My 305 firebird has a minor issue: when run up to around 1,000-1,200 rpm it sputters, almost (or actually does, in one or 2 cases) stalls, then recovers. It will repeat this unless you take off or add throttle. Each time this occurrs, it can allways be reproduced at the same RPM that it just happened at, although this varies slightly from time to time (the RPM level it first happens at). I usually see it between 1000 and 12000, although it has occurred at 1600 from time to time. Being in drive, reverse, or park/neutral (auto tranny car) moves the RPMs where it happens around sometimes, but it's allways in this same general area.

I'm making an ALDL cable, and will get WinALDL data soon. The car is stock (afik) with the exception of: (a) new intermediate pipe (cheap one-piece... I didn't know better when I put it on), and (b) new Random Tech cat. The only thing that's disconnected is the AIR (Smog pump) line to the cat (the smog pump is still there, and still working, but I haven't rigged up an adapter to connect the Random Tech cat to the AIR tube yet).

The car runs fine, except at this RPM range. The only major mechanical problem while I had it was a severely restricted exhaust (caused by cracked cat guts falling infront of the cat exit) which took me about 2 months to figure out... After replacing the cat, I noticed this problem (Since before that, I thought it was related to (what i found out was) the exhaust problem.

Any ideas? I've checked the spark plugs, PCV valve, and tested this with my aircleaner off (in case it was intake related).

 

The TPS could have a bad spot. There is a tec article on setting and checking TPS. Or you could wait and and get winaldl up and running and use it to check (key turned in on possition, motor not running)for a flat spot in the TPS. Read your voltage in the closed possition then slowly open the throtle and watch the volage climb. It should climb at a steady rate. Should start out at about .5 volts and end up over 4 volts if I remember right.

 

Well, I got WinALDL working, and it seems that the TPS *is* advancing properly. However, I have determined that TPS position 37 or 38 (the raw WinALDL sensor output number, not the voltage) is the point where the problem allways ocurrs (so far anyhow), regardless of gear.

 

Then check your MAP sensor, too.