I recently replaced my exhaust cam reset solenoid. Prior to replacing, there was a lot of knocking, similar to what a desiel engine might sound like.

Replacement of the exhaust cam reset solenoid was easy. It's on top of the block and held by 4 screws.

Final Entry

The car continued to have hesitation on hard acceleration. Progressively got worse and more frequent, to the point of the car was stalling constantly and having no acceleration. I tested the fuel pressure for an extended period of time, and fuel pressure was around 44psi. When the ...

My PEM was inside the car, under the seats and carpeting.

Fuel filter was replaced. No change.

Also replaced the turbo control solenoid. No change.

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 ...

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 ...

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.

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 ...