Help. I have 92 Firebird L03 305 Tbi 100k miles. Purchased recently. Having running/idle problem. Replaced cap and rotor, plugs and wires, vaccum lines, map sensor. On vehicle start, with no throttle, Idle surging, on cold start won't stay running without gas pedal down. With steady throttle/gas pedal not going up or down at 2k rpms- still slight surge on steady throttle 3k rpms still slight surge.
Rpms rise to 4k easily. If engine hasn't been warmed up on WOT it bogs and hesitates heavily and rpm struggles to rise. When the engine warms up it seems to be able to accelerate all the way with decent throttle response.Suggestions? I was thinking about changing the fuel filter. I sprayed carb clean inside where injectors are spraying and it started to run perfectly fine while it was surging, when I stopped spraying it ran like ****. Upon warm up of engine it seems to run alot smoother and less surging. ECM Code 44: Lean Exhaust Indicated. Fuel pump? Maybe fuel pressure regulator? Any ideas?

 

What’s the fuel pressure at ?

 

Haven't checked fuel pressure yet, seems not the easiest on tbi. Will try and rent an adapter once the week comes by to test on fuel line. On Cold start, engine won't idle on its own. Will also stall in gears. After engine warms up with the help of the gas ped 10 minutes of surging and dying gone by, the idle smooths out alot. The surging corresponds to the moon light dimming as well as oil pressure gauge rising and battery gauge moving slightly correlating. On warm engine WOT seems normal in park. Cold engine WOT/gas pedal pushed all the way down in park car will bog down and die. Starting fluid in tbi and the engine runs fine while spraying. Seemingly thinking it's fuel pressure problem? After vehicle has been running a while..slow speeds and from stop signs it has bogging issues. At highway cruise speeds 60-70mph, minimalistic issues. Still code 44 running lean will also grab a voltmeter Monday to test fuses sensors and relays.

 

I couple of easier things to check: (I have a 305 TBI GMC truck and these were the TBI problems I encountered over the years), spray some of that carb cleaner at the TBI base gasket watching for changes, and your IAC is probably stuck and leaking too much air causing your poor idle. Clean & reset it and try again.
It's probably not your fuel pump if you can run at highway speeds.

 

Thank you. It fixed. I changed the gaskets/fuel pressure regulator and also changed out the original ignition coil.