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Dodge Repair/'91 3.0L: loses power

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Question
Hi Roland, you asked me to get back with you. Well, we found out that the ecm is going out but we cannot find a part number to replace it. My mechanic contacted the dealer and they don't even have a part number for it. Any suggestions? Again it is a 3.0 litre. '91 Caravan.

Answer
Hi Chris,
I wonder whether you verified that the engine control module is "going out" by means of the fault code readout using the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time?
You earlier reported that you had an 11 code and a 22 code. Did you verify the wiring that I last told you about (see HISTORY, below) to decide what to do about distributor photo-optic sensor and the coolant temp sensor fault codes? If those wires are ok, then I wonder if you replaced the photo-optic sensor and the coolant sensor already?
IF the ecm is indeed failing/failed it should cause there to be a 53 code. So do verify now that is the case. If so, then probably the best approach would be to find a '91 3.0L caravan at a wrecking yard and get that one. Wrecking yards have nationwide networks to search for specific vehicles. Another approach would be to check out RockAuto.com and see if they list one for sale. But unless the 11 and 22 codes are resolved and you do now ONLY have a 53 code I would not go to the trouble and cost of buying a used ecm.
That is how I see the situation.
Roland
PS Thanks for the rating and nomination.






HISTORY:

QUESTION: The problem I'm having is my Caravan seems like it is loosing power/not getting enough fuel when it is too warm. I have replaced the fuel filter, pump and the thermostat. The cooling system was checked and there was a coolant leak at the water pump. Replaced that pump also. The cooling fan comes on for only a few seconds (every 20-30 seconds) and idles high when it comes on. Then it drops the idle low before leveling out. Tried replacing relay and temp sensor (That is the code it gives) and that did not stop the fan from kicking on and off. When it gets warm it will die going uphill (I live at the foothills of a mountain) so this presents an issue getting home. Is this an electrical or fuel problem. My mechanic and I are really frustrated.

ANSWER: Hi Chris,
What are the present fault code numbers?
Which engine do you have (L).
When the fans come "on" what is the temp gauge showing?
When you use the AC does the fan come on and stay on?
Which relay did you replace, the fan relay?
Have you checked the egr valve as it may not be closing tightly when it needs to do so, i.e., when accelerating or slowing to a stop?

Roland

---------- FOLLOW-UP ----------

QUESTION: It is a 3.0L v6. We tried to replace the fan relay and the temp sensor. No help. I didn't ask what the number was but I will. He just said that the fault was the temp sensor. The temp gauge shows below half way. I figured that was normal but I replaced the thermostat anyway, not trusting the gauge. I can't remember if we checked the valve but I will ask that too. When I use the AC it does not stay on, it just continues doing the same thing.

Answer:
Hi Chris,
Use the ignition key to get the fault codes. Turn it: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which remain "on" to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat the process to be sure of an accurate set of flash counts. Then tell me the counts in order of appearance.
Let us focus on the issue of the problem when hill climbing and set aside the fan question for later.
Do check the egr valve as it might be gummed up and not closing tightly. You can spray some WD-40 on the valve stem and then move the stem back and forth to free-up the action.
Roland

Ok, the mechanic and I searched for the valve and could not find one. He showed me where one should be and he looked behind the manifold to. Any other suggestions? The codes that came up were #22 and #11.



Hi Chris,As to the egr, only 3.0L engines sold in California originally had that in the '91 model year. So forget about that as the cause of your power output issue.
As to the 11 fault code, that suggests that either there is a problem inside the distributor with photo-optic detector assembly or one of the 4 wires from that assembly is flakey. The orange wire goes to pin 7, the tan/yellow to pin 44, the gray to pin 24, and the black/light blue wire goes to pin 4 of the 60-pin plug at the engine control module. So you would want to check the continuity of those wires and if OK then replace the photo-optic detector inside the distributor as that code says the signal from the unit is not being reliably "seen" at the ecm.
As to the 22 code it says that the coolant sensor voltage seen at the ecm is outside the expected range. The black/light blue wire is a reference voltage (probably 8v) which is also found on the same color wire at the MAP sensor/throttle position sensor, etc. so verify that  the same voltage on that wire is found at those 3 sensors. The tan/black wire of the coolant temp sensor is variable depending upon the temperature, but in any case test the continuity of that wire to pin 2 of the ecm. The sensor resistance between its two pins should read around 4k ohms when cold, and drop gradually down to around 1k ohms at the normal operating temperature of the engine.
Let me know how this works out, please.
Roland  

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Roland Finston

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Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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Five decades as a 'do-it-yourselfer' on domestic and imported cars

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Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

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Degrees in Physics/bruised knuckles.

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"Top expert" of 2010, 2011, 2012, 2013, 2014, and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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