Here the full story:

The enginelight came on about 6 weeks ago. Evaluation with the OBD reader
showed a P0123. So I replaced the TPS. While doing that I stripped a thread
on the throttle body. The tps was fixed with one screw, the error was still
there. I found a god throttle body on a junk yard and replaced the existing
one. The one from the junk yard came with all sensors (MAP, TPS and Idle
Motor) and the problem was exactly the same. All Voltages measured right,
error code P0123. So I got a new ECU from the junk yard and put it in. Same
exact error message, not resetable P0123. I put the old ECU back in and gave
the ECU back to the junk yard. Then I gave the car to the mechanic who did
some troubleshooting and told me its most likely the ECU. When I told him I
replaced it allready, he mentioned that on some vehicles (he had problems
with chevy ecus) a reprogramming is required that just the official dealers
can do. A new ecu for the jeep is 480$ approx. As you could see in the
newsgroup I followed the advice and checked all electrical connections,
measured the common ground and the grounding of the engine block, cleaned
the contacts and did reteaching of the ecu.

The driving is not bad with the car. It starts at 2nd try always, in the
beginning with the old throttle body it would stall when it was cold, but
now it doesn't anymore. When the engine is cold the first couple of hundred
yards it runs a bit rough (throttle response is slow)but then it just jumps
a little bit for example on the high way when accelerating from 65 to 75
with little gas. There seems to be one position of the gas in that regime
where it almost goes into a resonant oscillation (difficult to explain, it
feels like going on and off the gas in 0.5 sec distance even though the
throttle isn't moved at all).

If you have any additional ideas and good advice that would be highly
appreciated. I want to make sure to do everythiong possible before I put the
car to a Jeep dealer.

Thanks

Joachim

"tim bur" <dbrider@cac.net> wrote in message
news:42B36941.18635780@cac.net...
> can u email me with the whole story from start to now,and include the
> fault code
>
> DougW wrote:
>
>> reigelser did pass the time by typing:
>> > Hi,
>> > I did the proposed alignment procedure and I cleaned all contacts with
>> > a
>> > special contact cleaner. Nothing changed. I can not reset the error.
>> > The
>> > voltages are 5.1V constant supply ground to pin 1. Then the voltage
>> > between
>> > Pin1 and 2 is between 1.1V (fully closed) and 4.2V fully open. Between
>> > the
>> > pin 2 and ground the voltage is 3.9V fully closed and 1.1V fully open.
>> > I
>> > measured the resistance of the common ground of the Map, the TPS and
>> > the
>> > Crankshaft sensor and its good.
>> > I guess I am running out of options, since I also cleaned the throttle
>> > body
>> > with carburator cleaner prior to putting it into the car.
>> > Does anybody have another idea? The thought to get a new ECU for 450$
>> > without knowing if it fixes it is not funny.
>> > Thanks again
>>
>> As much as I don't like throwing parts at a problem you might
>> want to try the MAP sensor before the ECU. When it comes to paying
>> out $450 it's also a good idea just to take it into a dealership
>> and have them do a full diagnostic on the engine.
>>
>> I've gone through two MAP sensors and the symptoms are usually
>> some stubling along with a gutless acceleration except when the
>> gas is floored or when the engine is running in warmup-mode.
>>
>> Just for grins, check the O2 sensor lead as it goes up the front
>> of the block and make sure it's not melted or abraided. This
>> can cause headaches to the ECU.
>>
>> --
>> DougW
>

 

Hi, the problem is solved. 2 days after I sprayed everything with contact
cleaner, the error went away by itself. That was 4 days ago. Self healing
Jeep. Let's see if it stays like that.

Thanks for all the help and advice.

Jo
"reigelser" <reigelser@sbcglobal.net> wrote in message
news:NuBqe.9401$_A5.776@newssvr19.news.prodigy.com ...
> Hi,
> does anybody know, if there is some programming or calibration to be done
> if the engine control unit is replaced? Or do I just plug it in and thats
> it?
> Thanks for the advice.
>
> Jo
>
>

 

Hi, the problem is solved. 2 days after I sprayed everything with contact
cleaner, the error went away by itself. That was 4 days ago. Self healing
Jeep. Let's see if it stays like that.

Thanks for all the help and advice.

Jo
"reigelser" <reigelser@sbcglobal.net> wrote in message
news:NuBqe.9401$_A5.776@newssvr19.news.prodigy.com ...
> Hi,
> does anybody know, if there is some programming or calibration to be done
> if the engine control unit is replaced? Or do I just plug it in and thats
> it?
> Thanks for the advice.
>
> Jo
>
>

 

Hi, the problem is solved. 2 days after I sprayed everything with contact
cleaner, the error went away by itself. That was 4 days ago. Self healing
Jeep. Let's see if it stays like that.

Thanks for all the help and advice.

Jo
"reigelser" <reigelser@sbcglobal.net> wrote in message
news:NuBqe.9401$_A5.776@newssvr19.news.prodigy.com ...
> Hi,
> does anybody know, if there is some programming or calibration to be done
> if the engine control unit is replaced? Or do I just plug it in and thats
> it?
> Thanks for the advice.
>
> Jo
>
>

 

Hi, the problem is solved. 2 days after I sprayed everything with contact
cleaner, the error went away by itself. That was 4 days ago. Self healing
Jeep. Let's see if it stays like that.

Thanks for all the help and advice.

Jo
"reigelser" <reigelser@sbcglobal.net> wrote in message
news:NuBqe.9401$_A5.776@newssvr19.news.prodigy.com ...
> Hi,
> does anybody know, if there is some programming or calibration to be done
> if the engine control unit is replaced? Or do I just plug it in and thats
> it?
> Thanks for the advice.
>
> Jo
>
>