race tune not working

stangdriven · Dec 11, 2011

ok guys... i got a 100 octane race tune from vmptuning.com ... i have bigger maf housing, cai, throttle body, and more... i also believe my fuel pressure is turned up just a lil bit, cant remember how much but not enough to over do it... ok so everytime i upload this tune into the pcm, i start it it only runs for like 2 seconds then shuts off, its almost as if its not getting enough fuel, but my other pump gas tune works just fine, now justin at vmp said my bigger maf housing is allowing to much air in considering race gas has high air content and i need to install the stock housing, im not doubting him one bit, but curious to see what you guys think or have read or heard from anyone else???

g36 monkey · Dec 11, 2011

Justin knows his stuff, I would try that to see if it works before doing anything else. If that doesn't work, we can start picking apart other issues

stangdriven · Dec 11, 2011

yea true... i just hope my dad didnt toss my stock one away... and i gotta wait for him to ship it to me... and lol i got 3 gallons of race gas for it to
this sucks... if that does the trick... im gonna be ticked... my bigger housing gives me quite a bit of air... i dont want to have less lol

g36 monkey · Dec 11, 2011

I know what you mean, but it doesnt hurt to see. You can net quite a bit of power from the higher octane

stangdriven · Dec 11, 2011

yea thats true... just gonna have to swapped em around from pump to race i guess if... this is the case

g36 monkey · Dec 11, 2011

Just try that first and let us know how it goes. In the meantime I'll be thinking of possibilites ;p

stangdriven · Dec 11, 2011

sweet .. right on man

ttocs · Dec 11, 2011

just outta curiosity, are you sure the maf is facing the correct direction? I ask because I recently did it backwards and that is what happened to me. I was putting in on my anderson power pipe in the fender and just grabbed it and was not paying attention.

stangdriven · Dec 11, 2011

yea its in right... other wise it wouldnt run with my pump gas tunes lol .... but good point...

LilRoush · Dec 12, 2011

If you don't have a supercharger or turbo, you don't need a bigger MAF to meter air. I'd go back to a stock unit.

And just to be clear, you say bigger MAF housing... what size it is? And I assume it's the sensor for that larger housing, and not a stock sensor in the bigger plastic tube.

ttocs · Dec 12, 2011

I was not sure if you just put it on for this tune like I did or had it on before.

So it ran fine on the pump gas with the bigger maf but with the new tune nothing?

stangdriven · Dec 12, 2011

its c&l 73mm stock sensor... supposed to read more air, ive ran this 73mm for years now... it works for pump gas but not with the race tune

LilRoush · Dec 12, 2011

How are you switching fuel back and forth when you swap tunes from pump to race?

g36 monkey · Dec 12, 2011

Roush, aren't you supposed to fill up with race fuel then run till its almost empty, then fill up again before switching tune files? That way with the advances in timing, etc. you are sure to have only the higher octane fuel.

I was just assuming you were boosted OP because of the larger MAF housing.

robb15033 · Dec 13, 2011

Why didn't VMP take into account the size of the MAF? They should have for your other tune files right? Doesn't make sense. No matter what, you have to question where the programing went wrong. It works for the other two tunes but not for the third.?.? It's not right that you have to swap out the MAF housing everytime you want to run that tune. It just doesn't seem right to me, like some kind of communication problem or something maybe. Update us & let us know. Good luck with it.

g36 monkey · Dec 13, 2011

Robb, my guess is that he has too much low octane fuel in and is loading the high octane tune.

ttocs · Dec 13, 2011

LilRoush said:
How are you switching fuel back and forth when you swap tunes from pump to race?

I was wondering as well.

LilRoush · Dec 13, 2011

g36 monkey said:
Roush, aren't you supposed to fill up with race fuel then run till its almost empty, then fill up again before switching tune files? That way with the advances in timing, etc. you are sure to have only the higher octane fuel.

I was just assuming you were boosted OP because of the larger MAF housing.

Yeah, it takes a good flush to get low octane out and pure higher stuff. I've had that issue before, so that's why I asked. I got in a pinch and had to run 91 in the black car. I only put in enough to make it to the next stop. Took two full tanks of higher octane fuel to get the 'sputter' out of it 100%. Such a pain to switch back and forth... so now all my tunes are for 93.

stangdriven · Dec 13, 2011

rob thats exactly my point... i shouldnt have to swap maf housings... and i run the pump gas til damn near empty before i put race in, then i tune, but being that supposedly the maf is to big... still doesnt make sense why it doesnt work, rob is right, why should i have to switch... im gonna try my stock housing and if it doesnt work, im gonna pissed... and of course talk to justin again and get it to where my bigger housing will work... otherwise what point is there to get a bigger housing for more power if i cant use a tune.... now i understand im not forced inducted, but that housing has proven gains on n/a v6 motors... and it could be the tune, but i noticed a gain after i put it on... but im gonna find out one way or another... didnt spend 60 bucks for nothin... i even specified bigger maf housing, i didnt specify what the size was, but justin told me use stock maf should be fine... its like well if the bigger works for pump why not for race, and why cant you tune it for race?????

robb15033 · Dec 13, 2011

Ok, Good luck with it. I hope you get it straight and are happy, and hopefully happy while keeping the same MAF housing. I live in Northern Virginia. If by chance you live close enough to drive, I can recommend a Mustang shop that can help out on the dyno. Cost is relatively low too. My dyno numbers were a bit higher than Justins highest apples to apples. Good luck!