Contour Enthusiasts Group Archives Forums Modifications Forced Induction Wierd Shudder

All was fine last evening and this morning I put back on my Strut Bar and started the car up. It had a wierd shudder or miss or hesitation at about 2k rpm's. It feels like a vacuum leak or a spark being blown out. I also threw a CEL. It will build boost but it doesn't act like it want so hold it. I have NGK TR6's with .035 gap. I looked for about a half an hour for the leak, to no avail. I am going to Street Flight tomorrow to use the OBD2 scanner. I am planning to get a new/upgraded Blow-Off (Bypass) valve tomorrow. I have three suspicions... Let me know what you all think.
1. Vacuum Leak due to boost pressure popping seal.
2. Spark being blown out or fouled plug.
3. Bypass valve is failing (cheap-ass Bosch that is in the kit) due to boost pressure.

Important to note- this stumble happens in all RPM ranges and not nessecarily only in the boost range.

I would guess its a vacuum leak. Spark blowout usually only happens at higher RPMS, and since you said the stumble is happening in all rpms, I would eliminate that. I've had vacuum leaks, and it causes some weird stuff to happen.

Good Luck finding the problem.

I told Chris to check the POS valve since you're only hitting 7 lbs. He has a line on some custom pieces. Also, since you just put the bar back on and now it is missing, having you checked to make sure you didn't crak a plug wire or are grounding out on the coil pack on the back side of the motor since I'm assuming your bar goes right over the top of it? Always check the last thing you did when a new problem arises that wasn't there before.

Rick

I am a Super Jack-ass..
I found the problem. I had popped one of the plug wires loose from the rear bank, while putting on my strut bar. While under no load, the wire would arch and make the ignition. When under a load the plug would miss all together. Duh!

Oh well, in the process of trying to fix it, I picked up a really kick-ass Bypass Valve that is billet aluminum which caused me to pick up another LB of boost. I still have some tuning to do, but I am heading in the right direction.

BTW- My CEL read "Error with RAM" or something like that. I assume that the Chip was not alowing the computer to diagnose the loose wire. Anyone got an idea???

Hehe, a swing and a home run for Buckshot!!! LOL

I'd try clearing the computer and seeing if you get another CEL Jason. BTW, what did you guys get for a # last night on the dyno?

Rick

Jason, did you get the RFL BOV that Chris told me about, and does it vent back into the system or to atmosphere?

We got him an upgrade for the bosch. It vents back in. The RFL bov's are all gone and I don't think we will try another one.

I've still got the vortech supplied bypass valve. Is that a bad thing? It holds 10 psi, no problem. Why is it supposed to be such a bad peice?

Just curious

I'm interested in a upgraded BOV can you tell me more info?

Why did you gap to .034 wasn't the correct supposed to be .054 that's what mine are at.