gellymonster

So, I've had this 1987 S4 NA base model FC3S for about 7 months. She has never run quite right, so I've slowly been working on problems as they come and as I have the time/money. A couple of days ago, she started acting weird, and now she's running on one rotor as soon as she hits idle, which is too high.

Things I've done: cleaned wiring harness connectors with electronics cleaner, reset TPS, cleaned the throttle body and BAC valve, cleaned all ground spots and replaced some of the larger ground wires, upgraded alternator to S6 one

Things I haven't done but plan on doing once I figure out how and have the tools: compression test, cleaning fuel injectors, replacing wiring harness and ECU (from a parts car I own with a blown engine)

In the process of all of this, I've managed to make her run more steady and not bounce the idle around so much, as well as fix all of the interior woes (lights, stereo, clock, etc).

So here's what happens: I place key in ignition, wait 30-60 seconds for the car to see everything it should, and then I start her (not instant crank, but not terrible). She bounces idle to about 3000 RPM, then drops to around 1500 to idle (TPS is at proper setting; air control on top of throttle body is as lean as it will go - adding air makes idle bounce). About 10 seconds into idle, she drops into limp mode and starts running on only one rotor (not sure which one, but I know it's only one). It continues to run on one rotor then, no matter how much fuel it's given. It has no A/C, no power steering, and no air pump.

I'm afraid this is electrical or a component, not engine failure. I've done what I can, and I'm not a fantastic mechanic. I'm determined to fix her, so please help! Suggestions or stories of similar problems are welcome. Flaming over my ignorance is not welcome. I bought a rotary because I love them and am determined to keep this one running and make her happy!

satch

iTrader: (1)

Is the TPS set to 1 volt w/the car fully warmed? The TPS causes fuel cut which might contribute to your problem. Are you sure the compression is good on the rear rotor? The AFM also causes fuel cut so you might want to jumper the fuel check connector and unplug the AFM and see if it runs exactly the same. Are you certain the plug wires are running to the correct positions (leading =lower and trailing =top). And of course your fuel injectors on the rear housing might be questionable especially the rear primary injector. Make sure the plug is connected firmly to this injector.

gellymonster

1. TPS is set properly, promise! I checked several times to make sure, and it's staying around the 1k mark, though it changes just mildly sometimes after it's been driven. It doesn't change more than 100 off the magic number, up or down.

2. I said that I haven't compression tested yet. I don't have a tool to do it and have to wait on one from a friend.

The injectors are well plugged in, but I'm not sure how great the wiring harness is. It's been mutilated by the idiot that owned the car prior, so I've done what I can to help. I'm also not sure of the quality level of the injectors. I am planning on cleaning them, but that's a few days down the road.

This is a fresh issue, and the car has been running fine for months. The plugs and wires are new and on correctly, as I've replaced them all and made sure they were good. The car ran fine for a while with them in, so I don't suspect them at all. They're all NGK.