JGC 2000 still idles rough, surges, serviced twice

[amhunley]

Symptoms began with surging, rpm would dip below 500, then surge up on its own. Also, often a very unstable rpms when in park. Had the O2 sensor replaced. Didn't fix it!

Was told fuel pump wasn't holding pressure, and causing fuel injector #3 and #6 to cut in and out. Had the pump replaced and injectors cleaned. Didn't fix it!

Still rough idle from time to time, especially when in park or stopped at a light, even at a stop light the jeep did not want to accelerate. Somebody help me out, obviously the mechanic is having a hard time pin pointing this one!

[Dale Aeppli]

Originally Posted by amhunley

Symptoms began with surging, rpm would dip below 500, then surge up on its own. Also, often a very unstable rpms when in park. Had the O2 sensor replaced. Didn't fix it!

Was told fuel pump wasn't holding pressure, and causing fuel injector #3 and #6 to cut in and out. Had the pump replaced and injectors cleaned. Didn't fix it!

Still rough idle from time to time, especially when in park or stopped at a light, even at a stop light the jeep did not want to accelerate. Somebody help me out, obviously the mechanic is having a hard time pin pointing this one!

HI, SOUNDS LIKE THE IAC MAYBE DIRTY OR STICKING, THEY CAN BE CLEANED. BUT IT IS POSSIBLE IT IS BAD, YOU COULD TRY CLEANING. IT ALSO COULD BE THE TPS THROTTLE POSITION SENSOR , BEING IT HAPPENS WHEN YOU ARE ACCELRATING DALE
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[carlos80]

you can also have a bad injector(by bad i don't mean completely shot))you can check them by using a mechanics stethoscope listen to them see they should all sound about the same it's a quick check good luck

[dksob81]

Mechanic Stethoscope - You could also use a long handled Flat-Head screw driver and hold it against your ear and place tip on the Injector(s) while listening for it to open and close, this works really well.

[Chazz100]

Originally Posted by amhunley

Symptoms began with surging, rpm would dip below 500, then surge up on its own. Also, often a very unstable rpms when in park. Had the O2 sensor replaced. Didn't fix it!

Was told fuel pump wasn't holding pressure, and causing fuel injector #3 and #6 to cut in and out. Had the pump replaced and injectors cleaned. Didn't fix it!

Still rough idle from time to time, especially when in park or stopped at a light, even at a stop light the jeep did not want to accelerate. Somebody help me out, obviously the mechanic is having a hard time pin pointing this one!

I have this same problem HELP HELP!!!!

[Dale Aeppli]

have you cleaned the throttlebody. Have you changed any of the sensors? dale [email protected]

[dksob81]

Sounds like a bad Throttle Position Sensor (TPS).
Try cleaning the TB 1st, like dale suggested.

[amberlm26]

I have the same problems with our 94' JGC Laredo 5.2L. We recently bought it and thought the surgeing could be an easy fix. It only surges when it is fully warmed-up and you put it in park. We have replaced the TPS, IAC, plugs, wires, cap, rotor, fuel filter, sprayed the throttle body with gumout plus several in the gas injector treatments, and changed all fluids.(figured I would mention it all)
With no change, at all, to the idle to 1000rpm surge. What next?

[dksob81]

Manifold Absolute Pressure (MAP) Sensor.

replace the MAP sensor that should take care of it. Ussually the TPS is the cause but I have seen a couple symptoms which originally thought were the TPS but ended up being a bad MAP sensor.

[Dale Aeppli]

Originally Posted by amberlm26

I have the same problems with our 94' JGC Laredo 5.2L. We recently bought it and thought the surgeing could be an easy fix. It only surges when it is fully warmed-up and you put it in park. We have replaced the TPS, IAC, plugs, wires, cap, rotor, fuel filter, sprayed the throttle body with gumout plus several in the gas injector treatments, and changed all fluids.(figured I would mention it all)
With no change, at all, to the idle to 1000rpm surge. What next?

Have you had the oxygen sensors changed, could lead to you surging which you say happens after fully warmed- up just a thought
dale