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Discussion Starter · #1 ·
Serious problem here... almost ready to turn her over to the local shop for help. My '89 RC has taken to a serious bout of hesitation and bucking when warmed up. The check engine light always accompanies this. I've run the ignition codes several times and am getting mixed messages. The code for rich air/fuel comes up, but so does lean air/fuel. I'm getting a shorted or open circuit in an air switching solenoid (where/what the heck is that??), no speed/distance signal during road load conditions, as well as a few other codes. Y'all... I am not good at troubleshooting. :p I changed my fuel filter for hoora's and gave her a fresh air filter too. Old one reeked of fuel. Also had a severe case of vapor lock when I undid the fuel cap to help relieve pressure for the FF change. I've had an O2 sensor kickin' around and I thought of changing that out to see if it helps, but I don't know if it really will. :-\

I am pretty lost here and can see myself spending incredible amounts of $$ replacing things that don't need replacing, just to find the magic fix. If anyone has any clues or ideas, I would greatly appreciate it. I want my daily driver back! I miss her companionship! I just bought her new tires for Pete's Sake! ;)
 

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Can you list the code numbers that you got off the computer so that we can look at all the problems from a different perspective. Pull off your distributor cap and rotor and check for anything burned or unusual. Check the wire from the coil to the distributor cap for burning or arcing. How's your plug wires and spark plugs? If your filter smelled like fuel than you probably have an ignition problem or maybe a bad fuel injector? Get back to us. :)
 

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Discussion Starter · #3 ·
The last time I ran the codes, I sat her in the yard and warmed her up until the check engine light came on. I ran her through all the gears, full range of RPM's, a/c on and off, heat on and off.... Hopefully this would be the most accurate set I've gotten yet. I'll list the cade and what the FSM says about it.

24 - Throttle position sensor input below or above the acceptable voltage
37 - An open or shorted condition detected in the torque converter part throttle unlock solenoid circuit
52 - O2 sensor signal input indicates rich fuel/air ratio condition during engine operation OR Adaptive fuel value
leaned excessively due to a sustained rich condition
21 - Neither rich or lean condition is detected from the O2 sensor input
51 - O2 sensor signal input indicates lean fuel/air ratio condition during engine operation
15 - No sensor distance signal detected during road load conditions

Now if this stuff came naturally to me, I suppose I could fix it with a pocket knife. But it doesn't. And I'm stuck. For what it's worth though, I will be changing out my O2 sensor sometime very soon, time permitting. My husband decided to "surprise" me by taking off the exhaust manifold and literally breaking out the old unit. Hope it helps, doubt it will!

-Squid
 

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Ok here it goes. FSM's have a GREAT flow chart for rough idle conditions, but if you want to tackle each code

15 is your distance sensor. AKA speedometer signal. Could actually cause a problem /rough idle condition at least this was an issue on MANY FWD Chyslers. I dont know if it causes and issue here . Let it be for now.

24 TPS again could cause and issue. get your Volt meter out and make sure its within spec. You'll have to check a service manual cus I dont the specs handy. Would deffinitely cause your issue. While your in there, check the ohms.

37 Your lockup selenoid is clogged (usually), busted or just unplugged. The plug is on transmission. A new one is about $50 and is in your transmission. Its not working so its not engaging the lockup. leave it for now.

52, 51, 21 o2 is busted. Check wiring and if OK buy a new one. Its a B*TCH to change. Its in the driver's side manifold by the number 3 cylinder. If its really in there take the manifold off. Whatever you do if you cant move it with a long wrench and penetrating oil for gods sake resist the temptation of using an impact wrench. Damn threads will comeout with the O2. Not that i've done that once.

While your in there, even if its runnig good now, check the Ohms on the Coolant Temperature sending unit and make sure its in spec. Although not a given code (37?) , its real easy to check with a meter and will cause your computer to go into limp.

I built a pigtail Extension from a junk yard wiring harness and relocated my 02 to the collecor on my 90. A weld in 02 sensor bung is only $5. Yours should be a three wire heated o2 so heating it up to operating temp isn't an issue.
 

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FYI, if your RC is a 4x4, then the converter is most likely not a lockup unit, so you will always have a code 37.

