I'm in the process of a blackbear tune and I'm trying to find the problem. The problem is that the MAF is reading a certain amount of air intake, but the engine itself is seeing more. Most obvious answer is a leak between the MAF and Intake Manifold or a bad MAF sensor, but I'd like to check other options before swapping MAF's

-I cleaned the MAF (mine has been descreened as well)
-Took the Throttle Body off and made sure the seal was good
-Checked ever connection between the filter and TB
-Made sure the Intake Manifold bolts were tight
-Brake booster line was secure
-Fuel Pressure vacuum line was secure

I'm trying to arrange to swap MAF's with some people, but I'm just trying to have a backup in case that doesn't solve the problem

thanks
-John

 

does it have stock injectors? my trims were high when i had it tuned for the wrong injectors. also any exhaust leaks?

 

stock injectors, as far as I know.

there are slight exhaust leaks at the LT/ORY connections, but none before the primary O2 sensors. Those tiny leaks go away when the pipes warm up and expand.

 

I'm really hoping swapping MAF's solves the problem. It's got me losing sleep and study time not knowing the problem, I just wish I could acquire a MAF faster haha

 

have you tried to re-cal the MAF . . . % error checking? . . . since it's descreened

 

how do you do this?

When I'm logging, the LTFT bank1 is upwards of 20% and never goes negative and is rarely 0.0. The LTFT bank2 is somewhat better but still bad. Most it ever saw was -4.8 and that was at one small point in a 20min drive

not sure if that's what you're asking

edit: I bought the truck descreened, so I'm not sure what needs to be done

 

Swapped MAF's and apparently that was the problem. I'm going to work on finding one now in a reasonable time frame so Justin can work his magic...

-John

 

Any exhaust leak could affect the 02 read outs...
***Edit*** Any exhaust leak near or before the 02's....

If it is getting tuned why not calibrate the maf? (this is one of the many things your tuner will do) In other words, how do you know anything is wrong with the maf (other than it being de-screened)

 

I really don't, but the problems went away after swapping MAF's with another stock truck... I think it would be dangerous to assume what the engine will do and compensate for that without a 100% sure reading from the MAF.

 

That is what the trims are there for, to compensate... Yes, ideally you don't want to use them. That's closed loop for ya.....

So the new maf got the trims back in line?