Hello all,

I have a 05 EVO8 with all basic bolt ons plus FIC injector, cams, turbo, fuel pump.

The battery died last week, recharged it and started it. The car runs very rich all of sudden, looking at the AEM UEGO, the A/F is @ 11-12ish, normally it is between 14-15ish.

The car ran fine before the battery died, and I know the Tune won't go off by itself.

One thing I suspect now is, I swapped my spoolinup ignition kit with a friend, and I took his OEM coils with Ralliart wire. The car started and ran fine with the OEM setup the day I swap the kit. But now after the battery died car runs very rich, pull the plugs, they were all fouled.

My car is tuned with spoolinup kit, I'm going to switch the ignition kit back, but could the individual ignition coil kit makes this big of difference? The car won't even stay on b/c of rich A/F.

What else could it be?

Thanks for your help!

 

That rich at idle, cruise, or WOT? Posting in the right section will help too.

 

Upate: I have attached a copy of my log, pay attention to the voltage, it's only 1.466 volt once it's started.

Hello all,

I have a tuned 05 EVO8 with all basic bolt ons plus FIC injector, cams, turbo, fuel pump.

The battery died last week, recharged it and started it. The car runs very rich all of sudden, looking at the AEM UEGO, the A/F is @ 11-12ish, normally it is between 14-15ish.

The car ran fine before the battery died, and I know the Tune won't go off because of the dead battery.

Thanks for your help!

 

I don't have access to any manuals right now but I remember reading that the car has a system whereby the voltage to the injectors is kept constant. Possibly, this system, as the old manuals translated from Japanese say, is troubled.

 

hey thanks, I think that will be a good start, subscribe to this thread if you come up with anything new, thanks again!

 

I was a little off base, the Evo has a resistor pac that limits the amount of current flowing through the injector coil. The injector coils themselves are low resistance for quick current rise and quick action. I'm not sure a problem there would cause what you are seeing.

 

Hey thanks for your input.

Update: My friend swap my ecu and injector (oem) with another evo, the car started right up, my friend says it's the software in the car makes it runs rich?

But how can the tune go off when the battery died?

 

maybe ecu reset kind of thing?

 

seems like it... but i'm afraid the ecu is malfunctioning

 

Your tune is fine but your fuel trims reset when the ECU lost power

 

Yes, I've heard about this, and I have had dead battery and have unplug the ground to the battery before but the car never run this rough

 

bump for help

 

ttt

 

evo 8 fuel trims don't reset with a battery disconnect.

the injectors are not on a voltage regulated circuit. if battery voltage drops during engine operation, then injectors latency increases. there's a table in the ecu code that stores the inj latency as a function of battery voltage. if those values are not accurate, afrs will fluctuate. the biggest fluctuations will be at idle and cruise where inj latency is a big fraction of the total pulse width.

 

They do from my experience. They don't reset when you reflash, but once you cycle the power they reset.