I just reciently bought an '89 Pontiac Trans Am with a TPI 305. I have been having trouble with the car no wanting to run smoothly, stuttering and lurching between 1,000 and 1,600 RPMs. At higher RPMs the car runs great, even with the A/C on. Just when it's at idle, it runs rough, and of course, the stuttering problem at low RPMs. I have no idea what's going wrong. Fuel injection is new to me. Any help would be appreciated!!!

 

Welcome!

First advice, Since you just bought the car- Do a tune up! Change filters,oils,plugs, wires and so on. Check TPS (throttle position sensor) and the ignition.


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GTA -89:Free flow muffler,dual 3" HF cats, Edelbrock headers, Vette heads, 1.52 RR 7/16, ZZ-9 cam, Big Mouth, AS&M LTR, !plenum, 52 TB, MSD 6AL, TPIS level V prom, Superior shift-kit and all the minor mods, a AFR 195 headed 383 in the works!! ready May 2001...
http://www.itv.se/tacs/members_cars/m279/m279.html (Swedish Trans Am Club)

 

I had the same problem and I changed everything I could think of: spark plugs, spark plug wires, fuel filter, etc. Nothing helped, but the thing that really caught my attention was the oil around the threads of my spark plugs. Oily spark plugs due to leaky valves could cause stuttering when you start up the car. Just something to think about while you're doing that tune up.

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'89 Firebird Formula-
K&N Air Filter, Holley Throttle Body Air Foil, Hotchkis Strut Tower Brace, Hotchkis Panhard Rod, Hotchkis Trailing Arms, Kenny Brown Subframe Connectors, GT Auto Assesories aero wing

[This message has been edited by 89FormulaRoth (edited March 21, 2001).]

[This message has been edited by 89FormulaRoth (edited March 21, 2001).]

 

I did do a tune up on Tuesday and found a bit of oil on the plug from the number four cylinder, but when it starts, it starts up normally, it only acts up when it's at operating temp, and in the city. It doesn't have problems on the highway. And still, leaky valves can have an impact???