Cobra hesitates under part throttle just like when traction control is active

[The Saint]

For the past 2 months the car sometimes hesitates at part throttle. It feels and sounds like when traction control is active. Now if I go WOT then all is normal. It seems to do this every other time I drive it. I replaced the plugs and fuel filter with no luck. The dealership could only find codes for no cats so I replaced the MIL's to get rid of the engine light and that doesn't help.

Any idea where I should start looking for the problem? :shrug:

 

[pipeliner]

Coils.

Mine did it had to go through and check them. Was time consoming and a pain in the ass but #7 coil was bad.

 

[The Saint]

How did you check them?

 

[Kysnake03]

+ 1 on how to ck coils !
Saleen cobra, what plugs are you running ? I have started having the same issue. My car stumbles on start up also. Mine has Motorcraft 22`s in it for the last 8k, came stock with 12`s. I may try the NGK Tr6`s.

 

[pipeliner]

I bought 4 packs.
Changed 4 on drivers side.
Run on Dyno GOt lucky fixed it
From there you can eliminate which one was the cause.

Make sure you change plugs and gap them correctly. As a PM I changed them. I just happend to get lucky it only took me 3 pulls to fix it, then I returned the Packs I didnt use.

Not really a good way to tell if coil is sparking correctly as mine would only do it about 4k then everyonce in a while would stumble bad.

 

[The Saint]

+ 1 on how to ck coils !
Saleen cobra, what plugs are you running ? I have started having the same issue. My car stumbles on start up also. Mine has Motorcraft 22`s in it for the last 8k, came stock with 12`s. I may try the NGK Tr6`s.

I am running the TR6's at the stock gap. I put these thinking they would fix the issue, but the car ran the same..... I'm going to pick up some coils today and swap them out and see how that works.

 

[The Saint]

Alright I replaced the FRPS first with no luck. I replaced all the coils with new ones and i'm still having the same problem.

Could the MAF or TPS cause these symptoms?

 

[MikeW]

I'm having the Stall and rough idle too... I may try Coil packs.

 

[The Saint]

I'm having the Stall and rough idle too... I may try Coil packs.

Carefull before you try that. I finally found my issue and it was a frayed wiring harness on the passenger side front O2 sensor. Check those before you do anything. If you really think it's the coils then maybe we could work something out and I could send you my used ones for you to test with.

 

[ScrmngYellow04]

How much did the car hesitate?

Can you describe it?

Does traction control cut out power when its on or just when the rear tires are spinning?

 

[MikeW]

Carefull before you try that. I finally found my issue and it was a frayed wiring harness on the passenger side front O2 sensor. Check those before you do anything. If you really think it's the coils then maybe we could work something out and I could send you my used ones for you to test with.

I will take one out of my dads 03 and use it to test with if changing the plugs does not cure the proble.

Here is a link to my ongoing problem .

http://www.modularfords.com/forums/2003-2004-mustang-cobra/update-on-my-problems-not-good-53396.html


My car does not hesitate real bad it just stalls out. It goes way lean on my wideband and shuts down like someone flipped a switch. It comes and goes. I can drive one whole day without and issue and the next time I drive the car it stalls out like crazy.

Coil packs are just one of the things on my to do list for the weekend... I will add checking the 02sensor wires to my list.

Thansk for the tip :beer:

 

[The Saint]

I have seen similar problems like this caused by a incorrect TPS voltage and failing fuel pumps. Have you checked those?

 

[ChicagoMike]

I was having a similar problem recently. I found a vacuum line blown off.

Check your lines behind and next to the blower!!!

 

[MikeW]

I have seen similar problems like this caused by a incorrect TPS voltage and failing fuel pumps. Have you checked those?

I will datalog tonight and see if those are out of wack... Fuel pumps are what the dealer wants to check 1st.

ChicagoMike I think I checked all the lines but I will check'um again while i'm under the hood.

 

[03Sssnake]

I had the same thing happen when my alternator went tits up..car fell flat on its face under WOT.

 

[MikeW]

I datalogged voltage at the track when this stall became a big problem. The voltage does drop below 13 volts like to 12.4 at WOT but a Ford tech that was at the track said that that is not reason for concern. another stragnge thing is sometimes when it stalls it will start right back up and others times it will take 2-3 minutes before it will start. Once it start the problem it gets worse as the day goes on.

Saleen Looks like I hi-jacked your thread... SORRY man.

 

[The Saint]

I datalogged voltage at the track when this stall became a big problem. The voltage does drop below 13 volts like to 12.4 at WOT but a Ford tech that was at the track said that that is not reason for concern. another stragnge thing is sometimes when it stalls it will start right back up and others times it will take 2-3 minutes before it will start. Once it start the problem it gets worse as the day goes on.

Saleen Looks like I hi-jacked your thread... SORRY man.

Hey man don't worry about it because I know exactly how frustrating this can be. The sad part about all this is that it's going to be something real simple that we all missed like my O2 sensor.

If hi-jacking my thread gets your problem solved then just make sure to post what the problem was and how you fixed it. :beer:

 

[MikeW]

Thanks Saleen :beer: