ken3983

Or that what it feels like. Its been doing this for weeks now. I've changed plugs,wires,dizzy cap and button to no avail. Sometimes I can crank it up in the morning and don't even notice it. As it gets up to temperature, it will start again. No codes at all. I'm thinking a bad FPR or maybe injectors. Fuel pressure was at 44 psi when key is turned and around 40 running. I probably need to let it sit for 20 mins. to see if the pressure drops after pump primes to see if I might have leaky injector(s). I've sprayed throttlebody cleaner on every vaccum line I can think of and around the plenum or where there is a gasket. Sputtering exhaust is getting on my nerves.

Ken

chevyracingrox

where does the car idle? does it drop down immediately when you let off the gas? maybe its your idle air control valve. if you take it out of the throttle body and spray it with brake cleaner it could help. it made a huge difference for me. same goes with the MAF sensor. let the parts dry naturally and make sure there dry before you put them on.

ken3983

Well the car usually idles around 800 rpm according to Tunerpro. My factory tach is off. I've cleaned the IAC and passages along with the TB and it did'nt make any difference. I can come to a stop and the engine revs down gradually... it's just when the engine is at idle you can really tell it. I don't think the 3.1s came with a MAF.

Ken

jstrdn90rs

If your sure its a ignition miss...you didnt mention ignition coil or ignition module?..these two components could cause a miss when warm?.You probably need to do some more checking,to get some more suggestions.If you got some miles on those two items, I would just replace them anyway.Usually if you have a prob in the fuel system it will start hard or get flooded or not start at all... which would indicate a injector, regulator,or pump failing.if you dont have symptoms like that I would focus on the ignition and basic engine items.

chevyracingrox

if it revs down gradually that could mean one of your sensors is being thrown off. don't just start replacing stuff though. look at every sensor on that car for obvious defects. are you sure they don't have a MAF sensor? because that usually means it would have a MAP sensor instead.
its also very possible that the ignition components you didn't replace are crap but that doesn't explain the gradual rev down. how about oxygen sensor? have you done anything with that? it controls your air/fuel ratio and can cause it to run lean/rich.

gcgarner

I'm watching this closely. Please keep us informed. I am having similar problems with my new 350.

jstrdn90rs

You should have a MAP sensor.MAF disappeared somewhere around 88-89...usually when the idle gradually comes down slowly it indicates a lean mixture...or a stickin throttle cable.How many miles do you have on the engine?and other then what you stated you replaced is there anything else you did to it or had someone do to it?