Granatelli MAF?

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redmustangt

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May 14, 2009

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Jun 18, 2011

#1

• Jun 18, 2011

• #1

I just finished my build on my 04 GT (Vortech V2, Fully built heads, fully forged block, etc etc). When I start the car if I dont keep my foot on the gas it dies. Its getting good spark and fuel flow there arent any vaccum leaks.
I did buy a new Granetelli 90mm MAF and its not programmed. I was thinking that maybe that could be the cause.
Do I just need to get a tune (car doesnt have one at them moment) or do I need to do some more troubleshooting? Any info would be appreciated.

 

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redmustangt

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May 14, 2009

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Jun 18, 2011

#2

• Jun 18, 2011

• #2

Oh another thing: I have my Idle air control valve vaccum line getting pressurized air from the SC.
Can it read boosted air?

 

nyuk98gt

15 Year Member

Oct 10, 2000

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Chesterfield, MO

Jun 18, 2011

#3

• Jun 18, 2011

• #3

redmustangt:

You really will need a tune for the large MAF or you risk running lean and then you will be rebuilding. At the moment, the engine thinks that it is getting much less air than it actually is getting. Your tuner should know what to do. The isc_air table can be modified to account for pressurized air. But, at idle, there should be vacuum only (deeper vac at the throttle body where the IAC is than in the intake (upstream of the throttle body)). If the IAC air is not taken from the intake (between the MAF and the throttle body) then there is unmetered air entering the engine and this is not good!

If you installed aftermarket cams then a tune is necessary, too. Your tuner should be able to provide you with an initial tune to allow the engine to run (perhaps not very well) - just enough to get from Point A to Point B without the engine stalling every 20 feet.

HTH,

Chris

 

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redmustangt

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Jun 19, 2011

#4

• Jun 19, 2011

• #4

Im definitely going to get a tune, I just wanted to start the car after months of putting it together. All the vaccum lines are after the maf so its all metered.
So essentially I just need a good tune and then the car should idle without dying?

 

nyuk98gt

15 Year Member

Oct 10, 2000

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Chesterfield, MO

Jun 19, 2011

#5

• Jun 19, 2011

• #5

redmustangt:

Yes, the tune will get it idling nicely (assuming there are no mechanical issues like a vacuum leak). It's quite natural to be anxious to start the car but it is going to be very difficult with a larger MAF. You might try unplugging the MAF (electrical connector) since there is a table (load with failed MAF) in the tune that allows the engine to operate (reasonably well). This *might* let you start the engine and let it idle since the PCM thinks the old MAF is installed. HOWEVER, there is always risk in doing these band-aid sorts of things so you may want to just wait for a temporary tune from your tuner that will allow you to limp over to the shop for a proper tune. That's the better thing to do (patience, friend, patience!).

HTH,

Chris

 

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redmustangt

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May 14, 2009

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Jun 20, 2011

#6

• Jun 20, 2011

• #6

Yeah I tried unplugging the maf and starting the car but that didnt keep the car from dying. Im going to route my IACV vaccum line to my intake before the SC and see if that yeilds different results.
And patience is good advice, I just want to at least listen to the car cuz between deployment and building the motor I havent driven the car in almost 18 months

 

nyuk98gt

15 Year Member

Oct 10, 2000

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Chesterfield, MO

Jun 20, 2011

#7

• Jun 20, 2011

• #7

redmustangt:

Off topic: Thank you for your service to our country. Are you home now or just on a short leave?

Chris

 

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redmustangt

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May 14, 2009

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Jun 20, 2011

#8

• Jun 20, 2011

• #8

I moved the IACV vaccum line to the intake before the SC and now the car will idle very roughly (jumps from 500-1000 rpm) but it doesnt die right off the bat. I also ordered a tune from blow by racing. Im home now for a few months then I roll back out

 

nyuk98gt

15 Year Member

Oct 10, 2000

1,427

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Chesterfield, MO

Jun 21, 2011

#9

• Jun 21, 2011

• #9

redmustangt:

Glad to hear you have Old Paint running again. Nice work!

Thanks for the update on your situation. Enjoy the time with family and zipping around in the Mustang.

Cheers,

Chris