1996 Volvo 850 Wagon - all of a sudden misfire codes

[Ozark Lee]

I did have the Bosch platinum plugs in the car, so had the mechanic replace them with Bosch copper, he said that they came auto calibrated, so they were already .028.

Every one of them I have ever taken out of the box were gapped at around 0.037 and I have had to close the gap. I have not yet purchased the newly numbered plugs though, I always bought FR7-DC plugs before Bosch changed the part number.

It might be worth the time to yank them out and double check the gap with a feeler gauge.

...Lee

[1996Volvo850]

Thanks for all the suggestions.
The car ran fine again for a day, and then died again yesterday (on the way to soccer practice!)
but the car started right up after it died, and ran fine all the way home.

Brought it back to mechanic this morning, could not pull any codes out of it.

So far, the only codes were the misfire ones that I received the first time this happened.

He took one of the plugs out to see if it would trigger a code (to make sure the computer was working) and it did trigger a code.

He feels it might be the fuel pump - and I have an apt to have that changed next week... I did not ask if he checked the pressure, I will double check with him when I go back. He did put it up on the lift to look at the pump and listen to it, and he said he could hear some hesitation in it....

Dont know if I should put this 850 to rest and buy a newer used Volvo, or if it can be saved. The mechanic said that it has a strong engine and a smooth transmission, (other than the misfiring and stalling out) and we are both hoping it is something that can be fixed...
I did notice that yesterday, when the car's rpm's dropped, I tried to give it gas, and that made it hesitate and buck more, and then when I tried feathering the gas, it kept the engine going a little while longer... until it just stalled out and died.
But it started right back up, and was fine right away....
It feels like when I am giving it gas, almost like I am flooding the engine and the car stalls and dies....

[Ozark Lee]

He feels it might be the fuel pump

Fuel pumps normally don't die that way, they either work or they don't and they don't tend to come back to life without a good hard smack. Try jumpering the socket positions associated with pins 15 and 87 on the fuel pump relay (#103) and see how it behaves. Your issues sound more like a relay than the pump.

Here is more information on the relay location and how you can actually repair if for a couple of bucks worth of Radio Shack parts if you know how to solder.

https://www.matthewsvolvosite.com/forums ... php?t=9681

...Lee