[SVTSnak]

Howdy all!

I just bought my first Ford...a 1996 Cobra

I love the car, but having some issues with it and since I'm not familiar with Fords at all (yet!!! ), I thought I'd request some help.

I noticed that the idle tended to stay up around 2k or so and SLOWLY drop back down to around 800 or so. Since I'm in Vegas (read: hot as hell would be. LOL), I always had the air on since I bought it a week ago. Also, it seems like sometimes when the idle comes down from 2k, it drops like a rock and stalls the motor. Sometimes you can tell the engine "catches" itself and recovers before it stalls.

It finally threw a "check engine" light the other day. I only got to see one of four codes because the mechanic went through it too fast, but one of them was something like "Engine running lean (Bank 2)". Oh and it feels like the car tends to hesitate a bit around 3,500 rpm and up.

I took it back to the dealer and told them the issue (and they noticed it on my test drive as well). They said they'd send it to their mechanic. Well, got it back yesterday and the light/codes were reset, but it still seemed to act the same. GRRRRR!

So, that night I ended up driving home after the sun went down and did NOT turn the air on. All of a sudden, I noticed the car seemed to act "normal". It would idle around 750 rpm. Wouldn't idle high, wouldn't drop like a rock or anything. It felt great. Even seemed like the "hesitation" at 3,500 rpm and up went away. I was thrilled.

Got in it this morning and started it up...check engine light is now on again! I kept the air off and it still seemed to be okay. Maybe a very slight hesitation, but not much at about 3500 rpm and up.

Driving home later, I drove without the air and it was acting fine. Turned the air on at a light and the idle went haywire again! Up to 2k on it's own, then dropped like a rock and almost stalled. Then, while driving it, I could turn the air on and off and feel the hesitation either show up or disappear around 3500 rpm and up (according to whether the air was on or off).

I have no idea what to do to fix this. I'm going to take it back to the dealer on Monday and tell them they have to fix it and reset the codes (again), but if I have an idea or direction to tell them to look into, it would be great...then maybe they could finally fix it and I could enjoy the car!

Oh and when I told the dealer I was bringing it back, they said that their mechanic put on new intake seals and thought that would fix it. Something about it being $350.00 worth of work. I told them that was fine and dandy, but it didn't fix the issue.

When it runs right, it's a darn fun machine to drive...but you definitely can't drive around in Vegas without A/C in the summer!

Any help would be appreciated. Oh, and the car does have 151,000 miles on it...ya, I know it's a lot, but it really does run nice when it's working right. LOL

Thanks!
Mat

[RandyStinchcomb]

sounds like a bunch of problems statring wth stuck or sticking IMRC's which is short for "intake manifold runner controls" located between the cylinder head and intake and they are activated right around 3250 or so rpms...and sounds like you have issues wth the O2 sensors

[SVTSnak]

Randy,

Thanks for the reply. I had the local CSK shop check the code today for the Check Engine Light and this time it has only one code set. A P0155 code has come up. To my understanding this is: O2 Sensor Heater Circuit Bank 2 Sensor 1

What's funny is before I took it in the other day, the codes were different and it indicated the engine running lean in bank 2. So, it seems like it's a problem on that side.

My question is though, if the IMRC's are stuck, then why would it only be an issue when the AC is turned on? The car seems to run fine without the AC on. It's only when the AC is turned on that I have the idling and hesitation issues. The more I drive it without the AC on, the more it seems like the car is okay that way. It's only when you turn the AC on now that the idle goes nuts and you can literally feel the hesitation while driving.

I don't believe I had the AC on when this most recent code came up, but I did notice that the light came on as soon as I turned the key on and started the car (AC off). But don't the codes normally take like three cycles before they come on? I thought that's what I read somewhere.

[SVTSnak]

Well, got it back from the "so called dealer" today and they didn't do a damn thing to it. They cleared the O2 sensor code and then took it and got it smogged so that it would pass.

When I questioned them about it, the guy just kind of stuttered and stammered about it, but didn't say anything. I drove off and sure enough, the idle issue still exists. GRRRRRR

If I turn the A/C off, the car runs great. The idle settles down with no issues and there is no hesitation while driving it. As soon as I hit that A/C switch to turn it on, the idle goes nuts, the car wants to die at a light after it sits for 30 seconds at 2k (idle) and it hesitates like there is no tomorrow. But if I turn the A/C off (even when throttling and it hesitating), the hesitation disappears and the car will start to pull again.

I'm lost...apparently the dealer is not going to help me. I'm about ready to take it to an actual Ford dealer and have them fix it and send these yahoos the bill. This is stupid.

If anyone has any ideas, please let me know...I just might have to fix this darn thing myself so I can enjoy my A/C!!!!!

[Cobra Boy]

I have a 96 cobra also with the same issues, I only have problems when the ac is on. I have changed the iac, egr, and dpfe and still have the same problems does anyone have any ideas?

[soundwave3100]

This sounds like a vacuum leak issue to me. That explains the lean code. I would carefully check all the vacuum hoses for small cracks, and look for a loose pcv valve grommet, make sure you take the time to take all the vacuum lines out of their neat split loom to look at the actual line inside them. If you are still having issues then spray some carb cleaner around the intake manifold and and vacuum hose with the engine running, if the engine revs up and down in just a certain spot, look closer and you have found a vacuum leak. If you imrcs where stuck open you would have got a code for that and not for lean. I think you notice it the most when you ac is on because it just puts a bigger load on the engine