Ive been helping a buddy get his truck switched over to a 2bar. Its a 99 4.8 with a whipple on 8lbs. I've never messed with a 2 bar before.

I upgraded the os, copied the old ve to corresponding areas on the upgraded os, and set these codes to no error: 0101,0102,0103. The truck will not start. It smells ridiculiously rich.

I checked the scanner, that is not setup for a 2 bar yet, and the map sensor read 105kpa during cranking. It never budged. My buddy told me the sensor was for a 2005 or 2006 cobalt ss. It was purchased from o reilys. I'll put a link below to show which one I THINK IT IS.

MasterProŽ Ignition 2MS15 - MAP Sensor | O'Reilly Auto Parts

Does this sound like a symptom of the wrong map sensor?

 

When you upgraded the os did you do a write entire? What are you using to tune? Set the offset and slope correctly?

 

Yes I did a write entire. Each revision after, I just did a write calibration. I'm using hptuners to tune with. Map Sensor Linear: 200kpa , Map Sensor Offset: 10.33kpa

 

I dunno about the sensor...what is the output voltage with key on engine off? Should be about 2.45v.

 

Output voltage reads 4.8v with key on, engine off. I'm guessing I dont have my config setup appropriately to see the full range of the map. So, this could possibly be reading 210kpa. Ive heard of some of the wrong map sensors reading backwards.

 

Aha! That is a 1bar map. The pcm figures out what the pressure is based on the voltage...the sensors sole purpose is to output the voltage relative to the pressure it sees. A 1bar map will read ~5v at 1atm, a 2bar will read 5v at 2atm, 3bar 5v at 3atm, etc. Also works for half way in the range... 1bar will read 5v at 1atm, 2bar read 2.5v at 1atm (half its range), 3bar will read 1.67v at 1atm (1/3 its range).

You want the GM P/N: 12580698 or AC Delco: 213-1631

 

set the MAF codes to NO MIL LIGHT. Having them set to no error will not fail the MAF.

 

THANK YOU SO MUCH! This makes perfect sense. I do have a question about this though. I understand the 1 bar map reading 5v/105kpa with the key on and engine off, but why did it not fluctuate at all during cranking? Surely cranking should have created some sort of vacuum. Is it because the upgraded operating system?

EDIT: Just checked the logs and the MAP KPA stayed at 105kpa, but the MAP Voltage went down to 2.8V.


Thanks bud. I didn't realize this. I will set them up appropriately on the next revision.

 

When you log map make sure you log the special 2 bar one, and not the normal one. It should be the next one on the list.

 

Yes only a dealer can get a 2 bar.