Lambda light on and rough jerky driving

[ANDTWENTY]

Volvo V40 1997 1.8 138k

Right so basically I've had the lambda light come on for quite some time now but hasn't caused an issue to the car running so didn't take much notice. About a month ago I got in and started driving as normal with the light on but it run very very badly, it was jolting and jerking, really rough! It wasn't doing it at any specific points exactly, it would do it while accelerating and also just driving normally along the dual carriageway or back roads. When I stopped and restarted the car it ran fine again but with the light, it only ran rough for a few miles anyway and then it was okay.

As it was a one off and I wasn't in a position to investigate I ignored it, it continued running fine but the light was there. I had to do a 5 hour drive which I did every other week and it did it again for a while but juddered worse this time, again it stopped though. Out of desperation I changed the lambda sensor as I thought it could be this causing the issue and it was quick and easy to do as I was only about that weekend and needed the car. It seemed to be okay for a while after, I left the battery off for a bit the reset the light and no light came for a while after. about a week later I had to go away and left my car for 4 days, when I got into it the light came on and it ran like a bag of sh*t again!!For the past few days its been very off and on, the light would come on after a few minutes sometimes, sometimes after 20 mins and sometimes straight away. the jolting is also random but if I turn the ignition off and bump it as I still roll it goes off and stops jolting, but may come back on later.

I got an obd ii reader but this won't register with the car so I'm lost, what the hell can it be without me spending lots of money and time which I don't seem to have at the moment.

I know its long winded but if theres anything I missed please ask!!

thank you in advance.

[ANDTWENTY]

Something else I just thought of actually was that the first time I noticed the light come on was just after I put a fuel system cleaner in my petrol and drove a 5 hour trip, could that have anything to do with it or just a coincidence??

[martin93]

The lambda light on the phase 1 cars like yours and mine is a general engine management light, but unfortunately (as you found out) an OBD2 reader won't work on this model year.

From the symptoms you're describing I'd say it's ignition related, either a faulty coilpack or HT leads. Your car should have the twin coilpack system under the big plastic cover. One operates cylinder 1 and 4, the other 2 and 3. I'd start by taking all the spark plugs out (taking note on the condition of the HT leads), laying them in cylinder order on the bench and examine the colours. If one or two plugs seem much blacker than the others, then those are your misfiring cylinders. Hopefully you'll find that 1 and 4 are blacker than 2 and 3, or vice versa, which will point to a faulty coilpack.

Edit: If your big plastic engine cover says 'GDI' on it, then yours is the Mitsubishi engine, not the one I'm describing

Martin

[ANDTWENTY]

Thanks for that, I hadn't thought of being able to do that. I do have the engine you describe as have had all the cover and stuff off before and seen the 2 coil packs.
I did connect and disconnect the MAP sensor the other day and the car ran ruff at first with it off sometimes I took it off but quickly worked fine without it connected as if nothing was wrong which made me think this was faulty so I changed this and touch wood its been fine since but its done that before so i'll check the plugs too