CEL - miss fire cyl 3

ds2728 · Post by **ds2728** » 31 Jan 2016, 13:19

Hello,

I have a 1999 S70 2.4 turbo AWD

My car started missing, got the codes read, miss fire cyl 3. So I bought 1 coil pack, as I have a similar issue in the past. I installed coil pack into cyl 3, car still missed, so I swaped cyl 3 with cyl 2 to see if I could move the problem. Car started running even worse, so I went back and had the codes read again. This time it said cyl 2, 3 and 5.

I decided to just buy all new coil packs and plugs, I just installed them and I still have a miss. I got my codes read yet again and found out that I have miss fire on cyl 3. I swapped back in one of the old ones that I am sure is good, came off cyl 1. I still have a miss.

I am now at a loss of what could be wrong. Any ideas on what to do/check next would be appreciated.

Thaanks, dave

Post by **bskeels** » 31 Jan 2016, 15:20

check your compression would be a start, I have typically found when I had a miss that it was a vacuum line that either broke, rotted of came off somewhere.

101 · Post by **101** » 31 Jan 2016, 23:02

+1 on the compression test.

Rule out an engine mechanical issue before anything else.

Post by **rspi** » 01 Feb 2016, 08:33

Probably a burnt valve. Disconnect the fuel injector if you are still driving the car, until you get it fixed. Dumping fuel into the cylinder is bad for the engine and exhaust.

ds2728 · Post by **ds2728** » 02 Feb 2016, 17:52

Thank you for the responses. I checked compression tonight and found cyl's 1,2,4,5 had 110lbs and cyl 3 has 0 lbs pressure.

I have a curious question, I have owned volvo's for 20 years and the only ones that have ever given me issues are the 2 2.4 turbo's AWD, one is a 1999 and the othe was a 2000. Both of these cars have ended up with burnt valves, this one only has 157k miles on it. I have a 98 850 nonturbo with 200k no issues.

Is there something that causes these cars to have an issue with burnt valves and is there anything that could have prevented the issue.

Thanks again for the responses, at least I have solved the why it is missing. Not very happy about it and not sure what I am going to do about it. Will it hurt it to drive on 4 cyl if I have the injector unplugged for cyl 3?

Thanks again, Dave

Post by **abscate** » 02 Feb 2016, 18:22

You can drive it sedately with the injector unplugged. We had someone here drive 8000 miles once, I think.

Head off and rework it for < 1000 bucks and you can get another 150k miles

Post by **erikv11** » 02 Feb 2016, 18:43

The "why burnt valve?" question gets posted about a lot. For sure leaky valve stem seals is part of the problem. Maybe running low octane fuel, too. Lots of pet theories on here, do some searching if you are curious.

It is not peculiar to the turbo models, I have had it happen twice, both NAs.

ds2728 · Post by **ds2728** » 02 Feb 2016, 18:47

Thanks again for the replies, I really didn't want to do another head job on one of these volvo's. But the car isn't worth paying a shop 2-3k to have it done either. So now I have to decide to junk it or fix it.

Post by **rspi** » 03 Feb 2016, 04:52

https://www.matthewsvolvosite.com/forums ... =1&t=74171