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Discussion Starter · #1 ·
Hello all,
I replaced the plugs this weekend with OEM plugs. Please note the issue I am describing was a preexisting problem (at least I thnk it is a problem, it may just be the nature of the car), before I replaced the plugs. I replaced the plugs to attempt to solve the issue. We replaced the PCV cracked pipe issue under the factory recall, and no other vacuum leaks that I can find.

Essentially, only with the AC (which I assumed was loading up the motor), at cruise speeds, occasionally in town, you will get a skip or lurch etc... almost like a misfire. I can replicate every 45 seconds or so if I just leave it with the cruise control on. At WOT no issues, at decel no issues, just at a steady even pace do I get this.
I use 93 regularly. I ran a bottle or two of lucas fuel injector cleaner through it. I am not quite sure what direction to head in to help rectify the issue.
The condition does not throw a CEL either.

Thanks for any insight
 

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I don't think it's related to the above the thread, shouldn't be causing a misfire when the pump kicks on.

To start I would scan for codes, if it's missing you should have a misfire fault, won't necessarily turn on a CEL even with a code present.

Any chance the lurch is just the a/c pump kicking on causing a slight reduction in power, can sometimes feel almost as a surge.
 

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And you're certain it's only when a/c is on? Sounds like how my fuel pressure sensor felt when it began to crap out.
 

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Discussion Starter · #5 ·
for sure only when the AC is on, with it off it is smooth as can be. It is a continual thing, IE drive 10 miles at cruise, it should lurch or misfire around 11 times etc... (geusstimate not a precise value at this point). So I don't think that is the AC pump is kicking on, because it continually happens while the AC is on (I don't think the AC cycle on and off while activated,right?).

Fuel pressure sensor, that would make sense, but with it only being related to the AC makes me raise an eyebrow.
I may go have the codes pulled at AZ, if there are any at all, then report back.

Is the consensus that if there is no misfire codes to just dismiss it as me and the wife's imagination?
 

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Discussion Starter · #6 ·
It does just feel like a surge or slight reduction in power, but I wouldn't think the AC would cycle on and off. That is what it feels like, but unlike any other car I have drove previous
 

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My car did the same thing for a bit. With AC and cruise control it would skip, I notice my rpms would faulter a bit too and the needle would bounce a bit. FPS fixed it though. Im still having a hard time connecting the too but I know it doesnt do it anymore.
 

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It does just feel like a surge or slight reduction in power, but I wouldn't think the AC would cycle on and off. That is what it feels like, but unlike any other car I have drove previous
The A/C does cycle on & off. You may want to do some further investigation exactly like FF suggested. If the cycling gets to be extremely rapid & the A/C function seems to diminish check out the many threads dealing with a worn compressor clutch.
 

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Discussion Starter · #9 ·
thanks for the heads up I will try and educate myself further before posting back to the thread. Good work on the insight!
 

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It sounds like a fuel pressure sensor to me as well. I just replaced mine a few weeks ago. I would be driving on the highway and start to go up a slight incline and it would miss. It was almost like the fuel was being shut off but my RPMs never dropped. I also noticed when taking off from a stop that it was slow to accelerate then it would just take off. When mine was starting to go bad I check my spark plugs (only had about 5k on them and gap was right), mass air flow sensor, throttle body, cleaning connectors, put B12 in my gas to clean the fuel system, then I finally replaced the fuel pressure sensor and it fixed the issue. The cheapest place I found the part was rock auto. They have a standard motor products part that is the updated Volvo FPS part for about $74.
 

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Hmmm, just returned from a long trip (~1500 miles) and after a couple of hours at ~75mph on long motorway sections , with or without cruise control on, I was getting this "misfire" every minute or two for maybe a dozen times. Can't recall if I had the A/C on or off (it may have been on). Had a similar feel to dirt in the fuel. I'm assuming most of the examples above are on petrol (gas) engines - this is happening with a diesel (DRIVe eco version).
I did notice a slight 'hesitation' in both the demonstrator and my car while driving and I mentioned it when I took the car in for it's 3500 mile QA check, raising the point I'd noticed it two DRIVe V50s. No faults were found when the workshop ran a diagnostics check. It's logged with the dealer now and I'll be taking it in first opportunity to get them to look at this "stutter".
It happened once again the other day on a 30 mile dash down the motorway.
 

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Discussion Starter · #12 ·
i presume the T5 and the 2.4I fuel pressure sensor is in the same location/procedure for changing it out. That would be an easy check to see if the issue goes away, especially after similar symptoms and multiple complaints.
 

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2.4i doesn't seem to suffer from the FPS problem AFAIK. Anyone have one go bad?
 
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