Recently my car started to hesitate and misfire at low rpm's. It's completely inconsistent and comes and goes. Sometimes it's worse then others.

The fuel filter was changed recently, as well as the o2 sensor and coolant temp sensor. The coolant temp sensor is just plugged in lying on the block because the old one is stuck in the bung on the head. I was thinking this might be causing it to be doing this, but also it could be the computer or fuel pump, no?

thanks for reading

-kevin
volvo@rapidhate.org

is ryour warm air intake hose still intact, as well as the valve inside the air box?

Resolder your fuel pump relay if you haven't in recent memory. Also check your 25amp blade fuse for corrosion. And check any and all connectors in the engine compartment, especially the ones between the driver's side wheel well and the battery, underneath where the coil is. Take them apart, clean them all up, and put them back together with dialectric grease. And also check the connector at the IUC. With the car running, you might try wiggling the various wires and connectors to see if you can get it to stall, then you'll know for sure where the problem is. Make sure you have a new cap & rotor and new spark plug wires. While you're in there, clean out your throttle body. It's probably not the cause of your stalls but if it's really dirty it will make your car run like crap.

I had a similiar problem with an '88 245. No power on take off, rough idle, missing, backfiring at all speeds. At first I thought it was bad gas, in part due to the fact the fuel gage only registered half full on a fill up.

Eventually though, the in-tank fuel pump was changed out and the air mass (flow) meter was changed out and the problem was fixed. I tried putting in a rebuilt air mass meter, in fact two of them, but the car wouldn't run with the rebuilt ones so I had to put in a new one. Also, put in new spark plugs and a fuel filter but those repairs didn't help at all.

I now have 226,000 miles. The air mass meter was changed in 1997 at about 100,000k miles and the fuel pump changed out at 140,000 mile originally, so I guess it was time them to be replaced again. Anyway, so far so good.

Fuel pump relay might be acting up. The symptoms are consistent and it is a leading contender.