2001 Cobra problem

[Cobra#23]

Hey guys, I just recently had a problem with my 2001 cobra trying to figure out what's wrong or at least what direction to head.

On my way to the gym (10 min away). I came to a stop light and as I inched up, the car all of a sudden began to shake (motor) slightly under slight acceleration low rpms. It also did it when I was moving out of first. Along with at stop I would just rev the engine up to maybe 1500rpm and it seemed to dip in to this gap feeling then back out. The revs dropped a few times at idle, down under 500rpm almost seeming to shut off but never did. I parked it once I got home, oil seems relatively normal, and no noticeable leaks yet. Since the incident, it has a rough idle, with whitish smoke coming out of the pipes (left one more then right) in a noticeable but by no means horrible fashion. Smells like gas, not really sure what a sweet smell would smell like. Not sure what to do or where to head, any help would be appreciated!

 

[Zemedici]

no codes or anything? It smokes at idle?

 

[Torch10th]

First thing I'd check is all the vacuum lines. A stumble at idle is usually indicative of a vacuum leak.

However the fact that you're getting white smoke out of the tail pipe isn't really a great sign. While smoke can be a sign of a blown head gasket and you're pumping water into the combustion chamber. You should check your oil for coolant contamination. If you find a frothy mess in place of oil, you've got a blown head gasket.

 

[Cobra#23]

No codes popped up whatsoever, I checked the oil and it seems to be the same brown color if anything a little low but nothing out of the ordinary that I could particularly tell.

 

[Cobra#23]

Smokes slightly at idle seems after its warmed. It's noticeable, but not bad or excessive.

 

[Cobra#23]

It also sounds like it's missing, from what I hear in the exhaust.

 

[Torch10th]

Pull a couple plugs and see what they look like. Post pictures if you can.

What does the smoke smell like?

 

[kevinatfms]

Didnt the 99-01 year Cobras have the brass valve guides that would wear out and drop a seat?

 

[Cobra#23]

I'll try the plugs later when I get home. The smoke smells like gasoline. The car heats up like it should, no visible coolent leaks. Just a slight vibration under initial throttle between 800-1500rpm. The smoke is noticeable but very light, it's just more then what would normally come out, not a very distinct white either just the closest color I would say is white.

 

[Torch10th]

Sounds like you might be dumping fuel into the combustion chamber. a bad fuel rail pressure sensor can cause this problem. Might be something to look at.

If you're sending that much fuel down the cylinder the miss is probably because the plug is soaked in raw fuel and not firing. As an added side effect, you may be washing the cylinder wall which can have an effect on ring seal. Fuel in the oil can then cause bearing failure if you degrade the lubricating properties enough.

 

[Cobra#23]

I will check that sensor.
Now that you say that I did happen to smell the oil on the dipstick when I checked it and it smelled like gasoline to an extent.

 

[Cobra#23]

Shouldn't that sensor trigger the check engine light?

 

[Torch10th]

Shouldn't that sensor trigger the check engine light?

Not always. If it's not functioning correctly it may still be communicating with the computer. I never had this problem on my 99 Cobra, but I had one go bad on my 2003 Cobra and it never threw a CEL.

It's a cheap part, so if you swap it out it's just piece of mind and you move on to other areas that could cause the issue. Given the age of the car, I'd replace it and see if it helps.

 

[Cobra#23]

Alright I'll head to Ford in the morning and see if they have one in stock. Appreciate the advice! Think the car will be alright to drive there?

 

[Torch10th]

Keep the revs down and fresh oil in it until you figure out the cause. That won't do a whole lot about the ring seal issue if the fuel wash is particularly bad. I would keep trips in it to a minimum if possible.

 

[BlksvtCobra01]

Sounds like you might be dumping fuel into the combustion chamber. a bad fuel rail pressure sensor can cause this problem. Might be something to look at.

If you're sending that much fuel down the cylinder the miss is probably because the plug is soaked in raw fuel and not firing. As an added side effect, you may be washing the cylinder wall which can have an effect on ring seal. Fuel in the oil can then cause bearing failure if you degrade the lubricating properties enough.

I was thinking this as well.

 

[Cobra#23]

So an update, I went to ford got new spark plugs replaced them, had the diagnostic test run on the fuel pressure injector sensor and injectors themselves. Test came back with all injectors firing correctly and the tech informed me that if the sensor was bad the injector test wouldn't of ran. The minimal smoke wasn't really noticeable after a warm up start of about 5-10 minutes, but still has the rough idle during the ititial acceleration between 800-1200rpms seems to shake/stumble. Not sure what to look into next.

 

[BLOWN9646]

Change fuel filter yet?

 

[cobra_neill]

When my maf sensor took a turd I had a similar issue. Want to test the maf quickly and easily? Unplug it. If it runs better its not a mechanical issue. Doesn't always mean its the maf sensor at fault though. My barometer inside the maf sensor was reading incorrectly and causing identical issues to yours with the addition of a smoking hot cat converter on the side that had the smoke.

Neill

 

[Cobra#23]

Haven't change the fuel filter since the last oil change about 4k miles ago, but I can try that and I can definitely try the MAF seems pretty easy. Thanks for the help guys! I took pictures of the sparks they seemed normal to me, nothing I could see however not exactly sure what I would be looking for either. I was trying to post pictures of them but couldn't figure it out.