reaching 3000rpm and then jolts...

[xllifts850]

Just bought my first Volvo ....1996 850 T5 car is awesome!

Having bled brakes with new fluid and carried out an oil change, we noticed a couple of the actuator pipes were severely perished and I have replaced them with new silicone ones, I noticed on the way home tonight that the car pulls all the way to 4000rpm no problem and gives the usual whoosh as it dumps.... however when you get into second gear and arrive at 3000rpm it gives a loud hissing whoosh sound and jolts almost like its hitting the rev limiter, the gauge is showing halfway through the white at this point and does the same 3rd and 4th gear.

Would I be looking at the boost pipe having a split in? or something on the actuator pipe side? That said the boost gauge didn't work until we changed the pipes earlier today, it used to just sit in the middle now it starts in the first quarter of the black and moves across to half way in the white.

I have half an idea at some point there has been a boost valve plumbed in some where on the pipe work but am unable to see it at present, any help or advice would be gratefully received.

Thanks Dave.

[p fandango]

sounds like your hitting the maf limit/boost cut. The ecu's probably got used to the leaking air from the perished pipes, then with you replacing them the extra boost its compensating for now non-existant leaks is pushing it over the limit. Try removing the battery or ecu to reset it & let it learn the new spec

[xllifts850]

Ah of course , makes perfect sense now you say it, superb thank you will try that tomorrow. :)

[xllifts850]

Tried the ecu reset today, unfortunately this didn't work, but however having got totally frustrated with the problem, myself and my mate Graham set about looking further in to the problem.

We found one pipe we had missed yesterday from the manifold back to actuator, this pipe was that perished it crumbled as we touched it!!! we set about replacing it with a new silicone one, went for a test drive still no joy!
after much scratching of heads we found that when driving the car would not boost past 3500 rpm but when stationary would go round to 6000rpm no problem, we looked into the fact that the actuator was not moving at all under boost condition........ found that the actuator had seized cleaned it up and test drove it OMFG! insane difference!

We decided that the aftermarket boost bleed off that had been installed by previous owner should be shut down to bring the engines running back to standard. It amazes me that this car has been serviced to the hilt by a main dealer and none of this had been picked up, the poor people who sold it can't have ever had the car operating at its optimum, I still have a few items that need addressing but it is a totally different car again today.

Will this car ever stop amazing me???