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Discussion Starter · #1 ·
Calling all resident experts!

I started having an issue with the car jerking a little both at even throttle (minimal jerking/rolling), as well when doing light to medium acceleration (very noticeable). A few times the jerking was very noticeable. I was coming out of a bend where I had lifted off the gas and when I accelerated (medium throttle) out of the bend, it felt as if the car went from 5th gear to 2nd gear in one change. One big jerk or clonk type of sound. At first I thought it might be transmission related as I had the converter replaced some months ago. Because at first it seemed as if the car could not find the correct gear. However, I think it was rather a jerky movement coming from the engine, rather than transmission related, as the RPMs were consistent and not jumping up and down.

I am starting to suspect things like the ignition system or some sensor or a throttle related issue. I can't consistently replicate the issue, but it does seem to show its ugly head primarily when the engine is warm.

It only happens about 10-20% of the time and seemingly when the engine is warm after e.g 20-30 miles of driving. Another common theme, which may just be coincidence, is that it is mostly when the weather is wet/rainy/humid and cold (but the car is warm). When keeping the foot evenly on the throttle (medium throttle) and accelerating up through the gears it will suddenly jerk/roll back and forth. If I come off the gas as it jerks, it goes back to normal. Any ideas?

I am getting really desperate and really hope someone can point me in the right direction! I have decided to sell the car as it has caused me too many headaches and is draining me financially. But I can't sell the car with this issue lurking. In fact, a few days ago a potential buyer noticed the jerking when test driving it. Obviously that was a big turn off for him, so no sale :(

Any help is greatly appreciated!!
 

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try replacing the fuel pressure sensor
i'm sure the lower engine-transmission mount is worn too

both are easy to replaced-- check out the FAQ section for links and step by step instructions
 

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This is a common problem that can be caused by a few things. The symptoms I was feeling didn't feel electrical or shaky like a mount but more like the engine itself was sputtering or skipping, if this describes what your feeling then...

The first and cheapest thing to do is regap or even replace your spark plugs, this solved my issue when I would accelerate or crawl into boost.

After if that doesn't work then replace the fuel pressure sensor, then check the mounts and if still doesn't work after than you'll need to start digging into a but more.


"Embody god... Then go crazy"
 

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Discussion Starter · #5 ·
Thanks guys.

I already checked the spark plug gaps and even spray cleaned the coils not too long ago and it ran fine for several months (and has always done so). I guess the fuel pressure sensor is the next to check.

Is there are a way to check if the spark plug cables are worn (apart from physically inspecting them?).
 

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Thanks guys.

I already checked the spark plug gaps and even spray cleaned the coils not too long ago and it ran fine for several months (and has always done so). I guess the fuel pressure sensor is the next to check.

Is there are a way to check if the spark plug cables are worn (apart from physically inspecting them?).
What are they gapped to? Is it turbo? Search elevate tune and see the thread for yourself but I believe the gap where they should be is .25.


"Embody god... Then go crazy"
 

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Discussion Starter · #7 ·
What are they gapped to? Is it turbo? Search elevate tune and see the thread for yourself but I believe the gap where they should be is .25.


"Embody god... Then go crazy"
As far as I remember they are gapped to .70 mm as per the standard. It is a T5 and I am using the original plugs.
 

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As far as I remember they are gapped to .70 mm as per the standard. It is a T5 and I am using the original plugs.
So try regapping them or buying new ones ( and still regap them).


"Embody god... Then go crazy"
 

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Discussion Starter · #9 ·
They are quite new and the correct gap is 0.7mm. Last time I checked them, all 5 of them were at 0.7 mm, so no need to re-gap them. Not sure I understand you correctly?
 

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They are quite new and the correct gap is 0.7mm. Last time I checked them, all 5 of them were at 0.7 mm, so no need to re-gap them. Not sure I understand you correctly?
Ok so you have a turbo and you have a sputtering when going into acceleration correct? Me and a few others on here were having the same issue and our solution was regapping our ngk plugs to
.25. There is another thread on here titled " elevate tune" you can read thru, provided we are running tunes and a few bolt ons this worked for us and cured symptoms of what your describing.

I'm saying this might work for you and since you don't wanna put to much more money into it this is a cheap first option to at least try and see if it helps.


"Embody god... Then go crazy"
 

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... our solution was regapping our ngk plugs to .25.
Are you sure you mean .25mm, 1/4 of 1 mm? That is incredibly small. Do you mean .025inch, i.e about .635mm?

More important than the gap is the plug itself, IMO. I had a slight miss with NGK that vanished when I went back to stock. I did not try adjusting the gap though.
 

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I think the confusion here is Euro vs US gap conversion. The OP is stating gap as .70 mm which is about .028" so both are the same depending on the tool. Every gap tool I've ever used was measured in inches not millimeters. Volvo OEM plugs typically come pre-gapped at .028", but I always check them. If using a metric gap tool and trying to get to a .025" gap that would be .635mm like Tom stated.
 

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I'd also suspect the turbo control valve. Right now I have a bit of a spiked power at 1800rpm which then smoothes out and builds power - I'm guessing the turbo gate is being left open by the TCV and it needs to be replaced since it's probably the original unit. Just a worthwhile check.
 

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Sounds like ignition coils to me. They tend to act up after warming up. I have the same problem with a Nissan back in the early 90's - jerking, sputtering, hesitating after a good drive. Problem fixed with new coils. I'd highly suggest replacing them if you haven't done so since your car is 10 years old.
 

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Discussion Starter · #17 ·
I checked, cleaned and re-gapped the spark plugs to 0.7 mm. No change.

So I just ordered a Fuel Pressure Sensor. Will replace and hope that does it. If not, I will start replacing the coils.

Thanks for the suggestions so far.
 

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I'm leaning towards plugs. This is 2015 you don't clean, And gap plugs. Try a set of VOLVO plugs. I don't care what anyone says, They don't need to be gapped out of the package. Unlikely its the fuel pressure sensor if theres no codes. Do you smell fuel ? Because fuel pressure sensor fail rich, Ussually the fuel pressure will be double of what it should be. It's probably plugs, Or a transmission issue.
 

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Discussion Starter · #19 ·
I'm leaning towards plugs. This is 2015 you don't clean, And gap plugs. Try a set of VOLVO plugs. I don't care what anyone says, They don't need to be gapped out of the package. Unlikely its the fuel pressure sensor if theres no codes. Do you smell fuel ? Because fuel pressure sensor fail rich, Ussually the fuel pressure will be double of what it should be. It's probably plugs, Or a transmission issue.
The plugs are original Volvo plugs and they are a couple of years old but with only about 11K miles on them. Some of the plugs were at around 0.75mm, so made the gap a little tighter.
 
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