850: 850 T-5R misfire

[Bob Meadows]

A useful link here:~
https://www.matthewsvolvosite.com/fo...ic.php?t=52252

Bob.

[PSJVTHEBEST]

Originally Posted by Bob Meadows

A useful link here:~
https://www.matthewsvolvosite.com/fo...ic.php?t=52252

Bob.

Thanks Bob. I did the jumper on the relay socket right at the start before I changed the pump but not after all the work I've just completed which I should have done to eliminate it as a contributory problem.

[ASt85]

Originally Posted by PSJVTHEBEST

Thanks for all the suggestions, friends, in the meantime I have done some more research and it's leading me down the path to a possible problem with the camshaft position sensor - seemingly a common thread running through a lot of people's issues. So I have taken it off and apart and uploaded some photos. There is some oil seepage around the seal but inside looks reasonably clean. Tried to get a photo of the 'contact's but I would have to drill out rivets for that and although I have ordered another (Bosch), I don't really want to trash it just yet! Any thoughts on the possibility this might be the cause? Thanks again to all.

Given the symptoms you describe, and the parts you have already replaced, it would seem highly likely that the camshaft sensor is faulty and it is also possible that the crankshaft sensor has issues.

It is a fairly common issue with the Volvo 5 cylinder engines. There are a number of YouTube tutorials showing how to test the sensor(s)
eg
https://www.youtube.com/watch?v=8T8UNTA3lsU
or
https://www.youtube.com/watch?v=RvuzZJqQDf4

[PSJVTHEBEST]

Originally Posted by ASt85

Given the symptoms you describe, and the parts you have already replaced, it would seem highly likely that the camshaft sensor is faulty and it is also possible that the crankshaft sensor has issues.

It is a fairly common issue with the Volvo 5 cylinder engines. There are a number of YouTube tutorials showing how to test the sensor(s)
eg
https://www.youtube.com/watch?v=8T8UNTA3lsU
or
https://www.youtube.com/watch?v=RvuzZJqQDf4

Thanks for that. I know that the crankshaft sensor may be a possibility too but now having put everything back not the easiest to get to! The camshaft sensor arrived this morning and just finished watching qualifying at COTA so will report back once tested. Cheers again. Love the retriever-I've had two and agree with your sentiment.

[PSJVTHEBEST]

Changing the camshaft position sensor has made no difference I am afraid.
I have spark at the plugs and 40psi at the fuel rail.
It tries to fire and dies.
I will check the injector solenoids are receiving power but other than changing the crankshaft position sensor, I am at a loss!

[PSJVTHEBEST]

Just checked power at the injectors and with the ignition switch on, I'm getting constant c.12v. Shouldn't the injector solenoids open and close with the engine cycle? Not be on continuously? Any help gratefully received!

[PSJVTHEBEST]

Now also tested the crankshaft position sensor and resistance is in the range quoted on line - between 200 and 500 ohms. Only £12.95 for a Lucas one so ordered to replace anyway. Just need to test relay if I can. Any ideas how to? Thanks.

[PSJVTHEBEST]

I have got her started after fitting a new crankshaft position sensor - thanks to you guys for the suggestion. But it sounds like I have a misfire. I have got electrical pulses at all injectors after testing with a noid light and spark at the plugs. But if I remove the plugs from the injectors on two of the five cylinders and/or the HT plugs from the same cylinders there is no difference to the engine note / misfire! I have switched spark plugs between cylinders and the same cylinders have the problems.
I have good fuel pressure at the rail and cleaned all the injectors.
Also cleaned the Idle air control valve for good measure.
What with all the other stuff I have done and replaced I am at a loss again - sticky valves maybe? I have had and still have an on/off ticking noise.
Although I'm not looking a gift horse in the mouth with regard to getting her started, I would just like her back to her old self!
Any suggestions will be gratefully received.

[Luxobarge]

Although you've replaced the dizzy cap and rotor arm it's still possible there's a fault there, especially if you used cheap aftermarket items.

Next thing I'd do (and this is the ideal time of year for this) is to run the car in the dark with the spark plug cover off. It's amazing what sparks you can see flying around in the dark even on a well running engine, this may give you a clue as to where the fault is - if you can sort out the HT such that there are no stray sparks you'll have improved things and hopefully cured the problem?

[PSJVTHEBEST]

Thanks mate. Dizzy cap and rotor arm are Bosch, I am afraid. Gave myself a few shocks with the HTs mucking around and I did notice a strange arcing going on at the dizzy cap when one plug was dangling with the engine running! Maybe a problem with the leads? I haven't changed them yet (and maybe should do now) because I couldn't find any decent ones on line.