High rpm hesitation and loss of power..

[Dave04M3]

I have read quite a few threads on this topic and thought it could be my fuel pump going bad. My car after it has warmed up, never cold...at high rpm under load the power will cut in and out. It only does this when the car has been driven for over 20 minutes lets say. When cold the car runs like a bat out of helll. I read about the Fuel Pump TSB, took it to Mercury they told me my car wasn't involved with this campaign and that I would have to pay if I wanted the fuel pump replaced. First off, does it sound like it could be the fuel pump? The car only has 35Kmiles on the car. It is a 99 Cougar V6 MTX. The IMRC's were replaced about a year ago under warranty at 28K miles. Any help greatly appreciated. I still have the original plugs and wires on the car, but these should at least last to 70K miles right? Need help thanks...Dave

[DanG]

Sounds like the pump, could also be the IMRC motor, but the former is more likely. Hook a test gauge up to the Schrader valve on the fuel rail to see if you're losing pressure at high RPMs under load.

[Dave04M3]

Dan is there a guage that I can hook up to get to the [censored]pit so I can see this when Im driving?? Also, thanks for the response..greatly appreciated. Dave

[DemonSVT]

I'd start with fresh plugs (APP764 gapped with a feeler gauge) and a new fuel filter.
Once you have those ruled out start checking the other two things.


The fuel pump issue is normally fuel level related but not always.


The IMRC flutter is heat related.


It sounds IMRC related because you mention it only does it after the engine's warmed up.


There are several posts on IMRC cleaning and extra support for the motor. That's a first step procedure.

[Dave04M3]

Thanks Demon, I'm new to working on Cougars. My forte is SVT Mustangs..I believe the IMRC's are under the UIM...with only 35K miles on the car could the lower intake really be carbonized that it will keep the IMRC's open?? I already cleaned the MAF, new fuel filter, as well as a new airfilter. It seemed to help a little, meaning to me that some of it could be tune. However when that hesitation comes back that issue was probably exasperated by this. I'll try the plugs as well and maybe some new wires. Dave

[C4L3]

Originally posted by: Dave04M3
..I believe the IMRC's are under the UIM...

Its just that metal box underneath the plastic engine cover. Easy to get to, easy to work on.

[B3NN3TT]

Right. The IMRC in the Cougar is electrical, not vacuum-powered like a lot of other Fords, and located under the plastic engine shroud over the front valve cover. The electrical motor can develop a little play, allowing the teeth of the gear to lose contact with the gears on the cable mechanism, causing the butterflies to flutter, rather than stick open like they should. In this case, the JB-Weld fix discussed in other threads may solve your problem, short of buying a new IMRC mechanism altogether.

[jslickman]

I'm having somewhat of a similar problem, but this was the closest thread, and I didn't want to start a new one.. I have a V6 2000 Cougar that has had the fuel system replaced under the recall, but when I gun it from like 50ish to go to infinity and beyond, i'll hit maybe 7-8k rpm's and kind of sit there as my car studders and the battery light flickers.. it actually almost got me hit, namely because I was a jackass who was passing a guy who passed me after I passed him. you know.. fun stuff but I have to let off the gas before it will shift into the next gear. any idea's? (aside from getting a standard..lol i want one.)


*oh and I'm fairly new to the world of tuning and fixing cars, thus i'm a technical retard.*

[GTownCougar]

7-8k?

[DanG]

Now THAT'S a fine thread resurrection.

You're bouncing off the rev limiter, which is put there on purpose to keep you from hurting the engine by over-revving it. The limiter normally sits at 6750RPM soft, 7000RPM (?) hard stock. It's been a while since I've had to recall those numbers so they may be slightly off.

The ATX is told by the ECU to shift at or near redline during WOT- Sounds like something's wrong with the ECU and/or the trans valve body, which is electronically controlled.

Unless you're just d*cking with us. But going back to a post from '05 is a convoluted way to d*ck with someone...