940 having intermittent difficulty starting

[Laird Scooby]

Was fuse #1 pulled for 30+seconds after fitting the new CPS? Given the amount of starts in between, probably too late now as the ECU will have started to relearn and behave itself if that was indeed the fault.

[Laney760]

Originally Posted by Laird Scooby

Was fuse #1 pulled for 30+seconds after fitting the new CPS? Given the amount of starts in between, probably too late now as the ECU will have started to relearn and behave itself if that was indeed the fault.

Duh, no it wasn't. I probably didn't realise I had to do that as the CPS doesn't bring up a code. So that's probably why it was still iffy starting immediately afterwards?

[Laird Scooby]

Originally Posted by Laney760

Duh, no it wasn't. I probably didn't realise I had to do that as the CPS doesn't bring up a code. So that's probably why it was still iffy starting immediately afterwards?

Quite possibly, i'd leave it for now though as you've started it a good few times since without problems, also i'm not 100% convinced about that wiring near #4 injector. It might be something, it might be nothing. For now it seems the problems are solved, if it does it again, give that wiring a wiggle and see if it starts as it should, if so then that wiring will need looking at.

Fingers crossed i'm wrong about that wiring though!

[Laney760]

Back to the drawing board! The easy starting lasted just one day, Tuesday, since Wednesday morning I have had the same problems still!

Dave, when you didn't answer my ''ecstatic problem solved post'' I knew it was because you were wary that I still had a problem ref the lead to petrol injector one and sure enough you posted about that after that BUT I think I have had a breakthrough!

Just read the codes again, still get only the 3-1-1 on the fuel side which according to VOC is no signal to speedo and as we know my speedo doesn't work

BUT according to brickboard 3-1-1 is:


I get ... 3-1-1 ... consistently.
Code 3-1-1 suggests a failing crank position sensor (CPS) or failing connection between the CPS and the fuel control ECU. (Funny. I thought 3-1-1 a socket 6 ignition failure. Forgot. Had this on my 1992 and found a thread here treating it.) Do you get a high idle when coming off a run on the highway? (Probably not as noticeable with automatic transmission.)

https://www.brickboard.com/RWD/volvo...s_231_113.html


I HAVE HAD THIS HIGH REVS WHEN COMING OFF THE MOTORWAY which they speak about for years, I have to switch off and re-start when I come off of the motorway. I raised a thread on it on here years ago but never got to the bottom of it and my Volvo indi in Wales didn't want to start investigating and throwing money at it in case it was something to do with the lpg system

So, could I have a failing connection between the CPS and the fuel control ECU? Should that be the next thing to look at? I can't however find fuel fault code 3-1-1 anywhere else on the internet linked to CPS, everywhere else shows missing speedo signal

NB - She seems to have fallen into a pattern where there in an increased crank time but then she will start. I don't think flooding, how much gas given, etc is even coming into it, there is this pattern of increased crank time, almost to the point when I can predict it now, when she will start


.....

[Laird Scooby]

Did you spot this bit further down that brickboards thread Ellie?

From the LH-Jetronic 2.4 fuel system Engine B 230 F Volvo service manual

1-1-3 Fault in injector (Break in [wiring] lead. clogged. etc.)

The cause is the measure resistance measure through the connected wiring with the electromagnet field coil winding in the injectors the ECU encounters. All injector fire simultaneously. (Batch injection, as Art described some time ago. I presumed it sequential, yet as old as these Volvos are ....)

Have you smelled the exhaust when warming up and warmed up? If rich, you'll easily or slightly smell gas smell in the exhaust. If too lean, the exhaust will smell exceedingly sweet and be much hotter than normal.

Other causes may be (usually causing a lean condition - in no order):
- a faulty injector ground
- bad connection connection at one of more connectors
- bad connection or faulty radio suppression relay (See Dave Barton reference, below.)
- Faulty cold start valve (another stupid name for a cold start injector) or connection to it
- corrosion of the connection at the wire harness and ECU connector interface.


It's easy enough done to misread the flashes as 3-1-1 instead of 1-1-3, i've done it myself on my Rover and read 4-1 instead of 1-4 for example.

The 1-1-3 fault coincides with firstly #4 injector being disconnected and the car running in the garage and secondly with a potential fault in that area. Have you tried wiggling the wiring in that area? The bit of loom it goes into and also feeds across to the plugs mentioned further up (C55 etc) also (i think without checking) carries the CPS signal to the ECU so it could be a general degradation of the wiring in that part of the loom.