Duane
 

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The new O2 sensor should come with anti-seize compound on the threads...if it didnt...put some on. My first suggestion after the o2 is replaced is to remove the negative battery cable for a few minutes. This should clear all codes from the computer...then take it for a drive and warm it up on the highway. When you get back home pull the error codes again off the computer and see what you have. I'm sure you will have at least a 12,37,55 which are normal. See what else pops up and get back to us. :)
 

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Discussion Starter · #7 ·
Wow - so much advice! This is great! Thanks guys! Hopfeully I'll have a day off next week somewhere to get the O2 sensor back in its' hole and the manifold back on the motor.

Got a few questions though, since you're all so much more knowledgable than I...
It was mentioned about a 4x4 not being a "lockup unit." She's only a 2x4 so I am guesing this means she IS one of these. What IS a "lockup solenoid" and what it its' purpose? Would a wonky one possibly cause rough/hard shifting? I was hoping that maybe (just maybe) her previous owner had installed a shift kit and this was why we have issues against smooth shifts. Ideas??

Also, if code 15 was an issues for lots of 4x4 Chrysler products, what does this mean for a 2x4? Does this means she really wants me to put her big sisters T-Case under her when it becomes available? ;-)

Ok - that's it for now. There's so many more questions I have, but I'm going to crack open the FSM again and try to navigate through myself. You know, learn by doing. I'll let y'all know what happens when I get it to happen!

Thanks-a-Bunch for the help!
-Squid
 

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Discussion Starter · #8 ·
Ok, I finally got the dang O2 sensor replaced. Let's play "good news/bad news!"

Good news is that my fault code list got a whole lot shorter! Codes 21,51,52 are gone from my list-o-codes.

Bad news is that my check engine lamp still came on, she still ran like poop, and I still have some codes left. I think I know what I need to try next though. Any thoughts?

12 - No. of key-ons since last fault or since faults were cleared
(Just letting me know my battery was disconected?)
13 - MAP pneumatic signal OR MAP pneumatic change - No variation in MAP sensor signal is detected OR No
difference is recognized between the engine MAP reading and the stored barometric pressure reading.
37 - PTU solenoid curcuit - we've already talked about this
55 - My personal favorite! No more codes to list!

I am guessing that I have a crapped out MAP sensor now? And given that I have an auto. 2x4, I think I need to investigate this code 37 a little further. I am wondering if that transmission plug deal involved is the reason she idles like snot when in gear.

Anyone have any advice on MAP sensors?

Thanks-a-Bunch!
-Squid (the one and only!)
 

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i am having the same trouble you are. let me know what you find out. I replaced O2 sensor with no luck. maybe map sensor. hope it works out for ya
 

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Usually if a map sensor sets a code,its faulty.they are famous for bieng out of range and not setting a code too.looks like that would be the next thing to look into.check for vacum at the sensor first,looks like thats the scenario you would get if it had no vacum .
 

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Discussion Starter · #11 ·
I have a MAP sensor on order at the local NAPA just in case. But todays project is going to be a vacuum line check. Hopefully a few new hoses will take care of the problem. Otherwise it's a $75 "maybe" fix!

-Squid
 

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Discussion Starter · #12 ·
Ok, here's an update. 1) The very first vacuum line I checked had a big 'ol nasty hole in it. 2) Ran to Napa and got a chunk of hose to fix it. 3) Installed hose. 4) Started truck. 5) Ran ok, there was some clunky noise to it though. 6) Remembered I hadn't fully shut the hood. I had just lowered it. 7) Slammed the hood down. 8) Ran her in the yard for about 10 minutes waiting for check engine light to pop on. It never did. 9) Took her for a ride into town. 10) Got onto her and blew out some nasty exhaust 11) Everything looks great! She's running smooth as I can realistically expect, no check engine lights have reared their ugly heads, and no new fault codes have popped up. Of course, I still need to disconnect the battery to get rid of the old MAP sensor code, but I can do that tomorrow.

Lesson learned: old trucks = cracked and broken lines/wires/hoses. Even if your FSM makes no sense to you, read it anyway. It will eventually help somewhere along the line. A website full of Mopar enthusiests who know more than you and are willing to share knowledge also helps! Thanks for all the info everyone! Eventually someday I'll be able to help someone out too!

-Squid (and the now happily running SquidCharger)
 

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Glad to see you got your problem solved :)
 
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