Hello everyone recently I have ran into an issue that has stumped me on my 1996 Volvo 960 Wagon. I have owned the car now for about 1 year and put 20,000 miles on it, currently the car has 269,000 miles. Although the mileage is high it was maintained well at its life and was mostly freeway miles. About a week ago it developed a misfire mainly under acceleration which slowly degraded to at idle also. The codes were P0172 Running Rich and P0303 Misfire Cylinder #3. I let the car rest and tried to diagnose and test drive in my available time.

This where I'm at now. On a drive around the block it was missing as usual this is after I swapped the #3 coil pack to the #1 slot. Driveability did not change with the coil pack switch was still missing but would not trip the codes again( I reset them before the test drive) I was only about 2 minutes in around the block when it just died rolling through an intersection. I had power and was accelerating through it with the usual miss in the engine and it just stalled out. After it stalled I tried to start it again twice the engine started didn't even get to idle and died. Now it is just cranking with absolutely no attempt at trying to start not even a sputter.

Small issues with the car ( trying to get as much info out there as possible)

When running for about an hour or so ONLY in stop and go traffic the oil pressure light will when stopped. Lightly pressing the gas and increasing RPM to about 8-1000 will get rid of the light. I have been able to have better results using a 20W-50 oil. No driveability issues with this or anything and its only when the oil is nice and warm.

A couple weeks ago (this may or may not be really close to when the misfire started) the thermostat failed closed and ended up blowing a heater hose from the pressure build-up. According to the in car temp sensor the temp never got passed the middle normal temperature or I would have noticed it. History has made me watch that gauge religiously.

Last but not least the car fuel pump was replaced with one from Autobone that just happens to be a High Pressure Fuel pump. The only issue I've had with this is blowing fuel lines that come right off the pump inside the tank. Now I have a high pressure fuel hose and the fuel pressure is solid and fuel pressure regulator appears solid as well.

Long story short the engine was missing on #3 which lead to bad acceleration and now a car that will not start (Crank for days just wont catch) . I don't believe fuel delivery to be the issue due to a recently replaced fuel pump and the fact that the misfire issue persisted through any of the fuel hose replacement without differing at all. I also ruled out the fuses checked everyone related to Ignition, Fuel, or Engine Management. Strapped for ideas here would a sensor of some sort i.e. crank or cam slowly go out like that? Anyone else run into anything similar. I just wanted to get this post out there I am still scouring the internet for anything related to this.

Thanks in advance for your time!

 

it may be the fuel pump again. my 97 got a few misfires and car died at stop light before the fuel pump stopped working. an OEM fuel pump should be used.

 

first, the running rich could be the O2 senor. they are only good for about 100k miles.
you could have air leaks. you could also have bad injector/s giving you problems.

coil pack 3:
could be several things. this could be an injector issue. you could be fouling that plug or others due to running rich, (which BTW when my frontO2 went bad on my jeep, it ran like crap. bad idle and low). could be a bad coil pack. i dont know if a bad coil would kill the computer, either terminally or jsut loading it down.

not starting:
as said above. fuel pump. sounds a bit odd that you are busting lines unless someone replaced the hard plastic lines with rubber. you might look into the regulator and return path. make sure that is not clogged causing very high fuel pressure.
CPS. they can do strange things. the CPS is the first place to look.
could also be the computer. i would figure out if the injectors are firing or if you have spark. if you have either of these, the CPS is good.

oil pressure:
this would be my biggest concern. sounds like your oil pump may be bad. that or your motor is just flat wore out.
i would not spend money on ANYTHING else until i figured this out.

i have a complete 95 parts car that ran great until the head gasket blew. i broke a head bolt off inthe block and i am now done with it.
i also have a 93 engine and tranny with about 120k on it along with some other 93 parts. the 93 also has a bad HG.