If you guys think you're good, listen to this question and tell me whats going wrong. Ok, 89 IROC approx 76,000 miles. It idles fine but whenever I give it more than 1/4 of throttle she stumbles, regardless if shes in neutral, drive, 1st, 2nd, reverse, etc. So, what can it be?

 

Fuel delivery

Pump, filter, regulator.... start with the easiest first

 

I suck, but does it run rich, what's the state of tune, etc... I'm definately not psychic.

 

ECT reading high or pcm faulty and thinking the temp is overheating.
Or it could just be a normal fuel or spark issue
my 88 did that and it was the pcm reading 241 deg temp all the time

 

Plug a fuel pressure gauge in at the schrader valve and get a reading.

 

fuel pressure is reading fine, used to run rich, then i changed the autolites back to ac delcos and now it runs fine, idles fine, no black smoke or anything

 

Could be plugged injecters. What kind of output do you get from them?

 

dont know, i put injector cleaner in a while back but i'm gonna try it again and hope that it fixes it

 

Check your TPS and adjust it accordingly. Is the car throwing any codes? Could also be MAF related. Also check the CTS as mentioned. What's your oil pressure at (just curious)?

 

i dont know how to adjust the TPS that well, the cars got no codes what so ever, MAF should be fine i ran by that already, oil pressure is normal.....whats the CTS?

 

ignition system?

 

i'm going to try a new coil soon and i want to upgrade my spark plug wires soon also...new cap and rotor is also on the list i just need to save some money for it

 

Coolant Temperature Sensor.

Is the car hard to start sometimes? I'm leaning towards a clogged fuel filter.. $6.99 at Autozone, part number FF504 in the filter aisle Even if its not the problem, they should be changed every 10k miles or so anyways

 

My suggestion was aiming towards that. My car did the exact same thing in the past, and it was that damned coil.

 

Sometimes it is hard to start, mostly when shes been running for a while and is up to operating temperature. Recently she was in the 4th of July parade and it was hot, first time i saw the temp gauge hit 220.....fuel filter was changed a while ago, its a fram, i know they're not good but i didn't feel like spendin a ton on it

 

If it seems like it is in the same place of linkage travel with load or no load I would lean towards it being a bad spot on the TPS, especially if it is in the area where the linkage would be at if you were cruising 30 mph since that is where most of the wear occurs.
You can sometimes check the TPS with a DVOM if the spot is bad enough and you go really slow you sometimes can see it otherwise unless you have a scope the only good way is to replace it.

 

ok so that whole thing about the TPS sensor means what....how do i go about fixing it, buy a new sensor?? or can i mess with it somehow and get it to work?

a side note, before this whenever i'd be driving and decelerating (i think thats the right term) around 40 mph the car would jerk forward a little bit, sometimes it would last down about 5 mph to 35...anymore ideas?

 

If its bad you can't fix it you have to replace it. What you are describing sounds like it could be the TPS but without seeing it first hand its hard to tell.
To check it you need a ohm meter since the TPS is basically a rheostat with a contact that runs over a thin piece of foil and gains resistance as it goes from one end to the other if the foil wears through (usually at the spot you are doing 30-35mph) it will loose the reading, sometimes that bad spot is small enough that the ohm meter will not read it but your ECM will so the only good way to know for sure is to replace it. I don't know how expensive it is but I don't think it is that bad

 

alright tmrw i'll take an ohm meter to it......so what do i do to test it?

 

so nobody knows...

 

It might be stupid, but check the tan/black ignition interrupt wire. You know the one that you unhook when you set the timing. The engine will not rev far if the timing is bypassed.

 

Has anyone said "Check the ignition module!" many parts stores will test it for free.

 

There's an article on checking the IAC and TPS on this site in the Technical Articles section..

 

not sure of the wire colors you need to test...... someone else will have to step in here............set your DVOM to a 5k or 10k ohm scale then unplug your tps connector and put one DVOM lead on each wire, rotate the tps very slowly and watch for the meter to jump if it hits a bad spot.
Once again this test is not 100% acurate since the bad spot might be small enough that the DVOM wont "read" it but the ECM will since the ECM "reads" signals much faster than the DVOM

 

Yes



I'd bet you have a pressure drop, plugged tampon or inline filter or a fuel pump going bad.

 

I think it's the old banana in the tail pipe!!!!!

Seriously, it sounds like fuel pump to me. When you give it gas right before it stumbles, does the fuel pressure go down. Pump might be strong enough to deliver at idle, but not under load.