Jfsram

Have a 93 with a code 63 and 67.

Power is good, partial throttle is good. Idle is poor and just off idle is down on power. For example. If you don't throttle it when engaging the clutch, it will stall.

Code 63 tells me it's the throttle position sensor, low voltage.
Checked it and it's exactly where I left it 3 years ago. 1.01 volts and verified with a second meter 0.99 volts.

History. Car ran perfectly before winter storage. It's a bit damp in the place I kept it. Plugs, cap, rotor, MAF sensor. All check.

mattdel

If the PCM is telling you low voltage, it can be anywhere in the entire RPM band that it is seeing the problem.

If you're at 50% throttle, and suddenly the TPS starts bouncing from 2.8v to 0.4v, you'll throw the code. Don't call a TPS good unless you have the correct scanner where you can watch its waveform. You won't be able to see the fluctuations with a volt meter, either.

lxman1

Could be a vacuum leak causing the idle problem. Check for a dry rotted vacuum line.
As for the TPS code, like said above, could be good at idle and have a bad spot somewhere else in the rheostat.

eviljeanyis

First off did you put Stabil or another fuel stabalizer in the tank before storage, if not get some fresh fuel in there. Next (if problem persists) check the vacuum lines to and from your intake. Next (if still bad) remove and clean your idle air control valve with some carb cleaner. Check your TPS wiring, or if it were me I would order a TPS either way.

Jfsram

I am aiming my efforts on that dead spot in the rheostat theory but I don't see how a poor spot at 50% throttle could affect off idle and idle. I'm not debating your theory, just testing it.

Tomorrow, I'll check again for vacuum leaks.

As for the fuel stabilizer. Thanks for the input. All is appreciated but I never use it. I own 7 cars and at least 2 or 3 are in storage at any given time. None of them ever had fuel issues after storage. All I do is make sure they are parked with a full tank.

TrimDrip

I would do a tps before anything else you are thinking of doing.

AdderMk2

setting your TPS to anything near 1v will cause issues. set it back down around .8-.9v, perform a base idle reset and then check where you are at. You will be surprised at what a difference, keeping your sensors in the proper range will make.

lxman1

^^^ this is true. I actually has to elongate the screw holes in mine when I installed the 70MM TB on my ride to get the voltage down to .95v. At 1.0 or above, it will cause idle issues.

Jfsram

I will adjust to the middle of the range but on a side note. It's been at .99 for years.
This idling problem just started since after storage.

wydopnthrtl

I'd clean the MAF wires with the special spray cleaner, set the TPS to the proper voltage, and look for vacuum leaks.

I don't wager.. but if I did, I'd put it on a vacuum leak.