3 weeks ago idle started to surge up and down.mechanic says go look for a idle control unit, he adjusted idle so it was calm, car runs fine. 2 weeks ago car starts in morning runs like a champ. after shutdown and for the rest of the day car stumbles, bogs, hammers all day long. every morning starts and runs beautiful. after shutting down and restarting - horrible monster! check engine light comes, on voltmeter diagnosis shows code 11 oxygen sensor. go to mechanic he says no, bad computer. pull computer 1 cap on its way but no leaks or burns, replace caps car runs better than ever! go for another drive 20 minutes later, here we go again, hammer, stumble, bog BUT not as bad as before. if computer is bad why does the car run so fine first thing in the morning but only acts up after shutting down!

when the caps go or have gone and been replaced sometimes the ecu is still messed and will run sometimes and not others

it happened to me

did u replace the isc? you didnt really say if you did or not. like the last post the ecu could be fubared because i replace caps on motherboards quite often and that doesn't always fix them because they could have been overheated or surged to bad. Similar crap different pile, but if you didnt replace the isc then do it.

part i can't get a handle on is why the car runs so well first run. if ecu was bad wouldn't the car constantly run bad?

haven't replaced isc yet,boneyard man claims he has one coming this week. guess i am trying to save replacing more items than need to ($$$) also why would ecu store O2 sensor as problem?

I would guess the O2 or some other thing is messed


at first the ECU is reset and runs proper. once it goes to fine tune itself it ****s up.

Replace the O2 sensor. When you first start it up it is closed loop for a few minutes until the sensor warms up. Once it warms up you can see it cycle the O2 voltage output. Once it starts to cycle the ECU will try and use the feedback. You might also want to check the wiring harness for the O2 sesor and while you are at it check the wires on the thermostat housing. They get very brittle with age and will break.

I am quite sure the isc only affects idle operation not off idle.And guys have unplugged the isc and seem to get along just fine.

I had bad surging idle when I first got my car.
I am still not exactly sure what fixed it.
First thing I did was put in redline injector cleaner and then changed out plugs and wires and fuel filter.Then did the mopar compustion chamber cleaner treatment one can.Idle is perfectly smooth now cold or warm.The above should also eliminate most all bog and those kind of problems.

Recently I put in my new fuel pump,new afpr,fuel pressure gauge and new FIC 650 injectors.

Bad 02 can affect offidle but not wot.Tps could definitely cause some symptoms you are describing.

Misfire if the plugs and wires are new could also still be caused by bad coilpacks.I had some of that too but in hindsite my misfire might actually have been fuel cut.I changed out the coils anyway.

I also changed out as basic maintenance now my knock sensor and o2 sensor and coolant ecu sensor and soon the tps sensor.That tps is one pricey sensor.!!!

Also bogs and stuff like you mentioned can be caused by boost /vac leaks.Common places for boost leaks is the intercooler upper outlet.It can rot out.I jb welded mine fixed it up.Loose outlet hoses on end of turbo or anywhere between turbo and tb.

Vac leaks are common with rotted vac lines.I went to taboo racing elimination and got rid of most of the factory crap.Other common vac leak locations..injector lower insulator seals,throttle tb shaft seals and intake manifold gasket..the old ones were paper crap the new ones are metal.

Likely your problems can be solved with something mentioned above.Some of it is cheap to test and some is a bit more pricey.Especially if you keep going to the dealer.

You can make a cheap boost leak tester,buy a vac tester,a fuel pressure tester.Plugs are cheap,wires pretty cheap ,fuel filter cheap but annoying.02 sensor a bit pricey,tps outrageously pricey and coilpacks very pricey.And new ecus well we won't go there.

I also was a bit worried when I got my car,it was an auction special but after persistance and
parts and a bit of dollars its running quite nicely.

thanks for the input guys. i guess the part that has really gotten me to pull what little hair i have left is the first run of the day no problems, but terrible all day after. in manual it says that on first start the O2 sensor is cut out and control is done by ecu, control going back to O2 sensor after it is warmed up. this almost sounds
like a logical reason for the split personality the car seems to have developed.

sorry, forgot most important question, what and where do you guys recommnend for replacement O2 sensor. have 2l turbo AWD and have read of some people using NTK and doing some rewiring? and can this thing really be pulled without the special socket?

Bill

If you have a princess auto in town they have OS sensor sockets for $5