2006 XC90 Occasional Hesitation on Hard Acceration

batman00024 · Post by **batman00024** » 30 Sep 2015, 13:00

2006 Volvo XC90 2.5L
Occasional hesitation on hard acceleration.

Original problem started with stall on highway, no restart. Had vehicle towed. We diagnosed problem to the fuel pump. Replaced with OEM fuel pump. Ran fine at idle, stall under load. Swapped out PEM (with used part). No change. Checked fuel pressure.

While driving, occasionally the car would hesitate repeatedly on hard acceleration. Lots of power loss during episodes. On hard acceleration, might start out with good acceleration and then sputter, then good acceleration again. Seemed to do it more when engine was warm. Only does it when engine under load.

Replaced fuel pressure sensor (on fuel rail). No change. Replaced spark plugs. No change. Added Redline injector cleaner into the fuel tank. No change. Changed turbo control valve TCV. No change.

I'm stuck. Any ideas?

Ou2mame · Post by **Ou2mame** » 01 Oct 2015, 02:52

Have you checked out the throttle body?

batman00024 · Post by **batman00024** » 01 Oct 2015, 08:38

I forgot to list that. Yes, I took off the throttle body and it was a little dirty. Cleaned it and still no change.

I've read this hesitation issue on a number of forums but no solutions.

Ou2mame · Post by **Ou2mame** » 01 Oct 2015, 12:40

Hmm.. Only other thing I can think of it the maf?

Post by **stone36** » 02 Oct 2015, 08:17

PCV or vacuum leak???

batman00024 · Post by **batman00024** » 02 Oct 2015, 10:12

If I push it hard (lots of full acceleration) to recreate the hesitation, engine light comes on and I get code P0089 (fuel pressure). The hesitation is occasional and usually when engine is warm (not cold).

I've read forums of similar problems and haven't an a solution. Some people listed fuel pressure sensor or spark plugs as the fix, but I've done those and still no change.

batman00024 · Post by **batman00024** » 03 Oct 2015, 20:31

I did some testing today. I connected a obdII scanner that reads in real time. Problem seems to be fuel pressure related.

Fuel rail pressure at idle is 44psi and staying around that during normal operation. On more aggressive acceleration, the pressure drops instantly to 9psi. If I stay hard on the accelerator, the psi stays between 9psi and 15psi. If I remove my foot from the accelerator and quickly reapply pressure on the accelerator in a less aggressive manner, the fuel pressure instantly returned to 44psi.

When I experience the hesitation, the fuel pressure at the rail seems low (9psi- 15psi). This problem only happens when engine is under load. It will not happen when aggressively pressing on the accelerator with the vehicle in park.

The question is, what is causing the slow recovery of fuel pressure during aggressive acceleration?

robertshar · Post by **robertshar** » 16 Oct 2015, 15:50

Have you tried changing the fuel filter? It could be partially blocked with fuel tank/gas pump debris.

Ou2mame · Post by **Ou2mame** » 16 Oct 2015, 19:13

Mine wasn't idling right when I got it and a new filter fixed it.. 145k and probably original

Post by **tailor** » 18 Oct 2015, 20:43

+ 1 on the fuel filter, mine was so corroded it was leaking.