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Discussion Starter · #1 ·
Hello everyone!

My car is currently getting random misfires on startup. At first it was just the #2 cylinder, which made me question whether or not it was a cracked cylinder issue. The resevoir has not moved at all and there is no smoke on cold start after sitting for 12+ hours, so a cracked cylinder is not likely. I tried swapping coils around to determine if it was a coil issue, it did not follow the coil. Since then, there are now misfires in #2, #4, and #5 cylinder on startup. Car drives fine when warmed up. Does not misfire everytime i start it just sometimes.

A few things to note:
- i need new gaskets for the cvvt solenoids. My gasket is torn on exhaust cvvt but it's been fine up to this point
- Spark plugs are unknown age
- Coils are unknown age, have volvo written on them

Thanks, Andrew

PS: Car is due for an oil change in a few weeks. Switching from castrol 5w-30 to mobil 1 5w-30.
 

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You may have a head gasket failing. Have seen that on a few of these engines.

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Discussion Starter · #3 ·
Hope not... i've been told that the headgaskets on these cars do not fail... but while i do experience somewhat frequent coolant system issues, i do not have loss of coolant right now as the resevoir is staying solid and level.
 

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Check your plugs, swap coils to the ones that aren't misfiring and see if it moves, do a compression check.
 

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Best way to check is to drive it for 20min then pull the plugs a nod let it set over night. Check in the plug wells the next day for coolant.

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I was master tech for 20yrs. I have seen them develop pin hole leaks that only show up when the engine is cooling down.

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Discussion Starter · #7 ·
Check your plugs, swap coils to the ones that aren't misfiring and see if it moves, do a compression check.
Scared to do a a compression test for fear of what i might find.... i think i might try to do spark plugs soon as i do not know when they were last done. Surely if cracked block was an issue it would stay isolated to most likely just one cylinder. If it was a headgasket issue i would understand 4/5 misfiring but 2 is out there. Car has overheated slightly due to the lower radiator hose popping off but the gauge didn't even reach max and i only drove it less than half a mile after the hose blew off.
 

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If the cold start requires a bit more cranking time then fuel pump check valve leakage can be the cause. I often see misfire codes on Volvos with that complaint. The rail drains and some injectors will have the air pockets and not fire for a few beats until the air purges via injector cycling. Dead end fuel systems have no way to purge except for escape by injector opening cycles.
 

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Discussion Starter · #9 ·
Well let me add on to my symptoms....

Car starts fine as usual and idles briefly at around ~1300-1500 RPM. It isn't until the engine settles down to around ~700-800RPM that it starts to idle poorly and misfire.
 

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Intake manifold gasket?


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Start with spark plugs and while you have it off do a compression check and peek into the cylinders and see if you can see anything obvious

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so you can take some brake cleaner while it's running and sprayed around the intake manifold gasket and see if it changes how it runs

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Best thing to do is if you're doing those kinds of checks would be the hook it up and monitor live data such as th 02 sensor.

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Only I can suggest is the Stars doosan diagnostic work pull codes to see if there's anything hidden see if there's anything hidden and monitor live data

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Discussion Starter · #16 ·
I think it could be fouled plugs due to an 02 sensor issue i've been having so my car has been running rich. I will take a look and most likely replace them. I could also do a compression test. I don't have time to do any of this now, i'm currently doing an engine swap on a BMW for somebody else so thats taking most of my time. The car drives fine, it actually drives amazing. The misfire at idle AFTER startup is random, sometimes it happens, sometimes it doesn't.
 

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Well let me add on to my symptoms....

Car starts fine as usual and idles briefly at around ~1300-1500 RPM. It isn't until the engine settles down to around ~700-800RPM that it starts to idle poorly and misfire.
Mines been doing that for a month or so.... turbo just blew last night and sent it’s insides into my engine causing it to detonate...


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Discussion Starter · #18 ·
A little update to give more info....

Yesterday i had a hunch and was curious... I unplugged the MAF sensor and the car then idled beautifully with no misfiring at idle. Plugged VIDA in to confirm... no misfire codes. I plugged the MAF in while the car was still running, it begins to stutter/misfire at idle and vida began throwing misfire codes.

I cleaned the MAF (no effect) and looked at the value at idle... its around 16 kg/hr at idle with a partially warmed up engine and no a/c on.

I think i might be looking at an air leak somewhere but my car pulls strong vacuum so who knows. Maybe i will take the intake off again and clean the throttle body even though it was cleaned about 6-8 months ago
 

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guess what you got?

cracked block.

Sad to see that in 2019 we are still trying to call this anything but.
 

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Discussion Starter · #20 ·
guess what you got?

cracked block.

Sad to see that in 2019 we are still trying to call this anything but.
As much as i would like to proceed with a shimmed 2.4L swap and start my build, my wallet would not agree with that right now and i'd rather rule out all possibilities before doing a compression test, borescope, and ruling cracked block.

Tell me how unplugging the maf makes the idle smoother without misfires, points to a cracked block. Everybody i've talked to so far agrees that unplugging the MAF most likely points to a problem with another module or a vacuum leak of some sort, not cracked blocks, head gaskets, or bad valves.
 
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