Serious turbo lag/delay....

[Dan-T5]

hi,

What would cause the turbo not to 'kick in' until 3500rpm??

That is when the car starts to pull like my audi S4 did, only that pulled hard from 2200rpm.

I remember driving my mates 850 GLT T5 and that was so much more responsive.

i've got traction control fitted on car but even with that turned off I won't slip the front wheels (unless i'm on gravel!)

Would an aftermarket BOV cause this delay? Should the car as standard be fitted with a re-circ? I've heard some T5's were and some weren't?? Is this correct?

Cheers,

Dan

[gtiteen]

I believe ME7 engines dont like BOV so much but i think being '98 your will pre-ME7.

Checked for boost leaks?

[p fandango]

if the BOV isn't tensioned up enough then the air could be leaking out of there instead of spooling the turbo up, was it ok before you fitted the BOV?

some BOV's are adjustable (either an adjustment screw or add spacers) to increase the spring tension

[Alan M]

It could be that your dump valve is a single piston type ad not a twin piston type.

[Dan-T5]

if the BOV isn't tensioned up enough then the air could be leaking out of there instead of spooling the turbo up, was it ok before you fitted the BOV?

some BOV's are adjustable (either an adjustment screw or add spacers) to increase the spring tension


I haven't fitted the BOV. I only got the car on sat and only removed the window tints and rear light tints. along wit some black horrbile paint on the door frame.

Dan

[Dan-T5]

It could be that your dump valve is a single piston type ad not a twin piston type.

How can i tell the difference?? Is the piston the large piston in the casing where the vent holes are??

[Dan-T5]

i found this whilst looking around the throttle area....
http://i40.photobucket.com/albums/e217/Tdi_dan/Thing-1.jpg

THe large palstic thing in the pic has 3 exit parts on the right hand side. The top pipe and the bottom pipe and connected by a long, (about 20inch!) length of pipe?!

Is this correct?

I've had a look for cracked pipes etc but cant find anything. i will try and get a compression test done by well lane turbo, leeds asap.


Cheers,

Dan

[Alan M]

Well Lane should be able to pick up any faults. You can check for most problems yourself before spending money elsewhere. That black thing in the last picture is the vac tree. You should have your boost gauge reference and fuel pressure regulator connected to this. The hoses are easy to trace out so hust follow them along and see where they go. Your dump valve should have two pistons that you can see, one inside the other. What make is it? The recirc valve (CBV) should have a hose from it to the lower (IIRC) vac nipple on the inlet manifold below the vac tree. Sometimes people run the CBV and atmospheric dump valve together but this can be the cause of some vac leaks if not plumbed in correctly. Just trace your your hoses back and check to see if the turbo has the CBV still attached on the turbo compressor housing. If it is it may be worth either just using that and removing the dump valve or fitting the dump valve and removing the CBV and fitting a blanking plate. If you decide to go with the CBV remove it first and check the rubber diaphragm inside it for cracks and damage that may affect its operation. The vac tree has a rubber o ring on it that seals it to the inlet manifold that is usually a leak point so its worth replacing that. Check all your hoses and where they are fixed as sometimes the clamps used on them can cut through them and hide leaks covering daaged hose.

[Dan-T5]

Well Lane should be able to pick up any faults. You can check for most problems yourself before spending money elsewhere. That black thing in the last picture is the vac tree. You should have your boost gauge reference and fuel pressure regulator connected to this. The hoses are easy to trace out so hust follow them along and see where they go. Your dump valve should have two pistons that you can see, one inside the other. What make is it? The recirc valve (CBV) should have a hose from it to the lower (IIRC) vac nipple on the inlet manifold below the vac tree. Sometimes people run the CBV and atmospheric dump valve together but this can be the cause of some vac leaks if not plumbed in correctly. Just trace your your hoses back and check to see if the turbo has the CBV still attached on the turbo compressor housing. If it is it may be worth either just using that and removing the dump valve or fitting the dump valve and removing the CBV and fitting a blanking plate. If you decide to go with the CBV remove it first and check the rubber diaphragm inside it for cracks and damage that may affect its operation. The vac tree has a rubber o ring on it that seals it to the inlet manifold that is usually a leak point so its worth replacing that. Check all your hoses and where they are fixed as sometimes the clamps used on them can cut through them and hide leaks covering daaged hose.


Thanks for the info! Will have a good look today.

From the Vac tree, I dont have a boost gauge fitted, not even as standard on dash! I can't understand why someone has 'bridged' the top right exit of the tree to the bottom right exit of the tree? Pressumably this is maybe where a boost gauge could be tapped in?

When you state CBV on turbo compressor housing, what is it i'm looking for? there is a large round silver unit with a vac? hose fitting right into the middle at the top? But this seems to a rod from bottom of it leading to under the heatshield?

