I am new to svt performance, so bare with me, im sure there are other threads on here about this but I just purchased an 04 cobra that has basic mods, pullied, cai, hand held sct tuner, ice box. problem is when im under hard acceleration it cuts out when i shift to 2nd and 3rd. When i accelerate hard but steady at a slower pace its fine. Im guessing its a fuel issue but i dont know. the guy i bought it from said the next step for more hp was bigger injectors and a better fuel system. he also claimed the air fuel was around 95%. any help would be great. thanks!
04 cobra cuts out at wot
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Sounds like you need to look at the PPRV DELETE in the how-to's. Factory flaw that is pretty easily fixed.
Is it a hesitation, or does it cut out and stay out?
What size upper pulley?
Ported Blower?
Stock lower?
Stock exhaust?
If it seems the fuel just cuts out:
If the upper pulley is small enough and you have a very free flowing exhaust with a ported blower, you may be passing enough air through the engine to max out or peg the MAF.
At this point the duty cycle on the fuel pumps can often max out.
A higher capacity MAF or a MAFia might be needed and it is possible that a KB BAP may be needed to help out your stock fuel pumps.
Data logging will be the way to find out.
If it is more of a hesitation, a retune or doing the PPRV delete may resolve your issue.
When it cuts out, i let off the gas and the "cut out" or "hesitation" stops,then i can get back into the gas again. The guy told me it has a ported blower, he doesnt know the pulley size. its a bronze-reddish color is the best way i can explain it. exhaust is a o/r mac x pipe and mac cat back.
I am with Jimmy on this one , sounds like you need a MaFiA , Bap and a retune.
The pulley is pretty easy to measure and that is information that will be very helpful going forward, tuners will ask.
Ported blower, cat less off road exhaust and a small upper pulley will often max out your MAF and fuel pumps.
Plan on getting this resolved ASAP, every time it does that you are going lean at WOT and can result in detonation which can do extreme damage.
Advice given thus far is sound...look into the fuel side.
For what its worth, I had a very similar issue. Car drove like a champ normally, but a WOT it cut out and stumbled like a pig.
All it was were a couple bad coils. Get em tested before you start spending a bunch of money on other parts.
Hope you figure it out soon and cheap.
For what its worth, I had a very similar issue. Car drove like a champ normally, but a WOT it cut out and stumbled like a pig.
All it was were a couple bad coils. Get em tested before you start spending a bunch of money on other parts.
Hope you figure it out soon and cheap.
boost4me
Banned
You need to visit the dyno for sure and make sure your not running out of fuel and running lean. With ported blower and pulley you are probably running out of fuel, and/or your stock MAF might not be able to keep up.
At a minimum - get your coils tested, check to see what plugs are in there too and what they are gapped at. You should be running TR6IX (Iridiums) and they should be gapped at least 0.032 and may be as low as 0.028. The stock coils will break up spark if the plugs are not gapped very narrow. At .032 mine was still breaking up, not noticeable when driving but you could see it cutting out on the dyno graph. I re-gapped to 0.028 and it smoothed out.
Man when I hear stories like this, I'm so glad I bought a virgin.
At a minimum - get your coils tested, check to see what plugs are in there too and what they are gapped at. You should be running TR6IX (Iridiums) and they should be gapped at least 0.032 and may be as low as 0.028. The stock coils will break up spark if the plugs are not gapped very narrow. At .032 mine was still breaking up, not noticeable when driving but you could see it cutting out on the dyno graph. I re-gapped to 0.028 and it smoothed out.
Man when I hear stories like this, I'm so glad I bought a virgin.
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boost4me
Banned
Please Dyno before you spend money on anything else!
13-14 psi is all I'm running also... stock injectors, stock MAF, stock pumps, fuel system.... *some* Cobras for some reason just run out of fuel with a pulley, no one seems to understand why, just wierd... very few need a BAP and/or MAF with a pulley change.
The Dyno will tell all...
Well i have the exact same problem in my 03 it has a cut which at first was diagnosed as a fuel problem then i proceded to go through every fuel component on the car which the car had a Stage 5 ported steig on 17 #'s, 60# inj, sct 2600 maf, aviator pumps,stock fpdm. Changed the frps,fpdm, removed pumps checked them worked fine, removed the pprv valve, cleaned maf, changed coil packs, changed plugs, datalogged it maf was fine several times it was loosing fuel at wot in 2nd gear and up. Soooo i installed a returnless fuel system got tired of looking for bad wires and chasing ghosts lol and to my suprise same issue so then we moved onto thinking a computer issue so swapped computers and same thing still exists so now cars been sitting since last spring and im about to strip it and go crazy with it car never had one issue and during a night in mexico it suddenly appeared and has been pissing me off ever since so figured id through this out there . gl
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Same ^^ 12.5 psi stock everything. Get it on the dyno so you know where you stand before you do anything! I just put on a few other bolts on and changed the MAF just to be safe. Where at in Northeast PA? If your up for the drive and schedule an appt, Booze Brothers Racing in Marion PA (bout an hr south of Harrisburg down 81) is who does the pain in the butt jobs for me as well as tune. Just got mine tuned on sat morning there. They are very good, Charlie Booze runs NHRA and has set quit a few records with his all motor 8 sec fox body.
boost4me
Banned
Dude... That's rediculous!! I got to wonder how that's even possible...
So its definitely a fuel pressure drop at WOT, that you verified on the dyno? Have you at least had a couple different folks look at it?
Probably a very Stupid question, BUT I have to ask have you replaced the fuel filter?
BTW OP - replace your fuel filter before you do anything else.
So Im not sure if this helps in any way or not but I just drove my car again, and if I ease the throttle down to the floor it will climb rmps norml. I took it to about 5500 give or take. just thought id put this out there as well. thanks guys.
boost4me
Banned
hmm, not an expert but just thinking about it logically... If your fuel system isn't keeping up, the sudden slam to the floor makes it run out of fuel, but when you lay into it slowly it gives it chance to catch up.
Did you at least check/replace your fuel filter?
Did you at least check/replace your fuel filter?
No, I havent yet, I'm going to a local shop and the guy is going to hook up a fuel gauge so we can see if it drops when it does this hiccup if you will. I will order a fuel filter right away though. I'm hoping it's a simple fuel issue and not something like 22floyd was talking about. Thanks a ton guys!
So I have a little more info. I had a fuel gauge hooked to the fuel rail and watched the gauge as I would drive. Normal cruising was around 32-35. High rpms was 55-58 and when it would cut out like I've been saying it would drop to 12-15.
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