition timing?

 

[TravThePro]

I'm not sure if this is logical or not but I'm going to put this out there. I bought my knock sensors last minute at the auto part store instead of ordering OEM. I was thinking about putting the originals back before I put it together again Just to rule it out. If the knock sensors are sending incorrect information would it mess with the ignition timing?

I felt much better leaving 25-year-old, 325k mile and 22-year-old 200k mile knock sensors on the engine rebuilds than I did than putting auto parts store knock sensors on my rigs. If yours aren't extremely corroded and the vehicle did not have issues before the project, then I would bet that they are still fine now.

I think if they were having issues the vehicle would likely run slightly rich unless they were having full cuts periodically that could cause misfires. You would get a CEL extremely quickly if that was the case.

We still really don't have enough information to help with this issue. My next suggestion would be to carefully make sure that you have the correct wires going to the correct coil banks and fuel injectors. The plastic sections that act as an insulator for those areas cracked and broke into pieces to the point that I had to fix those portions of my harness. It is possible to swap those wires if that happened to you.

I can try talking to you through a voice app, but I likely won't have time until Sunday at the soonest.

 

[gamefreakgc]

I have the intake off right now so that I could tie in the fuel pressure gauge. I had originally ordered fuel injectors that weren't going to get here in time and I planned to install later. They'll be in early next week so I might as well wait for them at this point.

I'm not sure if this is logical or not but I'm going to put this out there. I bought my knock sensors last minute at the auto part store instead of ordering OEM. I was thinking about putting the originals back before I put it together again Just to rule it out. If the knock sensors are sending incorrect information would it mess with the ignition timing?

No, that wouldn't do it. I tried aftermarket knock sensors once that failed within weeks. They will throw the P0325 code but does not affect anything at idle or startup, the ECU just dials in maximum timing retard to protect the engine. It will still start just like normal, just be down on power.

 

[ectech]

Could you possibly record a video of this taking place? I can't promise I will be able to diagnose anything without having the vehicle and my diagnostic tools there, but I think people on this forum could point you in the right direction if we get a little more detailed information.

Seeing how rough it idles, how hard it backfires, how quickly it revs, etc would be extremely helpful to narrow down the potential issues.
.

4runner

Here is a video. In the video it sounds like a clacking noise but in person it's a lower frequency and it's from the exhaust. This is idling at 1200 rpms and If I put it in gear it kills.

 

[heat]

Sounds like an exhaust leak; shaking looks like a misfire.

 

[ectech]

Sounds like an exhaust leak; shaking looks like a misfire.

I have the exhaust removed after and the sound is exhaust blowing into the cat side of the exhaust.

What would be your explanation of the misfire with no cel?

 

[gamefreakgc]

It sure does look like either the timing is off or the spark plug wiring is all messed up. The rhythmic stumble sounds to me like it's firing wrong on every stroke.

 

[HiLife]

Ooo, that is rough. You plugs could be toast with soot from rough idling. What are your LTFT and STFT readings?
Have you tried troubleshooting with a vacuum gauge? It can be a great tool in seeing what the engine is doing while running rough. Could help with the direction onto where to look at.
The parts stores used to rent these but, I can't find the tool number now.

Edit: You can't get the ltft/stft readings if the engine hasn't fully warmed up and is in open loop.

 

[TravThePro]

4runner

Here is a video. In the video it sounds like a clacking noise but in person it's a lower frequency and it's from the exhaust. This is idling at 1200 rpms and If I put it in gear it kills.

It sure does look like either the timing is off or the spark plug wiring is all messed up. The rhythmic stumble sounds to me like it's firing wrong on every stroke.

It is a very rhythmic-sounding misfire. This suggests a major timing issue or 1-4 cylinders are misfiring. Even when enhancing the audio to the video the speed of the shaking and number of misses sounds more like it is specific to certain cylinders.

There are several ways to easily test if it is cylinder-specific or if it is something more major.

