Rattaan

I've been having some hesitation in my car when I hit the accelerator hard. The engine seems to miss bad for a split second, then rev fine. Today I noticed while looking at it, the little rubber cap on the idle set screw is being pulled in at idle and pushed out with a blip of the throttle. I also checked for codes and came up with 12 and 17. I looked at the online service manual and 12 is the throttle sensor (full range) and 17 is the feedback system. Can anyone tell me what I should do at this point? The idle speed was correct, as was the timing. I just recently reset the TPS(to what I thought was correct???). Would this little air leak cause the hesitation all by itself? Does it have anything to do with the codes? Messing with the reading of the O2 sensor, and TPS? How should I go about fixing these problems? Any suggestions on what to plug the leak with or how to plug it? Thanks in advance for any help!

Rattaan

ummmm.... anybody gonna suggest anything at all? just a word or two maybe?

Turbo III

Have you replaced your spark plugs lately? Fuel filter?

I personally like the dual volt meter method of adjusting the TPS, I would do that as well. I bought a '91 NA as a project car to fix and sell and instead of screwing around with all those stupid vacuum solenoids I just bypassed them to help remove vacuum leaks as an issue. Just leave the one for the VDI and 5th/6th port actuator. The fuel pressure regulator on the secondary fuel rail you can just detach the nipple and run it straight off the manifold. The feedback system...get rid of that altogether, it's just emissions stuff.

I'd also bypass the coolant to the throttle body because every car I've looked at (ok...4 so far), has had the coolant jelled and blocking the TB passage.

I thought that needle adjuster was supposed to move a little since it goes right into the TB. Just spray a little carb cleaner, starting ether, WD-40, above that area and if it makes a difference, then there's a leak... or you could try to seal it off and see if that helps...use some saran wrap and a rubber band for a quick try and see.

Rattaan

Alright now I'm bumming. I sealed the idle adjust screw because there was definitely a leak there, small but there. Then I disconnected the battery for about 10 minutes to reset the computer and reconnected it. I went for a test drive, only to find the hesitation is much worse. The plugs are new since yesterday, even though the symptoms are the same as bad plugs(in my experience anyway). I came home from the drive, and tried blipping the throttle to find that it almost kills the engine after two or three times. I then checked for codes again, and 12 is there. Should I try to reset the TPS again? with help this time? I checked visible wires and harnesses for bad connections, and used the carb cleaner spray to check for vaccuum leaks(none as far as I can tell). I'm at a loss here. I have the feeling I'll get raped at the dealership to have it looked at. Anyone have any more suggestions for a course of action?

Keith

Hey, 2 quick thoughts. As far as the code 12 goes, don't worry about it - the full range throttle sensor is used only for the OMP. I would add a little premix for insurance, though.
For test purposes, I would disconnect the O2 sensor and take the car for a drive. If the hesitation is gone, replace the sensor.
Oh, and I would check the narrow range sensor for bad spots (non-linear resistance - sudden jumps to a high or low value). Red/green stripe wire and black/orange stripe wire on TPS plug. Good luck!

Irv, Keith's dad