04 cobra falls on its face in high rpms

well im trying to help out a buddie, he cant log in to the site
he sent his blower out for a steggie stage 4 had it installed with a 2.8 or 2.9 and a 4lb lower pulley put it on the dyno makes boost then falls on it face like he let off the gas. they thought his cats where clogged so they installed a orh or orx and a borla cat back (got rid of the loudmouth) and still the same problem. now with the 4lb lower and 2.8/2.9 upper it made i think 17lbs of boost and i wanna say 440rwhp (flow jet dyno?) so then they kept the 4lb lower on and went back to the stock upper and still made the same hp numbers on less boost and it never died down

what could be wrong? bad port job from steggie?

sounds like he needs to delete the pprv. what are his mods???

keep it simple, folks...

datalog!

what is the MAF doing? could be a pegging MAF sensor.
what is the fuel pump duty cycle doing? could be running out of fuel.
what is the system voltage doing? could be running out of juice to drive the fuel pumps.

the pprv delete only helps between shifts. not if you are just in a single gear going WOT. the pprv delete is not a end all be all fix for hesitation/fall on it's face. there could be other things. I have also seen the hesitation/falling on it's face stop when the driver shifts faster.

in this case, I recommend what Shelbyguy stated. you are probably looking at either a fuel/spark or MAF issue of some sort.

i also think its the maf or fuel

We have had several local cars (both in and not in the club) exhibit the same issues.

We are in the process now of datalogging and testing. But the issue seems to be Alternator failure as first diagnosed by Herman (of Horsepower by Herman)

At high RPMs the alternator starts loosing voltage and a primary victim of the lack of voltage is the fuel pumps... resulting in low fuel, and possibly engine failure.

Will know more by the end of the week..............

If you haven't upgraded the fuel system and mass air then you definately need to. With that combo he should be making around 500rwhp and those systems are defintely maxed out. I made that mistake and it's and expensive one. Datalog and find the real problem.

Maf or Fuel

hey guys, this is the guy that owns that cobra..my tuner has tuned many cobras with 500+ rwhp on a stock fuel system, and he has never seen this problem. We've changed plugs, did a compression test. The car had a granatelli MAF on it when i bought the car but my tuner didnt like granatelli MAFs so we got a stock cobra MAF and thats where we sit. Maybe that is where the problem is?

BK04SVT said:

hey guys, this is the guy that owns that cobra..my tuner has tuned many cobras with 500+ rwhp on a stock fuel system, and he has never seen this problem. We've changed plugs, did a compression test. The car had a granatelli MAF on it when i bought the car but my tuner didnt like granatelli MAFs so we got a stock cobra MAF and thats where we sit. Maybe that is where the problem is?

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I think you are not on the edge but past the edge.

I think you are pegging your MAF... and I think you have maxed out your fuel delivery.

If you want to run stock pumps get a boostapump...

For measuring your air get a Mafia or a MAF that won't peg at 500 rwhp worth of air.

Do you or your tuner have data log capability???

Get it data logged ASAP...
Log fuel pump duty cycle
Maf counts
and if you can borrow a wide band...... do -> air,fuel..



or start pricing a new set of these...

Jimmysidecarr said:

Do you or your tuner have data log capability???

Get it data logged ASAP...
Log fuel pump duty cycle
Maf counts
and if you can borrow a wide band air,fuel..



or start pricing a new set of these...

Click to expand...

Those are some seriuosly screwed up pistons! WTF happened!? Cyclopse get a little to close?

http://www.lethalperformance.com/pa...sf7373-diablosport-mafia-for-03-04-cobra.html

Get one of these no problems here at 612rwhp

BK04SVT said:

hey guys, this is the guy that owns that cobra..my tuner has tuned many cobras with 500+ rwhp on a stock fuel system, and he has never seen this problem. We've changed plugs, did a compression test. The car had a granatelli MAF on it when i bought the car but my tuner didnt like granatelli MAFs so we got a stock cobra MAF and thats where we sit. Maybe that is where the problem is?

Click to expand...

That is the worst kind of arrogance on your tuner's part. This is not about ability to tune. It's about math. The stock fuels system does not deliver the fuel required for 500+ rwhp.... The stock MAF does not read at the airflow levels required for 500+ rwhp.

Get a new tuner

thats some kind of hot-shot tuner that doesn't even bother to datalog the MAF so he could at least get the transfer function right...

any tuner with half a brain would spot the MAF pegging.

I didn't look at the whole thread, but in my old '04 Cobra I had a similar problem with the car nosing over like that and it turned out to be a bad cylinder #6 ignition coil. I didn't have the proper tools to test the coil, but I found there was a TSB out for it, so I bought one coil and switched it and that ended up being the problem. Got lucky that time.

Edit: I read the rest of the thread....your tuner sounds like a fool. Disregard what I said about the coil as I doubt that's the problem now.

Come on guys. There are too many reputable tuners out there for some of us to still be going to jack legs. Just like anything else, research before you spend your hard earned cash. And never take a dealer/tuner's word for it.

-Jeff

HISSMAN said:

Come on guys. There are too many reputable tuners out there for some of us to still be going to jack legs. Just like anything else, research before you spend your hard earned cash. And never take a dealer/tuner's word for it.

-Jeff

Click to expand...

+1k

It's kinda scary that this tuner would even THINK that the stock fuel system could SAFELY handle 500+rwhp.

Definately needs to look at the maf and fuel. These cars are not cheap ones to mess around with.

thanks guys, it's definitely a frustrating situation. I am about to put someone else's stage 1 ported blower on my car and see what it does on the rollers. What upgrades of MAF and fuel will I need? 60 lb injectors.... what else?