1997 850 - intermittent starting issue

[asdrewq]

Yeah, just to clarify on the starting issue & try to explain it a bit better:

So I go to start, cranks over fine, gets to the point the engine would ordinarily just smoothly burst into life & happily idle.
Just at this point it sort of splutters into life, clearly not happy - lots of vibration like it's running on maybe 2-3 cylinders?; rpm gauge gets up to maybe 500-700rpm.

Then it just dies within approx 1 second of being started.

Instinctively you think you can 'keep it going' by turning the key again to give it another burst just as it's about to die, or jabbing the throttle, but it doesn't work. I can't for example keep it partially running in this misfiring state for 5 seconds or more - it stops within 1 second.

Then I go to start again, same thing happens.

Then 3rd attempt - it just starts normally and smoothly and runs/idles fine.

[T5R92011]

Try replacing the EVAP purge valve clipped to the top of the radiator fan (under the air duct).

If that valve is stuck open your engine will randomly choke and stall, especially after refuelling or if its been sitting overnight etc.

Cheap and easy to replace yourself.

Replacing it immediately fixed the issue on mine.

[Baffler]

Please take the time to read back through the thread as the answer to your problems most likely lies within. We want you to succeed as cheaply as possible without spending on parts.

It's probably a culmination of various issues, lack of maintenance, and will continue to behave in that way until you inspect, clean and service the aforementioned list. Arm yourself with contact and carb cleaner. Please post your findings. We love pics here!

You will most likely need the Idle Air Control Valve and Throttle Body serviced too.

[VerdeV70]

Sounds like what happened to mine. Starts and then as you think it will idle it dies. The suggestions on here are a good place to start. Its likely to be the antenna ring, which is a really quick and easy fix, and also cheap if you source a second hand part. its literally take the steering wheel cover off, unclip the old one and clip the new one in. Just watch for the airbag cables.

The other place is the fuel pump relay which is what caused the issue on mine. The other place to check is the throttle body and ensuring that is clean as it sometimes goes on these cars.

Originally Posted by asdrewq

Yeah, just to clarify on the starting issue & try to explain it a bit better:

So I go to start, cranks over fine, gets to the point the engine would ordinarily just smoothly burst into life & happily idle.
Just at this point it sort of splutters into life, clearly not happy - lots of vibration like it's running on maybe 2-3 cylinders?; rpm gauge gets up to maybe 500-700rpm.

Then it just dies within approx 1 second of being started.

Instinctively you think you can 'keep it going' by turning the key again to give it another burst just as it's about to die, or jabbing the throttle, but it doesn't work. I can't for example keep it partially running in this misfiring state for 5 seconds or more - it stops within 1 second.

Then I go to start again, same thing happens.

Then 3rd attempt - it just starts normally and smoothly and runs/idles fine.

[lightyears]

Sounds exactly what happened to my 850 the other month, cheap and free advice would be to pull the plugs/leads/distributor off. Mine were completely destroyed at 110K so it might be likely someone has lucked it to 140K. Symptoms were identical.

[asdrewq]

Thought I'd update the thread,

I replaced the electrical portion of the ignition switch so that's that issue solved. When you turn the key you actually feel like you're turning against some resistance now which is nice .

Also slowly started working through the recommendations - fiddled about with the connection to the key antenna ring, cleaned contacts to fuel pump relay etc, but no difference.

I also got the code reader (OBDlink LX) working with the 850-obd-II android app but... despite the engine/lambda light still being on there were no codes stored? The app was definitely working as I could perform the instrument cluster test routines, reset the service light etc.
Not sure where to go next on this point - I've seen some reference to using an LED to do a bulb-flash type code read direct from the OBD2 port - but would that be necessary on a 1997 model?

[asdrewq]

I forgot to add - I took some videos for a while every time I used the car to try & capture the problem, please see the following, perhaps it helps?

Starting fine:
https://www.youtube.com/watch?v=Id_6OR1Af2g

Cold start - issues:
https://www.youtube.com/watch?v=1YWX_X8yRqg

Another cold start -issues:
https://www.youtube.com/watch?v=9wEUVuwTvw0

Hot start at petrol station - issues:
https://www.youtube.com/watch?v=2702QXkiXH0

[Baffler]

No mention whether you have checked the condition of the distributor cap and rotor arm...

What condition are the sparkplugs in and are they correct for this engine?

See post #18 in Lightyears thread: Volvo 850 2.5 10V SE ongoing project


Thoroughly clean the Idle Air Control Valve and Throttle Body butterfly valve.

Check the Engine Coolant Temp sensor for resistance (~200 Ω @ 20°c & ~3k Ω @ 90°c) and that its harness isn't making contact with top of the engine.

When they are all in good order you can move onto software and fault codes.

[volvo2]

Not sure if already mentioned but if not check the main earth cable lug where it connects to the body from the battery. It can be difficult to detect but mine had failed in the lug itself and caused intermittent starting issues.

[asdrewq]

Quick update:
I've gone over the plugs/cap/leads and can't see any issues. It looks like the leads & coil were replaced not that long ago; the coil & the component next to it are shiny'ish new Bosch parts.
What I think is the crank sensor (on engine below the coil, white plug) also looks new.
Also I can hear fuel pump relay clicking/pump running.

Anyway, had 2 worse events of non starting/dieing yet:
1)
Struggled to start when hot after being run for approx 10mins.
I did eventually get it to start and keep it going, and it was actively backfiring!
Like popping and banging from the exhaust.
It did this for about 10 seconds before I decided to switch back off. A bit of waiting and eventually got it to start/drive normally. It hasn't done this since.

Backfiring to me screams incorrect ignition timing - what could cause this -cam sensor?

2)
Then a few days later, another new failure mode:
Warm'ish start - Struggled to start, got it going.
When I went to pull out onto the road, the instant I touched the accelerator the engine died.
Multiple goes to get it running again.
Get to the next set of traffic lights, instant I touched accelerator pull off, engine died again.
Eventually got it going and limped home.

Cutting out when throttle is touched I have no idea, but happened twice on the trot, hoping someone else has diagnosed similar fault?

Throughout all of this, still no engine error codes via OBD.
There was one from the Immobiliser IMMO- code 221/234 (I got excited - clearly immobiliser ring as someone suggested!) but it doesn't seem to have come back or be consistent.
Does anyone know if additional codes can be read using an LED on the OBD2 port, over & above what i'm seeing in the 850 OBD2 app & adapter?


I'll keep going over things - I'm really trying to find a smoking gun rather than just startthrowing parts at it

New starting issues video too:
https://www.youtube.com/watch?v=21tllR-JZ7k

And some pictures: