940 having intermittent difficulty starting

[Laney760]

At this stage I'm not sure whether this is a hot starting problem or whether it's confined to petrol starting or applies to both petrol / lpg starting. I suspect it is worse the hotter the temperature is. Edited to say after some research and thinking that my problem is best described as sometimes due to poor hot starting but at other times to starting and then immediately stalling.

On Wednesday morning when the outside temperature was probably about 10 or 11 degrees I started the car up to go to work, no problem, drove just half a mile up the road when I switched off the engine to try and catch a stray dog, got back in the car and she would not re-start. Cranking over fine, nice strong battery / starter but she just wouldn't fire. Left it a couple of minutes, didn't give it any throttle for fear of flooding, eventually she started. Came out of work on Wednesday, the temperature was very high, in the twenties. She fired up immediately but then immediately died and refused to re-start. I gave up cranking it over, sat and waited a few minutes and then managed to start. Didn't use the car again until yesterday afternoon. She started fine in very hot weather but after being switched off after a short journey she refused to start again, took about 5 minutes, again after being left for a few minutes she re-started. Came out of work today in very hot weather, she fired up immediately but then died immediately and wouldn't re-start for ages again, again I had to leave her for a few minutes and re-started without giving her any gas. Just out of interest I went out to the car just now, now that the air temperature is quite cold outside now and she did start up immediately AND kept running but after I turned her off she refused to restart again.

The car had a new Volvo fuel pump just last October. I have eliminated the fuel pump relay, it plays up with it's new (last October) fuel pump relay inserted or it's old working one inserted. The throttle body was cleaned and a new lambda sensor fitted coming up to four years ago now, coming up to 40 thou ago, although I don't recall the hot start problem I had prior to that being like this problem. The car is booked in for full service in October, can a blocked fuel filter cause this problem? The car had a new radio suppression valve last year and a new MAF a few years back.

I have my own code reader, I will see if that brings up a code in the morning. I've just read the 940 FAQ on hot starting problems.

Any advice gratefully received, thanks

[aardvarkash10]

lh-2.4?

Is the tachometer "pulsing" when the engine cranks but doesn't fire? If not:

Crank position sensor; possibly ignition amplifier.

If the tacho is pulsing, more likely to be fuel.

[Laney760]

My rev counter isn't pulsing on cranking but then I don't think it normally does?

Just tried to start her, she fired up but then immediately stalled and doesn't want to re-start.

I've just read the codes, I consistently get these same codes


On the ignition system I consistently get a code which is not listed in the Volvo FAQ: 224


On the fuel system I consistently get the same 3 codes, the first is not listed in Volvo FAQ:
1-1-nothing and 1-2-3 and 1-3-2

Volvo FAQ lists 1-2-3 as ''Signal missing to/from coolant temp. sensor. Wiring fault to or in ECT sensor;grounds corroded on intake manifold or engine. Difficult to start engine when cold

Volvo FAQ lists 1-3-2 as battery voltage too high/low which creates no evident faults

[Laird Scooby]

Before you try Ash's excellent suggestions Ellie (which was going to be my second suggestion), aafter having read your speedo thread as well it generally points to a very silly fault.

Try pulling each fuse in turn and giving the blades of it a clean with emery cloth/wet'n'dry and refitting. Also do the same with all the relays.

Have a look at this fuse :



Looks fine, yes? It wasn't, here's why, one side then the other :





The discolouration you see on the blades is a combination of corrosion, dirt and general tarnishing through age.

That fuse killed my offside sidelight circuit during the MoT - fortunately after he'd tested the lights so didn't go down as a fail and i sorted it the next morning. That was on my other beast but i had a similar one with my 760 a few weeks after that, suddenly cut out and refused to restart. Left it a while and it fired up straightaway without a problem - fuel pump fuse!
Went again a minute or two later so i started checking the fuses associated with non-starting, pulled the fuel pump fuse and found it was "dirty", cleaned it by refitting it and pulling it several times, finally refitted it and no problems since.

The fusebox is an often forgotten problem in diagnosis because usually it either works or it doesn't. Fusible link is intact, it works, fusible link blown, it doesn't work. Simple as that usually.
However, if those fuses are 20+ years old and have never been out, they have collected dust and dirt and general grime reinforced by humid atmospheres which are the prime conditions for starting corrosion.

There was a time when an essential tool in any autoelectricians toolkit was a 1/4" drill bit when we had the old "Continental" style plastic nee ceramic fuses.



These would corrode around the points of contact which in the fusebox was a hole in the sprung contacts the fuse sat between - hence the drill bit to clean this off the contacts.
On the fuse itself, there would be an oxidised ring on the end where the metal of the fusible link had corroded.

This brings me to another corrosion problem. Most fuses are aluminium or brass, most fusebox contacts are steel or sprung brass which if memory serves, has a higher content of (i think) iron to provide the springiness.
This gives rise to electrolytic corrosion between the two dissimilar metals.

I can't remember the fuses off the top of my head that are associated with the fuel system on yours, i'm fairly sure they are 1, 11, 12 and 13 though so try cleaning those first and if that pays dividends, do the rest of the fuses in the fusebox.

I suspect your wire wiggling was just enough to clean the contacts enough to get you going again (and the speedo too) so a more thorough clean should restore reliability again.

As this is the cheapest (like free to try) do and will generally improve matters while eliminating a potential trouble source, i'd do this first before investigating the CPS - don't forget if this theory is right, the CPS won't get any power to work in the first place!

[Laney760]

Hi Ash and Dave, thanks for the advice. I've still got loads of ceramic fuses knocking around from older cars, I'm a bit of a hoarder! (I can't now find the wire I accidentally wiggled which caused the speedo to re-start, I am hoping somebody will be able to tell me what this wiring was behind the fuse board so I can advise my garage)

I just re-read the codes, to be sure!

Ignition definitely reads 2-2-4, just the one code

I was wrong on fuel, there are 2 codes: 3-1-1 and 1-2-3


3-1-1 according to Volvo FAQ is: Signal missing from speedometer Speedo wiring or instrument cluster wiring fault. Idling problems.

1-2-3 according to Volvo FAQ is: Signal missing to/from coolant temp. sensor. Wiring fault to or in ECT sensor;grounds corroded on intake manifold or engine. Difficult to start engine when cold

Edit - Interestingly, I've just found code 2-2-4 on other Volvo forums and sources on the net and that too is coolant temperature sensor.

[Laney760]

Ok, just found some sandpaper and will go and clean up those fuses

What is so annoying is that it is just 38 days till I go on my American road trip and the garage are picking up my car when I am away and doing everything on it whilst I am away, service, MOT and other work and they would have ample time then to sort this out. I am hoping I can keep getting her stated for the next 38 days to be honest but the weather is going to get colder soon and I am not sure if that is going to worsen the starting

[Laird Scooby]

Originally Posted by Laney760

Hi Ash and Dave, thanks for the advice. I've still got loads of ceramic fuses knocking around from older cars, I'm a bit of a hoarder! (I can't now find the wire I accidentally wiggled which caused the speedo to re-start, I am hoping somebody will be able to tell me what this wiring was behind the fuse board so I can advise my garage)

I just re-read the codes, to be sure!

Ignition definitely reads 2-2-4, just the one code

I was wrong on fuel, there are 2 codes: 3-1-1 and 1-2-3


3-1-1 according to Volvo FAQ is: Signal missing from speedometer Speedo wiring or instrument cluster wiring fault. Idling problems.

1-2-3 according to Volvo FAQ is: Signal missing to/from coolant temp. sensor. Wiring fault to or in ECT sensor;grounds corroded on intake manifold or engine. Difficult to start engine when cold

Edit - Interestingly, I've just found code 2-2-4 on other Volvo forums and sources on the net and that too is coolant temperature sensor.

With a bit of digging, i found code 224 on the ignition Ellie, it also points firmly at the CTS as does code 123 :

https://www.matthewsvolvosite.com/read-codes-volvo-850

Scroll down the section "A6" - although it says the codes are for the 850, it also says they are the OBD codes for Volvos from 1992-1995 and lists the other codes with the same causes as you've already found.

