MAF reads air when you let off the throttle

[Dwayne]

When I let off the throttle, such as a burnout, my car wants to die. It acts like it is pig rich. I've been told that when you let off the throttle that some of the air passes back over the maf. The maf reads it as incoming air and tries to add a little fuel. This problem is really annoying especially with the bigger injs. Has anybody figured out how to get the ecm to ignore the maf reading when say the tps is under a certain value? Or should I just break down and buy the FAST system.

 

[bruce]

Originally posted by BigDaddy
When I let off the throttle, such as a burnout, my car wants to die. It acts like it is pig rich. I've been told that when you let off the throttle that some of the air passes back over the maf. The maf reads it as incoming air and tries to add a little fuel. This problem is really annoying especially with the bigger injs. Has anybody figured out how to get the ecm to ignore the maf reading when say the tps is under a certain value? Or should I just break down and buy the FAST system.

Try readjusting your Min Idle Speed so the IAC is 0, at hot idle in drive.

Too low of min air setting lets the engine stall before the IAC can catch it if your relying on the IAC to maintain your idle speed.

The ecm has a routing called Decleration Fuel Cut Off that disables the injectors in situation like you discribe. Looking at a DC log should show it being highlighted when enabled.

If that converter is a 9", that worsens things a little since the engine has less rotaional enertia, and it can drop faster then with a big converter.

 

[STP]

FAST and be done with it

 

[salvageV6]

I thought the Fast system still used the IACV?

 

[STP]

It does...But you can tune around it.

 

[TurboBob]

What kind of MAF and chip are you running?

What converter?

What intercooler (if any)?

Bob

 

[Dwayne]

stock MAF with no screens
Precision 9" non-lockup
spearco front mount
Red's 72# chip (race)

 

[TurboBob]

Well, your stuck with MAF backflow with that chip. I believe that the reds chips handle the lighter converter ok. You might adjust the throttle stop screw until the IAC numbers bottom out, and then perhaps even raise the idle speed some with it. That may help some.

Bob

 

[Dwayne]

Bob....we have had the idle and IAC all over the place, but nothing seems to make a difference. Red is the one who told me about the MAF backup. He even said he had a fix for it, but it wasn't ready for the public.

Bruce......I looked at some of my DS files and it shows the deceleration mode coming on when I let off the throttle.

 

[TurboBob]

DFCO won't help this since the LV8 is too high from the all the measured MAF flow.

Perhaps red will get his working in time for next season. In the mean time I guess you will just have to be careful when you drop the throttle.

BTW, Extenders and Extremes have had software to fix this for 4 years. (Shameless plug) These won't work with the stock MAF though...

The MAX-E has a fix for this also if my memory is correct.

Bob

 

[STP]

I say MAXE or FAST Dwayne.....I've run both the ME and FAST with success. If anyone can work around that problem it's Steve Yaklin at ME

 

[Steve Y]

The Max E has a fix for that as Turbo Bob said.

His Extender programs work very well also.

Steve