Engine: TDI: 1999 V70 2.5D D5252t unbelievably slow

[V70Zig]

I think that is the TVC, looks like this......

[V70Zig]

And the EGR controller......

[V70Zig]

Have a read here...https://www.volvoforums.org.uk/showthread.php?t=151558

[PNuT]

Originally Posted by ttocsc

There's a component marked 8/28

8/28 is the turbo control valve.....

[ttocsc]

Good news! Turbo is back and the car is utterly transformed. As PNuT pointed out, the mystery component 8/28 behind that fuse is my turbo control valve. The preheat device had shorted and caused the wires' insulation to melt and short together all the way back to the junction where the preheat device is separated from the other components on that circuit. Hacked the loom apart, pulled the preheat thingy wire all the way through it and chopped it off at the junction.

Started her up, and she spat an almighty cloud of grey smoke - which indicated something was different. First few tries on the throttle didn't seem to be any different but after about 10 miles the turbo seemed to start boosting, but only at about 2750rpm. Took it on a drive up north at the weekend, ~300 miles revving hard to blow out the cobwebsand it just kept getting better and better. Smoke has calmed down a great deal and it'll do 125 (private motorway ofc). Full boost seems to come in about 2100rpm now. Will report back with continued driving as it still seems to have more to give.

Thanks everyone for their help and especially to Richard for the code read and hand troubleshooting. What a great forum this is.

Tuning box time, methinks!

[doingitsideways]

Glad you're sorted now.
Boost does come in a little late on these, so yours sounds about right there.

Once you're sure everything is as it should be, give Martin_r_smith on here a shout and talk to him about one of his remaps for these.
Infinitely better than a tuning box

Link to my little review

Mine keeps up my T5 and V8 XC90 now

[ttocsc]

The saga may not be over - yesterday I contended with a particularly steep hill - the one which goes through Dunning up to Path of Condie for anyone local.

Coming up the hill in 2nd at about 30mph, probably 3-3500rpm. Put my foot down for a straight (still steep uphill) part and the car boosted for a split second and then just spluttered and acted as if I was trying to hustle it up there in 4th - needed to change down to 1st to get the rest of the way up. Once I got to the top a lack of boost was once again apparent. Turned ignition off and back on again and everything went back to normal. Since then it has been doing that every time I rev past about 3500rpm at full throttle. Have rechecked all my vac and boost hoses. Any ideas?

[doingitsideways]

Sounds like it's overboosting and going into limp mode. (It resets with ignition off)

Hasn't got a manual boost controller fitted has it?
Maybe see if you can plumb in a simple boost guage to see what's happening

[martin_r_smith]

What sideways said. Sounds like an overbooked situation. It has more than likely stored a fault code.

[V70Zig]

As Martin said in his first reply.......have you checked the hose that goes to the MAP sensor as mine would only boost once till I restarted.....then only boost once again. Remove the engine cover and at the left hand side of the manifold there is a pipe which goes to the MAP sensor......inspect it carefully...could also be the sensor though.
Once your up and running, and before you try a tuning box, try adding some 2 stroke oil, and ask Martin about the hammer Mod......but you will need Vida + a hammer for that....