Hi,
I have a 1998 Volvo V70 T5 Auto. It has developed a misfire. The misfire isn't noticeable when the engine is cold but once it is up to temperature it will misfire during acceleration. If driven gently then it is very difficult to notice a misfire, but driven normally and during acceleration it misfires quite badly.
Any suggestions as to the most likely problem.
Thanks

 

Go have your codes pulled at a shop, or you can usually have it done for free at your local auto parts store. Report the codes back here and we can help you out.

I had some shuddering under load that felt like a misfire, turned out it was the turbo control valve that needed replacing. Under slow acceleration it was fine, but when the turbo engaged around 4K RPM it would shudder like it was misfiring. I had no codes stored.

 

Hi,
I have checked for codes myself and there are none stored. It is booked in to go to the main dealers on Monday to see if they can give me a diagnosis, but would be good if can get some ideas off here too.
Thanks

 

Do you ever get an intermittent "check engine" light blinking? That will indicate a misfire, but a consistent misfire will store a code based on which cyl. it's in.

 

If there are no codes, it may possibly be a clogged fuel filter. Easy to replace and cheap.

BTW, how is your V70 holding up besides the current problem? I am thinking of getting this model considering it is probably the best of the V70s and most problem free.

 

Hello,

I have a 98 T5 with a misfire problem too.

Sometimes it takes a couple days or a week for codes to register with your computer. I replaced my spark plugs recently on my own. I bought some autolite brand plugs and I automatically was getting misfires during moderate to heavy acceleration. I spoke to a mechanic friend. He's NOT a volvo specialist but he said try ngk brand plugs. I bought those and replaced them myself. I noticed a major drop in misfires (I could now accelerate moderately without misfires but I'd still get misfires when I really floored it).

I took it to a volvo specialist shop and they read the codes and it said a specific cylinder was misfiring, cylinder 3 closest to the engine oil cap. They suggested I buy the dealer plugs ( bosch I think?) and also the engine oil cap's rubber seal was leaking a little bit, allowing some oil to leak down into where you screw in the 3rd cylinder spark plug. This is probably creating a bad contact for the plug.

I'm guessing you began getting the misfires after you replaced or unscrewed your spark plugs?

Please update us on the outcome. Thanks!