98 V70XC no start P0455

[chopsieze]

Ugh. Head gasket or valve failure.

Pull plugs and evaluate

Yeah, I was bummed.... the plugs looked pretty normal to my untrained eyes. No coolant lose and oil is nkt milky. Until last week when the car wouldn't start one morning it ran fine until the other day

Is it strange that it's 2 cylinders (probably valves) next to each other that failed?

[misha]

I'm reading your 1st post over and over again....and i doubt that you suddenly burnt 2 valves on normal driving.
1st....spark plugs on those two cyl would be black or soaked with gas
Your engine might be flooded from overfueling and thus there is no compression on those two cyl.
Overfueling can come from bad Maf,O2 sensor or most likely the ECT.
Put a spoon of oil in every cyl,replace the spark plugs,recharge the battery and hit the starter with full throttle without stopping until it starts(for a minute or so).When it starts don't let the gas pedal completely.Give it how much it needs to run.
Disconnect the maf before trying to start it and leave it disconnected.
Recheck compression after it runs a bit and smooth itself out(hopefully).

[chopsieze]

I'm reading your 1st post over and over again....and i doubt that you suddenly burnt 2 valves on normal driving.
1st....spark plugs on those two cyl would be black or soaked with gas
Your engine might be flooded from overfueling and thus there is no compression on those two cyl.
Overfueling can come from bad Maf,O2 sensor or most likely the ECT.
Put a spoon of oil in every cyl,replace the spark plugs,recharge the battery and hit the starter with full throttle without stopping until it starts(for a minute or so).When it starts don't let the gas pedal completely.Give it how much it needs to run.
Disconnect the maf before trying to start it and leave it disconnected.
Recheck compression after it runs a bit and smooth itself out(hopefully).

A full spoon full of oil will be ok and not hydrolock? I'll disconnect the MAF before hand. Can the ECT be unplugged for it to run? I tried flooring it last night and it didn't want to start but I can try with oil in the cylinders. Do I put it in all 5 or just the 2 with no compression?

The #3 plug was a little gassy (I don't recal #4 being that way) but I assumed it was from continually trying to start it and not firing.

[abscate]

It won't hydro lock. These engines are prone to temporary loss of compression , also called lawn mower, thanksgiving, and other syndromes.

[misha]

...lawn mower, thanksgiving, and other syndromes.

Whatever you do DON'T disconnect ECT while trying to start it

Did you had erratic behaviour of temperature gauge needle while the car ran?
Did the cooling fan ran all the time while engine ran?

[chopsieze]

...lawn mower, thanksgiving, and other syndromes.

Whatever you do DON'T disconnect ECT while trying to start it

Did you had erratic behaviour of temperature gauge needle while the car ran?
Did the cooling fan ran all the time while engine ran?

I didn't drive the car much, it was mostly my wife. I do remember the fan always being on when I would be done with a drive but don't remembered if it wasn't when starting it cold. Wecouldn't roll the windows down because the headliner was coming loose haha. The gauge was never erratic.

Other than last week one day when it acted up in the it was fine till 2 days ago.

[misha]

The fan being ON after the engine turned off is a classic case of bad or aftermarket ECT.Both cases are BAD.
That's why assumed that engine is overfueling.
You will need a new oem one,but first check it's connector for corrosion or being loosened.

[chopsieze]

Ok, I'll check the tightness and for corrosion at the connector. There's a junkyard with a 95 850.... does anyone know what years would have compatible parts?

[bmdubya1198]

The fan being ON after the engine turned off is a classic case of bad or aftermarket ECT.Both cases are BAD.
That's why assumed that engine is overfueling.
You will need a new oem one,but first check it's connector for corrosion or being loosened.

Good to know. My cousin's fan runs for probably 5-10 minutes sometimes after turning off the engine, and his car has had an intermittent "miss" for a while now when it's up to temperature.

called lawn mower, thanksgiving, and other syndromes.

The Thanksgiving one is new! Haha

Definitely sounds like lawnmower syndrome. Do what Misha said and let us know if it starts.
It's probably over fueling for some reason. For now, just add oil to the two cylinder with low compression. No need to oil the other cylinders.
The purpose of adding oil is to seal up the piston rings and restore compression to the cylinder. With too much fuel, it soaks down the cylinder walls and washes out oil from the cylinder, leading to loss of compression.

[chopsieze]

The fan being ON after the engine turned off is a classic case of bad or aftermarket ECT.Both cases are BAD.
That's why assumed that engine is overfueling.
You will need a new oem one,but first check it's connector for corrosion or being loosened.

Good to know. My cousin's fan runs for probably 5-10 minutes sometimes after turning off the engine, and his car has had an intermittent "miss" for a while now when it's up to temperature.

called lawn mower, thanksgiving, and other syndromes.

The Thanksgiving one is new! Haha

Definitely sounds like lawnmower syndrome. Do what Misha said and let us know if it starts.
It's probably over fueling for some reason. For now, just add oil to the two cylinder with low compression. No need to oil the other cylinders.
The purpose of adding oil is to seal up the piston rings and restore compression to the cylinder. With too much fuel, it soaks down the cylinder walls and washes out oil from the cylinder, leading to loss of compression.

I will definitely be doing that with the oil and the rest of the advice and post back. Probably won't be till tomorrow evening... had to tow it to my uncles. The fan only runs if the key is turned...