Cobra spits and sputters

2003 cobra developed a problem. When I hit 4k+ rpm it looses power almost like hitting a rev limiter I have researched the problem on the Internet and have found sevrial ppl with the same problem and a long list of solutions... I assume it's a fuel delivery problem and have done a few things to try to remidy the problem. I got a diablo predator tuner and put a 91 octane performance tune on.. Didn't help. I replaced the FRPS fuel rail pressure sencer..didn't work. I am going to replace the fuel filter tonight and cross my fingers that it's the solution. I dataloged a 2 nd gear pull to see if my fuel pressure was low but it was 39psi at idle and 84psi at WOT.

Thanks in advance for any help and info.

Whats the Air Filter look like? Is the belt in good condition? How is your charging system, battery and alternator? Seems like you are missing fuel spark or air. If you are getting 39 psi, you are probably getting fuel. I would check the charging system. This is the same problem I felt when my alternator was going out.

I would also be careful running the Diable tuner. It creates a lot of power, but they also use a lot of timing. This could turn out bad if you are not getting the right air, fuel or spark. I would be cautios with an aggressive tune until the motor is running properly.

Im guessing burnt plugs and or a coil pack

My 06 was doing something similar and it turned out to be the plugs

Yes, check plugs and gap them in the .030 range.

Woody, what are you doing tomorrow? If you want to meet up after work, we can go over some things and see what could be the problem... definitely sounds like it's either suck, bang, or blow... one if them ain't working properly...

Have you done any type of tune-up to it since you got it? That's generally the first thing I do, no matter what the previous owner/stealership told me...

plugs
coil packs
air filter
fuel filter
seafoam treatment

Plugs are my guess.... spark blow out could be the culprit.

I mesured the supercharger pully to make sure it was stock and it is..i put new plugs and fuel filter on it and no change...as far as i can tell it has minor bolt ons...exaust, K&N air filter is all i can spot.checked the alt voltage and its putting out 13.8-14.0 volts.

I thought "take it all back to basics" and put the orignal tune back on it and it ran worse so i had to put the 91 preformance tune back on.

how would i go about checking coil pacs?

I believe you can check the packs with a volt meter

Have you tried pulling the DTC Codes with your hand held tuner?

yes i pulled codes and got a P0148 fuel delivery error...but just one time then it went away and no codes have shown up sence..

Fuel delivery...hmmmm Bad injector? Bad fuel pump?? Man I hate chasing gremlins!!

I guess it is possible your fuel pump is going south. Does it do it more after the car is hot or is it all the time?

i need to research the diablo tuner deeper but i think there is a way to get fuel pump , injector ,and coil pack info with the live data ..

all the time above 4500 rpm...it runs smooth without any problems below 4k

One thing you havent considered is bad gas...Did you fill up recently? When I got water in my gas it would studder like crazy in the upper RPMs and finally through me into limp mode.

Damn habeeeb gas stations!

This is a possibility

Check your alternator yet?

yes he checked the Alt.... 8 posts in

Hmm thinking... may invest in a wideband and check to see what your afr is above 4500... could let you know if its fuel or air thats missing... no vacuum leaks?

When it starts cutting out are you in boost or does it do it both in and out of boost?

I happens in boost for sure.. But if I run it up above 4 k gently it don't cut out till I mash the gas.. That's what leads me to beleave it's a fuel problem...

Do the 03 cobra have imrcs? They could be malfunctioning. If vtec dont kick in, hondas get flooded by gas because of the decreased airflow...

Pull a few spark plugs and see what color they are...

Shelby10' wrote:yes he checked the Alt.... 8 posts in

Sorry guess I over looked it.

Id be willing to bet its a problem with the fuel pump. As the demand of the fuel increases, it seems the flow of fuel cant keep up. Be careful driving it like this. Have you tried posting this on the SVT Performance forum? They have a Terminator section that might be more of help with your paticular vehicle

It is a strange thing. The only other thing that might cause this would be something in the mass air meter. Have you by chance oiled a cleanable filter such as a K&N lately? Your sensor may be reading wrong. More airflow across the sensor should change your fuel delivery tables to compensate but if your getting an inaccurate air reading this could be an issue.

If u google 03 cobra 4500 rpm...it brings a bunch of ppl with same problem...One of the fuel pumps being weak is one of the solutions listed but I have in excess of 80psi at WOT...

Here are some other suggestions I have found

1) look at your MAF counts and if it hits 1024 its maxed.

2)Your fuel pump could very well be going bad. When you datalog check for the FPDC (Fuel Pump Duty Cycle) and if it hits .5 its maxed.

3) Check your air intake temp sensor

4) possible loose wire on one of the coils

5) Could be a loose wire on the injector or the injector could be dirty.

6) Are you running enough octane for the tune?

7) Are you sure its not bad gas? Where do you fill up?

What do your timing tables look like on the datalog? A lot of people put in too much timing with 91 octane. Did you buy the car from somewhere that ran 93 octane?


What boost are you making? Should be ~8lbs with the stock pulley.

Sounds like you are running out of fuel...


Do you have a wideband? Get it on the dyno and look at the AF.

Also, clean your MAF with some cleaner. That can cause all sorts of shit to be thrown off.