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frustrated
Dodge Dakota
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11/05/2009
22:02:15
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 Subject: Question about PCM
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Hello again everyone ....just a small recap..I have a 92 dakota 3.9 automatic. It appears my PCM is bad. Currently the PCM in it is a Federal emissions / high altitdue emission Part #56028742 ..the replacement is 250$. I have found another PCM that fits my truck... Part #4741521 ..still Federal but not high altitude emissions for 130$ cheaper. Can anyone tell me if this will affect my truck adversely or should it be ok ? Thanks for your help!
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92dakotabasta
Dodge Dakota
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11/06/2009
02:05:47
| RE: Question about PCM
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correct me if im wrong, but once the pcm is reset, should it not
learn the new altitude?
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Bob Lincoln
Dodge Dakota
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11/06/2009
08:24:56
| RE: Question about PCM
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What diagnostic led you to decide that the PCM is bad? Failures are *very* rare.
These trucks have the infamous bad power splice from the factory. Have you ever checked or reworked it?
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Frustrated
Dodge Dakota
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11/06/2009
13:14:05
| RE: Question about PCM
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When I start my truck it runs fine ....then after it starts to warm up it starts to backfire, stutter, barely idles runs real rough ... it totaly seems like a timing issue .It backfires from the exhuast and the throttle body. I can push the gas pedal to the floor and it does nothing ( will not rev) ...the only thing I can do to keep it alive is to pump the gas pedal slightly to keep it from dying ...after 5-10 minutes of this ...it clears itself and runs fine .But then on the highway the engine will cut out at unknown times . Totaly feels like ignition. If it had jumped a tooth I don't think it would run good at any point ...but it does . It's too predictable when it will occur and when it will stop . I will list all the things I have done in an effort to correct this problem .
New EGR / transducer
New TPS
New IAC
New coolant temp sensor
New thermostat
New distriubtor / pick up coil / cap rotor( indexed)
New battery and cables
New ignition coil
New crank sensor
New throttle body gasket / cleaned throttle body
Fuel pump 2 yrs new
New fuel filter
New oil pressure sensor
New starter
New ignition switch
New muffler ---removed cat ( does have an exhaust leak right after the 02 sensor )
Plugs/ wires are recent
I have fixed 3 splices by the fusebox..2 of which I know are notorious for burnin up on this truck . I have checked all ground connections . I have checked all electrical connections . I have checked all vacuum lines . The truck does not throw any codes other than 12 and 55 .
After all this I finally took it to the shop my parents use.They tried hooking it up to 3 different diagnostic tools....everytime it came back that they were unable to communicate with the PCM. Since I know I repaired the splices ..one of them to the PCM...and with their diagnosis that the PCM is bad ..and knowing all the parts I have changed ...there really aren't too many parts left to change ... the other thing is ...they aren't trying to sell me the PCM or do the install... so I ask myself...why would they lie or give me false info ? So at this point I am inclined to try the PCM ...I don't have the money to tell the shop " spend as many hours as you need and fix the truck " ...so basically it's process of elimination . Another thing is I read somewhere that jump starting the truck too many times can harm the PCM ....I have jumped it tons of times .
I realize there could be a few other things that are doing this ...but with 220k miles on the truck and was all orignial parts ..it just makes sense at this point to try the PCM . The question is will the non high altitude PCM work in this truck? Also what could be the drawbacks of using the non high altitude PCM? I do live at 4400 ft elevation . Is it true the PCM will learn the new altitude? To save a 130$ on the parts would be of great help to me . Thanks guys I appreciate the response!
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daddio
Dodge Dakota
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11/06/2009
13:24:02
| RE: Question about PCM
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Without knowing if the factory changed any other components along with the high altitude PCM it's hard to tell if the non high altitude PCM will run it OK or not. I believe we have a couple of Dodge techs on here, maybe one of them will post something.
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Frustrated
Dodge Dakota
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11/06/2009
15:02:47
| RE: Question about PCM
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Thanks daddio . :)
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bump
Dodge Dakota
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11/06/2009
22:23:53
| RE: Question about PCM
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bump x2
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mario
Dodge Dakota
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11/13/2009
01:35:20
| RE: Question about PCM
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what ever you do when you recieve the new pcm DO NOT TOUCH THE PINS WITH YOUR HANDS. the static electricity in your body has the capabilities of frying some of the diodes....so be safe not sorry and dont touch the pins. even though you wont feel a spark you can still ruin it.
just a little word of advice, and i hope it fixes your problem
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frustrated
Dodge Dakota
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11/13/2009
17:35:09
| RE: Question about PCM
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new PCM works fine ...went with the cheaper one...however it didnt fix my truck. It did communicate wiith diagnostics. According to them everything is fine ...but clearly something is wrong . I even put new exhaust on my truck ...cat/ muff/ new pipe. Still no change other than my truck sounds better lol. I am thinkin there must be a short somewhere . this gonna take me forevr to find it . sigh:(
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daddio
Dodge Dakota
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11/13/2009
17:44:38
| RE: Question about PCM
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No codes? The symptoms lead me towards the engine coolant temp sensor. I know you listed it as changed but, I'm not sure what years or if all Dak's had 2 temp sensors. One for the PCM and one for the gage. It seems like your problem occurs during the transition from closed loop to open loop operation as the engine gets to operating temp.
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frustrated
Dodge Dakota
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11/13/2009
20:20:27
| RE: Question about PCM
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Correct ..no codes . yes the coolant temp sensor is new . And yes I agree with you that it occurs during transition . It is extremely predictable when it will occur and when it will stop . Looking at a parts catalogue ( because you mentioned 2 sensors )I have just come across a " air charge sensor" .. I am unsure what this does ..in process of researching it ... I also don't know if it would throw a code if bad . Thanks for the response daddio . Any other thoughts would be greatly appreciated . It's startin to snow here in these parts and now more than ever I have to get this truck running correctly . thanks again .
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daddio
Dodge Dakota
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11/14/2009
07:41:20
| RE: Question about PCM
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The "air charge sensor" or IAT(intake air temp) sensor measures the incoming air temp. It's usually in the intake manifold, left side #2 intake runner. Right behind the A/C compressor. It does help the PCM determine fuel mixture and ignition timing according to the air temp it reads in the manifold.
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Frustrated
Dodge Dakota
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11/14/2009
12:51:06
| RE: Question about PCM
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Ah ok...I thought it was a part I had missed or something . It was one of the first parts I replaced on the truck . I didn't list in the parts I have changed (oops). It should throw codes if bad . It kind of messes me up when there is several names for the same part.
I have been sorting through the forums and came across this thread....http://www.dodgedakota.net/boards/v6/7236.html The part im interested about is on the first page . I am curious about the intermediate gear and bushing . When I changed the distributor the rivets were extremely worn and loose. The rotor currently can move a total of maybe 1/4-3/8 . When I changed the dist I was unaware of this potential problem . My question is ... could this be it? Would it display the symptoms I have described? If this were the problem ...would it be so predictable as to when it starts and stops ? Would it even clear up at all if this were the problem? Thanks for the help everyone .
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