940 LPT 2.3 problems starting in damp

[Dirty Rooster]

Originally Posted by Bugjam1999

To remove some coolant put a suitable container under the brass drain **** on the rear right side of the engine and drain a bit. Easy to reach, 13mm spanner.

My guess would be n-i-p-p-l-e

[Laird Scooby]

Originally Posted by Dirty Rooster

My guess would be n-i-p-p-l-e

I was thinking more along the lines of c0ck - that seems to be censored a lot on here - poor male chickens!

Nipple has too many letters for the 4 **** obliteration.

[haymitch]

Right, I have an update. Bottom line is that the car is still not fixed. The garage I mentioned earlier diagnosed it as the mass air flow sensor and this seemed to fix it for a while. Unfortunately, however, the problem has returned - going to phone them later this week but it looks like I need to fix this myself.

I'm going to try Laird Scooby's suggestion this weekend and monitor the revs whilst going uphill as he described early. I've also bought a replacement radio noise suppression relay and I'm going to try and fit it - I've read that this is a potential cause of no start situations that match my symptoms.

Could someone describe the replacement process for this relay please? It looks like it could easily break with too much force. Do you have to lift the relay up and then down to remove it and the metal clip from the side of the wing? Or is it a case of just pulling it down? My plan is to detach it from the side of the car then remove the electrical connections.

[Laird Scooby]

It could be the RSR, i would suggest you unplug it first and check the car definitely doesn't start - do this once you've already had it running to avoid confusion. Then plug it back in and check it starts again.
Then switch off, unplug it and plug the new one in - check it starts, if it doesn't, reconnect the original to prove that it is still capable of starting/running.

By now, you should have been intimate enough with the relay to see how to unclip it from the bracket. If not i'll try and explain later.

[haymitch]

Cool, will do! I can see from the replacement relay that it attaches to the bracket with a metal clip. It looks like I can remove the old metal clip by squeezing the clip open with my fingers at the bracket?

[Laird Scooby]

Originally Posted by haymitch

Cool, will do! I can see from the replacement relay that it attaches to the bracket with a metal clip. It looks like I can remove the old metal clip by squeezing the clip open with my fingers at the bracket?

Much easier to slide a flat bladed screwdriver into the back of the clip to release the barbs on it so it'll slide up and off the bodywork bracket it sits on. THey're usually made of quite strong spring steel, unless you have fingers like Arnold Schwarzenegger, a screwdriver is much easier!

As mentioned before, unplug the old one and verify you've got the corrrect relay by trying to start it while disconnected, there are 2 or 3 relays that are very similar so it's easy to get the wrong one!

[haymitch]

Ha! That's a much better plan, why didn't I think of that? Thanks

I don't suppose you have any tricks for disconnecting the electrical connections? When I changed my headlight assembly they were a pain in the a**e to disconnect. I found that repeated wiggling did the trick in the end though!

[Laird Scooby]

Sometimes a squirt of WD40 helps to loosen the plugs that have had 20+ years of combined dust, dirt, grease, heat, damp and so on to help stick them together but it can also make your fingers slip on the plugs so wiggling is usually the best option.

Once apart, a squirt of WD40 or silicone lube spray will help protect and lubricate for the future or switch cleaner with added lubricant.

Something else worth checking is to get a piece of wire and connect it between the coil +ve terminal (should be red/blue wire) and the battery +ve terminal then try starting it when it won't start. Make sure you can remove the wire easily from the battery +ve terminal to be able to stop the engine though, adding a switch in the wire is helpful or use a crocodile clip to make the battery connection.

[haymitch]

This morning I had a look at this on my day off and I think I’ve made some progress.

I replaced the oil cap. There’s been an oil leak at the oil cap for a while. I had the idea that there could be a vacuum leak caused by the oil cap so I thought I would change the cap as I’d need to replace the at least the seal anyway. I didn’t think it would help with my starting problem at all. I did this and wiped the oil from about the cap and top of the engine so I can see if it leaks again.

Rather than going straight in and changing the radio suppression relay. I thought that I would try Laird Scooby’s flooded engine procedure for the Bosch 2.4 Injection system that I've read about on other posts. I tried this and the car started right up after idling badly as usual for a while. I went for a drive as the car has not been moved for a few weeks.

Towards the end of my drive I noticed that the engine lambda warning light was on. This has not come on before at any point. I’m wondering whether replacing the oil cap has solved a vacuum leak and allowed the ECU to detect the warning code if readings have been effected previously. I excitedly drove back knowing this would mean a code had been registered!

- When I got back I got my code reader bought from this forum and looked at the engine codes. There were no codes on ‘Ignition’ but on fuel there was the code: 1 2 3. On the Engine and OBD codes from the Volvo Owner’s club this is ‘Signal missing to / from coolant temp sensor’ with the cause ‘wiring fault to or in ECT sensor’ or ‘ground corroded on intake manifold or engine’. I’m assuming that I’m reading the code from the right section as the codes on this page look like they cover the injection AND fuel codes. Is there another 1 2 3 code that this could be?
From all this I think I have faulty ground connections because:
- The coolant temperature sensor has been replaced 3 times in 2 and half years. Each time the fault has recurred over shorter intervals. Perhaps indicating the ground connections deteriorating over time.
- The flooding procedure appears to work (I need to try this again to confirm - the fault is intermittent.
- I’ve replaced a lot of parts like the distributor, spark plugs, ignition leads which might have helped but not solved the problem.
- The last time a garage looked at they immediately thought it was the coolant temperature sensor, but the fault recurred. I think this is because of extreme corrosion of the grounds. They then dried the plugs and disconnected the MAF sensor, and the car started, so they thought this was the fault as they’d replaced the temperature sensor.
- I’ve checked some of the grounds and the ones on the back of the engine bay looks rusty and in need of a clean. I can’t see the one on the intake manifold.

I’m thinking of cleaning the ground connections as a next step as the sensor is brand new and been replaced multiple times. If this fails, my plan is to replace the sensor with a Bosch sensor.

Has anyone got any thoughts on all this? 😊

[Laird Scooby]

First thought is replace the CTS with the Bosch unit, don't use any PTFE tape on the threads, it is self sealing - a lot of people don't realise this and put PTFE tape on it only to create a problem as the CTS sensor is in fact TWO sensors in one, one provides the fuel injection system with engine temperature information, the other provides the ignition control ECU with information. If someone has used PTFE tape on the threads, this could show up as an earth (ground) fault in the fault codes.

I would also try the jumper wire trick next time it doesn't want to start first time. If that has no improvement straight away, go for the flooded engine procedure.

Assuming the jumper wire doesn't improve things, then go for the Bosch CTS, it seems as if you may have a double-headed problem here but with perseverance we'll get it sorted.