In the last several weeks the car started to intermittently stop running.
If we let it sit and cool down it would then restart.
After a few weeks, the car would not restart after cooling.
But if it sits for days and days, occasionally it will start right up.

When the car runs, it runs strong.
When it stops running it shuts down immediately.
When it won't start there are no signs of starting beyond the rotation of the engine.

Right after we purchased it we put in a new fuel pump & filter, cleaned up the in-tank fuel pump and filter, and also put in a new main fuel pump relay & radio supp. relay, and associated wiring/connections are all good.

In all cases when the car does not run the fuel system is producing ample pressure and the engine has no spark.
The OBD error code 131 is present and no other error codes are displayed.

The check engine lights comes on even though the OBD literature I've found says that error code 131 won't trigger the check engine light. (seems odd)

Things we have done or checked or observed:
1) new crank position sensor --- changing between the old one and new one makes no difference
2) coil: the coil ohms out just fine. I got another one from a junk yard that ohms out fine. as with the CPS, if we interchange the coils it makes no difference when engine is in the mood to run or not running
3) ignition control module: same thing as the CPS and coil --- We have two of them and changing between the two makes no difference running or not-running.
4) the coil has power to it when the ignition is on
5) when the engine is in the mood for running if I wiggle all the ignition related wiring at and between the components, nothing happens (was hoping to find a bad connection)
a) ignition coil
b) CPS and connectors
c) ignition module
d) EZK 116 box near brake pedal
e) ECU passenger side of car
f) fuse / relay panel (just kind of tapping and wiggling that whole assembly to see if there was in intermittent connection in there somewhere)
g) took apart the EZK 116 and looked it all over: solder joints look good and there are no signs of anything having burned up
h) sent the ECU to Programa company who tested it and said it tested fine. They also said that the EZK units typically do not go bad and a visual inspection should be enough to confirm that the EZK unit itself is OK (also phoned micro-tech company in Louisville, KY - they were very helpful on the phone! and said same thing basically as Programa --- nice when people give you good advice and vs. taking your money when they feel quite certain you don't need their services!)

I took the Ignition control module and heat sink off and cleaned all of that up before putting it back together.
The multi-pin grounding assemblies: one near the ignition control module and one near the ECU --- took them apart and cleaned up and reinstalled with conductive paste.
Removed, cleaned and reinstalled a few other grounds: straps to cam cover, one near the EZK.
Cleaned all connectors on the ignition system components including on the EZK and ECU boxes and their connectors.

And right now the car is running fine.
Bu sure don't trust it to drive anywhere but around our immediate neighborhood
Any suggestions on next steps to diagnose the root cause of my problem and fix it will be greatly appreciated!!!


Thank you
'82 242T M46, '90 745T AW71

 

I'd swap out the MAFS. I know, the symptoms don't call for that but the MAFS is a mysterious bugger which can cause odd behavior. I just went through a similar head scratcher with all the Volvo advisers stumped, it was the MAFS!

 

next time there's no spark, connect a 12V test light to the trigger wire into the ignition power module, and crank the engine and see fi the test light blinks. Thats pin 5 at the ignition module, a grey wire.

if it blinks, then connect the test light to pin 1 of the ignition coil (red white wire), and if that does NOT blink, odds are its a bad ignition power module.

if pin 5, the grey wire, does NOT blink, and there is power at coil pin 15 (blue wire), then the problem is likely the EZK (assuming your CPS is in fact good).

 

Any update on this? I'm having similar issues. Code 1-3-1. Intermittent starting. Would like to where to start with the issue.

 

Re crank position sensor...did you buy a good one from FCP or similar? I got one from ebay (China made) and it lasted about a year.I actually saved the old one, which was the original factory one and used it for half a year. New one from FCP is going good for a year now. I also changed the fuel relay with a new one and ended up putting the original one back in at the same time I put the original cps back in. I was having a similar problem, would start and then stall after a few minutes and then just crank and no start. Also changed the cap,rotor, plug wires and plugs at this time and that did not do anything.

 

Yes. Eventually I started getting additional error codes that didn’t make sense.

I sent the main ECU (#563 mounted by passengers foot outboard side) to Programa for testing. They said it was fine. But after trying everything could think of eventually just found a compatible replacement ECU (#954) online - eBay -$100– and installed that one. All problems are gone. It was the main ECU !

you may well have a different problem and testing as noted above and ensuring main components are in good working order are 1st steps.

more details here: https://forums.turbobricks.com/showthread.php?t=351935

https://www.brickboard.com/FAQ/700-9...#ECUWorkaround

 

Thats cool that you fixed it! ECU....good solve!

 

For the record, I got the CPS replaced. I also found some hints on the internet that it might be due to leak from windscreen wiper grommet, and I think there was a connection between rainy weather at not starting. So I slathered the rubber seals with WD40 and also black-taped over a rust-surrounded gap in the windscreen bottom seal. All ok so far.

 

wd40 is a terrible choice to use on rubber seals. its basically kerosene, which will rot the rubber, and it won't last very long. i'd use a silicone plumbers grease (the clear white stuff).

but I can't imagine any possibly relationship between a leaky washer bottle and a hard-to-start scenario. in rainy weather, the whole engine compartment gets soaked in road spray.

 

most likely it was the cps that was causing your problem..

 

Update:

Car stopped starting 1 hour ago. Lambda dashboard light and code 131. Rainy during day.

Just tried again and it started, though smells like it’s running rich.

All this just before Christmas, when I really need it…