The symptoms seem to fit dodgy wiring, i have a problem with my oil pressure warning light for a similar reason, when cold it doesn't work but always works when it's hot. Wiggle the wiring when it's cold and it works for a few days hot and cold. Then it gets warm again and does whatever it does when it gets to that point and stops working when cold again.

[Laney760]

Cheers Dave but it is definitely 3-1-1, I've read the codes so many times now over the last few weeks. Zero error codes on ignition, 3-1-1 on fuel

I will take a look at that wire tomorrow, and the wires in that area. The car is in for a lot of work in a few weeks time, I will tell them to examine that wire and wiring in that area. I can live with it for the time being, I've mastered the starting, just have to allow 2 -3 minutes and a bit of embarrassment!

She had a brand new radio suppression valve last year but it was a pig to get in, I'll check it's fitting in properly. I've still got the old one which had nothing wrong with it, I'll try swopping them around

If there is something going on surrounding both ECUs for gas and petrol in the starting process, I'm not sure I've tried a cold start when she is switched over to petrol only or will this make no difference?

[Laney760]

I'm losing the light now but wriggling all of the 4 wires that lead into the injectors one at a time didn't make the engine cut out whilst running on petrol or lpg BUT there is a dodgy bit of wiring to injector 3 as you can see and maybe tomorrow with better light I may find some more dodgy wires. Wriggling this wire did not make the engine cut out, I did wonder if it was making the revs fluctuate a very little but maybe they were doing that anyway as she wasn't yet warm? From what you can see of this wire could this cause a starting problem?

The radio suppression relay is plugged in properly but it's not seated on the metal bit on the car in the way that it ought to be, its just sought of hanging off of that? Does that metal to metal form part of it's function, some sort of earthing?

My fault feels like a fuel pressure fault maybe, like she takes a while to build up fuel pressure but I don't have any other symtoms of low fuel pressure whatsoever?


007 by Strider'swoman, on Flickr

[Laird Scooby]

Originally Posted by Laney760

Cheers Dave but it is definitely 3-1-1, I've read the codes so many times now over the last few weeks. Zero error codes on ignition, 3-1-1 on fuel

I will take a look at that wire tomorrow, and the wires in that area. The car is in for a lot of work in a few weeks time, I will tell them to examine that wire and wiring in that area. I can live with it for the time being, I've mastered the starting, just have to allow 2 -3 minutes and a bit of embarrassment!

She had a brand new radio suppression valve last year but it was a pig to get in, I'll check it's fitting in properly. I've still got the old one which had nothing wrong with it, I'll try swopping them around

If there is something going on surrounding both ECUs for gas and petrol in the starting process, I'm not sure I've tried a cold start when she is switched over to petrol only or will this make no difference?

You could try switching to petrol only Ellie but i doubt it'll make any difference. Also if my theory is correct that it's to do with the wiring from the injectors to the ECU, it will effect both gas and petrol as the LPG gets the injector signal to fire the gas injectors from the petrol ECU

[Laird Scooby]

Originally Posted by Laney760

I'm losing the light now but wriggling all of the 4 wires that lead into the injectors one at a time didn't make the engine cut out whilst running on petrol or lpg BUT there is a dodgy bit of wiring to injector 3 as you can see and maybe tomorrow with better light I may find some more dodgy wires. Wriggling this wire did not make the engine cut out, I did wonder if it was making the revs fluctuate a very little but maybe they were doing that anyway as she wasn't yet warm? From what you can see of this wire could this cause a starting problem?

The radio suppression relay is plugged in properly but it's not seated on the metal bit on the car in the way that it ought to be, its just sought of hanging off of that? Does that metal to metal form part of it's function, some sort of earthing?

My fault feels like a fuel pressure fault maybe, like she takes a while to build up fuel pressure but I don't have any other symtoms of low fuel pressure whatsoever?


007 by Strider'swoman, on Flickr

The main thing is the copper conductors aren't broken, just the insulation so shouldn't make any difference. If there is some dodgy wiring i would expect it to be between #4 injector and the plug on the bulkhead and that would likely effect starting.


As for the Radio Suppression Relay bracket, no electrical connections there so no worries on that score.

[Laney760]

Originally Posted by Laird Scooby

If there is some dodgy wiring i would expect it to be between #4 injector and the plug on the bulkhead and that would likely effect starting.

.

Cheers Dave, I'll have a really good look in the light tomorrow