Chrysler Repair: LHS losing power, 97 chrysler lhs, chrysler lhs

Question
QUESTION: Dear Roland,

I have a ’97 Chrysler LHS with 133,000 miles. I am having an intermittent problem. The car loses power, but does not stall. This happens when it is cold or hot. When at a red light it will start idling rough, then will not have enough power to do much more then roll slowly from the stop. On the highway, it will just lose power. The speedometer will fall and so will the tach. Sometimes it is just momentary and recovers on it’s own and all is well. If it doesn’t recover right away, I pull off the road, put it in park and rev the motor and all is fine, or if I just wait a little while, the car recovers by itself and all is well until the next time. The car has never stalled out completely, it just idles really rough until it recovers.
I replaced the fuel filter thinking at first maybe it was clogged. I have checked the codes with the service engine light. I get a funny reading that doesn’t make sense to me. 12/21/21/55. I have repeated it and always get the same thing. I am quite certain that I have started the car more than 50 times since the O2 sensor replacement a couple of months ago, so the 12 puzzles me. Also the 21/21 is curious because I thought it would only display a code a single time.
I replaced an O2 sensor a couple of months ago, guided by the folks at autozone with their scanner. The only code they had gotten was the O2 sensor. After replacing the sensor, the light still stays on, but occasionally winks at me, autozone says it doesn’t show any codes now.

I was advised to replace the power train control back in 2004, but never did. Since then I have read that they don’t shoot codes to the computer (don’t know if this is accurate information), so it left me wondering if it was in fact bad. If this is true, how can you tell if it is bad?
I have taken it to the mechanic, but of course the car drove just fine at the mechanics, it then acted up after leaving the mechanics about a mile down the road.

I have priced the powertrain control module and have found rebuilt’s from autozone for about $200.00, dealer rebuilt’s from $460.00 and a new one at $870.00. Also heard that the module needs to be programmed, at the dealer of course.

I didn’t want to throw parts at the problem, but I don’t know where to go from here. This is starting to sound like the point of no return on this car (costs more to fix than the cars worth).  
I could use any light you might be able to shine on this intermittent problem.

Any information would be greatly appreciated.
Thank you very much,
Sheri


ANSWER: Hi Sheri,
It wasn't clear to me if you can read the codes using your ignition key or not (that was a transition year,'97), but if you can and you still get the 55 then the PCM is reading out codes. I think too if there is a problem with the PCM when scanned with a tool it will so-indicate.
So if there is no more 21, that would verify the sensor and its wiring are OK. The persistence of the 12 makes me wonder if the battery cable clamps or the cables at the clamps might be loose/corroded as an intermittent of the battery supply voltage to car will also set a code, just as if you unhooked the battery. So I would check those clamps and also check the ground wires (the ones attached to the - post clamp) as they go to attachment points on the body near the battery and the engine/transmission to be sure that the bolts are tight after you clean the surfaces of the eye and the metal to which it is attached.
Then see if that helps. Of course this will renew the 12 code but see if it helps in the operation. Thanks for the detailed history. Let me know what happens and we can try some other things.
Roland
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---------- FOLLOW-UP ----------

QUESTION: Hi Roland,
I was getting the codes using the ignition key. I’ll check the battery and connections.
Do you think the PCM could be the cause of the car losing power?
Sheri


Answer
Hi Sheri,
I wouldn't put it high on the list as the cause, and there should be a setting of a code of some sort regarding PCM communication or the like. Maybe after all other possibilities as a last resort and without any codes would I opt for that.
The other item you might check is the egr (exhaust gas recirculation valve) to be sure that its stem moves back and forth freely, for if that doesn't close when it needs to the mixture will lean out and cause a loss of power or rough idle. You'll find the valve in a small pipe that runs from the right exhaust manifold back toward the air intake/
throttle body at the rear of the engine. The body of the valve proper is bolted into the pipe, and it has a round vacuum operated device on its top with a flange area in between. Inside the flange you will see a rod with a circumferential slot into which the tip of a screwdriver can be inserted to move the rod back and forth. In one direction spring action will try to close the valve to a stop. If the rod (stem of the valve) doesn't close fully it will hang up ajar. So if you find that to be the case then spray the stem where it enters the body with some WD-40 to freeup the movement.
I'll await a report back on these suggestions.
Roland