Urgent: 03 cobra sputtering and limited to approx. 3000 rpms after warm up

[KentuckySVT]

Okay so I will say this. I have searched and searched the forums, google, etc. and cannot seem to find a case such as mine. I have been finding similar cases but have not had any results. Basically my car was hit in the front by a truck and had to have the drivers side fender apron and radiator core support replaced. I removed the cooling system to clear room for the damage to be repaired. I also removed the air intake, maf, filter as well and various sensors to facility the removal of the cooling system. The body work with paint took roughly 2 1/2 months to complete (yeah I know, way too long). Anyway upon reinstalling everything I am having a serious issue that could very well be a careless error I made without knowing so. The car starts, idles, and drives perfectly. After about 15-20 minutes once it reaches operating temperature it begins to sputter, limit itself to approx 3000 rpms Like its hitting a rev limiter and the idle is very weak and will fluctuate until the car dies. Once it dies if I wait about 10 to sometimes 20 minutes the car will start right up and repeat the same thing. So of course I started throwing parts at it in my niave age without any results (it needed a tune up anyway so why not) Here is what I have replaced cleaned and checked so far.
Cleaned air filter
Clean MAF
Checked for vacuum leaks
Checked TPS
Replaced all spark plugs
Changed oil
Changed fuel filter
Treated gas tank with injector cleaner and full tank off premium from BP
Checked all visible grounds
Checked battery
Checked fuel pressure at Schraeder valve
Checked belts
Fuel pump from all appearances sounds like it is healthy and fuel pressure is fine
Pretty much any and all fuel, air, and spark component I am aware of. The exhaust is not catted also so that rules out the catalytic converter.
I really need to figure this out soon and any and all help will be much appreciated. I work full time, go to college full time, and work on my car all other hours. I'm so sleep deprived you can probably see it in my posting. Thanks all.

 

[KentuckySVT]

Also no check engine light

 

[J.Kincaid]

FRPS? I've heard of a similar problem and in that particular case it turned out to be the rubber fuel hose inside the gas tank. It becomes soft and would collapse once warmed up. I know you said you checked the fuel pressure, but were you able to check it when this problem occurs?

You're probably gonna have to data log it, to figure this thing out.

- Joe

 

[KentuckySVT]

After doing more and more searching I saw that the fprs could be the culprit. I'm going to triple check some more items and gets some numbers to hopefully clearly explain this issue. Also would that occur all of a sudden or would it gradually get worse? Could it being garaged for 2+ months cause any other issues. Thanks for the help and if I ever find the fix I WILL be sure the post the fix (keep finding similar stories now but poster never provided solution).

 

[KentuckySVT]

Update: I checked the frps and all is good. Also checked the egr valve, TPS again and o2 sensors with no results. The fuel pressure, upon warmup caps at 40 psi. This has to be a sensor of some sort right guys?

 

[KentuckySVT]

Could this possibly be the fuel pump on its last leg? When I turn the ignition to the on position all I heard is a faint click from the fuel tank and nothing else. Could someone please describe the noise their fuel pump makes on their fully functional terminator please?

 

[miztigerszou52]

Could this possibly be the fuel pump on its last leg? When I turn the ignition to the on position all I heard is a faint click from the fuel tank and nothing else. Could someone please describe the noise their fuel pump makes on their fully functional terminator please?

Mine will make the click as well but it is always followed by approximately one second of a priming sound. Hard to describe what it sounds like but it is very apparent.

 

[Ukfox89]

the fuel pumps cycle for a split second to prime the system. you can measure voltage down to the pumps in the wiring harness that goes to the tank. you can data log the car and measure fuel pressure drop across the rail and it should be around 39-40 lbs at idle and should increase with load on the engine, not rpm. because the car is boosted fuel pressure should be varrying dependant on load. do you have a laptop and/or handheld? im having the same issues righ tnow and am not looking forward to spending $115 on a fuel pressure sensor to see if its the problem. Good luck man.

 

[AteYourLS]

i know there is no CEL on, but ever think about the Engine Coolant Tempature sensor. Just throwing it out there new ideas you never know

 

[KentuckySVT]

Cool cool cool. Thanks guys I'm going to see if I can give the pumps a good check over tonight while still managing to get some sleep. Also I'll check the cts. This is a long shot and I'm going to feel dumb if it's the problem but could a badly connected ground cause this problem at wot? Maybe even a coroded or loose battery terminal?

 

[TRBO VNM]

Check the block ground. Goes from driver frame rail to block. factory is a braided wire and is connected just in front of the kmember on the driver side and then runs up behind the oil filter to the block.

dirty terminals are never a good thing.

Did someone mention check alt. voltage?

Do you have another stock MAF you can try? I assume yours is still stock. Make sure your intake tube has a good seal and clamps are on correctly and tight.

there are some grounds on the upper core support. couple by the battery and then one on the passenger side in a similar location, but I think some of those are just for the headlights, but I know a couple on the driver side are connected to the battery

 

[KentuckySVT]

All chassis grounds are tight and clean. The maf is an act unit with maybe 5000 miles tops. I haven't checked the ground that you spoke of or the alt voltage yet but I'm going to immediately when I get home. I'm starting to lean more and more on that this is some sort of electrical problem. Problem is finding it........

 

[itSSlow98]

Did you clock the MAF to where it was exactly when you took it off?

 

[KentuckySVT]

Yes I did. I changed all hoses and fuses this morning as well. Correct me if I'm wrong but if a major ground was loose or getting poor connection and the ECM didn't receive a certain amount of voltage could the car exhibit these symptoms. Almost as if the computer is getting false readings (specifically air/fuel ratio)

 

[TRBO VNM]

Try also disconnecting and reconnecting the cam position sensor and crank position sensors.

 

[KentuckySVT]

Okay so the alternator apparently was going south very quickly. The voltage was slowing lowering after startup and alternator position was dropping from 50-12%. I replaced the alternator and belt and the car ran great for about 15 minutes then the problem came back so i parked and got some readings. The new alternator that started putting out approx. 14 volts and at 100% is now already at 62% and 13.1 volts. Car still will not rev above 3000ish rpms after running for around 10-15 minutes. Ideas?

 

[BlankTP]

I had a customer's car with a very similar issue about a year ago. It wouldn't throw any codes or check engine lights either, ended up being the crankshaft position sensor. It would pull to about 3000 rpm then just cut out. I'd give it a shot, rather inexpensive part, or you could just borrow one if you know someone who has their engine down.

 

[blwn03sonic]

I'm having the same issue and have checked all the same things. I'm trying the crank position sensor next to see if that helps.