Experiencing a bit of a idle/engine surging problem at start up with my 2000 Trooper LS, 3.5L, Automatic 4wd TOD forseveral weeks. Transmission was replaced by dealer under warranty at 118K miles. Vehicle currently has 123K miles. I am the original ower having purchased the vehicle in Jan 2000. No other problems of consequence until now.


On startup the engine rpm will slowly rise to about 2000rpm, then drop until the engine almost dies; then increase again to about 1500rpm, drop to 500rpm or so the finally rise to normal idle for a cold engine. I do not touch the gas pedal during this cycle. Placing the transmission is gear tends to smooth things out other than a flashing CEL only when the gas pedal is depressed. Let off the pedal and the flashing CEL goes off. Drove to the dealer service dept this am and service tech rode with me to confirm drivability and the flashing CEL. Upon return to the dealer he connected a scanner to check codes - none present although the CEL was still flashing. I shut engine off, restarted; perfect idle and no CEL.


Had picked up the Trooper the night before after service dept had installed new intake gaskets. They were convinced the problem was due to a leak and that would take care of it. Service Manager did say that they would not charge me if the intake gaskets did not fix the problem since they had been diagnosing the problem over four different service visits. The have checked to to ensure sensors and such were properly connected after the transmission swap; adjusted a "electronic idle switch" or something to do with the fly-by-wire thingy.


Something is still amiss and we can't seem to put our finger on it. Vehicle runs fine otherwise. I am still wondering about some type of idle solenoid or other type of electronic switch being on the fritz. Any help or comments will be appreciated. Thanks and glad to be here.

the check engine light will flash like that when the ion sence module detects a miss fire, hopefully you didnt get fooled by those bosch plus 2 or 4 spark plugs if so remove them an put back the ngk iridiums.also ive seen the light flash that way do to the o2 sensor connectors crossed.bnk 1 sen 1 an bnk 2 sen 1 are crossed.since you had a trans put in that proably could be the case.the pcm can tell the difference if they are connected wrong.also some injector cleaning jobs will cause this to happen.do to carbon deposites,it usually clears up.an another thing this goes for everyone who reads this.the way the are mixing fuels now with 10% ethelyn its been effecting vehicles with high milege on cold start ups.will cause hesitation,missfires,stumbling the firts few minutes of running until the engine warms up then its fine the rest of the day.take note on where you purchace gas,try to find places that dont mix the gas yet an see what happens .........correction ethyenolEdited by: ISUZUGURU

Thanks for the input but my initial problem continues. Thus far the dealer has replaced the intake manifold gaskets and the MAP sensor. Plugs were changed about 20K ago with factory replacements. Fuel system was cleaned with the BBK(?) system cleaner everyone is so hot on. It was done a weekbefore intake manifolds were changed about 3 or 4 week ago. Picked up Trooper one week ago today. Have started vehicle every morning just to ensure startup/idle is ok. Generally good on most days; three days ago startup idle was a bit erratic but no CEL. It smoothed out pretty quickly. Startup yesterday (Thursday) was like a new vehicle - perfect. Wife told be when she started it up after work (vehicle had been setting about 6 hours) the engine rpm spiked at 3k on startup; then began to idle-down. She said it was still "racing" so she shut it off. Started it back up and idle was ok but he had a flashing CEL only when depressing the gas pedal. The flashing CEL continued as long as the pedal was depressed; no CEL at idle. She said after she got on the main highway the flashing CEL stopped at around a constant 55mph. We drove the Trooper about 50 miles round trip to a football game last night with no problems. I started the vehicle this morning with no idle or surging problems. Throttle sensor; fuel pressure regulator; gremlins? Appreciate any help/advise.