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Discussion Starter · #1 ·
Hi,

I've got a small problem with my 2007 S80 V8 having a somewhat rough idle the moments after starting up. I spoke to a mechanic about it but he figured it probably was nothing since it wasn't consistent and only happened after startup. But this morning it was particularly rough. I had used the electric engine heater as it also powers the cabin heater so the engine wasn't ice cold. About 8 degrees celsius outside, about 46 F.

My battery's not in perfect condition I believe but when I accidentally almost drained it the idle was fine, only issue was that the starter barely wanted to crank.

Battery? Spark plugs (what's the lifetime of those anyway? It's been Volvo serviced all its 60k mi life, by the book. Coils? It only happens sometimes and only right after startups and never for more than 1-3 seconds. Performs great under acceleration, no indication of problems at all.

Figure I might need VIDA diagnostics but would be nice if someone had any theories. Already spent a bit of money at the dealer a week ago so I'm in no hurry to book another appointment really.
 

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Mine does the same thing but it goes away after 15 seconds. I haven't had a chance to diagnose it yet. I have 123k on mine so I'm thinking at least plugs and maybe coils in the near future.


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Discussion Starter · #3 ·
Do you have any idea on the lifetime of the plugs? I think they last for very long. Someone mentioned around 56k and someone else said 68k mi so I don't really know if they've been replaced...
 

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If you don't know, then do it so you know :) that's how I handle my maintenance. Otherwise find out what part number your plugs are and google them to figure out their lifespan


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Discussion Starter · #5 ·
Since the car has a full service history with Volvo (certified workshops or what ever it's called, sort of specialized and good with volvos anyhow) I was able to get a full history of all the work that's been done. I went through the papers earlier today and I couldn't find anything about sparkplugs having been changed yet. Next service isn't due until next summer and I've had another sketchy startup since.

All I want to know is that there's nothing wrong really but I don't feel like pouring money on something that doesn't need to be changed. Especially for such a very intermittent problem. I am a bit concerned though that if the car runs hard the spark plugs would wear (if that's how it even works?) which I think could damage the coils. I think it's at the least not good for the coils to run with bad plugs or plugs with the wrong gap.
 

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As good as companies are making parts these days, there will always be "bad" parts due to mass production.


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I also have changed my plugs every 75k miles. My S80 is overdue for plugs right now, and I have begun to notice the exact same condition. Just a slight stumble after startup and then everything is fine.
 

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Discussion Starter · #9 ·
Seeing as I'm 15000 miles from a spark plug change and as the problem is very intermittent (hasn't happened more than once or twice since I started the thread), do let me know if changing the plugs makes any difference.
 

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I'd suggest you run a bottle of Redline SL-1 in a tank full of Shell Premium 93 octane gas and see what results. I suspect you will see some improvements.

But if it's really time to change the plugs, I'd suggest you do that after the fuel system cleaning.

"If in doubt, change them out!"
 

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Discussion Starter · #11 ·
Redline SL-1? Never heard of. What is it? Is it some kind of cleaner or an additive because I've heard some bad things about the latter, I think. I'm not sure as of right now but I can't help but to associate it with RAM-booster software for computers, sort of (or snake oil as I think some people call it, lol).
 

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Redline SL-1? Never heard of. What is it? Is it some kind of cleaner or an additive because I've heard some bad things about the latter, I think. I'm not sure as of right now but I can't help but to associate it with RAM-booster software for computers, sort of (or snake oil as I think some people call it, lol).
It is a very good complete fuel system cleaner, better than BG44K (the old version), that also does a good job cleaning the intake valves, plugs, piston tops, etc. You use a bottle once or twice a year in a tank of gas (not diesel). I tested and switched over to it as my twice a year fuel system cleaner (Chevron Techron is my 2nd choice). Not sure it is available in Sweden however but perhaps via online.
 

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Discussion Starter · #13 ·
Well, I had a hesitant startup yesterday so I figured I'd give it a try. I fuelled it up and ran a full bottle of SL-1 in the tank and... *drumroll* same thing again this morning. I've admittedly only driven around 30 km (or 20-ish miles) since I added the SL-1 but as of right now I have my doubts. Some driving should've shown some improvement I guess...?
 

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I fixed mine last night. I sprayed my mass air flow sensor with cleaner and cleaned out my throttle body because it was disgusting. My throttle response is now crisp and feels "new" again!


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Well, I had a hesitant startup yesterday so I figured I'd give it a try. I fuelled it up and ran a full bottle of SL-1 in the tank and... *drumroll* same thing again this morning. I've admittedly only driven around 30 km (or 20-ish miles) since I added the SL-1 but as of right now I have my doubts. Some driving should've shown some improvement I guess...?
The cleaning process will take the full tank, especially if things are really nasty internally. Give it 300~400 miles and report back what you find.
 

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Discussion Starter · #16 · (Edited)
As someone who only recently discovered that the plastic pieces over the spark plugs can be removed easily: Where and how? Do I need any special fluids to clean it? And how/where is the sensor cleaned? Any more info on that?

Edit: Just saw your response too, whizkid. I've just about ran out of the tank in which I put in the SL-1 (300-ish miles later). Had a really wonky start this morning at -2 degrees celsius despite having used my engine heater for an hour.

Edit: I just remembered something... I got what I think is called the MOT test done in July and I remember the lambda value was a bit off. A tad high, close to not passing on that count. Didn't think much of it but MAF does sound very plausible.
 

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The mass air flow sensor is on the top half of your air box. The throttle body is the first metal part that the air box hose connects to. Go to the auto store and get mass air flow sensor cleaner and throttle body cleaner. And if your not sure of its condition, get a new air filter


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Discussion Starter · #18 ·
Well, I've cleaned both my MAF and throttle body now. The engine was still moderately warm when I test drove it afterwards and in manual shifting during hard accelerations I could both let go and resume acceleration without any hesitation whereas it'd normally hesitate a bit. So in that sense it does feel like it's running smoother.

The morning after though I fired it up and had another rough idle. I'm suspecting my battery just might be to blame since I've been getting a bunch of parking brake not fully released messages, pretty much exclusively on cold starts. P-brake works fine though so hoping a new battery will do some sort of trick, or wonders or anything hopefully.
 

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Discussion Starter · #19 ·
I was hesitant to spend the $150 volvo charges for a new battery but then I learned that a) there's a date stamp on the negative terminal (WW YY) b) my battery was from 2005. The car was built a year later.

Swapped the battery anyhow and the starter is way quicker (feels like a new one, my mind is blown) and I haven't gotten any more p-brake warnings but the sporadic coughing startup remains. I've run out of things to troubleshoot on my own as I don't intend to start messing with the spark plugs or coils. If someone has a tip, let me know but otherwise I'm just going to wait this out until it either sorts itself out or until I have to dig deeper if it causes any trouble in the future.
 
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