MAF swap
09-08-2009, 06:42 AM
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MAF swap For anyone that has ever swapped, or tuned a car that had changed the MAF from a 75mm (ls1) to a 85mm (Z06) MAF, what type of issues did you have?
I have a blown car that I swapped out the MAFs, and now the car will barely run below 2000 rpm. I haven't tried to drive it, but it is running PIG rich, surging, and stumbling badly until it reaches 2000rpm I am getting some help on trying to tune it out, but my concern was that the MAF (came with the used blower) could be bad and I'm wasting my time.
I have a blown car that I swapped out the MAFs, and now the car will barely run below 2000 rpm. I haven't tried to drive it, but it is running PIG rich, surging, and stumbling badly until it reaches 2000rpm I am getting some help on trying to tune it out, but my concern was that the MAF (came with the used blower) could be bad and I'm wasting my time.
09-10-2009, 08:49 AM
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) have made a few adjustments to the idle base airflow and MAF airflow table. It runs a little better at idle, but when you ease into the throttle, it smothers and the AFR goes to 10x-11x. It will not run well enough to even move the car.I guess my primary question is;
Is it typical for a small change in MAF size to make a car go from performing perfectly at idle and part throttle, to not even running, or is it possible the Z06 maf I installed is bad....
09-10-2009, 09:23 AM
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I have swapped on 85mm screened and descreened
MAFs, even ported out an 85mm just for yucks. You
have to expect anything you do, may need tweaking.
The descreened MAF types are going to be more sensitive
to airflow nonidealities (bends etc.) and reversion (the
one I ported, became very unstable looking at low RPM
after I hacked out the center airfoil).
The 85mm and 75mm are fundamentally different curves
and diverge further, the more air they see.
If you read about 2500Hz at idle then the MAF is not
"bad", just misunderstood.
MAFs, even ported out an 85mm just for yucks. You
have to expect anything you do, may need tweaking.
The descreened MAF types are going to be more sensitive
to airflow nonidealities (bends etc.) and reversion (the
one I ported, became very unstable looking at low RPM
after I hacked out the center airfoil).
The 85mm and 75mm are fundamentally different curves
and diverge further, the more air they see.
If you read about 2500Hz at idle then the MAF is not
"bad", just misunderstood.
09-10-2009, 10:43 AM
#5
Changing MAFs has a huge impact. If you are running more than about 7psi, you are maxing it out too.
Just put the car in OL, put it totally 'on the MAF' and tune to make actual measured AFR = commanded AFR.
You should be able to have a new curve built up like this in just a few minutes and all will be well again.
09-10-2009, 06:30 PM
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Hmmmm... My MAf reads approx. 4300 at 900 rpm, adn around 4950 at 2200 rpm. I'm haveing trouble getting my inovate wideband to read in hptuners to log, but the car is runing pig rich at lower rpm
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09-11-2009, 06:39 AM
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When you refer to "knocking the scale down by hand", are you referring to adjusting the MAF airflow table, and if so, what area and how much to get started?
Thanks
