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surging/ tach oscilating at high speeds please help


ratman4
11-26-2004, 09:12 PM
Hi, I am new but hope someone may be able to help. I have a 2004 GC Laredo 4X4 with 17,000 miles. A couple weeks ago while driving on the highway the car began to surge/lurch (that's the best way I can describe it) at speeds over 60 mph. If I keep the gas pedal steady the tach will be at 2,000 rpm then go briefly to 2,300 rpm, back down to 2,000 then to 2,300 and this goes on and on. The first time I took it to the dealership they replaced the Crank Sensor. When it continued I took it back and they did a trans flush, solenoid replacement and replaced the tranducer (not sure how you spell it) and gov sensor. Well, I picked it up after work today got on the freeway home and guess what.....still happening. I would appreciate any thoughts or suggestions anyone may have.

Thanks in advance.

dksob81
11-27-2004, 10:45 AM
have the throttle Position Sensor checked take it into the dealer and have them check the TPS, it sounds like it's failing.

"The TPS is located on the throttle body at the end of the thottle shaft. By monitoring the output voltage from the TPS, the PCM can determine fuel delivery based on throttle valve angle (Driver Demand). A broken or loosen throttle position sensor can cause intermittant bursts of fuel from the injectors and an unstable idle b/c of the PCM thinks the throttle is moving."

I hope this quote helps.
I have the instructions for testing the TPS, email me if u would like it. Joe dksob81@hotmail.com

xj31
11-27-2004, 12:13 PM
It sounds like a trans issue.Is it shifting in and out of overdrive?If they changed the transducer, it's probably a 4.0.As far as simple things,check the t.v. cable but if it's at steady throttle that may not be an issue.

Off_Road
12-03-2004, 04:32 PM
Posted by ratman4 - 11-26-2004 at 10:12 PMHi, I am new but hope someone may be able to help. I have a 2004 GC Laredo 4X4 with 17,000 miles. A couple weeks ago while driving on the highway the car began to surge/lurch (that's the best way I can describe it) at speeds over 60 mph. If I keep the gas pedal steady the tach will be at 2,000 rpm then go briefly to 2,300 rpm, back down to 2,000 then to 2,300 and this goes on and on. The first time I took it to the dealership they replaced the Crank Sensor. When it continued I took it back and they did a trans flush, solenoid replacement and replaced the tranducer (not sure how you spell it) and gov sensor. Well, I picked it up after work today got on the freeway home and guess what.....still happening. I would appreciate any thoughts or suggestions anyone may have.

Thanks in advance.

I agree with xj31 (http://www.automotiveforums.com/vbulletin/member.php?u=222858) I think it's more of a transmission problem. Could possibly be the clutch in the locking torque converter engaging then disengaging. If it were to be your overdrive (4th gear) you should have a button on the dash to lock out overdrive. Try pushing the button locking out overdrive and see if the problem goes away. If the problem continues I would certainly lean toward the lock-up torque converter being the problem. As xj31 (http://www.automotiveforums.com/vbulletin/member.php?u=222858) also mentioned there is a throttle valve preasure cable. This cable effects the throttle valve presure inside the transmission. This adjustment regulates shift timing and quality (e.g. 1-2, 2-3, & 3-4 shifts). If the problem goes away after pushing the button locking out overdrive then it's very well possible a throttle cable adjustment would take care of your problem.

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