D5 issues, turbo adjustment

[outnumbered]

what i can not get my head round is why the vac engine mounts can cause ECM 6805 when there is no vac to them after 1700 rpm.
mike

[fgx318]

Originally Posted by outnumbered

what i can not get my head round is why the vac engine mounts can cause ECM 6805 when there is no vac to them after 1700 rpm.
mike

I can't figure this out either ! Mine are out of vac @1100rpm

[colzak]

i think the tcv valve does 2 things... 1. should allow the pads to vent to atmosphere after 1700ish revs, but at the same time 2. blocking off its own vac supply so no vac is lost in the overall system.... if the tcv leaks vac after 1700rpm, then i can see how that might effect overall performance of the govner and turbo vanes... THIs is purely my understanding of the hydraulic pad vac system...

[outnumbered]

while i was out and about i did a test and unhooked the front engine mount no codes or errors.connected that back up and disconnected the pipe that feeds both mounts at the Tcv valve at the airbox, no codes or errors.
mike

[fgx318]

Originally Posted by colzak

i think the tcv valve does 2 things... 1. should allow the pads to vent to atmosphere after 1700ish revs, but at the same time 2. blocking off its own vac supply so no vac is lost in the overall system.... if the tcv leaks vac after 1700rpm, then i can see how that might effect overall performance of the govner and turbo vanes... THIs is purely my understanding of the hydraulic pad vac system...

Yes if it leaks from the "in" vac port to the vent port but it's unlikely. You can disconnect the hose from the vacuum pump and plug it with a screw. If the engine works properly then the TCV may be the culprit.

[colzak]

Outnumbered,,,,Thats a strange one,,,?with the pads disconnected I would expect a vac leak and drop in vac to the tcg until the tcv switches to vent..
Are we missing something?,,perhaps the ecu requires several full drive cycles before a fault will log? or as your post suggests, maybe the vac loss is not significant enough to force the tcg out of expected parrameters.?
Perhaps an in line vac test between vnt vane actuator and tcg with pads unplugged will support one of those theories?

FGX318,,,,I agree,,,,blocking the 't' piece vac tube off to the tcv, should rule-out any tcv and pad leak issues if the car responds the same whether the tcv is connected or not..

Gents,,,I wanted to do my vacuum test comparison with Mikes videos, but the wheather here in Cumbria include gales and rain, no good for lifting the bonnet up on the v70, though a thought occured to me regarding the vnt govner.
The tcv govnor test pdf mentions needing a good air sensor, which is something I havn,t considered until now.

[outnumbered]

that was a load of rubbish i posted lol

mike

[outnumbered]

i have just read the pdf briefly and it also mentions the EGR valve, the EGR value at idle also effects the air mass meter.
mike

[outnumbered]

Amount : 480 millibar ( mbar ) minimum
Equals : 36.00 centimeters of mercury ( cmHg ).
thats according to the functional test on the pdf.the vac pump on mine only puts out about 28 hg.
mike

[colzak]

Rubbish?,,Lol, were just fellas trying to fathom the intricacies of a d5 engine, which keeps us off the streets and may save us some garage bills lol,

Good point about the egr though... I suppose with the egr venting into the mixer at idle, less air at the maf should be expected by the ecu,,,and I did block mine off with no improvements. So when I get the chance I will take the blanking plate off again, then do the vac test again.

Not sure what my vac pump is pulling at idle, I will test that too..although no results until Friday when I,m off half a day to do some propper testing..