Mass air Flow problems??
Thread Starter
TECH Apprentice
iTrader: (3)
Joined: Oct 2003
Posts: 370
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From: Woodstock, GA
Mass air Flow problems?? Hey guys,
I recently had a cam put in and tuned. It ran great untill yesterday when I had to disconnest my battery to clean the battery terminals. Now my service engine soon light is on. I used my predator and it cam up with 2 trouble codes. 1- Mass airflow sensor-low input. and 2- mass airflow sensor- high input.
Now it runs like $hit. 
feels like there is a bad tune on the car. Do I need a new MAF? If so what kind? PLEASE HELP!!!
Thanks
Anthony
I recently had a cam put in and tuned. It ran great untill yesterday when I had to disconnest my battery to clean the battery terminals. Now my service engine soon light is on. I used my predator and it cam up with 2 trouble codes. 1- Mass airflow sensor-low input. and 2- mass airflow sensor- high input.
Now it runs like $hit. feels like there is a bad tune on the car. Do I need a new MAF? If so what kind? PLEASE HELP!!!Thanks
Anthony
Check the connection on your MAF. It sounds like it's disconnected. If it's not, unplug it and disconnect your battery again for about 15 to 20 minutes. Plug the MAF back in, then the battery, and start your car. You won't lose your tune because of a PCM reset. Just the temporary information stored in the PCM.
These codes come about, when the mass air output
is way out of bed. Frequency stuck below 1300Hz
and above 13500Hz for more than 2 seconds.
The codes should clear themselves after 3 consecutive
no-problem ignition cycles. If this doesn't happen for
you then have to dig a little deeper. No reason for
either condition to exist. Unless maybe something
was done like setting the MAF fail frequency way
off to force speed density mode for tuning purposes
and then forgetting to put it back, or like that.
I'm thinking the speed density tune is now whacked by
the cam, and was not adjusted as part of the tune
(or improperly). The car learned to that situation, but
now the trims are reset by the battery disconnect.
This should improve too, with learn-time, but then
major learning is the sign of a not-good base tune.
A well tuned car will have low trims and you wouldn't
notice them being reset.
Big cams are said to confuse the MAF (reversion?)
which might add to the problem. But I would be
looking to the tuner, what did he do with the VE table
(right answer = substantial reshaping at the lower
and upper ends) and the MAF table (right answer =
"nothing" if it's a stocker) and IFR (right answer =
"nothing" if stock injectors) and PE table (should mess
around based on wideband results and/or best dyno).
Bottom line is that disconnecting the battery should
not perturb a well tuned car (idle or fueling) but
will expose the degree to which a car is making up
for tune data shortcomings, on its own.
If you have, or can borrow, a scan tool then look
at the MAF output frequency, something in the
3000Hz range for idle and 10,000Hz for WOT top
of gear is normal. Well away from either fail limit.
is way out of bed. Frequency stuck below 1300Hz
and above 13500Hz for more than 2 seconds.
The codes should clear themselves after 3 consecutive
no-problem ignition cycles. If this doesn't happen for
you then have to dig a little deeper. No reason for
either condition to exist. Unless maybe something
was done like setting the MAF fail frequency way
off to force speed density mode for tuning purposes
and then forgetting to put it back, or like that.
I'm thinking the speed density tune is now whacked by
the cam, and was not adjusted as part of the tune
(or improperly). The car learned to that situation, but
now the trims are reset by the battery disconnect.
This should improve too, with learn-time, but then
major learning is the sign of a not-good base tune.
A well tuned car will have low trims and you wouldn't
notice them being reset.
Big cams are said to confuse the MAF (reversion?)
which might add to the problem. But I would be
looking to the tuner, what did he do with the VE table
(right answer = substantial reshaping at the lower
and upper ends) and the MAF table (right answer =
"nothing" if it's a stocker) and IFR (right answer =
"nothing" if stock injectors) and PE table (should mess
around based on wideband results and/or best dyno).
Bottom line is that disconnecting the battery should
not perturb a well tuned car (idle or fueling) but
will expose the degree to which a car is making up
for tune data shortcomings, on its own.
If you have, or can borrow, a scan tool then look
at the MAF output frequency, something in the
3000Hz range for idle and 10,000Hz for WOT top
of gear is normal. Well away from either fail limit.
Thread Starter
TECH Apprentice
iTrader: (3)
Joined: Oct 2003
Posts: 370
Likes: 0
From: Woodstock, GA
Thanks Jimmyblue for the reply. I have had the cam in for over two months now and no problems. it is a 232/228 .595 .588. Bille from Prescribed power tuned the car and that is who everyone in the ATL area reccommended, he does really good work. Any other possibilities?
