As I have posted before, my evo idles very rough, with an intermittent stumble or "miss". When I started the car up leaving my office parking lot this afternoon (the engine was fully warmed up already, and the a/c was off), it began to idle at around 600 and struggled to stay alive for the first 5 seconds, then raised up to the "normal" (for my car) 900-1000. I will be taking it in to the dealership, but would like to know if anyone has had a similar problem. I was thinking bad coil pack? If anyone has some insight as to what the problem might be, it would be greatly appreciated.

Thanks,
-Dave

 

Anyone? Feel free to voice your opinion or share a similar experience/resolution.

 

Bad gas, vacuum/boost leak (hose off or loose), MAS unplugged, bad or disconnected IAC motor come to mind right away. Is the check engine light on?

 

It sounds like a boost/vacuum leak (Like the above poster noted).

I'd recommend checking all of your intercooler piping and associated hoses for leaks.

 

...On a funny note, when I first tried to install my AEM intake, I forgot to reattatch the ECU to the MAF. I couldn't figure out what the hell was wrong with my car.

 

Your normal idle seems a little high (1000), should be right around 850 after it warms up... 600 is low, is your battery ok? What about your spark plugs, have you checked those? (just throwing out idea's) hmm... yah check for leaks, and it says you live in FL so I take it that its warm there so it wouldn't be the weather......... good luck.......

 

Boost or vacumm leak.Do you have a boost gauge or anything to moniter the pressure lvls of the engine. You may have a lose hose or disconected line somewhere in the engine bay. Any mods to your car?

 

No boost controller. No mods. Always been like this, but I've never had that incident with the extremely low idle upon startup. Car seems to run ok once revs are up. Very strange...
Also, the idle is somewhat erratic. It will be at 900, then rise to 1000, then a little later fall to 850, then rise to 1000, all this with the a/c off. Thanks for all the replies so far guys.

 

I doubt it's a vacuum leak if it corrects itself within a few seconds. Everyone I've had makes it idle like ***.

Now, that's on a subaru...and you know crazy insane crazy those are *grins*

 

I went to the dealer and they checked it over. Hooked it up to a live data machine. Found nothing. Maybe the grounding kit will help.