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7 weeks ago my V70 T5 (year 2000) started to misfire at startup. The misfiring goes on for about 30-40 seconds and only occurs when the engine is really cold. Typically it has to cool off for about 4 hours at an outside temp of around zero degrees Celsius, before the error shows up. Once the misfiring has gone, the engine runs excellently and no misfiring shows up even if I shut the engine down after only a few hundred metres of driving (typically the drive from the garage to my daughters day care center). If I let the car stay inside at room temperature so it don't get so cold, there is no misfiring even if I let the car stay for a full night! This together with the fact that the error goes away so quickly, leads me to think that some component close to the cylinder block has temperature problems.

The "check engine" lamp sometimes lights up and my mechanic tells me the error codes stored indicates misfire at several of the cylinders. My car has been in and out of workshop loads of times during the last weeks and I now start to get a bit "desperate". We have checked the ETM and all values are within range (there is also no error codes being stored about the ETM). All thinkable wiring has also been checked and we have replaced the ignition coils (one by one) and there was no change...

I use a non-Volvo mechanic for cost reasons and also because I have developed a solid relation with him and have confidence in him (he also has access to a Volvo "electronics-guru" because he's a friend of his) but he now starts to run out of options. One drawback of using a non-Volvo workshop is that he does not have access to the Volvo store of replacement parts... and this makes everything take longer time. I also feel reluctant to switch over to a Volvo workshop, because there has been so much time invested in the error already. It's a bit like turning around and swimming back when you're swimming across the English Channel and find that you can't manage the last 100 meters.. All checks we have done, will be redone if I switch mechanic now... I do have a friend that works at one of Volvos own garages though, and he tells me that a similar problem he had seen on 2001 V70 N, had been fixed by an upgrade of controlling software. From what we can see on my car though, the software has the latest version.

Has anyone seen anything like this or does anyone have any ideas?

All ideas are warmly welcomed!!!

Kjell
 

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That could be possible that software might fix it.Also check the thermostat and coolant temp sensor.Other than that if you have replaced the coils and plugs then that would be about it.
 

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My car hates cold mornings, it has a leaky valve stem seal. Which causes oil to drop onto the pistons when left to stand for a couple of hours.

The oil contanimates the fuel causing it to burn unevenly and misfire.

However another very obvious indicator to this problem is the plumes of blue smoke associated with oil burning in the fuel, which pour out of the vehicle exhaust, especially if the engine is revved slightly.

Once it has been allowed to run and burnt off the oil then its fine, and no smoke is evident.

It might be that at normal temperatures the fuel burning causes enough heat to burn the oil, but if then engine block is cold there isn't enough energy to heat the engine block and burn the oil. I suspect a T5 petrol might be less sensitive than my 440TD. Though I might be wrong*

Also it sounds obvious but unless the garage leave the car long enough to get cold they will never see the fault.

Suffice to say I need to get this fixed, but as I just paid GBP 500 for a new head gasket ( guess they knocked a valve in the process ) I'm loath to take it back to the garage for another bout of expensive surgery.

Barmy

* Petrol engines get a spark plug to 'force' the fuel to burn, diesils use the compression of the fuel air mix to fause it to ignite and combust. Contaminated fuel does not compress or burn as well.

I am not a mechanic, I've just had lots of problems with cars. *=)
 
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