03 Cobra Pumps maxing out on my 2v GT -any ideas?

TonyG

Founding Member
Apr 12, 2002
200
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17
Owings Mills, MD
I have a vortech S-trim with a 3.00" pulley and front mount intercooler. Fuel-wise, I have 42 lb injectors and an 03 Cobra dual pump. I'm making ~440 rwhp. I was making ~10-12 psi before, but now (after longtubes), boost is down to ~9 psi.


Anyway, we got the car on the dyno and the A/F appears to be leaning out above 5000 rpms. The fuel pump is at 100% duty cycle.


Is this possible with the 03 Cobra pumps? The tank was dropped and everything appears to be OK. Also, I'm not sure if it matters, but some girl did smack me in the rear a couple years ago. At the time, it appeared to be only cosmetic damage, but she did hit hard enough to trip the fuel switch.


Any ideas of what to check?
 
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how lean is it getting? if you are hitting 100% duty cycle at 440rwhp, there's a restriction somewhere. replace the fuel filter and make sure all the fuel lines and injectors are clean and working properly.
 
Don't think it is your pumps. I am suppling enough fuel for 550 hp with just the cobra pumps. I noticed you are using 42 pound injectors where I am using 60 pound injectors and aeromotive fuel rail system. Your engine is probally starving at the injectors. Also get a Maf.i.a to make sure your maf isn't pegging to allow you the best tune.
 
I think your problem is with your MAF, even the 90mm maf will peg around 450rwhp... MAFia will help you out a lot.
Fuel filter is a no brainer...
also look into a Kenne Bell Boost-a-Pump for added peace of mind.

as for the injectors, I have run the 42's up to 600rwhp with no issues, but it's your call.

Start with the MAF, its most likely the cause... and cheapest to fix.
 
Steeda. I dunno, maybe my gauge is off.


Anyway, this morning, the fuel filter was changed, and the cobra pump is still maxing out. So we've decided to do a wire mod (thicker gauge wire) to the fuel pump, and switch to dual Focus pumps. I'll keep you posted.
 
Don't think it is your pumps. I am suppling enough fuel for 550 hp with just the cobra pumps. I noticed you are using 42 pound injectors where I am using 60 pound injectors and aeromotive fuel rail system. Your engine is probally starving at the injectors. Also get a Maf.i.a to make sure your maf isn't pegging to allow you the best tune.


Damn brother you got a killer looking stang. I am loving the way your car looks, feels like humping your car :rlaugh:
 
Do you have the cobra pumps in a cobra tank or the GT tank? If its in a GT tank, maybe your sucking the bucket dry too quickly with dual cobra pumps and going lean because of that. Maybe try a baffled cobra tank if you dont have one already.
 
Do you have the cobra pumps in a cobra tank or the GT tank? If its in a GT tank, maybe your sucking the bucket dry too quickly with dual cobra pumps and going lean because of that. Maybe try a baffled cobra tank if you dont have one already.


I have the Cobra Pumps in the GT tank. We already thought about that, so we tried filling up the tank...it didn't help.
 
I have the Cobra Pumps in the GT tank. We already thought about that, so we tried filling up the tank...it didn't help.

Filling the tank helps, but did you drill any holes in the stock basket? Even though your tank is full, having two pumps is going to suck that basket dry faster than gravity can keep it full of gas.
 
Bingo! That's your problem - you also need the '03 Cobra tank. Seen it happen to GTs numerous times on the dyno. Tuned many a '03 Cobras at >600 RWHP with stock tank/pumps with a BAP, so after you get the tank, your problems should go away.

The 90mm LMAF MAY be near it's limit, but I've seen some go to close to 480 or so before pegging - but the datalog gives the answer plain and simple, the fuel pump is maxxing out - and it's because it's sucking the fuel can dry - or low. The log would also tell you if the MAF is pegging - and apparently it does not - and the A/F goes so lean so fast when a MAF pegs, you almost cannot get out of it fast enough.

Don