A long one, but let’s start out w/ my thanks to all out there for helping me learn about the care and feeding of our bricks. This little story pertains to my wife’s 92 240 wagon, 139K.

Replaced the CPS this weekend. Symptom was random to increasingly frequent stalling to no start (miracles do happen – it quit while the Mrs. was driving into the garage). Honestly the Bentley/Hanes weren’t much help – to follow their diagnostics requires more gauges/tools/expertise/time than what’s in my toolbox and 8pm on a week night. What I needed was a quick , down and dirty check list that can be done in less than an hour. Mine was:
1. checked codes (none 1-1-1), 2. checked & spun the fuses in the drivers side fuse box, 3. listened for the fuel pump when key is turned on, 4 . checked the fuel pump relay (swaped it out w/ a spare), 5. checked for spark w/ a spare plug, 6. looked for loose vacuum hoses. 7. Disconnected the AMM plug. 8. Checked the throttle body to see if it “clicked”. Finally inspected the CPS and saw the insulation was cracked. Fiddled w/ it and asked the Mrs to crank her up and it restarted. Said a big prayer of thanks and ordered a new one the next day. The old one had lasted 100K (replaced at 39 K).

Question 1: Did I miss anything other than pulling a plug to check for gas? My thoughts are what do you do for the first ½ hour before you say, ok, it’s late and this will have to wait for the weekend.

Question 2: Is there a better way to check for spark other than trying to hold a plug against the block while it’s shaking from the starter motor?

Notes: Some weeks before I had (thanks to BB) became aware of the breather box. So I pulled that (took me a week to clean the crud out), replace the o-ring. Was able to remove it from underneath the intake manifold. Removed and checked the EGR (mouth supplied vacuum). Cleaned the throttle body (very dirty), replaced the flame trap and hoses and vacuum hoses. Probably all that work near the CPS disturbed it and cracked the brittle insulation.

This past weekend, along w/ the CPS, I put on new Bougicord ignition wires, Bosch cap and rotor and switched from Bosch Platinum’s to NGK copper. Next weekend will be fuel filter, coolant and AT fluid. For the CPS, I used all my extensions w/ a swivel, plus a nut driver, w/ a piece of blue tape over the bolt, it held in the socket. All that fit down past the rear of the block. First the CPS went in place, guided w/ a screwdriver that I could fit in from under the exhaust manifold. Then about a ½ hour of whispering sweet nothings before I got the bolt started in the hole, and then not too tight.

Needless to say, w/ all the love and attention it’s been getting, she’s running like a swiss watch (the car). The Mrs. is happy too.

At least on LH 3.1 cars, if the CPS is not sending signals to the ICU, the ECU gets no pulses that initiate the injectors firing, so if the plugs were mostly dry, I'd suspect the CPS. I believe the LH 2.4 systems were set up the same way.

For checking spark, keeping in mind I've been shocked a few too many times in life, I use a clamp on timing light, if it flashes you have spark, if not, you don't.

Since you have nailed just about every possible cause of random stalls, my only other guess (if the problem comes back) is the notoriously unreliable (after 16 years) pink label LH 2.4 ECU. There is a more reliable replacement, but I can't recall the numbers... I'm sure someone else will provide that detail.

jorrell
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92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!

Both my 93 240's came with the 951 replacement ECU, so I don't think he would have the pink 561. Dan

I think your logical thinking took you down the right path. My "binary" test for "is the cylinder getting gas?" is exactly as you suggest, pulling a plug and seeing if its wet from gas after cranking. Playing the percentages, if I hear the fuel pumps working I usually stop right there, assuming that the likelihood of the injectors not pulsing is pretty small.

For the visual spark check, I try to lean a plug next to some bare metal near the cowl but under the hood, so it's visible as I stand next to the driver's door, reach in and hit the key to crank it.
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In God We Trust. Everyone else, keep your hands where I can see them.

Thanks for the feedback, it is a 92 (typo on the subject line), what is a "Pink label" ECU and how do I know if I have one?

Hi there,

The 561 pink label ECU is not unreliable in the sense it will work sometimes and not others. When it dies, it is dead. Kaput. You lose fuel pump relay switching permanently. They don't revive.

The white label version has the improved chip that doesn't die. Or you can do like many have and replace it with a 951 which also uses the newer chip.
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Art Benstein near Baltimore

If you lend someone $20 and never see that person again, it was probably worth it.

The ECU sits behind the passenger's kick panel. Easy to pull that off and see what ECU you have if you're curious. 561 is the correct one for a '92, but a 951 is an acceptable (maybe even preferred?) replacement. I confess I'm not smart on ECUs, but it's easy to research them here on the BB.
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In God We Trust. Everyone else, keep your hands where I can see them.

That is true but the 92 I have came with the white label 561. Dan

This is too funny... I just looked at the spare ECU I got a few years ago. It's a 561 with a red label, still in the box it came in. Return address... "D. Page."

Maybe I should see if it works!

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In God We Trust. Everyone else, keep your hands where I can see them.

That is funny!

You'd better test it in the car you spared it for. Years ago I sent one to Randy after testing it in my car, and his car popped it right away. He sent it back for analysis, but I could do nothing but verify it no longer operated the fuel pump relay.

There's not much in the way of external influences on that particular chip problem - just the relay's coil winding and power quality of the system voltage. So I have no clue why a -561 pink label will live for decades in one car and not ten minutes in another.
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Art Benstein near Baltimore

Mother Superior called all the nuns together and said to them, 'I must tell you all something. We have a case of gonorrhea in the convent.' 'Thank God,' said an elderly nun at the back. 'I'm so tired of chardonnay.