1999 cougar surging at higher acceleration speeds

[alexx_007]

This is a new car to me and aside from minor issues, things have been ok until now. When accelerating to speeds past 50 mph or so the car starts to jerk, surge, stumble. Even after laying off the accelerator pedal and letting car slow to say 40 mph, when you try to slowly speed up again the car intermittently does this. The engine never stalls although it seems as though it wants to. Any starting points to helping me diagnose this issue would be helpful.

[wadespencer99]

Any check engine lights?

[Chromed CoUgaR]

Kinda sounds like my Fuel Pump problem that I had a while back. Cougars have really bad fuel pumps...

[alexx_007]

It does not show a CEL at first. After it bucks and surges a few times it did show up though. Noticed that if I keep the RPM gauge under 2500 it would operate smoothly. Also when this condition happens the RPM gauge is all over the place. In addition the fuel tank is full. I called the dealer and described the symptoms to him and asked about the recall but he said that my car does not fall under the fuel pump recall.

[wadespencer99]

Go to Autozone and get the code from the CEL scanned. Even if the light isn't on, it should still be saved in the ECU. Come back and post the results.

[alexx_007]

Took awhile for me to get back but the Ford place had the car (doing recall repair for the heater blower resistor) for a week.

Anyway, when I got it back I took it to a guy that used to do my smog. He ran a check for the ECM codes and it came back as “Intake Manifold Runner Control stuck closed.”
After reading codes left in memory he then cleared the codes and started a diagnostic check fresh. I cannot remember the exact code but on the scanner, it reads out something like this:

Bank 1 lean (voltage numbers that fluctuate slightly)
rich
Bank 2 lean (voltage numbers that fluctuate slightly)
rich

I know this is not exact but the thing he pointed out tome was that on the bank one voltage reading mine stays at 3v and does not change like the other banks.

[alexx_007]

Bump!!

[B3NN3TT]

The IMRC is supposed to be open above 3500 RPMs. That might be a big part of your issues...

Lean conditions are almost always due to a leak in the intake tract. Make sure all hoses and tubes are plugged in and tight, and all hose clamps are square and tight.

Have you done any work to the top end lately?

[alexx_007]

No I just bought the car. I am proceeding with checking for leaks but I guess the switch on my IMRC is dead is there a way to fix that and if not what is the part # for a new one?
When I opened the unit the gear that the spring is on was turned all the way around to where it would take a full rotation of the gear for it to pick up the spring and open the runners. Here, I just created a web page with a picture to better explain it.
Index of /alexx_007

[B3NN3TT]

I don't know the part number, but the parts counter at the dealership should be able to find it for you. It's a dealer-only item, as far as I know. New units are between $150 and $200, depending on how much your parts dept marks up their parts.