I am finally getting around to trying to get a decent street tune on my car, but have an issue I need help getting figured out. My setup is a ZPI stage 0 kit with a SSQV (waiting to put my intercooler on until I get this issue figured out), RC 440 injectors, and an AEM F/IC. I have done the injector compensation to get the fuel map adjusted for the larger injectors (it set all cells to -15 IIRC) with no adjustments other than that so it is running pretty much off the stock ECU. I have pulled timing a little bit when I am in boost (one degree per PSI of boost IIRC).

The issue I have been having is when the engine is under load and I am going up in the RPM band. My UEGO goes from 14.5 and drops suddenly to the 10.0-10.5 range and stays down there until I let off the gas. It isn't a smooth transition and drops very quickly. It seems to be more reliant on how much air the turbo is moving rather than the boost pressure itself. It makes me wonder if it has to do with the MAF sensor voltage getting too high and causing it to make the car's ECU go super rich.

Has anyone else experienced this issue and if so, how did you go about correcting it? I want to take care of the sudden drop so that I can work on tuning the car for a nice gradual drop in the A/F ratio.

 

Send me a copy of your map to my work email addy at nicholas_pound@dell.com - also have you tried resetting the ecu?

 

Yea, I have disconnected the battery and left it off for a while and it does the same thing once reconnected. That is why I think it is being caused by the MAF being "overloaded" and dumping fuel because it doesn't recognize boost.

The map I am using right now is simply -15's in all of the fuel map cells and I pull 1 degree of timing for every PSIA over 15PSI. That's it. I want to figure out my A/F problem before starting to really "tune" though so I am not fighting with it.

 

so all your fuel map is all on negative even on boosted area and still run that rich or you are talking about the ignition map? that seems odd, you should be adding fuel when you are boosting other wise it will be lean.. rc 440's are high impendance right?

 

You did something wrong if ALL cells are -15. It doesn't work that way. I made a base fuel map for 440cc and it ranges from -27.3 to 33.6.

Right click in the fuel map, create base fuel map. New size = 440. Stock size = 320. Max RPM = 6400. Max PSIA = 20.

 

My bad, I meant I did the injector compensation wizard thing since my car ran fine off the ECU with a zeroed out map before the different injectors. I'll try and create a new base fuel map and see what happens. However, I am not sure how adding more fuel will help my problem with my car going super rich.

 

It won't be adding more. The base map, in all vacuum is -27. Doesn't get up to 33% until 15PSI of boost.

I'd suggest just getting a Dezod Map or some kind of base map, and just starting with that. The O2 map and MAF map are just as critical as the fuel map, and those 2 maps are nearly impossible to write.

Also, drive with someone in the car, and keep a laptop plugged into the F/IC. Use the Gauges in the F/IC to help determine exactly where on the map you are. It helps A LOT. I tuned without using this and it took me forever, since I only made changes everytime I got out of the car. With another person and a laptop in the car, I was able to finish fine tuning it in about 10-15 miles.

 

Thanks Carbon. I'll try to play around with my maps over the next couple of days and see what I can figure out.

 

did u say u ran fine on stock ecu on injectors? im still trying to find out what the a/fs are for a stage 0 with no tune

 

Yea, my car was running ok on stock injectors except at full boost at higher RPM's where my duty cycles were maxed out. I can't remember what the AFR while in boost was though.

 

If all you did was the injector compensation and didnt alter any other values, you are basically running off your stock ECU like you said. That is why you are dumping fuel under boost. The stock ecu sees more air so it compensates and adds more fuel. Until you put in your values and TELL those injectors what you want them to do, the stock ecu is just going to do what it wants.

 

and i think that is a lot of timing you are pulling. alot of people are only starting to pull timing around 9-10psig