Misfiring 2002 V70

02V70 · Post by **02V70** » 01 Jul 2023, 23:47

I was driving on the freeway about 65mph up an incline, and I noticed that the car was vibrating a bit, and seemed to lack power, I pressed on the accelerator to try to speed up, and the check engine light started blinking indicating a misfire. I pulled over to the side, and went to look at the engine to see if anything was wrong. I couldnt find anything visibly wrong, but when idling, the engine was vibraring a little bit, and the exhaust was pulsing.

There was a gravel road nearby which I drove on, which lead to a winding, up and down hill road that I drove on for half an hour in search of cell service as there were tons of cars on the freeway, and I dont think my volvo would get up to speed. When driving on the windy road, when going up hill, the check engine light would start flashing for a few seconds until I slowed down to 20ish mph. While it was flashing, I faintly heard some 'not good sounding' noises from the engine. I eventually found cell service, and called a triple A.

Could I have damaged anything while driving with the check engine light flashing? What can cause this, how can I fix it, and what can I do to diagnose it?

I replaced the head gasket about a year ago, and the car has not been driven much since. I wanted to take it to college, but was unable to get a parking permit until next school year. Even though it was 100 degrees out, the car was not overheating when this was happening, so hopefully that rules out head gasket issues. Also, when the car was home and cooler, the issues still remained.

Im going to try diagnosing it more tommorow as well as providing some videos about how the engine sounds.

Post by **jonesg** » 02 Jul 2023, 05:53

sounds like a bad coil, !

Post by **abscate** » 02 Jul 2023, 09:43

Read out those codes and let’s see if there is a cylinder misfiring

Don’t worry about damage , these engines are tough

02V70 · Post by **02V70** » 02 Jul 2023, 12:54

Im going to go to autozone (not with the volvo) and get a code reader, 1 coil, and maybe a compression tester if they can loan me one. I noticed there was this weird clicking sound coming from the right side of the engine bay seemingly by the pipe that comes out of the airbox. I attached a video of the sound.

Post by **Krons** » 02 Jul 2023, 16:25

You’ll ideally want a Volvo compatible code reader, the iCarSoft one on Amazon is about $150.

I didn’t notice anything that sounded strange, I’d suspect a bad coil or plug as mentioned above.

02V70 · Post by **02V70** » 02 Jul 2023, 17:18

So, I read the code, and it said cylinder 3 misfire. I took the coil out, and there was oil in the spark plug well.

: IMG_3230.jpg (279.11 KiB) Viewed 287 times

The oil in the little holes above the spark plug well was from me spilling some oil there awhile ago, and somehow forgetting to clean it. Some of that probably made its way into the well. I also noticed it seems like there is a small oil leak between the upper and lower part of the head. I did take off the top part of the head when replacing the head gasket, and put anerobic sealant on it. Can I try to fix that small leak with some rtv?

I cleaned out that oil with a rag and and compressed air, put a new coil and spark plug in, and it seems that it has fixed the misfire!

I noticed that the spark plug seemed slightly wet. Is this just becasuse it was misfiring, or does this indicate another problem?

: IMG_3240.jpg (316.5 KiB) Viewed 287 times

Post by **jonesg** » 02 Jul 2023, 18:15

drive on. !

Post by **Krons** » 02 Jul 2023, 21:45

Likely wet from fuel in cylinder but no spark. I’d run it and check that plug in a couple hundred miles.

02V70 · Post by **02V70** » 02 Jul 2023, 22:21

I tried cleaning small amount of oil out of the old coil, but that didn’t fix it. Is the oil that was in the well what cause it to fail, or just the old age of the coil? If this happens again, how far can I drive the car at highway speeds with a misfire without damaging?

Post by **abscate** » 03 Jul 2023, 03:25

Plugs should be replaced every 30k miles on these cars for coppers. There are new style plugs that last longer but I don’t like leaving a steel plug in an Al head for 50-100k miles

Coils last about 150k miles, so decide if you want to run the most economical , run-to-fail model…..or the least hassle , preventative maintenance model and replace the remaining four with Bosch. You can diagnose a coil and swap it out in under 10 minutes on the road if you keep a cheap reader in the car, and spare coil

See here… viewtopic.php?f=1&t=91347&p=520304#p520304

It’s best to disconnect the fuel injector on a misfiring cylinder so you aren’t dumping fuel into your exhaust, then you can run a misfiring car almost indefinitely* .Otherwise I would keep it under 30 minutes/30 miles

*I just ran a burnt valve v70 200 miles through NYC, then another 2 months of Town driving with fuel injector disconnected.