P2 V70R Hesitation at 5k

[Squirtydog]

Hi all. I've briefly mentioned this in a previous thread but can give more detail now.

I have a pronounced pause in acceleration at 5k revs in 3rd (and in 4th if I'm ever pushing on that much).
This only seems to occur when accelerating in full auto mode.

Specifically...
The car passes 5k in second smoothly then changes up to 3rd. It hits 3rd at 4k ish and begins to accelerate. As it reaches 5k there is a slightly more gruff engine note, acceleration pauses for maybe a second or so then the car pulls well and very smoothly until the next change up.
In contrast. If I am in manual and climb from much lower revs through 3rd gear, it seems to sail past 5k without much problem.

Martyn volvokid was very kind and loaned me a fuel pressure sensor and a boost control sensor (attached side of air box). Today, I first swapped in the boost sensor with no effect, then the fuel pressure sensor, again no effect. So these should be excluded.

Any ideas?
Why the difference between hitting 3rd at the 4k mark and accelerating from lower revs? Feels a little like the car has to 'settle' into the next gear then settle again.?

Cheers.

EDIT:
Have cleaned MAF sensor.
Plugs and two coil packs 20k ago (fault still there)
General service within last few weeks

[Squirtydog]

Had the fault codes read at Volvo today. Also had the car up on the ramp.
'Pretty moist' around the angle gear.
They suggested starting with fuel pump control module, then fuel pump and seeing if that fixes the problem.
Also service angle gear and flush transmission. I'm putting in some extra shifts to cover the bills.
Car had plugs and 2 coil packs (cylinders 1 & 3) at 69k, now on 91k.

[Al115]

How can it be a fuelling issue if it's fine in semi-auto mode? Unless either the rate of acceleration, and/or the boost / ignition / fuelling, is different. Now, I don't know enough about the engine mgmt. on these cars to know if it runs different maps in 3rd gear when in auto vs semi-auto, but my guess would be not.

So for me, that would point towards the transmission (gearbox) as a possible root of the issue.

Discuss...

[Harvey]

I think in auto mode it changes gear lower in the rev range.but in sport mode it will get close to the red line.
My guess would be to fit a pressure gauge onto the fuel rail and see what changes when it driven in auto - sport.

[Squirtydog]

Cheers. On careful listening today there is a hint of it when accelerating from low revs in manual but nothing too noticeable.
I was thinking transmission initially.
I was more relating the difference between auto and manual to the fact that I can change gear where I like in manual if you understand where I'm coming from.
i.e. It seems to relate to hitting 3rd at close to the trouble spot.

Anyway. Transmission service is firmly on the cards. The problem existed before the codes showed up so gonna look elsewhere first.

EDIT:
Present both in normal and sport and advanced - MAP not affecting?
Also present just the same in manual when pressing on and shifting from 2nd at high revs - (hitting 3rd around 4300)
Can't detect any gruff note passing 5k rpm in 2nd, but it passes pretty swift.

[ShadeTek]

Have you had a look at your coil packs? They can cause problems at specific RPMs. They tend to deteriorate over time due to the heat. This was a similar issue I had with a friends C70 although it happened at a lower RPM. His insulation on the coil packs had disintegrated and had been previously bodged and taped up.

[Squirtydog]

Have you had a look at your coil packs? They can cause problems at specific RPMs. They tend to deteriorate over time due to the heat. This was a similar issue I had with a friends C70 although it happened at a lower RPM. His insulation on the coil packs had disintegrated and had been previously bodged and taped up.

Coil packs 1&3 replaced 20k ago. No misfire registering on other cylinders. I'll check em out though.

When they needed doing the car became undriveable however.