2.2 dti power loss

**dylan1875** · 13th January 2011, 16:55

hi, i have recently aquired my first vauxhall (04 dti estate) and am already having trouble's

. the car pulls and drives great until motorway speeds and then power dissapears. (spanner light)
it has a new maf sensor, cleaned egr, throttle body and boost sensor. also have checked boost hoses (no splits). the same with vac hoses but am going to change them anyway.

any ideas what to try next??

**dylan1875** · 19th January 2011, 18:37

Well have now changed the vac hoses and has cured the motorway and spanner light problems!! However now it runs a little rough around town (no lights).
I have noticed that if i leave the vac hose off that goes to the vac pump thingy next to the egr it runs a lot better but light returns. With the hose back the vac thingy behaves quite erractic causing rough idle!!!!
ANYBODY???? PLEASE?????

**James24** · 19th January 2011, 19:07

The vacuum unit at the front of the inlet manifold (the vacuum pump is the round metal thing on the end of the engine facing the battery) operates a valve inside the manifold. I think it is open and allows air through all the time except when you switch the engine off when it closes briefly to cut off the air supply to help the engine to stop quickly and not run on.

It sounds like something is faulty - either the vacuum unit itself or the unit above the radiator that activates it (i.e. allows the vacuum through or not, follow the vacuum pipe to find it) and it is closing the valve when it shouldn't causing a drop in air supply to the engine.

Perhaps you need to either leave the vacuum pipe disconnected (you won't get any error lights if you don't have the position sensor on the back of the inlet manifold next to the boost pressure sensor), or find and fix the problem.

**Gayno** · 19th January 2011, 19:25

When you say "behaves erratic" do you mean it seems to fully close, engine almost stalls then it opens again to let engine get back to normal.......and the repeat? If disconnecting the vacuum stops this, and when you plug it back on it starts again?

If so, I'm afraid the TPS is your problem. You can't buy these seperate, but need to buy the whole inlet which has new TPS and boost sensors.

Cost is around £220 and AFAIK only from the dealer.

**James24** · 19th January 2011, 19:47

Originally Posted by Gayno

When you say "behaves erratic" do you mean it seems to fully close, engine almost stalls then it opens again to let engine get back to normal.......and the repeat? If disconnecting the vacuum stops this, and when you plug it back on it starts again?

If so, I'm afraid the TPS is your problem. You can't buy these seperate, but need to buy the whole inlet which has new TPS and boost sensors.

Cost is around £220 and AFAIK only from the dealer.

That's what I was assuming but we'll see if the OP confirms.

There are 3 versions of the inlet manifold for the DTi. The first has no vacuum unit or TPS so the OP obviously doesn't have this one. Of the 2 others, one has the vacuum unit but no TPS, while the the other has both. So, it could be the TPS if the OP has the type with both the vacuum unit and the TPS.

See the picture in the first post on the page below which shows a DTi with both vacuum unit (inside the white circle numbered 2 along with - and above - the EGR valve) and TPS (circled in red and numbered 5).

http://www.vectra-c.com/forum/showth...+sensor&page=2

**dylan1875** · 19th January 2011, 20:31

Mine is the one with vac unit and tps by the looks of things...
When i say erractic i mean that it seems to flicker between open and closed quite quickly.
Thanks for the reply's guy's. KEEP UM COMING..............

**Gayno** · 19th January 2011, 20:38

Don't think there's any more to come, it's almost certainly your TPS.

The electrical contacts wear down and it send erroneous signals to the ECU, then the ECU doesn't know what to do with the butterfly valve (controlled by the vac unit) so it moves it about trying to find a good signal but can't.

**dylan1875** · 19th January 2011, 20:54

Ok, makes sense, thanks,
i'll try to find one and give it a whirl ....

**James24** · 19th January 2011, 22:11

Good luck.

Take a look at these posts:

http://www.vectra-c.com/forum/showthread.php?t=101062

http://www.vectra-c.com/forum/showthread.php?t=100313

I think I'm lucky in that I have a DTi with the vacuum unit but without the TPS.

**dylan1875** · 29th January 2011, 20:00

well, have now changed upper manifold for a nice shiny brand new one!! but still has the same problem although the vac unit has calmed down.

i have noticed that it does run a bit better when warm. it drives great when you give it some foot!

but generally upto 2k revs lumpy and also when backing off the throttle around same revs.

????