The CTS will certainly give starting problems, both hot and cold and i daresay the low battery voltage code was generated by the repeated attempts at starting the car.

Pull fuse #1 for 30 seconds or so and refit to clear the fault codes then drive it again and re-check the codes later.

If once more it comes up with the codes for the CTS (Ignition 224 and Fuel 123) then it's probably fair to say the CTS has failed. It's the one further back towards the bulkhead under the inlet manifold, not the onenear the front and if memory serves, the knock sensor is in between. It can be done with a spanner and a long stretch, if you're nimble fingered you can unscrew the old one and fit the new one without too much coolant loss.

The other code about the speedo, i believe there is a sensor on the back of the later speedos, i don't know much about it but it can cause idling problems.
However, i would confirm the CTS, renew if necessary and reset the codes first before you condemn the sensor on the speedo. You may still find cleaning all the fuses helps cure that as well.

[Laney760]

Cheers. I will clear and re-read the codes later. Volvo main stealers in Reading are open till 5 today for orders and sales. I just did a quick internet search to get the right part number for the coolant temperate sensor and it led me directly to this!:

Originally Posted by Laird Scooby

According to the Volvo Parts Webstore, that part number is in fact an Intake Air Temperature sensor.

https://www.volvopartswebstore.com/p...chTerm=1346030

However a bit more digging reveals :

https://www.ipdusa.com/products/6210...ure-ect-sensor

More digging reveals :

https://www.ebay.co.uk/itm/Volvo-740...0AAOSwNRdX~2HY

https://www.ebay.co.uk/itm/Volvo-940...4AAOSwNRdX~2Hq

https://www.ebay.co.uk/itm/Volvo-960...oAAOSwPCVX~2IN

Also found this once i found the Bosch part number :

https://www.ebay.co.uk/itm/Coolant-T...IAAOSwq8BZbVsw

The Bosch number is 0280130032 and fits umpteen different makes of car and umpteen different models from each make.

There are 2 choices above, the PartsMonster and the Cambiare (the cheaper one) and i've used parts from both companies without complaint so "you pays yer money and takes yer choice".
For the record, OEM is Bosch, it is after all their injection system.

Meyle should be good as well but about 18 months back i bought some Meyle drop links that were fake. They lasted about 2 months.
Not saying that the temperature sensors are likely to be the same but there's always that chance.

[Laney760]

Crikey, you can get one from Taiwan on Ebay for £4.43 with free postage but I don't think I'll chance it! Cpautoparts - they have actually got good feedback!

[Laird Scooby]

Originally Posted by Laney760

Crikey, you can get one from Taiwan on Ebay for £4.43 with free postage but I don't think I'll chance it! Cpautoparts - they have actually got good feedback!

A few people have had problems with non-Bosch sensors Ellie, i've got an Intermotor one in mine and for a while thought it was playing up until i found other faults causing similar symptoms. Logic says if the sensor is within limits (it has about a 10% tolerance even on the Bosch ones) then it should work fine, regardless of brand but i would seriously avoid Taiwanese, Chinese or similar products for tuppence ha'penny and a brass farthing and buy a reputable brand such as Bosch, Intermotor, Cambiare, Delphi etc.

If you do go to the Volvo main stealers, get them to show you the exact location of the engine management CTS (further back on the head, just under #3 and #4 inlet tracts), the position of the knock sensor (sort of guitar body shaped thing) and also the temp gauge CTS (below #1 and #2 inlet tracts) so you have a good idea of the geography of the left hand side of the head before you start.

I found this pic on t'interweb thingy :



It's not perfect but gives you an idea, the black one is the front, temp gauge sensor and the blue one is the engine management one, the one you're interested in.

I think the spanner size is 19mm but checking against the new sensor is always useful (might be 17mm) and once you've unplugged it by squeezing the wire loop opn the connector and pulling it off, you can slip the spanner over, loosen the sensor by 1/4 - 1/2 a turn and should be able to undo it by hand then.
If you have the new one ready to go in as soon as the old one is out, you can literally do a one out/one in job, minimising your coolant loss.
Don't forget you can raise the bonnet vertically for more access, good luck and let us know how it goes!