LFA951

When I accelerate, mostly in third gear, but sometimes in second, the car just chokes, or cuts out past 3K. I can describe it as letting go of the throttle or just cutting out. It's frustrating and when it happens I upshift, but it sucks when I'm passing. I've checked all the grounds, reference sensors are clean and tight, plugs and wires are tight, I don't know what else it can be. All electrical connections are fine, checked all vacuum lines, vacuum is at 17-18 hg when warm, clamps and IC pipes, BOV, everything checks out ok. Plugs were changed 3 months ago. I have an Autothority MAF and no knock sensor and I have the boost set to 15 psi in 3rd gear. I took the TPS cover off and found no traces of oil in it, however, I did notice some oil in the throttle IC to intake pipe, and I read here once that the IC can sometimes fill up with oil and blow it into the intake and that would cause these symptoms. Any ideas or suggestions?

Tom M'Guinn

Have you checked your cap and rotor recently, and how old are your plug wires? If the car runs great under boost in low gears, but stumbles and bogs under boost in higher gears, it is often weak ignition.

LFA951

The distributor cap, rotor and wires were replaced about 2 years ago, since then I've put about 15K on her, I'm gonna disconnect and test the TPS tomorrow and see if maybe that's it...

jmj951

1) When was the last fuel filter replacement?
2) Will the FPR and damper hold vacuum? (don't know if you can get access to one of these vacuum testers, but definitely worth checking)

Could be fuel-delivery related (even possibly the pump) because the car is stumbling at a point where considerably more fuel needs to be delivered.

TurboTommy

Yeah, I don't think it would be an ignition issue, because that would cause a gradual degradation of power; not like a sudden thing.
With the aftermarket MAF it can't be overboost or fuel cut.
I've had the same symptoms, in the past, with faulty injectors. They get to a certain flow and/or boost and they don't open. Try diagnosing the injectors, the wiring, and the DME.

LFA951

The fuel filter was changed almost a year ago in October of '07 and the 3 bar FPR as well as the fuel pump are 2 years old as well.

Tom M'Guinn

I've had weak ignition cause both stumbling and what I'd call a "bog" where it feels much like the motor floods beyond a certain level of load. Regardless, sounds like this ignition is fairly new and unlikely the culprit here.

LFA951

I went ahead and cleaned the electric ports with parts cleaner as well as the AF meter, TPS, MAF, grounds, and all electrical circuits, I found some oil behind a wire on the coil, cleaned all sensors as well and injector caps, turned her on and purred like a kitten, gonna take her out in the afternoon to see if there is a change....

LFA951

Cleaned out all metal electrical ports with Brake cleaner and problem is solved, no more cutting out!!

Jeff N.

Congrats. What specific plugs did you clean?

LFA951

Both ends of spark plug wires, coil, distributor cap, reference sensors, AFM, injectors, MAF sensor, all connectors such as the temperature, turbo cooler, TPS harness, battery terminals, grounds, everything...no more cutting out, prrrrss like a kitten!