So heres the deal. I have the current list of engine mods on my 02 OZ. Injen CAI, OBX header with header back 2.5" exhaust, no cats at all, and a grounding kit. I also have installed an AEM wideband UEGO guage. Heres where the problem starts. I used my car to jump a friend about 2 weeks ago. Ever since then, my charge voltage went from averaging 13.2 to 14-14.5. About two days after that, I figured out that my negative cable was loose as my car wouldn't start after work one day. That didn't fix my voltage problem. It did however reset my ecu and I'm sure we all know how fun it is to let our computers get used to aftermarket intakes again. However, it reset about a week and a half ago, and while my car doesnt die at stop signs anymore, it is idling at anywhere from 16.5 to off the charts on my air/fuel ratio. It will jump to the 14's occasionally but doesnt stay there for long. Keep in mind I am running premium fuel which around here is 92 octane. I was told my a/f should be about 14.7 to 15.2 which it is at cruise. What I'm concerned about was the under hood temps while idling. My headers are bright blue and while there isnt any cracking yet, Im sure its not far off. I just replaced the gaskets under my valve cover which were nicely cooked. I do have an openecu cable and I can download the program and defs if its something that could help me fix this issue. I didnt notice it before but didnt have the UEGO either. Oh yeah, also, today on my way home from work, I was cruising at 55 mph and my check engine light came on. I got to a stop light and it flickered and went out. I havent been to the auto store to check for the codes yet but prob will tomorrow. Anybody know whats happening to my car?

 

Why are you running premium? You do not need premium with your mods. Try resetting the ECU again and see if it fixes the problem.

 

I run premium because I get an extra 50 miles to a tank on it. If I drive normally. As far as the ecu, I have reset it twice since the first time.

 

Premium is bad for your car, if you're not tuned to run it, you can't use it correctly. Because premium burns slower, you're actually wasting it's potential since the car's ECU is setup to run regular which burns faster. What you're seeing is probably a placebo effect more than anything else.
Have you rechecked the intake install? Also, did you put a spacer on the rear O2 sensor?

 

I would say try tuning it. And if your cars never used premium it might react different since its a lot cleaner and could've cleaned out your fuel system.

 

Yes I have a rrm spacer on the rear. I've used premium for the last 6 mo's with no probs on the a/f till now. And the intake install was the first thing I checked. Found that my mounting bolt is broken but nothing that should hamper anything that would have to do with idle. I thought that our cars had a high and low octane fuel map available. Only run 76 gas if that makes a dif to anyone.

 

And as far as gas is concerned, im pretty sure all this ethanol crap theyve put in any of the gas has pretty well cleaned out my fuel system. Or hampered it.

 

The type of gas shouldn't affect the A/F ratio, and no, the car doesn't have a high and low octane map, it has a normal map and an emergency map. If you get a bad tank of gas, it'll resort to the emergency map to protect itself. It has no map to utilize octane above the recommended grade. Most turboed cars have a high and low octane map but that's because they're designed to use high octane in the first place. If you put race gas into a stock Evo, it won't suddenly make massive HP.
I would think that your issue is either intake related (maybe a leak somewhere) or fuel related (it's not injecting the right amount at idle). You could try cleaning your TB, running sea foam or fuel injector cleaner.

 

Yeah im assuming its your intake its making your car idle weird and with the maf sensor when having a aftermarket intake it can cause it to idle low. Mine use to do it sometimes also.

 

K well I ordered a g93 intake that im going to port out and I will make sure to clean everything very well when I change the g94 out. I will find out what error code it threw if it stores it long enough and update you guys asap. Would if be safe to richen my fuel at idle through ecuflash? Or is that a no no? The only prob I seem to be having is at idle. Or could you point me in the direction of someone who'll make a custom map for premium?

 

Why not just go back to using regular? It'll be cheaper in the long run. I doubt you'll gain a lot of power with a reflash, your mods are pretty minor and I don't see the point in spending the money for a proper tune when you already have a perfectly fine tune from the factory.

 

ok so say i wasnt looking for power and just wanted to fix this lean idle. Could I and would it be safe to use ecuflash to rich out the fuel at idle rpms? If it can do that? Im not too familiar with the program but have an evo friend who has uses it religiously.

 

I think you could do that.