88ROC1LE

iTrader: (4)

This is a 1992 bone stock 305 tbi setup, except for a K&N filter and a straight pipe exhaust with flowmasters.
On to the problem, it has a hiccup at idle, not real bad but enough you can notice it. Give it a little gas and you can feel it wanting to stumble, give it MORE gas, for say, a highway merge, and it feels like it's gonna die and backfires through the tbi unit. It's halfway driveable during this if I'm really light on the gas, I'm talking driving on ice light, lol. This problem is on and off again, does it maybe 3 out of 7 days a week. :/

No SES light during any of the missing/sputtering/backfires. No trouble codes stored either, so I'm a bit lost at tracking this problems source.
Any help would be appreciated. Thanks!

onebad89RS

check your ignition timing and make sure it where it needs to be...then check your TPS and make sure it's doing it's job correctly. when you snap the throttle it should go from a pulse to a constant spray. if yours looks like the one below, then grab the tps lever and open it quickly...you should notice the injectors dump fuel and the car will want to die. if it doesn't do that then you have a bad TPS. of course the quicker way is to simply find a scanner that can show live data and watch TPS voltage for dead spots or if it's functioning at all.

88ROC1LE

iTrader: (4)

Replace the TPS, still have the same problems. However now it seems the idle is getting progressively worse. Under load or about 1/2 gas pedal the engine about kills over. Can't even imagine merging into traffic now it's THAT bad. Thinking maybe checking the wires/cap/plugs and the timing, but I'm still lost. :/

Thanks for the help tho onebad. Any more ideas?

slow_90firebird

I had the same exact problem in my car. I took off the distributor cap, and it needed a new cap and rotor in the worst way. However, the little screws in the cap sheared off in the distributor base, so I had to drop in a new distributor. I put a new Duralast Gold cap and rotor kit in, and it runs like new. However, I cant say what it was exactly, because I think the ignition module was going bad, and the points were rusty too. And the pick up coil.

However, the new dizzy came with all that stuff already on it, so I was happy. I got it for $100 at autozone, reman with a core charge. The cap and rotor was like $40.

88ROC1LE

iTrader: (4)

Ouch...that was a bit worn out! I'll give all that a good look over too.... Thanks for the hint

slow_90firebird

Yeah, well that was the origional factory cap and rotor. It was already past 50k miles when I changed it. I also changed the factory plugs out for some rapidfires, but I am still running the factory coil and wire set with no problems.

salfirebird92

mine was doing the same thing,but after the tune up every is fine now Try that.

88ROC1LE

iTrader: (4)

Ok, well changed plugs, wires, cap, rotor, coil, and still a miss. So being lost I took it to a local shop. They tried giving me a doom and gloom scenario of a wiped cam lobe, dropped cylinder, bent valves, ect.... well anyway, just to update the thread for those interested I'm checking the fuel pressure next and putting a new fuel filter on too.