Acceleration problem

[chip_drive]

Hey guys, this is my first post.

I dont know what I wrong.

Okay, this is what happens. I am can be in any gear, and I floor it. The car accelerates at a constant rate with the rpms going up. But sometimes, between 5 and 7, it will randomly stop accelerating. My foot will still be down and the engine is still running and revving at whatever it stopped at, but I have no additional power past that point until I shift. I kinda move forward like I dropped into a different gear because I dont have the constant pull of acceleration anymore. And it seems to change, sometimes at 5k, 5.5k, sometimes even 7k.

This variation in rpms is what makes me think this is a problem. Others have suggested that it is a rev limit, but it changes. Others also suggest governors, and rev limit combinations. Others still think it is a problem, but I wanted to see what you guys think.

Thanks for any help and suggestions you guys can give me.

2000 Mercury Cougar
2.5L V6
1-8 rpm gauge stock, no redline
5 speed manual transmission

Mods so far:
A reroute of wiring from the alternator to the battery as described in a TSB.
New alternator
Short-ram K&N intake system
These are the only things that I have done that could effect the engine performance. I have done a lot of cosmetic work as well, but do not pertain to this question/problem.

Thanks again!

[skater]

Have you checked the IMRC?

[B3NN3TT]

There IS a redline; all internal combustion engines have a redline. It's just not indicated on the dial.

6750 is the redline. The cams run out of breath at 6250 or so, so you aren't making any more power past that number anyway.

Man, take it easy... I'm surprised you haven't floated a valve and hosed a cylinder yet.

[chip_drive]

I had read other posts about the IMRC, and I had considered changing it, but how do I know if it is bad? How do I check it?

And as far the engine, it stays pretty cool. I always change my oil, and I only use Royal Purple. So should I shift at my redline (6750) or my max power output when I am pushing the most horsepower of 6250? I am looking at getting a tack with a shift light, but I would need to know what to set it at.

Thanks again for the help.

[SpeedStyle]

look under the throttle body at something that looks like another throttle spring, this is your secondaries, look at it while revving the engine,it should open around 4k, make shore you do this while the engine is hot.I just had this problem, and i chose to move my imrc to a cooler area, some people will say theres no need, but its better to be safe than sorry

[B3NN3TT]

I've had the best time slips when shifting right at redline (sometimes I bump the limiter by accident - that hurts your ET's, of course). Even though you aren't making INCREASING power after 6250, the extra 500 or so RPMs leaves you in a better spot on the curve when you hit the next gear.

If your IMRC isn't working, you will fall flat on your face at 3500 RPMs and not get any further.

[Naturaltal3nt]

i had the same problem its like you hit a wall after 5k rpms. change plugs wires and get new air, fuel, filter, and check to see if it helps....it helped my car but i did the svt lite upgrade and it never stuttered at all after that...good luck

[chip_drive]

speedstyle:

I will check the secondaries after I drive home today. Hope this isnt the prob. But I have read about it in the other posts.

B3nn3tt:

So shift between the two for best times? or aim for just after 6250? and assuming what you say is correct, it is probably not my imrc considering just last night I hit 5.5k. So what should I set the shift light at? 6300?

Naturaltal3nt:

I would like to do the svt lite upgrade, but I dont have the cash right now. Right now, I have a k&n filter, fairly new, brand new fuel filter, I just filled up with premium (at $4.17 /gal., now its up to $4.29), new spark plugs, I still need new sp wires though.



Thanks guys, I am new to the forums. I checked in here a couple of times before, but now I think I am here to stay. Your help is much appreciated. Thanks again.

[chip_drive]

Okay, update:

I dont understand. I am cruising at 60, and I turn left and drop to 30 mph. From there I take my car from nearly 2k rpm to 7k rpm easy. There were no problems, no stutters, nothing.

But later that night, all same night, I take it from 40 mph and I am suddenly hit with a wall at 5250 rpm, and the car is not accelerating, just running. It is not going faster, slower, nothing.

I dont know what to do. I have no idea what could be causing this. Thanks for any help you can give from this update.

[B3NN3TT]

Sounds to me like you're having intermittent IMRC failure.

Replace it and be done with it. None of this "cleaning it" or "relocating it" BS. Out with the old, in with the new.