97 850 GLT crank no start after very cold temps

[mkc1]

Definitely weak spark. That plug looks really fouled. Do you have a clean / new plug to test? How old are the plugs, wires, cap, and rotor? Bad grounds / corroded B+ cable can't be ruled out either.

Plugs, wires, cap, and rotor were all replaced late 2020 -- Volvo plugs, Bosch cap and rotor, and IPD wires. What wasn't replaced is the coil, which I think is still original. Could a failing coil cause weak spark? Anyway, I have a new one ordered, so I'll give that a try and try new plugs afterwards if that doesn't help. Maybe time to do valve stem seals if the plugs are getting oil-fouled. Thanks!

[scot850]

Check all your engine ground wires are in place. A broken or bad battery ground cable or any of the ground cables will also give you a poor spark. Changing the coil is probably a good insurance as well due to age of the unit.

Neil.

[mkc1]

Well, it's working again, but I couldn't tell you exactly why. We replaced the coil. We were going to put a few mls of oil in each cylinder, but after doing #1, the rubber boots from the IPD spark plug wires stayed on the plugs when the wire was pulled off. There didn't seem to be any way of removing them without destroying them. So, there was a bit of oil in #1 and we put some ether (starting fluid) into the hose between the intercooler and throttle body. Cranked it a while, still no luck. Checked the spark from the coil, which looked okay and the #1 plug, which still looked kinda weak. Replaced #1 plug with new, shot some ether into the top of the air box and tried again. Still no luck. Added more ether in the top and bottom of the air box and cranked the hell out of it and eventually it started.

My theory is that all the cranking and not starting caused a kind of lawnmower syndrome where the unburned fuel had washed down the oil and there wasn't enough compression until it had been cranked quite a lot to get some oil pumped up from the sump. Of course being able to get oil into the other cylinders would probably have helped.

So, not really sure if any of the replacement parts were necessary, or if it just got lawnmowered from the initial unsuccessful attempts to start it in the extreme cold. Anyway, the next steps are replacing the spark plug wires with new Bougicord ones and replacing the plugs since they look fouled. After that, if it's reluctant to start again in the cold, I'll try some ether sooner rather than later, and/or add oil to the cylinders if it seems like it's getting lawnmowered.

Thanks for all the help!

[scot850]

I always appreciate the updates, however the issue gets resolved. Glad your car is running again.

Neil.

[moses3]

I live in a ice cold state, it's likely condensation in the fuel system. Next time try a bottle of HEET. I have been using this inexpensive product for 30 years with great success.

Also keep the fuel tank full in the winter to reduce condensation. Especially when it gets below 25 F.

[mkc1]

Thanks. I did fill up the tank before the very cold night, but still might've had condensation especially since I have a large evap leak. I put in some Kleen-Flo gas line antifreeze, which I think is similar to HEET, but not until after the fact, so it probably couldn't get where it needed to go to do much good.

[moses3]

Another thing, use Shell or Chevron premium fuel.