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240 '92 3.1 Intermittent No-Starts

Yeah, I looked into that and def found that they don't. So my mom abysmally misdiagnosed her ongoing issues years ago. :lol:

It’s a logical thing to blame though since it’s such a common failure on the 7/9 cars, and really they are pretty similar to the 2 series. I had to rewire the RSR and Aux fan relay on the 740 because I was chasing that dang CPS random no start issue. No ragrets though, the wiring was disgusting and ghetto and all good now.

I’m surprised it was functional at all. Wiring was stranded and gross, plastic insulators were literally gone:lol:
InfZxUg_d.jpg
 
After thinking about it, I'll vote for a failing CPS too. Can you unplug it and measure the resistance across the 2 pins? If the coil windings in the CPS sensor are corroded or partially shorted, the resistance will be low and the output voltage will be low too. Bentley has the resistance specs for the OEM sensor. Unplugging it, cleaning and drying? the contacts, might restore enough voltage loss to get it started once more.

The output voltage of VR sensors is proportional to the tooth speed, or engine RPM in this case. Thus, lowest output voltage will be during cranking. If the coil is partially shorted, cranking voltage will be extra low and may not be enough to trigger spark on every rev. (Beware, you may see occasional spark but not realize that it's not firing all the time.) If you can get it running, RPMs and CPS voltage will be higher and may let you complete your trip without failing.

I'd expect some sort of diag code to be posted for this scenario.
 
I know that NChoy had similar issues with his '92 wagon in July. In his case, his car is a 2.4 car that he swapped to M47. Turned out the ECU was a remanufactured 561 that somehow wound up in place of the original 951 ECU. He found a replacement 933 ECU in a '92 244 at the yard. Installed it, and car fired right up.

Jen, was your 244 a LH 3.1 car as well? If it was, still have the ECU from it? Could try swapping it in and see if the car runs. Otherwise, I'd check the CPS, even though it should be a white band sensor already and not a yellow band.

-J
 
Mine is 3.1, parts car is long gone and most of the parts with it.

It started right up after work yesterday, so I drove it home and had Sara follow me and take me back to work for the XC. Everybody is home now, just gotta get the time to do some troubleshooting. Which means it needs to stop F7CKING RAINING. :rant:
 
I swear everyone says not to fire the parts cannon, but sometimes these cars have such issues that are literally so cheap it makes no sense not to, if you know what to fire! They will say you don’t learn that way, but I have:lol:

Likelihood of all injectors failing at once? Probably 0%
Likelihood of a bad lh3.1ecu...idk

You can power up the pumps and still have a no start, so you’re probably either lacking injector pulse or more than likely, lacking injector pulse at the wrong time and also lacking spark at the wrong time. That’s why spraying starting fluid in might not always help and had me scratching my head.

As mentioned before you can measure resistance across the CPS. It might be in spec when you measure it one day, and not in spec later on.
 
Since the car is sitting spray that crank sensor with liquid wrench or something,many times it's stuck especially if it's been in there for ages.
 
Not very easy to troubleshoot when the car starts on the first try. :lol:

So yeah, there's no lie a few gallons of water in that car. Decided to clean it out and the floor behind the driver's seat is FULL of water. :grrr:

Don't really like the looks of the CPS wiring, so it's still on the radar.
 
Water in floor!? Probably fuse holder fretting. Clean the fuses and holders gently. Wire brush is too coarse. Some people say every cloth is the way to go. Dielectric grease can't hurt either.
 
The rear floor gets flooded from the heater box drain being clogged. Once the drain clogs the excess water goes to the floor vents into the rear floor.

Access the drain by removing the right side panel on the center dash and shine a light into the middle of the bottom of the heater box. You will see an S shaped hose from the heater going to a hole in the tunnel. Remove the hose by pulling it out. Have lots of towels for cleaning up the water. Clean out debris from the hole in the heater and the hose. There is a service bulleting to slightly trim the edge of the rubber for the hole in the tunnel so the water and debris comes out a bit easier.

I too still don't trust the crank sensor.
 
Water in floor!? Probably fuse holder fretting. Clean the fuses and holders gently. Wire brush is too coarse. Some people say every cloth is the way to go. Dielectric grease can't hurt either.

BTDT, that's not it. I knew it leaked on the fuses before so I had a rag jammed above the panel.

The rear floor gets flooded from the heater box drain being clogged. Once the drain clogs the excess water goes to the floor vents into the rear floor.

Access the drain by removing the right side panel on the center dash and shine a light into the middle of the bottom of the heater box. You will see an S shaped hose from the heater going to a hole in the tunnel. Remove the hose by pulling it out. Have lots of towels for cleaning up the water. Clean out debris from the hole in the heater and the hose. There is a service bulleting to slightly trim the edge of the rubber for the hole in the tunnel so the water and debris comes out a bit easier.

I too still don't trust the crank sensor.

Thanks! If the weather holds out, I'll try that today.


I dragged my big ol dehumidifier out of the basement and ran it on an extension cord for about 4 hours last night after sopping up as much as I could with towels. Gonna do the same again tonight.
 
If you're expecting rain for a few days then get a tarp big enough to cover the front and back window. Tie it down with rope. Beats mopping up water every day. Make sure it extends past the front vents.
 
I use a shop vac when heavy rain fills my passenger floormat.

Did anyone say check grounds and connections yet?

EDIT: Also get one of those $10-15 pump relays as a backup. Saved me once or twice.
 
If you're expecting rain for a few days then get a tarp big enough to cover the front and back window. Tie it down with rope. Beats mopping up water every day. Make sure it extends past the front vents.

Buddy, this is Pittsburgh. I might as well put a roof over the driveway. :lol:
 
I wish it was wide enough, I'd have gone there a long time ago.

S tube wasn't clogged. Lots of nature back there, though. I suppose if I really wanted to know, I could vinyl tape all around a tarp over the windshield during the next hard rain.
 
If you are going to tape to the car I would only use 3M automotive painters masking tape, the yellow one. It will stick to a dry surface but won't leave tape residue when you remove it. Also won't harm any existing paint. hope you find the source of your problem. Still betting on CPS.
 
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