99 Jeep Grand Cherokee. Randomly looses engine power sitting still at low speed or at high

jeep
grand-cherokee

#1

Please help, my jeep will randomly just loose engine power the rpms just drop off completely. Sometimes the whole car goes off but not always sometimes just engine power then it wil kick back in after a few secs… I have been looking everywhere see that it looks like a common problem but whole bunch of fixes. Has anyone had any success


#2

Sounds like a wonky ignition switch (the electrical part, not the lock cylinder).


#3

Will that effect it while driving or just at starting.


#4

It can affect either.


#5

Is the engine Light on?


#6

No engine light at all.


#7

I change the fuel filter thinking it maybe clogged or gunned up and changed the spark plugs.


#8

Lots of possibilities. How old are the plugs and wires? Have the fuel pressure checked under load. If you know anyone with a scantool, maybe drive around some with the scantool hooked up and check out the fuel trims. (I once had an intermittently sticking fuel injector - totally random loss of power. That’s how I found it).

It isn’t always associated with being off of or coming off of the gas pedal is it? It sounds like it does happen at idle. At the other times when you’ve come off throttle to coast? If so, the the idle air control valve may be wonky.


#9

If I let it idle for a little while it will just cut off completely. But does happen while driving at low speed as well as high speed


#10

Just a guess but it sounds like something around the throttle body. Maybe a worn IAC?

This happened to me once on my 98 mustang and it would not idle when started , just shake and sputter off. I had to keep revving it to keep the engine on. New IAC did the trick.

Some questions are does it do this just from a cold start? Will it run if you put your foot on the gas to raise and hold the RPM’s up to say 1500?

Another thought could be some bad gas. Water in the line. Just a few thoughts


#11

Also possibly a vacuum leak. Make sure all hoses are connected well and not rotted out


#12

“If I let it idle for a little while it will just cut off completely. But does happen while driving at low speed as well as high speed”

The question wasn’t about speed. It was about your foot. Ignore the speed for a minute. Does it only happen when your foot is OFF the gas pedal? Your foot can be off the gas pedal at 90 mph or 9 mph or zero mph.


#13

Sorry, no I can have my foot on the gas petal and it will just loose power


#14

I replaced the ignition switch to no avail…


#15

I read somewhere that it could possibly be the crank shaft position sensor? It looks like a real pain to get that out and back in…


#16

The problem might be with the Crankshaft Position sensor. I’ve replaced a few of these on Jeeps for the problem you describe.

The crankshaft position sensor is located on the bell housing of the transmission, drivers side. Way up there.

A crank sensor won’t always turn a Check Engine light on when it fails.

Tester


#17

I picked up a cps today going to give it a try tomorrow… Looks like a bear to get at read you can get at it through the inside next the gas pedal. I hope this is the problem. Running out of money lol


#18

If you want to replace the crank sensor, you’ll need a ratchet wrench with extensions.

You want to get at the back of the transmission and feed the extensions with the 10 mm socket onto the bolts thru the tunnel for the transmission Then reach up and remove the sensor.

When installing the sensor, put a small amount of petroleum jelly on the O-ring and push the sensor in as far as it will go. Then with the extensions and socket, start the mounting bolts for the sensor. Go back and forth while tightening the sensor so it seats squarely.

Tester


#19

I have the same problem in my 96 Grand Cherokee. Chased codes and replaced sensors until all that was left was to replace the ECM. Have done that twice now and the problem has come back. Let me know if you find a solution.


#20

I think it would be worthwhile to try to get your hands on a scantool that will show and record live data. Then hook it up and go about your business. When the vehicle has an “episode” - look to see what has gone wacky.