adjusting MAF

[n2brk]

Hello -

I have a problem... well, more accurately I don't have a problem! I replaced my last air filter last week (one old Donaldson swapped for a new Donaldson of the same appearance and part number). With the new filter, I get a MIL and Reduced Power within a short time idling. If I clear the code it comes right back. If I drive down the road and clear the code while underway, it will not come back again until I am idling.

I yanked the new Donaldson and put in my old dirty one -- problem GONE.

I data logged both filters with regards to MAF and frequency. '

old: 5.4lbs/min at idle of approx 37khz.
new: 5.7lbs/min at same as above.

Max showed the new spiking to 5.93lbs/min and the old maxed to 5.5lbs/min.

IMHO there's no problem here. So I'm thinking that I need to re-scale my stock MAF numbers. Agree? If so... help? When I go to my table I match 37khz to 7.10lbs/min, and it confuses me! I was expecting a lower number!!!

Hopefully someone can explain this a little and help?

Thanks in advance!!

Wally

[n2brk]

C0903 looks like I could set it to 6 and be done with this. Maybe?

[jay p]

I had a similar problem with my 2010 except it was at highway speed. I ended up replacing the MAF sensor and the problem is now gone. This happened at about 100,000 miles. They are not cheap, but I would replace your MAF before you mess with the scaling of the MAF.

Jay

[n2brk]

Thanks for the reply. Perhaps in your case the MAF was at fault, but with the data that I logged it doesn't appear that way with mine. Add'l reading has lead me to believe that the truck is looking for approx 5.3lbs/min at idle and with the Donaldson flowing perhaps a bit better than AC Delco, these numbers are believable. Plus, my MAF seems to pick up the slight difference between a clean and dirty filter, which again makes me think it's working properly. I'm all ears if I'm wrong though!!! I'm trying to learn

[n2brk]

bump. Any other opinions/advice? Thanks!

[Mitco39]

I would just increase the error limits slightly on the MAF and go with it. All that is happening is the truck says it should be ingesting XXX amount of air, now with a freer flowing intake its ingesting just enough over and above that table to make the ECM think that the sensor could be faulty. There is no expected airflow tables in the EFILive tune and you don't want to trick the MAF in this case since you know its fine. I would just increase the limits like you suggested and see where that leaves you.

[n2brk]

I tuned out the code tonight after logging this same filter in my buddy's LMM with no CEL on his truck; with slightly lower flow numbers. It's really odd but I'm ok trusting the filter. Thanks