My guess is that for whatever reason as you get closer to high RPMs the ECU is either not changing timing or changing it in a bad way. So that your spark is happening closer to when the exhaust cam is slightly open than when you are at TDC.
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My guess is that for whatever reason as you get closer to high RPMs the ECU is either not changing timing or changing it in a bad way. So that your spark is happening closer to when the exhaust cam is slightly open than when you are at TDC.
The front turbo seems unaffected but the rear glows. I was thinking the same thing as you posted above but I cannot find the problem.
Definitely seems that the rear bank is getting combustion into the exhaust but only at high RPMs
No, the turbo will glow regardless. It just hits something like a fuel cut around 4300.Quote:
Originally Posted by CoreyB
well, it doesn't glow at idle but its really really hot in comparison. Also, while the car is idling...I can hear a popping through the intake occasionally and the rpms will shudder and then stabilize.
Have you verifiyed the rear exhaust cam is timed correctly ? The rear turbo should not glow as you already know. This has to mean either unburnt fuel is entering the exaust, the exhaust is restricted, or combustion is entering the exhaust. Sticky valve guides may cause this.
The timing is spot on, I've verified that many times. That's what I was wondering was sticky valve guides as when I started the car it only ran on 5 cylinders. After trying to investigate it just kinda fixed itself I guess...lol. It runs on all 6 cylinders and has great compression. I've just never run into a problem like this before.Quote:
Originally Posted by CoreyB
I've never diagnosed sticky valve guides before, how do I diagnose this and correct it? I am assuming I would HAVE to rebuild the head.
I have no idea how to diagnose it. Seems they are only doing it at high RPMs, so you cant just pull the valve cover and check. And that may not even be the issue. Wish I was more help man. Maybe seafoam will fix it ?
Well, the car hesitates really bad. At idle it has 12.2% throttle. If I give it say, 5% throttle, it actually goes down in RPM, then if I give it a hair more, it will finally shoot up in RPM. When I go to drive off, it will do the same thing except I can feel it kinda having a tug of war with itself where it has power then it doesn't. If I start to go and give it around 40% throttle, it will boost and have some power but not full and if I give it 100% throttle, it will kick, backfire and hit what seems to be a fuel cut.
I have a few spare heads laying around, if I have to, I can swap the rear head but jesus that's alot of work and I just did that with a faulty front head.
I dont think is mechanical really. What are you running for mods if any?
Bone stock except for a Walbro 255.