2002 v70 Bad misfire and rough idle, cut out

barnes89 · Post by **barnes89** » 08 Nov 2015, 10:16

Hi everyone,
I've just bought a 2002 NA 2.4 volvo V70. Half an hour after driving it home the check engine like came on and the following code P0012 came up which pointed to the camshaft pos sensor so replaced that with new. No change, car still running rough / misfiring.

I changed the spark plugs and the car ran even worse, so put the old spark plugs back in, still running terribly. Did an oil and filter change, obviously didn't help. Changed the fuel filter as very rusty, no change. Cleaned the throttle body on the car as was very dirty, no change. Thought one of the coils was shot so replaced with brand new oem bosch one, no change. Unplugged the maf with engine running and the CVT and there was, you guessed it (no change ) Also looked for vacuum leaks but didn't see any.

Also there was oil sitting under the plastic covers on the top of the engine where the coils and plugs are. I've read that oil here can mess up and play havoc with coils? Ordered a new oil cap rubber seal. What's the best way to test the coils? spark plug tester or multi meter? Can't find specs on working coil pack resistances anywhere.

Car is currently running terribly, it misfires and the idle can sometimes be erratic. Sometimes will idle fine ( steady 1000 rpm ) while misfiring badly put put put put put. The spark plugs are black / suity and strong smell of unburnt fuel from the exhaust. Sometimes it won't start unless you give it a bit of throttle and once running it will cut out /die sometimes.

What is wrong with this car? losing patience with it.

Also only code it shows is P0300 ( random multiple misfires ) which i can hear so not very helpful.

Someone please give me some ideas what is going on?

Post by **abscate** » 09 Nov 2015, 04:57

Measurements and diagram here

https://www.matthewsvolvosite.com/forums ... il#p325109

Ignition systems on these cars are really reliable. Those fouled plugs are probably indicative of a fuel or induction problem ( the management system will dump in loads of fuel if there is an air leak) so start there.

With any new to you car, it really makes sense to remove all the plugs and check compression to make sure you have an engine worth working on.

barnes89 · Post by **barnes89** » 10 Nov 2015, 13:06

Used a spark plug tester today and all the coils are fine. Even used di-electric grease on the coilpack rubber boots incase they were arcing. Checked for vaccum leaks everywhere, even sprayed around the manifold but couldn't find anything. Checked the voltage feed to coils, cam sensor etc and all are within spec. Took of the CVVT solenoid and wasn't blocked or even dirty. Took of the injector wire clip / voltage feed to each individual injector and engine note changed / hesitated worse with each removed.

It drove home fine ( 40 minute journey ) and wasn't until after 30 minutes before the check engine light came on, seller had obviously cleared code ( P0012 over retarded timing ). Only once i had changed the spark plugs the bad misfire started. I don't have a compression tester or a fuel pressure tester unfortunately so will maybe try borrow them as running out of things to test.

Thinking somehow the timing has slipped or the fuel pump is failing?

Post by **abscate** » 11 Nov 2015, 10:40

Is this a turbo or an NA? An induction hose leak will cause all of the above and really make you think your engine is kaput.

barnes89 · Post by **barnes89** » 11 Nov 2015, 16:35

It's a NA 2.4, going to hopefully borrow a compression tester of the garage I worked at. I've sprayed every hose I could find, even brake servo hoses and couldn't see or feel any leaks. I just don't get how it was driving and running fine then suddenly a bad misfire materialises, it's strange.

I've seen a lot of info on the PCV cannister being blocked with oily sludge but don't think that would cause a misfire like this but might have to check that at some point. See how the compression test goes.

It's only done 71 000 miles so would hope the engine isn't kaput

barnes89 · Post by **barnes89** » 12 Nov 2015, 14:15

Did a compression test today and got 16 to 16.5 bar for each cylinder so good news but still no closer to finding the cause :S

Post by **abscate** » 13 Nov 2015, 03:44

Sounds like it is time to remove the fuel injector rail and check the spray pattern. Fuel is metered so precisely on these cars, if they are dirty it will run rough

barnes89 · Post by **barnes89** » 16 Nov 2015, 07:02

Found it finally for anyone that may be as unfortunate as me to have this problem. It was a sticky VVT solenoid. Hit it with a spanner and lo and behold misfire be gone. Nightmare over.

Thanks abscate for replying, much appreciated.