Really rough idle in the morning.

[Vortech347]

Lately its been getting worse and worse.

I start the car in the morning and almost immediately it starts idling super rough. If I put it in gear while its doing this the car will surge like it has a MONSTER cam. Only does it in the morning or after its say for 12 or so hours. I thought maybe a COP was taking a crap so I swapped the ones from my Terminator. Nada, still there... Also pulled codes...Nothing there either. Fresh spark plugs as of last fall. After about 30 seconds of this ******* idle its fine.

Other than that the car runs f'n awesome. Pulls hard, smooth running, and is knocking down 19-20mpg average.

I'm thinking maybe the idle air control is giving me issues. Going to blast that out with brake clean next.

Any other ideas?

[MOTOWN]

I would look at the FPRS, or the fuel pump.

[Vortech347]

I would look at the FPRS, or the fuel pump.

That's true, I forgot about that rail sensor. I've got a spare. I'll try that as well. But usually when they take a dive don't they throw a code?

[MOTOWN]

That's true, I forgot about that rail sensor. I've got a spare. I'll try that as well. But usually when they take a dive don't they throw a code?

Usually the car wont start at all

[ctrlraven]

EGR? 30 seconds or so would allow it to warm up some.

[Vortech347]

Usually the car wont start at all


It starts fine. Just idles like crap for a little bit.

[JoeBoomz]

To me it sounds like some sort of vacuum leak. Odd that it only happens for 30 seconds though. Maybe something is expanding that seals it up. Do you have a boost/vacuum gauge installed by chance?

[ChiTownMaraud3r]

Sounds like an MAF, IAC or EGR related issue. I have heard other Marauders surging when cold, mine included, but nothing serious.

[MM in MN]

Don't want to jack this thread, but Chitown...what is that surging? Mine fires up perfectly, idles smoothly, runs great , no noises at all, but if I hit the accelerator at all in about the first 2 minutes of run it surges. Then it's gone. Doesn't have to sit real long, 4 hours is plenty of time...Any thoughts?

[RacerX]

If you have an sct handheld, you can log the O2s and see what's going on with afr, etc.

[ChiTownMaraud3r]

Don't want to jack this thread, but Chitown...what is that surging? Mine fires up perfectly, idles smoothly, runs great , no noises at all, but if I hit the accelerator at all in about the first 2 minutes of run it surges. Then it's gone. Doesn't have to sit real long, 4 hours is plenty of time...Any thoughts?

Not sure what it''s due to. Almost as if the car is constantly throttling it to keep rpms steady when cold. Mine's done it only when the car's sat for a while (couple days.)

[a_d_a_m]

Vortech, let me know what you come up with. My car has done this since I bought in '08. I gave up trying to chase it after ruling out the EGR, IAC, vacuum leaks, etc...

[Vortech347]

If you have an sct handheld, you can log the O2s and see what's going on with afr, etc.

I tried that. But If I start the log right after I start the car by the time the SCT starts logging the problem is gone.

Let me know your suggestions. I'm heading out of town for a few days. When I get back I'll see what idea's you guys have posted.

Thank you for your input. Considering my car is mostly stock I know I can't be the only one this has happened to. From what I'm seeing. Looks like others have dealt with it too.

[RacerX]

Turn the ignition power on, start the log, wait until you see data streaming then start the car. I've fixed a lot of cold/hot/startup issues with all my changes this way. ;)