dsf79

Hi to all,
This will be my first post. I've got an 88 N/A, which I picked up for 500 with a bad clutch. The kid kinda ragged it out, so I'm trying to fix some issues. The car runs/drives pretty good for the most part, but it idles a little low at about 5-6 hundred, and will die at idle with the a/c on. I don't see a idle-up solenoid on the throttle shaft, so I'm guessing that the computer is aware of the clutch relay being enegerized??? No clue on that one.

Also, when I hold my foot steady at the 2K rpm mark, the engine can't hold an even 2 thousand- it ranges from 1,600-2,000 rpm, with the speed of the blinker relay...imagine the blinker going on, off, on, off- that's how fast the engine surges. I disconnected the mass airflow sensor, and it wouldn't stay running. I'm wondering if maybe it's the throttle position sensor? What could make the engine rpm fluctuate? It doesn't do it at 4K and above, but I also notice the surge at idle before it warms up. (all of this above is mentioned with the car sitting still)

Is there any way to pull OBDI codes from this computer? I don't know where the data link port would be at, even if I could pull a code. Thanks in advance , and I'm sorry for the long post.

Barn Dirt

Check the water temperature sensor connection at the back of the thermostat housing.
Checking the TPS is also a good way to go. I know some people have had to rebuild the harnesses on theirs to make them work.

HAILERS

http://www.teamfc3s.org/info/article...Signal%20Table

Idle LOADS are compensated by a thing called the BAC. It's a cylinder shaped valve on the front left side of the engine with one electrical plug. Warm the engine up and let it idle if it will idle. PUll the bac plug off while idling. The idle should change. IF it does not, turn the engine off.

Then put the key to ON, engine off. Go to the bac and listen to it. It should putter/buzz. If not, then reach over and move the throttle linkage a bit and see if the bac putter/buzzes now. No buzzz???? Pull the bac plug off and see if both contacts in the plug are fully engaged. They might have one pushed back not making contact.

Contacts look good? Key off and remove the bac but leave the plug on the bac. Key to ON now. Look and see if the diaphram is buzzing. Do not force the diaphram open/****. Do not touch it. It will either be vibrating or not vibrating.

No vibrating?? Write back if so. The bac has a duty cycle like a fuel injector so it will buzz if working. Just FYI.

HAILERS

About the TPS. There's several ways to do that. One is in the FSM that is free and online available for a download (FAQ thread at the beginning of this section).

If you buy and build the LED'S mentioned in this article.....http://www.teamfc3s.org/info/article...able.......you can also use them to set the tps by inseting them in the tps green check connector (three sockets) and following the FSM. The engine MUST be fully hot when doing that.

An easier/quicker/just as reliable way is to get a digital meter out. Put the neg lead on a known gnd. Backprobe the green/red wire on the TPS connector with the pos lead of the meter. A properly set tps will reflect one volt dc. Not one volt? Turn the tps screw til it reads one volt dc. Engine MUST be fully HOT to do this. And the TPS plug must be fully connected to the tps to do that. The green/red wire is on the HARNESS side of the connection. not a wire in the pigtail on the tps itself.

Just FYI..........one of the functions of the TPS is to cut fuel to the injectors when you let off the pedal while driving. In other words during deceleration. That is why setting the TPS is being mentioned as a possible bad actor. AND.....if the potentiometer in the tps is corrut, it might very well cause your problem. Corrupt as in having a short in the winding or open spot in it.

HAILERS

Again, about your BAC. Read this article.....http://www.teamfc3s.org/info/articles/idle.html look at the very bottom of the page on how to fix a bad transistor in the ECU. Ignore the rest of the article. In fact ignore the part about checking the ohms on the bac and or checking anything other than having 12vdc on the black/white wire going to the BAC.

A quick way to determine if the bac's transistor is good/bad in the ECU is to remove the bac but leave it's plug on. Then watch the internals of the bac WHILE someone puts the key to START FOR A MOMENT. When put to START the bac should go full open and stay there. Full open is only about a quarter inch from close. It will not vibrate while in START. If it does this, I'd say the transistor is good in the ECU, therefore when the key is put to ON, the bac should vibtate.