Volvo 940 Wanting to Cut Out on Startup in Mornings

[albertsmith]

Hi,

Our P reg volvo 940 estate is cutting out on startup, revs drop to below 1 and wants to stall. Its had new ht leads, spark plugs earlier in the year, we think it either will be the fuel relay, distributor or coil pack. Once the car is warm its absolutely fine its just on the first startup. Does it as the weather gets colder.

My husband albert has just gone to get some STP to clean the injectors, but I have been telling him for months it stalls on startup and to get it looked at by our good garage but its been ignored. This morning it wouldnt keep going but eventually warmed up. So I said 'I did warn you about getting it sorted as its an old car' and he's now learnt the lesson.

Anyway its going to the garage next week. But we are thinking to just replace the parts Ive mentioned as it is an old car and needs money spending on it as we are going to France in May for our anniversary and need it to be running great.

What do you think is more suspect and is this common with 2.3 volvos??

Tracey

[nutco]

Hi Tracey,
when this happened to 1 of mine it turned out to be the temp sensor for the ecu, (not the temp sensor for the gauge), the sensor wasn't telling the ECU it was cold and to richen the mixture, hope its the same in your case as its a easy fix,

[loki_the_glt]

If the fuel consumption has deteriorated badly - in my case from 28-30 down to 22-23mpg- then replacing the coolant temperature sensor is the sensible approach.

You'll need a new inlet manifold gasket as well as the sensor unit; the gasket is available from any Volvo main dealer but you'll need to get the sensor from the aftermarket as it's no longer stocked by Volvo dealers. The Bosch is is about £28 but an aftermarket one is about half that.

I can get you the part number for the sensor tomorrow, or you can search this section for "CTS" or coolant temperature sensor replacement.

[Dirty Rooster]

Originally Posted by albertsmith

Hi,

Our P reg volvo 940 estate is cutting out on startup, revs drop to below 1 and wants to stall.

I would just like to check one other thing : does the rev needle properly follow the revs of the engine dropping,
or
does the rev needle drop and then the engine dies?

[Laird Scooby]

Besides the obvious CTS as mentioned above, it's possible the PCV breather system is blocked and/or has a loose or split hose somewhere. Would pay to clean this out and inspect the hoses on it, also to clean the throttle body and AICV (Air Idle Control Vavlve) internally.

Depending how handy you are (or your husband) this is a fairly easy DIY proposition.

If it is the Coolant Temperature Sensor, here's a link to an Intermotor 55455 which should be the right one for yours :

https://www.ebay.co.uk/itm/Temp-Swit...Fr9V:rk:7:pf:0

They'll need to reset the fault code memory on the ECU after fitting it, i can't remember off the top of my head if it's fuse #1 or #11 to do that, pull it out for 30 seconds and refit - it can't be reset with a generic OBD code reader.

[aardvarkash10]

Originally Posted by Laird Scooby

They'll need to reset the fault code memory on the ECU after fitting it, i can't remember off the top of my head if it's fuse #1 or #11 to do that, pull it out for 30 seconds and refit - it can't be reset with a generic OBD code reader.

It's Fuse 1. Top left of the fuses.

[albertsmith]

Hi, thanks for the replies, this morning it was damp again. It wouldnt keep the revs. So my husband got the hot air gun and dried out the distributor and I got in the car (in my dressing gown) started and revved to revs2 to get the car warm, that worked. It seems to want to go down to low revs but once its warm its fine.

Im booking it in our local garage anyway because it has knocking on the left wheel, ball joint or drop links, so will mention the temp sensor. But why would drying out the distributor would help it I dont know.

Should I just order the temp sensor anyway???

[albertsmith]

Originally Posted by Dirty Rooster

I would just like to check one other thing : does the rev needle properly follow the revs of the engine dropping,
or
does the rev needle drop and then the engine dies?

Yes it does, but when revving whilst this problem happens it goes up and down like mad then settles.

[Laird Scooby]

Originally Posted by albertsmith

Hi, thanks for the replies, this morning it was damp again. It wouldnt keep the revs. So my husband got the hot air gun and dried out the distributor and I got in the car (in my dressing gown) started and revved to revs2 to get the car warm, that worked. It seems to want to go down to low revs but once its warm its fine.

Im booking it in our local garage anyway because it has knocking on the left wheel, ball joint or drop links, so will mention the temp sensor. But why would drying out the distributor would help it I dont know.

Should I just order the temp sensor anyway???

From what you've just said there Tracey, it sounds suspiciously like you need a new distributor cap and rotor arm, possibly also the non-return T-valve on the underside of the bonnet that supplies the washer jets.

As a general thing, Volvos don't usually suffer from damp unless something is wrong somewhere. When warm the idle speed should be about 700rpm, when cold between about 1000-1500rpm, the colder it is, the higher the revs will be until it warms up.

I'd hang fire on the sensor until you get the garage to investigate the dizzy cap and rotor arm, something is being effected by damp from what you've said, the sensor responds to temperature change within the engine.

[Jimsiss]

Best thing to do is give it a good high Rev to around 3000-5000rpm just quickly not for a prolonged period. This will clear anything out that might stop the idle control valve working. Mine idles well after that which shows it is the idle control valve being blocked up with oil. I don't recommend doing it all the time due to oil needing time to heat up and get around the engine but it will help diagnose what it might be.