I'm in the process of diagnosising... looking for guidance.

Car is essentially a stock '92 305 TPS w/ speed density.

Background.
Had low power. Ohm'd injectors, ok. Found I had 2 burnt plug wires (got loose and onto the exhaust manifold). Changed plugs, wires, cap, rotor, coil, tested ign mod (ok), and put it back on w/ thermal grease on the ign mod. Ran great at the next weeks autocross.

The following week, I dropped my car off at the paint shop (a month ago). Drove it off the trailer and parked it no problem. After a week I stopped in and the guy said it was difficult to move. I know that I had trouble adjusting to the loudness after I removed the muffler, I kept stalling it thinking it was at 3grand when it was actually only at 1 Guy said it was 'loading up' It's not carbed, it shouldn't be loading up. He made a comment about having to rev it to clear it out. Three more weeks pass, and I pick up the car. It starts, but is difficult to get going. NO response to throttle inputs. I can get rolling at idle, but it stumbles and wants to die with any throttle. Also dies when I pushed in the clutch. Barely got it on the trailer and home. Bought a compression tester, hoping that the shop didn't overrev it or something stupid.

Pull the codes... flashing 12, ok. Test TPS, ok. Check the stuff I just installed. Coil tests ok and all the rest look ok. Plug old plug wire and plug onto coil and place on exh man. Crank and it sparks. (I know this isn't the proper way of testing for spark, but it works). Check oil. Level is ok, smells like fuel. Fun. I will be doing an oil change as soon as I figure out the why. Hook up fuel pressure tester, key on, 45 psi. Key off, an hour later it's still ~42. I didn't checked it while the car was running (it was late and the car is loud) but will do that right when I get home tonight. Still need to do the compression check, just for grins.

What else do I need to look for/check/test?

 

I had a little gas mixed with my oil as well but that was because the valves were a little too tight and i lost compression because of that. I'd do a compression check on it to make sure the head gaskets not blown between a cylinder and oil hole or the piston rings aren't wore down. Car doesn't smoke does it?

 

No smoke. But then again, it hasn't run long enough to get enough heat into it.

Tonight: Had the fuel pressure gauge still hooked up from yesterday when I got home tonight... still had ~30+psi. Guess that means the injectors arn't leaking. Cranked the car, didn't want to idle unless I breathed on the gas. Fuel pressure was 45, varied from 40-50 when I modulated the throttle. RPMs still didnt' respond to throttle. Car wants to die.

Compression test ~150 on all cyl. No bent valves (yay!)

Tomorrow. Buy timing light and check for spark at the plugs. I'm open to suggestions as to what else I can check and the proper way to check for spark. I've always just set the plug still hooked up to the wire on the exh man, and looked for spark.

I'm running out of ideas.

 

well, you got good compresion, how well is everything else on the car working, it almost sounds like a bad ground somewhere you could check your grounds if that turns up good check voltage at the computer from tps see if the computers see the same thing as for fuel in the oil the only thing i can think of is maybe a cracked intake, hows your vacuum

 

try unpluging the mass air sensor

 

It's a '92 TPI, I don't think it has a MAF. I'm new to the whole fuel injection thing tho. Could it be a MAP issue (does it have a MAP sensor)? IAC issue?

I'll check the computer tonight as well as the grounds. Unfortunatly I don't have the ALDL connector rigged up.

I'll see if there is spark at the plugs tonight, and if not swap back the old cap and rotor.

 

Well, it has spark at the plugs. Now to go rent a timing light. Didn't find any vacuum leaks (as far as I can tell) and grounds seem good.

It sparks, it's getting fuel, and air is a no brainer. I would think that if it was computer or sensor related, it wouldn't be doing one of these.

Please help!

 

Check compression and set your base timing. And still I think you should try unplugging the mass air sensor, mine ran just like that when the sensor went bad.

 

Assuming that you are getting spark and your timing is correct, this sounds like a problem with incorrect fuel mixture. This could be caused by nearly anything, but you are on the right track testing the fuel pressure first. It almost sounds like a bad fuel pump, but since the pressure stays up when you give it throttle, the fuel pump is ruled out. Since this is a 92, there is no MAF unless it was converted. The MAP may be your problem. The best way that I have found to test this is to get a MAP that is known to be good and swap it in. Other than that, you will need a vacuum pump and a volt/ohm meter (which I assume you have, since you tested the TPS). Testing is basically the same as the TPS but you slowly change the pressure using the pump and make sure the voltage change is consistant. Besides what I have stated previously, a serious vacuum leak can also be the culprit. Do a search on how to detect those, as people have posted various different ways.

 

Much thanks to you guys. It runs like a champ now. Best part is, I didn't have to 'throw parts' at it.

The culprit? Timing was waaaay off. Best $50 I spent. (well $150 after buying the compression and fuel pressure gauges) That will be the first thing I check from now on.

Thanks again.

 

Glad to hear ya got it fixed.