I'm not very clued up on turbo mechanical side of things. As never had a problem with tubro'd cars before. lol

Dan

[Alan M]

On the silver compressor snail you shoud see either a triangle blanking plate if there is no CBV (compressor bypass valve) or triangular raised valve with a small nipple off it that goes to the inlet maniold and that will be the CBV. The actuator has a rod off the bottom of it that goes under the heatshield, this also hs a nipple off it and that will go to the BCV (boost control valve or boost control solenoid as some refer). I would check the PCV (positiv crankcase ventilation) system for age relted wear as this can be a soure of unwanted boost leaks and if blocked can cause problems with the rear main seal behind the flywheel.

[Alan M]

The bridged exits on the vac tree are probably because someone lost the blanks that were originally there.

[Dan-T5]

Any chance of a pic or diagram of this silver Compressor snail please??

Dan

[Alan M]

Look at this turbo. The compressor is the silver part of the turbo. The CBV bolts to it on the missing flat section.http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280346126127

[Dan-T5]

Look at this turbo. The compressor is the silver part of the turbo. The CBV bolts to it on the missing flat section.http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280346126127


So if i dont have a CBV i should have a triangle blanking plate in the flat silver piece in pic one??

Dan

[Alan M]

Yes you have the idea now.

[Dan-T5]

Yes you have the idea now.

Well, i've found time to have a look under the bonnet....and yes, i do have the CBV still in situ......but! where the ipple is on the CBV there is a piece of rubber about 2inch long with a screw in the end blocking it!!!!

What i'm thinking of doin now......removing the BOV and reconnecting the CBV to see what happens,

But where should the cut pipe be reconnected on the engine and other that the Vac tree, i can't see anywhere else for it.

oh, other than on the inlet manifold where the current vac pipe from the BOV, which will be free!

reason for removing the BOV is that its a single piston type which isn't correct for the car?!?!

Cheers,

Dan

[Dan-T5]

Right, another look today and found more baffling things....

On the Vac tree there is a pipe from the rear of it, which whilst i traced it today, again has been blocked with another screw!
http://i40.photobucket.com/albums/e217/Tdi_dan/vactree.jpg
(I removed the pipe linking the top and bottom right hand side vac tree exits, hence why there are open)

So at the moment, ALL exit on the vac tree have been blocked one way or another.

I have a hunch feeling that this blocked pipe (in pic with screw) from the vac tree should be connected to the Re-circ Valve on my compressor???

On the BOV (which i want remove) I have a pipe from the inlet manifold going to the BOV.

THIS IS WHERE I@M GETTING CONFUSED NOW!..................



Should the inlet manifold vacuum pipe be connected to the re-circ valve..............
Or should a pipe from the Vac tree be connected to the re-circ?
(although you cant actually see the nipple on the re-circ valve, you can see the valve is still in situ)
http://i40.photobucket.com/albums/e217/Tdi_dan/recirc.jpg

[Alan M]

The pipe from the front of the inlet manifold that sounds like is on your DV should go to the CBV (recirc). I would link up all the unused ports or blank them on your vac tree as it will be the cause of many a runing issue if unmetered air is entering the sealed system after the MAF. You can remove the CBV to check the diaphragm inside it to see if it is leaking (split or damaged whereit shouldn't be) by removing the three 10mm bolts into the turbo. Its worth chcking while you are there and i it is damaged you can replace it with another or buy a refurb kit from Japan via ebay.

[snoop69]

Not sure if this helps but i had serious lag on my Me7 when i first got it.

I adjusted the wastegate by one whole turn & it made a big difference.

I also had a dodgy Maf which was confirmed by un-plugging it & seeing
how it ran. It ran much better so a new Maf was sourced.

If tihngs dont improve after sorting out your vac tree/re-circ valve plumming
it may be worth looking at getting your wastgate adjusted correctly as if it
done wrong, all kinds of problems can be created.

This link is worth a read................

http://au.geocities.com/ozbrick850/engine-turbo-keithspage.html

[Dan-T5]

The pipe from the front of the inlet manifold that sounds like is on your DV should go to the CBV (recirc).

What i've tried so far is, reconnected the re-circ...but to the vac tree and leaving the DV in situ with vac pipe from manifold.

The result? Much better response at lower revs and NO compressor surge anymore.

So, next task is to remove the DV altogether and replace the split pipe (where DV adapter pipe is fitted) and get a fresh pipe from manifold to CBV and see what the improvements (If any) are.






My FPR on the fuel has no nipples or vac pipes to it...is this right? On another Volvo forum, a guy suggests my FPR should have a vac pipe connected from the Vac tree?? Unless i'm looking at wrong place on my fuel rail where the injectors are??


Dan