I have come accross the craziest problem with a local guys evo 8. He said one day it went to running crazy so he brought it to me to see what was going on. It runs super rich all the time. 10.0 afr. He replaced the maf, cam sensor, plugs,coils... all the usual stuff.

So i get some datalogs and this thing is going crazy. The engine load at idle is 95% which is why its running rich obviously. The crazy part is i can pull the MAF off the intake pipe and the engine load remains at 95% running pig rich even with the maf off.
The other weird thing is if you give it 20% throttle the load instantly jumps to 130ish and then slowly makes its way up to 300 load WITHOUT changing throttle position!! At this point the motor almost dies from fuel. It also does this with the MAF disconnected from the intake pipe.

Everything seems to be working fine although the maf reads high. All other sensors read as they should. I have already tried a different ecu and it does the same thing. Here is the datalogs, I have never seen anything like this in my life.

How do i post the datalog? evom says it does not accept a .csv file.... what gives?

 

sounds like the map sensor is bad.

 

ditto

 

yea but i can unplug it with no change... So should i be checking wiring? In the datalog it just reads 0 at idle. Is that wrong?

 

A logable map sensor should read a negative value at idle.

 

Thanks guys, i was under the impression it only read positive preIssure. I will get one....

 

BTW, to post logs put them in a .zip archive. Then you'll be able to upload them. Or just change the extension to .txt and leave a note for us to change it back after we download it.

 

Oh OK cool. Thanks man!

 

Bringing this thread back from the dead. I am having almost the same issue with a car right now. It idles at 10.0 and the load value at idle is about 95, MAF Hz are 100.

Injector scaling, maf scaling etc. is all correct. I have switched the maf with the same result. I have tried multiple different roms in case the rom has been corrupted, same thing. I now suspect something is wrong with the ecu but I don't have a spare to swap it with.

I am going to get a different ECU to try but in the meantime does anyone have any insight?

 

Nevermind, I'm an idiot. Got to thinking that the Maf hz value is a measured value so the car must be physically measuring increased airflow (seeing as the MAF is good). So the culprit must be a massive boost leak, which I found in short order.