Loss of Power...Hesitation?

[AaronB]

My 94GrCherokee, V8 used to eat up hills. But on last trip into Rockies, it stuttered and hesitated going up. Now also does that on highway between 60+70MPH. Around town it isn't at quick either, but no hesitation until on the highway. Don't know why it only does it at higher speeds. It seems to power through it OK if I just get on it a little.

Recently replaced-plugs,wires,fuel filter, dist rotor,air filter,intake man gasket,PCV valve,TPS. Had timing checked at mechanic(although I don't know what they checked since its all computerized).

Any suggestions what to investigate beyond what I have done? Thanks

 

[XJNick]

Hi,

So does it do it ONLY when the vehicle speed is past a certain MPH, or does it do it when the engine RPMs are past a certain point (such as above 2000 RPMs in any gear)? If it is related to the vehicle speed, what transmission do you have?

-Nick :!:

 

[AaronB]

I need a front axle for a 84 CJ7

Thanks Nick,
It only does it as it passes a certain speed. On the highway between 60 + 70, it is usually at or around 2000RPM at that speed. But at the same RPM's at lower speeds, there is no hesitation etc.

It is full time 4 wheel. Off the top of my head I'm not sure the type of transmission, it's and ASI or ASE, something like that. I can look it up and post back. So you are thinking transmission, rather than mixture or exhaust. Could the T-case also be suspect?

 

[XJNick]

Hi

The only reason why I began thinking about the problem as mechanical was because their aren't many reasons for the computer/electrical system to be causing the engine to sputter at 2000 RPMs in 1st,2nd,3rd, and 4th gears but not at 2000 RPMs in 5th (or overdrive). It just wouldn't be likely.

The only computer sensor i can think of right of that could cause problems on at a certain vehicle speed is the of course the Vehicle Speed Sensor (VSS). this is mainly used to drive the electronic speedometer and odometer, but I suppose the computer may use data from it to manage the engine as well (though I suspet this is all done through the Crankshaft Position Sensor (CPS) - which only responds to ENGINE RPMs, not vehicle speed).

Is your transmission Auto or manual (that's what I really need to know). if it is a manual, i'd rule it out as any potential problem. But if it is an automatic, you might be experiencing problems with the torque converter (like a clutch) not locking up properly.

I'd first investigate the electrical/computer side of things first, though. I can try to help you furthur, but I have never worked on a Jeep V8 so do not know the specifics of where sensors are located, pinouts, etc.. :mrgreen:

-Nick :!:

 

[AaronB]

Hi
This is an automatic transmission. Overdrive is the only gear that there is any sputtering/hesitation. I pulled what codes I could and came up with nothing. Is there any way to diagnos the condition of the torque converter without pulling it off?
Thanks a bunch for your help
Aaron