Car misfiring, random misfire code, constant knock counts, oh my.

[CoopKill]

Stock one. Nothing crazy here.

OK, just wondering if it was an oem "like" part.

[kywhitelightning]

Flakey MAF sensor?

It'll cause the lean issues and the lean issue will cause misfires. The knock may or may not be a byproduct of this (lean AFR under power). Log the conditions to verify.

Jeff

[Toni]

Well made it to work today no problem. Seems if it doesn't happen within the first 5 mi/5 min, it won't happen at all. Getting on the boost is no problem either.

This doesn't feel like a fueling issue to me. I've had problems with the maft gen II in the past because it used the same shitty connectors as the maft pro. Once you play with it, it comes alive. They sent me gold plated pins to fix it. So that was the first thing I checked. It was essentially a mas problem. However, when that happened, it felt much much different. This feels like an obvious imbalance, like I turned off an injector. Thing is it's happening on both banks.

So now my plan is to log the early starts every time to catch the situation. I have spare coils, PTU, and wires on hand. I think I need to catch the problem quickly because it's probably flooding some cylinders. I'll first try pulling the ECS cause that's easy. Then try swapping things without running the car much. An engine restart hasn't fixed the problem yet so I can be somewhat sure if it goes away, it's something I did.

If nothing fixes it, then I'll let it run for a while and pull the plugs to see which or if all are wet to get an idea if it's a global issue or all.

I could get a scope on the lines to the PTU to see if the ecu is spitting out junk but that will take some setup.

[kywhitelightning]

Is your Gen 2 mounted solidly? If it's moving around, that could very well be the problem. I know if I pick mine up while running it'll get stupid from time to time.

Jeff

[HellBringer]

It's your ECS computer. Disconnect it and the problem will go away. I believe they can be rebuilt, but you can usually find used ones for super cheap. In my experience, the ECS computer going bad is likely to take the ECU with it shortly thereafter.

[Toni]

It's your ECS computer. Disconnect it and the problem will go away. I believe they can be rebuilt, but you can usually find used ones for super cheap. In my experience, the ECS computer going bad is likely to take the ECU with it shortly thereafter.

Maybe not, don't be so sure of yourself Although you do make a good point so I debugged the ECS light last night and it's definitively the computer so I left it unplugged til I get a new one to prevent other issues from it. I've already rebuilt mine once.

Today it happened again even with the ECS unplugged. Drove the car all morning, came back from a dyno day and it happened. Stopped and started it and it didn't go away so I swapped the PTU. Started up fine, no misses, night and day.

Hooked up the old one again and I'll see if it happens again to swap it again to confirm, it may have just be coincidence.

[Toni]

Well it happened again the next time I started the car. Swapped the PTU again and it went away.

[Jimvr4]

PTU provides the rpm signal so that may be what you're fixing.

[Toni]

If I recall Greg has told me the RPM the ecu uses is from the CAS. Actually, a few months back I had a crazy RPM signal and car ran funny but a bit different than this. That's when he told me about it. I'm betting that was the first sign of the PTU going whack on me.

[NOMIEZVR4]

excellent thread. Never knew the POS ECS computer could cause issues...I'll be disconnecting mine as soon as I get a chance.