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New MAF = Backfire

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Old 09-18-2010 | 10:16 PM
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Default New MAF = Backfire

Borrowed a rebuilt MAF from Roger and installed today.

Originally did this to see if it would cure a surging issue I had a low RPMs.

Installed and noticed first:

It took longer to crank and fire the first time I started it up.

Tach "searched" up and down between approx 750-900 RPM for about a minute.

Went for a drive and it seemed there was a little low rpm stumble.

Pulled over, turned off the car. Started car and it does seem to turn over, start quicker and start smoother than with the old MAF. The car also used to idle at the notch below 1000 rpms. (about 850-900 i guess?) Now idles about a notch lower smother and quieter than with the old MAF.

If I have it stopped and at idle, I rev the motor quickly it seems to hesitate off idle. When I rev it quick and to high RPMs it will backfire every time. It NEVER backfired with the old MAF.

Should I pull the Neg cable and see if I can reset everything???

Looking for input.

Thanks!!
Old 09-18-2010 | 10:28 PM
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As I was reading, the first thing I thought of was resetting it. And making sure you put the MAF in right.
Old 09-18-2010 | 10:38 PM
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I will reset it.

The MAF only has one hook up on the side. It clicked in and I made sure it was seated well. Also made sure the MAF was seated into the lower elbow and the clamp was tightened.

Will pull the Neg ground, reset and see how she goes. If this does NOT cure, any ideas??
I didn't change ANYTHING else.
Old 09-19-2010 | 12:19 AM
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Default Just to be sure.

Originally Posted by Chuck Schreiber
I will reset it.

The MAF only has one hook up on the side. It clicked in and I made sure it was seated well. Also made sure the MAF was seated into the lower elbow and the clamp was tightened.

Will pull the Neg ground, reset and see how she goes. If this does NOT cure, any ideas??
I didn't change ANYTHING else.
Hi Chuck,
Double check the MAF plug to make sure the connections are clean and seating in properly. (DeOxit maybe?)
Old 09-19-2010 | 12:28 AM
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Reset and verify that the MAF is properly inserted.

However, if it is still like this after then you need to pop the intake off and reseal.
Old 09-19-2010 | 12:28 AM
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Gotta unhook the battery ...
Old 09-19-2010 | 12:40 AM
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Default And then

Originally Posted by Tony
Gotta unhook the battery ...
Go for a refreshment............
And then hook it all back up again and ....and...and....
Old 09-19-2010 | 01:07 AM
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I didn't mean plugged in wrong, I mean upside down. The MAF has an arrow showing which way the air should flow.
Old 09-19-2010 | 03:00 AM
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If that continues, try another unit. From even the best rebuilders, I only get about an 80% success ratio. I now keep an absolutely perfect Bosch unit as a "control", so I can confirm AFM problems.
Old 09-19-2010 | 07:00 AM
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Double check MAF is installed OK. Do a battery disconnect, drive for a few miles.
Old 09-19-2010 | 01:22 PM
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Thanks Guys,
Battery Disconnect cured problem.
Throttle response back and no more backfire.

Seems to idle a little lower than with the other MAF.

Car pulls like a ****!!! Took my son out this morn for donuts and romped on it out of first gear. He had a big smile on his face!!

Sean, when I put it in, I matched the orientation to the old one. Definately would look different if you oriented it upside down.

Noticed that the rubber seal to the airbox is a little buggered up, need to grab one of those from Rog.
Old 09-19-2010 | 01:54 PM
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Default In yr own words yr ****'d

Hook up a hammer and run the adapter mode test.
Old 09-19-2010 | 02:35 PM
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Excellent !

Your LH would have been trying to adapt to your old MAF, Those parameters are held in SRAM which looses its data when you unplug the LH or do a battery disconnect.
Old 09-19-2010 | 03:47 PM
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John, Got it. Good to know for future ref.

Herman, I'll get Sean to run it next time I'm over there.
Old 09-19-2010 | 04:12 PM
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Originally Posted by John Speake
Excellent !

Your LH would have been trying to adapt to your old MAF, Those parameters are held in SRAM which looses its data when you unplug the LH or do a battery disconnect.
So, is that just the "O2 adaptation" or another one?



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