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Discussion Starter · #1 ·
I recently purchased a 1984 Chrysler New Yorker. It runs great when it runs. It is chats down with no warning. Wait a few minutes and most of the time it starts right back up and wants is stopped it will only run about five minutes before quitting again.

We thought it was a Hidden problem. We removed the thermostat. We never saw the temperature go over 3/4 and the gauge. We were thinking a rheostat but with the fan running full time it’s still quit. Right now is the time we are running a flush but the longest it has run continuous is 25 minutes. A few days ago it would shutter a little before it stops. Now it stops like you Shut off the key.

It through I was no codes except 55. Any suggestions on where to go now?
 

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Discussion Starter · #2 ·
An addition. It is funny to me that you can remove the radiator cap almost immediately and pretty much at any time. The water is circulating. It has never flown out when the radiator cap is removed. We removed her thermostat thinking that the sensors may have not been able to read. Help!
 

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Luxurious 1985 New Yorker <3
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Welcome to TurboDodge! I don't suspect it's directly related to the coolant, because the LM will usually log open/shorted, out-of-range, or cold-too-long states. I've got a 1985 New Yorker, but I'm not 100% on the way the 1984 electronics work. (They're significantly different, but I'm not sure in which ways.)

There is a head temperature sensor and a coolant temperature sensor, and you can test both of those without the car running. The head temp sensor shouldn't affect the car running. The coolant temp sensor is used by the LM, so that should be tested.

Being that it used to shudder, the next two things I'd check are whether the fuel pressure is dropping below 50 PSI or if the coil is no longer making hot sparks. (Is the coil getting toasty?) If it always had that "sudden off" behavior, I'd suspect something is triggering the ASD relay, but I don't think so.

@NAJ do you have a flowchart for this one? I'm afraid to suggest too much if 1984 electronics and procedures are significantly different.
 

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If it's not the ASD relay or a fuel/spark issue I would check the connections and socket pins to the Logic Module. The only time mine did something like this my EPROM was falling out of the socket...but unless it has a socket (aftermarket or modded) logic module you chip will be soldered in so check the connectors to it for junk/corrosion or a loose connection. But boy was that was fun to figure out!
 

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Discussion Starter · #6 ·
Got new sensor today (temperature). Checked connections. Odometer quit, if that means anything. We have had extremely lousy weather here, so I have not worked on it very much. I am in a chair which limits when I can work outside. Thank you for th thank you for the assistance. When I get it figured out, I will post here.
 

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What engine is in this car?
Where are you located, warm/cold climate?
84 is unique and unto itself, 84 electronics are not very sophisticated or intelligent.
I would suggest that you do not replace any more parts as this could lead to more issues if something else is disturbed or a faulty part is installed, no more guessing, locate the issue with a logical diagnostic sequence.

Once I know what engine is in the car we can go from there.
 

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Discussion Starter · #8 ·
It has a 2.2 turbo. Checked all fluids, started, idled great exactly 20 minutes then shut off just like shutting key off. We live in desert, mesa,Arizona. Did change temp sensor in radiator.😟
 

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1)This is not a cooling system issue, however...
a)You say the cooling fan runs constantly and will not shut off?
b)This could be a relay issue, a controller issue or the vehicle is in "limp in mode", which seems unlikely since you say there are no fault codes stored.
c)Is the "power loss lamp" illuminated while the engine is running?
If the power loss lamp is not illuminated, you need to check and verify basics.
2)
Warm climate rules out condensation freezing in the Map Sensor line.
3)You will need to connect a fuel pressure gauge, verify static fuel pressure is correct, start the car and watch fuel pressure as the engine runs and when the car shuts down.
a)Did fuel pressure drop as the engine ran?
b)Was fuel pressure low when the car shut off?
c)You can rent a fuel pressure gauge at AutoZone for free, you leave a deposit which is fully refunded when you return the tool.
If fuel pressure is OK, continue...
4)
Verify the ignition system is capable of producing enough voltage.
a)Use an "adjustable spark tester" to verify the system is capable of 30 KV.
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b)If the system is capable of maintaining 30 KV, start the car and allow it to run until it shuts off. As soon as the car shuts down (do not turn the key off then back on) check to see if you have spark, hopefully the car does not start right back up.
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c)When the car shuts down do you have spark?
If the ignition system is fine, continue...
5)
With the engine running perform a wiggle test on the wiring at the HEP, logic module, power module and other connectors/harnesses underhood in an attempt to duplicate the problem.
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6)Be sure all engine grounds are present and securely attached to a clean surface.
a)The main controller ground on your car comes from the injector harness connector and bolts to the fuel rail, there should also be a ground strap on the R/S (passenger) engine mount bracket.
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7)Be sure to closely examine the logic module connectors for signs of corrosion/oxidation or other damage.
It was a common problem as water tends to leak into the R/S kick panel from the antenna mounting.
a)If corrosion is present clean it using a soft toothbrush, Q-Tips, baking soda and water, dry with compressed air and then use an electrical contact cleaner or 91% rubbing alcohol to clean any oxidation from the terminals.

Post back with your results or if you have any questions, concerns or run into problems.
 

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Discussion Starter · #10 ·
Whew! I will try and do everything! Please be patient, I will try each step. We see “low power” maybe twice and only briefly. I do see where previous owner replaced main ground. I can tell because the old one is still there with ends cut off. Also, fuse box is hanging, jammed sideways. I’ve tried to remount for a few hours but maybe I should try again. I think I told you, I am in a chair and with rain 🌧 I am grounded! Otherwise, I am just old and slow! (I am a retired First Sargent and it kills me to be stuck in)!
 

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Do not let the diagnostics/suggestions I made cause you anxiety, just start with step one and take it one step at a time.
Take your time, no rush, you do this at your pace, we will be here when you are ready.

If you have any questions/concerns/problems Please post and we will answer.
 

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Discussion Starter · #12 ·
OK! I wanted to be sure that the problem was fixed. This may be hard to believe, but I just returned from a 2 hour drive both in the city and on the highway. I know you told me to quit throwing money at the vehicle, but I had already ordered the temperature sensor that goes up by the upper hose and thermostat. Changing that made all the difference! Thank you for all the help and I would really like to keep all of this good information because I may find out that I spoke too soon! Thank you so much!
 
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