P0300 P0302 P0306

What would cause Injector #2 to look like this. I have replaced all Coils, Plugs, Injectors, CAM and Crank position sensor(s), Fuel Pump, and PCV valve and hose trying to get to the bottom of this. I now gave the truck to Toyota but since I removed the SAIS system they are finding it hard to look past that.

They are saying they don't think it's a valve / valve spring because of how random the misfires occur.

ECM is a possibility they say because they think the tune ruined the ECM. I think it could be just an ECM gone bad?

**SAIS system is long gone and I have ran the tune for over 8 months and 10k miles with no problems so I really don't think it's the tune**

When I hooked my HP Tuner up to my truck and did a live scan cylinder #2 is always the first to misfire with cylinder #6 to follow. Cylinder #2 has almost double the amount of misfires as #6 which leads me to believe (along with the black injector) something is happening in cylinder #2 which causes #6 to miss.

 

I highly doubt it's a bad PCM.
I don't see anything wrong with that injector?
What is the history of the misfire, has it always been the same 2 cylinders even before parts were replaced?
Has base engine mechanical been checked (compression, leakdown, etc)?

 

Hey DM93, first off thank you for reaching out.

The injector is black on the end and when I replaced them all it's the only one that looked like that the rest were perfectly silver on the nozzles.

History: Truck ran fine, one day I decided to do an Italian tune up (I wish I could take this day back) on the way to the gas station. About 2 minutes after filling up on my way home I got P0300. Shut the truck off, started it back up and it ran fine until the code would happen again two more times on the way home. For the next 4 months I would be replacing all these parts thinking to myself "It's the next electrical thing" and also treating it for bad gas since the misfire clears up after turning the truck off and then turning it back on (and clearing the code with my cheap scanner). Sometimes I will get all of the other cylinders to throw the code but it's rare and when this happens me clearing the code and turning the truck off doesn't immediately fix the problem. Only after about 10 minutes does it go away after all of them read misfire. The check engine light will stay on as permanent and then all the sudden I'm able to clear it. The initial code is always either P0300 by itself or P0300, P0302, and P0306. After I replaced the injectors the truck ran fine. I live out in the middle of nowhere so driving to town is an hour and I completed multiple trips with no problem and then I think about one to two weeks later I was going to replace an oil pan gasket for an older man at church and sure enough I got the code again. I cleared the code, went to his house and did the job and drove home with no code.

Compression / Leakdown:
I gave the truck to Toyota to see what they would say and the tech says because of the random nature of the code being thrown he thinks him performing a compression check would be a waste of my money. I don't understand this reasoning as I figured he would do all tests to rule out everything as he went but he seemed so sure it wasn't. I was really hoping they would find exactly what the problem is but it seems like I'm going to have to run the compression check to be sure and save myself some money when I get the truck back on Monday.

As for the leak down test, I doubt they did that either and I don't have that capability. I would end up renting the compression testing equipment from an auto parts store when I get the truck back on Monday.

 

Just wondering out loud here. Both of those cylinders are on the same fuel rail, #2 being farthest from the pump. Just wondering if something is wonky with the fuel delivery to the injectors on that side, maybe FOD in the fuel rail?

How does the ECM detect a misfire? Anyone know? Nevermind, looked it up: It uses the CPS to detect variations in the crank speed.

I once had a plug with a hairline crack, and I know that it misfired multiple times before it actually threw the code. This was right after a spark plug change, and I knew there was something wrong but wanted to wait for the code to tell me which cylinder. It took longer than I expected.

The only things in common between 2 and 6 seem to be the fuel rail and, well, the ECM.

 

I'd really want to verify engine health before changing any more parts.
When it sets the code do you feel a misfire?

 

Hey Tenbeers,

You know that's something I thought of but was thinking when I replaced the injectors it would have fallen out but possibly something lodged in there? When I get it back I could remove the fuel rail and blow compressed air through it to be sure.

Do the symptoms to you guys sound more electrical or mechanical do you think? To me (a novice) turning the truck off and on fixing the problem makes me think electrical but it could well be mechanical and my tunnel vision is getting the better of me.

 

Hey!

I agree with you and yes when it misfires I feel a lag in power like a quick hesitation and then when the engine light is flashing the engine has a noticeable vibration until I turn it off and back on again.

 

If engine mechanical checks out you probably need a good drivability guy to check it out, it could be bad parts or something else. Really hard to say without having hands on it.
Were the parts all OEM and not Amazon/Ebay specials?

 

All parts were OEM, I am careful about that as I have seen a lot of problems otherwise. Only thing I'd buy after market would be a Mahle or FelPro gasket and am ready and willing to be castigated and castrated if that's wrong.

I live near a guy who has been rebuilding transmissions and engines for most of his life I may just ask him if he'd like to go for a ride and will probably have him come down to help with all the pressure checks as well. He has helped me troubleshoot before but was as confused as anyone else regarding this.

Do you know if its true that cylinder 2 could cause 6 to miss as well?

 

I mean I have seen a single cylinder misfire set codes for multiple cylinders before, really need a scan tool connected when the misfire occurs and be watching live misfire counts to see if it's mainly just one or multiple cylinders misfiring.
You have no coil circuit (p035x) codes correct?

 

Thank you very much then it would match up with my live scan using my HPTuner VCM. Which would show cyl 2 hit first then sometimes 6 right after and sometimes not.

And no (as of now) I don't have a P035x code.

 

I think if I was diagnosing it some stuff I'd want to check is:

Relative compression
Bank 2 exhaust backpressure
Injector Balance
Scope injector current, injector 2 and 6 control, and coil 2 and 6 control when the misfire is occurring to see if something is dropping out or being turned off.

 

Did you use regular copper plugs or iridium?

 

I used the regular copper plugs.

 

You just made me think of something when you said bank 2 exhaust Back pressure. When I deleted my SAIS system I had to block off the exhaust manifold ports that originally led to the pumps. I used copper gasket maker and some of the OEM blocker plates (I guess for the models that don't have it). Maybe...just maybe when I ran it hard that day I got the blocker plate too hot and maybe loosened up the but or blew the gasket out a little bit? Or could I be off here?

 

Well I mean if the cat is plugged it would cause misfires on that bank.
Easy enough to test with an exhaust backpressure gauge if the upstream AFR sensor comes out.

 

I see what you mean never mind, I was thinking if too much exhaust was leaking out of the manifold block off plates and not getting to the AFR. Could that also be a possibility? A very weird one but my exhaust manifold system has a hole that's supposed to be plugged by the SAIS system.

Thank you so much for your patience and dedication to helping me with this it really does mean a lot. I will try and rent these testers and post my results on Monday - Tuesday after I get my truck back from the dealer.

 

Possible but unlikely, I would expect to see fuel trim/o2 sensor codes from an exhaust leak before any misfires.

 

Ah that makes sense thank you. Hey would you by chance have the ability to look at a live scan I took using VCM suite on my HP Tuner? I have parameters to show a lot of information (which will be posted in a screen shot) but I can send you the file compressed if you have VCM (free for Download) or I can send you a set of screen shots to see if anything jumps out at you. For instance the graph labeled "Spark" going frantically up and down and I have a plethora of parameters I can select to monitor on the left side.

 

I do have HP Tuners loaded on one of my laptops so yea I can take a look at your logs but it's at the shop so it will be Monday.