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rumdomrum
May 1st, 2016, 09:14 AM
Hey everyone,
I've been dealing with this C7 Corvette that the owner put a blower on. The MAF was so turbulent the trans would shift terribly at partial throttle. The MAF voltage looked like a saw tooth wave at steady state around 4k rpm. So I unplugged the MAF and turned the associated MIL to "NO MIL". The trans shifts MUCH better and the car drives great, HOWEVER, the MIL keeps coming on.

If I want P0102, 103 and 104 to stay off, do I also have to eliminate some others?

Please help.

Many thanks.

GMPX
May 1st, 2016, 10:06 AM
Pretty sure the MAF on these integrates other sensors, you can't just unplug it.
Another strategy is to go to the engine diagnostics section under MAF and force it to fail by putting in values to the tests that will cause it to fail.
Have a look at page 4 of the pdf below, it details what to set the MAF failure test values to.
http://download.efilive.com/Tutorials/PDF/Virtual%20VE%20Adjustment%20Tutorial.pdf

rumdomrum
May 2nd, 2016, 05:11 AM
The car has an IAT and BARO sensor break out kit. Both Baro And IAT are working and tracking properly, however, when the MAF codes come in, so do the IAT codes.
But again, IAT is working properly.
I truly believe it is an error on the EFILive side.
Why would an iat code come in when it works perfectly?

GMPX
May 2nd, 2016, 07:32 AM
I truly believe it is an error on the EFILive side.
Why?


Why would an iat code come in when it works perfectly?
You hadn't said anything about any IAT codes in your first post, what P code number are you getting that is IAT related?

Just a reminder, you cannot disable the MAF DTC's if the MAF is unplugged or the car won't run, the ECM has to know the MAF has failed so the MAF DTC tests must remain active. So all you need to do is turn off the MIL for P0102, P0103 and P0104 but when you check on a scantool with the MAF unplugged it will always show P0102.

rumdomrum
May 2nd, 2016, 08:47 AM
Why?


You hadn't said anything about any IAT codes in your first post, what P code number are you getting that is IAT related?

Just a reminder, you cannot disable the MAF DTC's if the MAF is unplugged or the car won't run, the ECM has to know the MAF has failed so the MAF DTC tests must remain active. So all you need to do is turn off the MIL for P0102, P0103 and P0104 but when you check on a scantool with the MAF unplugged it will always show P0102.

I apologize for the confusion. The title of the thread is MIL for MAF and IAT won't go away. I put "NO MIL" for the MAF only.
I was under the assumption that the car wouldn't throw an IAT code with a functioning IAT. Obviously that isn't the case.

There were two other codes that also came in that didn't have descriptions.

I'll get all the numbers and report back.

Thank you for your attention.

GMPX
May 2nd, 2016, 08:54 AM
I was under the assumption that the car wouldn't throw an IAT code with a functioning IAT. Obviously that isn't the case.
Well there is sanity checks on expected operation too, they monitor things pretty tight.


There were two other codes that also came in that didn't have descriptions.

I'll get all the numbers and report back.
No worries, let us know what they were and we'll see what we can figure out.

I know there is numerous DTC's that have no description but believe it or not on GM's own service website these missing one often don't show up either.