Stuck rev limiter?

[Andy G]

I have got an 03 ST and have acquired an interesting problem.



My engine will not rev over 4000 RPM. In any gear. So, as you can assume, it is not very easy to drive right now. I will be in 4th gear, start going up a hill, it wants to downshift, and the motor will not go over 4K RPM, so the downshift misses and it won't go back into a gear until I let off the gas.



At first I thought the transmission was going out, but if I put it in second gear, and push the pedal to the floor, it will accelerate up to 4000 RPM and stop, it will not rev further. And it will not free rev in Neutral or Park past 4K, but I think that is normal.



I am kinda thinking the some sensor that tells the computer that the transmission is in drive is broken, and the computer thinks the transmission is in Park all of the time.



It suddenly became gutless when this started happening as well, not gutless like tranny slipping, but gutless like the computer has been detuned. Again, I am thinking the computer thinks the tranny is always in Park. It starts getting reel gutless around 3k, which is where the rev limiter is supposed to come in right?



Any help, suggestions of where to look, what to try first, any help appreciated.



cheers,

 

[Ben Poche]

disconect the battery for 15 minutes and reset the computer is where i would start.and yes 3k is the limiter in park

 

[Richard L]

I doubt it's the rev limiter since that is active only in neutral or park. If your engine is gutless you probalby have a fuel or ignition problem. Perhaps a dirty or clogged filter, low fuel pump pressure, or dirty/bad injectors. You may also have a weak or bad ignition coil pack which may have a weak spark at higher RPMs, or bad plug wires or plugs? You can even have a clogged catalytic converter or restriced exhaust due to a badly dented or crushed exhaust pipe???



Even though you are not getting a check engine light, you might what to have AutoZone check for any diagnostic error codes stored in the computer.



Unfortunately, there are a lot of problems that can cause an engine to lose power at higher RPM, and only testing can isolate the real problem.



...Rich

 

[Andy G]

See, that is what I am wondering, if there is a sensor on the tranny that tells the computer the tranny is in drive, and it is not working. So the computer always thinks the tranny is in Park.



And I do need to do some checking around the motor for performance issues, but it starts dieing at 3K and will not rev past 4K, period. Almost like it is being "controlled" to not rev any higher.

 

[Todd Z]

There is a neutral rev limiter AND an in gear rev limiter.... If the neutral safety switch is bad, this could happen or the vehicle speed sensor is bad, but that VSS would give a check engine light...

Does your indicator that says PRNDL move when you move the shifter??..

Also in drive do your back up lights stay on???

And you may want to try tilting the steering wheel up and down a little to see if that helps...

Todd Z

 

[Gavin Allan]

Try changing the fuel filter. It sounds like a plugged fuel filter to me.

 

[Andy Szkutak]

I had the exact same problem around the exact same rpm...change your tranny fluid and filter. My filter was clogged...fixed it right away b4 more damage to the tranny occured...



Andy

 

[Andy G]

OK, so I changed the fuel filter, and the old one was ok. Not perfect, but not bad.



I have changed the plugs and wires, and they were admittedly, awful.



Full tranny service, including filter. Didn't look bad, in fact looked rather clean......



Air filter OK, No engine codes to report, no change by reseting the computer.......



I am really starting to convince myself the catalytic converters are bad. The exhaust pipe looks ok, not crushed or anything. The shift indicator on the dash is moving properly. And the backup lights do not stay on.



IT does run a bit better after the tune-up, but the problem still exists. My question now is, if it is the catalytic converter, would it be the one on the main pipe or the two in the y-pipe? Or all of them?



Anything else it could be?



Another symptom I just discovered...I just filled up the tank and got 13MPG on the last tank (HOLY @##%!!!)



I am really getting sold on catalytics at this point, but any more suggestions or information you may have to share would be great.



Thanks for all of the suggestions so far, I needed to tune up and service the tranny anyways. This gave me motivation



cheers,

 

[Richard Turnbull]

I think you could be correct with the cats. My buddy had an older Ford with a 5.7 V-8 I think it was, and it had a plugged cat and the engine would not rev up. He took the exhaust out and smashed up the cat with a bar throught the pipe opening. That was it, it worked perfect after that.



I had a 1991 Sprint with the same thing (common on that car).

 

[Michael Cacioppo]

Your cats should be covered under warranty up to about 75K miles I believe since it is a smog device.

 

[Andy G]

he he.......



76,250 miles....



What I would really like to do is replace the y-pipe and the main cat with Random technology parts.



But I need to do something fast, I travel over a 7000ft summit everyday on my way to and from work, and it is no fun at 50MPH.



Does fine on flat ground, but hills kill it.