Ok I have been having problems with my camaro, hesistation, intake backfire when trans shifts in 1st gear, failed emmisions with the preivous owner. This is what happened, took a long trip yesterday 50+ miles on the way I would here a pop sound followed by the ses light which would go out a couple minutes later. Today I decided to get my scanner and check it out , found a code for the maf sensor (48) clear the code and drive it. I watch the readings as I drive and see no real problems. So I figure I'll get a couple o2 sensors, tps and map sensor, thinking it was running lean causing a backfire through the intake thus a false maf reading. Well on the way back to the shop (scanner reading data) I punch it while going about 80mph same thing , pop noise and ses on. I set my scanner up to log data and try again when it happens I triggered capture mode. Pulled into the shop and started watch
the data and this is what I found:

WOT ALL DURING THE FOLLOWING:

WOT/Downshift

upshifts at 6100 rpm?? (stock pcm programming)

revs now at 4235rpm all looks right on spec

revs lower to 3658 and all hell breaks loose -maf drops to 12 gms ,pulse width drops to 5ms, spark avance 33*

next frame -maf drops to 6gm/sec, 3ms pulse width, sprak advance 33*

Next few frames Maf bounces around very low then at
3740 rpm maf jumps to 471gm/sec 22.1ms plse width, spark advance 33*.....Bingo

I tap the maf a couple times and it drops to 2gm/sec then returns quickly to 6-7 gm/sec at idle

Now does this mean it is definitly the maf or perhaps a wiring issue??
(I assume its the maf)

 

ok maybe I should ask a different question, has anyone had similar problem?

 

If you suspect a connection/wiring problem, wiggle and play with it while monitoring it with a scanner to see if you can make it fail.

 

what is confusing is thathappened after it shifted ,I tried moving/pulling on the wires. no change. guess I'll get a maf first to eliminate it.

 

Sounds like the wiring.. I had the same problem in the past. A few times the MAF cut out while I was doing 20-30 in traffic and it actually caused the motor to stall.