This is an intermittant problem, sometimes severe to the point that I can't get the car to move an inch without 'bogging' down the motor, sometimes it's perfectly fine and runs no problem...it almost feels like a ground problem I once had with a Nissan in the past, but I'm running the Ice Shark kit for grounds...it seemed to go away when I jiggled the coil a little bit, but reappeared quickly thereafter...it seems to disappear regardless of severity IF I can get the rpms above 3k which is also why my initial inclination was an electrical issue...all vac lines have been replaced recently with SVH, and boost controller was just installed. All lines are checked, can't find any indication of a leak unless maybe it's around the intercooler lines or the J-boot. Other than that, I did recently go to a different positive battery terminal which I'm not 100% confident in...it was very good at first, but with all the recent rain and the lack of a proper cover for the positive terminal, I do worry that there's been a bit of corrosion that might affect it...obviously I'll be replacing that asap, but does this ring any bells or set off any red lights for anyone?

 

Ack - the problem with typing posts at work is sometimes you get distracted and forget to actually describe the problem.

From idle, or at immediate throttle tip-in, the car bogs and hesitates, dropping rpms and making almost no power...occasionally as well while driving, the car will seem to be making almost no power, and I have to back the throttle down to nearly idle to keep the car moving at a steady speed. Part of me is reminded of a ground issue, but it also almost feels like timing is being completely pulled out...this may just feel like a similar symptom, and I do know this could be any number of a hundred things, but I just wanted to see if anyone had gone through a similar situation...

 

I should also add that the A/F seems to be normal, even during the hesitation issue...what little power the car makes seems to be in tune with a decent a/f, so this is part of why I wasn't initially leaning towards the fuel pump or filter...

 

Throttle Position Sensor. Unplug the TPS from the harness to verify, it should run in default mode when you unplug it. Holds you to 1.2BAR boost, and runs rich, but its a pretty sure test.

 

I'd check the tps like water said because it's free .. then .. you said that you jiggled the coil and it worked .. I'd replace it

 

Thing about the coil is it's a virtually brand new MSD blaster anti-vibration...I'll try unplugging the TPS and seeing if that works

 

Well...after driving it home from work, it was fine the whole way until I got on boost a little bit (never got beyond 5psi or so) immediately after which (coming to a stoplight) it started again...no ability to rev the motor at all...I had to play a game with the throttle until the light had already turned green trying to get the revs up enough to move the car...once I got 3500rpms it was ok, but sounded like a bad rotary motor (bwah bwah bwah bwah) as I pulled slowly through the intersection...as I got through, something changed and everything went normal, and the car shot forward...I didn't think much of it, but the same happened on the way to work...it was totally ok until I got on it a little and built some boost, and then it went apesh*t and started with the hesitation. I also noticed that the first couple starts it kicks over fine then dies. I'm starting to worry that it's a fuel pressure issue, even though the a/f seems normal...has anyone who's had a fuel pump (or clogged fuel filter) go bad experienced similar symptoms, and/or can anyone think of why boost would cause it, but it would rectify itself without me fiddling with hoses and connections? I'm going to play with it tomorrow, but the symptoms are puzzling to me...

 

I used to have what sounds like the same problem on my motorcycle (factory stock turbo). It turned out to be the spark plugs. I think they were too cold a rating and they kept fouling up. I could only ride if I kept it rather fast. After switching the type of plugs (I was using very expensive plugs) to a hotter plug, I have had no problems with it fouling the plugs. I can even cruse around rather slowly if I was to. I couldn’t do that before. This may not be your problem but who knows. If you pull the plugs and they are all black you may want to switch to a hotter plug. I hope I have that hot cold thing the right way around it has been a while since I had the problem.

 

I just fixed my nissan truck that was stumbling upon acceleration. I replaced the plug wires, fuel filter, and added a fuel additive called something like Gas Line antifreeze. I don't trust many additives but my neighbor, the Ferrari mechanic, recommended this one. I haven't taken the truck on any extended trips yet but it seems to be fixed after the short test drive I just gave it.

 

I'm having almost the exact symptoms. but mine happens with A/C on or when taking off on a hill. it is completely annoying. anybody please help!!
it feels like its a timing problem.

 

".it seemed to go away when I jiggled the coil a little bit, but reappeared quickly thereafter.."

This is a clue... Check your plug wires at night. With no lights, you can see the bad ones arcing to the block.

Also check your distributor and cap. Someone a month ago mentioned this exact problem and the problem ended up being the cap was loose. Sometimes mechanics get lazy and can't get the bottom clip on and just leave it.

 

Hmm... Sound's almost exactly like my last 2 days of horror.


Yesterday it went really bad, after i did a AFM tuneup, i assembled the car, and when i started it; it would only run idle. Every time i hit the Throttle, it died on me. After like 10 attempts the car died altogheteher, and refused to start at all.

I checked the DME-Relay, The fuel supply, Injektor voltage, AFM + Temp gauges, Idle Switch, DME power, Ign. Coil. resistances. before it turned out to bee a bad ignition coil, since i got no spark. I'm now running on a 924 Coil.

Try another Ignition coil, even thoug your's brand new, That would rule out that.

 

Two things come to mind.

1) TPS. Already been suggested. They will cause the engine to idle fine but the care will not get out of it's own way if you drive it. Not sure about just unplugging it for a test, never tried that.

2) AFM. Had this happen to my car. Intermittantly it would just fall on it's face and backfire through the intake, stall and not imediately restart. Not very convienient on the Dulles Toll Rd. in rush hour traffic. Occationally it would fall on it's face and then like someone flipped a switch, would run just fine.

 

Turned out to be a bad vacuum hose (one of the thick ones at the Jboot...was thick enough that it was OK most of the time, but on heavy boost, it would 'pop' open and stay that way, so idle was fine with ok a/f, but hit the gas and disengage the idle assist, and it dies...it would correct itself as the hose 'popped' back into the form and be fine...was irritating as it was the bottom of the hose and was a small crack, but long...

 

That's good news for you. Cheap fix!