I have a 1992 dodge shadow witth a 3 liter v6 mitsibishi engine l92,000 miles. At cruising speed after warmup, it will start surging,bucking severly at times , Rpm all over the place, transmission shiftingI think due to throttle surging. When throttle is mashed, it will takeoff to redline but when throttle is lifted will start surging again. I have replaced plug wires,dist.cap and rotor, tested map sensor, fuel filter ,and cat. converter,alternator/electical output OK,can't find an EGR valve. Engine is in good shape- no oil burning, etc. Anyone have any suggestions? Thanks for your help

 

you didnt mentionif you checked it but i would check the TPS (throttle position sensor). im not sure if there is a way to check it someone else would have to help you there

 

does the surging occur when driving or when lifting the foot off the accelerator?

 

It happens when driving on cruise control or foot control at a steady speed, anywhere from just off idle to cruising speed after the engine warms up. When in nuetral and reved to near red-line, it cuts in and out. (Question: Is there a rev limiter at near red-line?) When throttle is opened under power, it accelerateswell without cutting out until return to steady speed. This condition is intermittent. This "surging"can be described as severe bucking (cutting in and out). RPM's dropping and revving to the point of transmission shift-down. Any suggestions would be greatly appreciated. Many thanks.

These are the things I have ruled out: TPS, Map sensor, coil, cat. converter, fuel filter, wires, plugs, rotor cap, and rotor. Haven't checked pick-up coil. Can't see anything wrong with wiring harness, but not ruled out at this time.

 

I dealt with an issue on my Stratus that pointed to a vacuum or IAC issue. I pulled the IAC and it seemed ok. The car was sitting for about a week before I had enough time to put it back together. When I did, I noticed that the IAC pigtail insulation had crumbled away off the wires for about 1 inch from the connector and the wires were touching. I coated each wire with superglue and put a generous amount of glue right where the wires meet the insulation to prevent further cracking. Then I wrapped each wire in tape and bundled everything together. That seems to have fixed my problem. (Almost the same exact symptoms as yours)

 

stonentwolf:

Thanks for the tip on the idle air control problem with your Stratus. I checked the wires and found no breaks or corrosion, but found that the IAC was stuck - solid, probably from my prior cleaning with carb cleaner. (This apparently caused the solenoid to stick - This method of cleaning is not advised. Only clean the orifices with cleaner.) I replaced the IAC, took the Shadow for a long drive and no problems. Thank you very much for the tip!

smranch