Another Rough Idle Problem

[sethoo7]

I searched on the forum but nothing came up similar to my problem.

When I start the engine cold or warm (sitting about 1 hour) I get a really rough idle. It's almost like its got a dead cylinder. I tried a few things. I couldn't get to the MAF because of the security nuts. I cleaned the throttle body intake butterfly valve. I am aware of the cylinder like thing thats right next to the intake is that the IAC people talk about? It has the plunger like thing when i took it off about a year ago (Haven't cleaned that yet). With the plastic air stuff off the air intake it still idled the same. (Air flow not the problem, except maybe plunger thing). I started looking at the fuel system.
A while back I replaced the fuel pump relay because it was having difficulty starting in really hot weather.

The rough idle and engine rev has been consistent for the past two days. This morning I got fuel injector cleaner and added it. Now when i drive for about 5 minutes its like the engine idle and rev smooths out like its firing on all cylinders agian. I've started and stopped three times today running various errands and its the same. I let it sit for an hour and come back to it and it starts rough then smooths out after 5 minutes on the road.

Also rarely when starting I don't hear the sound of the fuel pump or vacuum when I turn the key to on but not cranking and everytime the car doesn't start.

At this point I'm thinking maybe the fuel pump or something to do with the electrical part of the spark plugs. Any Ideas.

 

[MrShorty]

I think I would start by pulling codes from the computer. The computer monitors the fuel pump circuit and will leave a code in memory if it can't start due to an open in the fuel pump circuit. If the no start were aresult of things monitored in the ICM, you might also get a code. If you get no codes (you should get pass codes if all is well), then there may be a problem in the computer's power/ground circuits, which can cause no starts.

Verifying the fuel pressure, preferably with a guage, when it won't start would also be a good idea.

 

[sethoo7]

a step ahead of ya took it in today for a computer read. thanks for the reply.

 

[410Fortune]

Use a small flathead and a hammer, the center pin on those "security" screws will pop out with zero effort, then you can use a regular T bit.

Or get the security bits at your local auto parts store.

I have also used vice grips to loosen those buggers.

First thing to do if you have a CEL is pull codes.

Second is clean MAS.