1) Get a laser temperature reader and test the heat at each of the bases of the exhaust manifold for every cylinder to see if there are any noticeable discrepencies between each cylinder (1-30 degrees is likely acceptable in this test) 50+ is a major misfire coming from that cylinder. I would strongly recommend this test if you can get your hands on one.

2) Pull fuel injector wires 1 at a time (plug them back in as you continue to test the other ones) If you pull one and the vehicle is running the exact same, you have an issue with that cylinder's spark/fuel.

3) pulling plug wires/plugs one at a time.


What worries me is that the thing is dying when you put it in gear. When I burnt up 4 spark plugs after unknowingly overheating the vehicle with dash issues, I was able to drive home up a fairly steep hill on 2 cylinders (Confirmed at home with laser temp reader).

Your 180 PSI in all cylinders made me want to think that timing wasn't the issue, but there is still a chance. Did you double check the timing after you put tension on the timing belt tensioner? I have had it be off time 1-3 teeth if I neglected to tension the belt as I set the timing.

Best of luck!

 

[ectech]

It is a very rhythmic-sounding misfire. This suggests a major timing issue or 1-4 cylinders are misfiring. Even when enhancing the audio to the video the speed of the shaking and number of misses sounds more like it is specific to certain cylinders.

There are several ways to easily test if it is cylinder-specific or if it is something more major.

1) Get a laser temperature reader and test the heat at each of the bases of the exhaust manifold for every cylinder to see if there are any noticeable discrepencies between each cylinder (1-30 degrees is likely acceptable in this test) 50+ is a major misfire coming from that cylinder. I would strongly recommend this test if you can get your hands on one.

2) Pull fuel injector wires 1 at a time (plug them back in as you continue to test the other ones) If you pull one and the vehicle is running the exact same, you have an issue with that cylinder's spark/fuel.

3) pulling plug wires/plugs one at a time.


What worries me is that the thing is dying when you put it in gear. When I burnt up 4 spark plugs after unknowingly overheating the vehicle with dash issues, I was able to drive home up a fairly steep hill on 2 cylinders (Confirmed at home with laser temp reader).

I'll get a laser temperature reader, give these things a try and post back.

Your 180 PSI in all cylinders made me want to think that timing wasn't the issue, but there is still a chance. Did you double check the timing after you put tension on the timing belt tensioner? I have had it be off time 1-3 teeth if I neglected to tension the belt as I set the timing.

Best of luck!

When I last confirmed my timing, I rotated the crank about 7 times to be positive that everything was lined correctly.

Thank you for your help.

 

[TravThePro]

I'll get a laser temperature reader, give these things a try and post back.


When I last confirmed my timing, I rotated the crank about 7 times to be positive that everything was lined correctly.

Thank you for your help.

Just as several other members have saved my bacon on this forum, I'll be glad to help you out where I can.

Hopefully this will help you to start narrowing a few possibilities. I was having serious issues with my ECU communicating with some of the sensors along with malfunctioning throttle body sensors when I put everything back together. My runner did not run (haha) until I unplugged the wiring harness from the ECU and put dialectic grease on all of my clips going to it. I also cleaned a few throttle body sensors to make it be able to idle on its own. My truck was sitting for roughly 4 years during all this restoration work, so I wouldn't be so apt to think you would have those same issues.

From everything I am seeing, you have the timing assembly set up correctly. Did you allow the tensioner to push the tensioner pulley tight before you went and torqued the tensioner pulley bolt? You would have wanted to do this with several rotations of the timing assembly before torquing that bolt down.

I found one of my pictures of the barebones timing assembly, so compare to all of your pictures very closely and see if everything matches up.
Shared album - Travis - Google Photos

Here is a tiny bit better look at the cams
Shared album - Travis - Google Photos

Good luck!

 

[ectech]

I stopped at AutoZone and picked up a laser thermometer. All of my cylinders at the exhaust manifold are within 10-15 degrees of each other, driver side being the side that is 10-15 degrees higher.