Power issues with a 1990 Jeep Cherokee 4.0L?

  • Thread starter Thread starter afreshpath_admin
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afreshpath_admin

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I am gonna do some basic work on the XJ(Cherokee) today but I have some symptoms while driving that I would like a better handle on.

When entering the freeway I have noticed that the XJ seems pretty "dogish" as long as the rpm's are below 3000. I press down on the gas, the trans shifts to a lower gear but engine response is very very slow. Once I hit 3000 rpm though, hold on to your hat because she takes off like a rocket and the rpms rise quickly from that point.

Tranny shifting seems to be right because it does shift down as needed. That also let's me think the TPS is working properly as it also feeds the TCU.

One other thing that may or may not be related is a slightly high idle - 1000 RPM once warmed up.

Today's work includes change the plugs and clean up the IAC and perhaps clean the throttle body.
 
I would definetly do gas and air filters and plug wires and dump a bottle of injector cleaner in the gas.
 
Sounds like you have an understanding of the vehicle but the high idle is telling you something. It is pulling scavenge air in from some place and this is allowing the idle to be at a higher than normal setting. Simply put, you have a vacuum leak that you need to detect and repair. If this vacuum leak is from a vacuum hose that supports the MAP=manifold absolute pressure sensor, this would account for poor throttle responce. A throttle body base gasket that is cracked would also effect this and cause poor responce. I have found that using throttle body cleaned and spraying suspected leaks helps to identify them easier. Good Luck Any sensor that is vacuum controlled is suspect, so check them all.
 
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