I am at my wits end. My FD has only 26K on it, but it's been giving me this strange issue. When I first start it up, itd drives perfect throughout the entire RPM range, then eventually the check engine on comes on, and it starts to buck (almost like a rev limiter or fuel cut) as soon as its time to make power. It wont go over about 2K and load has to be minor to avoid bucking. If I turn it off and start it again, it drives okay for a bit, then its back. The frequency has been increasing lately to the point where its unsafe to drive because thsi issue shows up after about one minute of driving. I have a Pettit computer, but I tried putting my old one back in and it still does the same thing. When I ground pins GND and TEN to read the check engine light, it behaves like the check engine light never came on (it's never on when I'm just starting up the car.) All I have for mods is a downpipe, cheap bastard intake, a couple of gauges and the pettit computer. Any help would be appreciated very much. Thanks in advance.

 

Tps?

 

Mine used to do that when the air intake sensor was bad. Replaced it and it went away. However, mine showed a check engine light.

 

have you checked the obvious things such as the spark plugs and map sensor

 

Limp home mode ,check things that send it to the limp home mode . Start with the O2 sensor

 

I dont get it, if you're jumping TEN and GND, why not just get the code and find out for sure why the check engine light is coming on?

And im 100000% sure its the TPS.

I had this problem, same exact symptoms as you. It was an out of whack TPS.

 

I'm using Ten and GND to get the Check Engine code (Advance and Autozone done read OBD 1 codes anymore), but you have to do it with the engine off. When I shut the engine off, the code goes away, and it comes up as not having any problems (no flashes.) Cheapest TPS at Advance is $307.42. Is this a reasonable price for a sensor? I got plugs today, because that solution I can afford, and I haven't done then in a while. Maybe I'll get lucky.

 

I know your mileage sounds low, but how crispy does your wiring harness feel? I had a similar problem with my old harness that very quickly lead to the blowing of my motor

 

Thank you all for your ideas. I really appreciate it.

So I changed the spark plugs, and it ran great for about 10 mintues. (One of the spark plugs had a cracked post inside the insulator that came out when I pulled out the plug wire.) Then it started running like crap again. This time I got a code (I left the 10 and GND jumped while driving.) It was 27 - Metering Oil Pump sensor open or short circuit or MOP sticking. IS it possible that I could have jostled that? Is that near where the plugs are?

 

If MOP is failing, then the car defaults to limp mode. Fix the OMP or get a standalone and a S4 front cover and start premixing.

 

I premix anyways. Isn't there any way to trick the computer into thinking it works?