Back story: Was taking a friend for a ride, 2nd and 3rd gear pull when I noticed puffs of smoke (gray I think) out of the tail pipe in the rear-view mirror. Lifted off throttle, and noticed a new, very faint noise under hood, almost like a slight air leak, but it was running okay. Upon reaching a stop sign, it would not idle or re-light.

After thinking about possibilities I decided to check all the intake manifold gaskets/ block-off plates/ vac. nipples for leaks. All checked okay, replaced gaskets anyway. After that didn't work, I started checking for electrical problems, all seems fine. So I attempted a compression check (cold engine, about 38degree weather, boo) with a piston-engine checker, got 6 even pulses. Running out of ideas now...

Today: Decided to try a bump start by towing it since it last ran decent until idle, and it fired, but had a new noise, or "miss" as I will call it. strangely the engine had quick revs/response, not like I'd expect if it was missing an apex seal, but there is a definite miss that varies with rpm. Also, will not idle or re-start without a tow.

Am I pissing into the wind looking for something else, or is this going to be a compression-related thing? It's the miss varying with rpm that keeps me thinking compression. I can't think what else could cause this.

-Setup: REW large street port with GT35r @ 14.5psi
- all emissions equip. removed
- manual idle control
- 850pri/1680sec injectors
- PowerFC/datalogit
- NGK Bur9eq x4
- large SMIC
- full 3" exh., no cat

 

it wont explain the air leak sound, but how old are your plugs?

 

plugs were about 1,500 miles old. I just replaced the primaries. Their electrodes were getting tapered. I'm starting to think the air leak sound is my v-band downpipe connection. I re-positioned the clamp after checking the turbine blades (which are intact and all there, thank God), but didn't get a chance to look at it when it ran today.

 

are you getting fuel pressure?

maybe you lost a coil pack?

 

I've got fuel pressure. The coils all test good for resistance per the manual.

I may try to swap primary injectors with some spares. My buddy noticed a huge flame jump out the tail pipe after it ran for a while. Could have just been loaded up from all the previous cranking though.

If I can get another tow, I'll try to take a video of the fault, and do another comp. test when its warm. thanks for the thoughts guys.