Need to reduce boost as get-me-home 1z engine

for questions and answers about alternative power transplants on the T25, GTi, Porsche,Subaru etc, this is the place. You must register to post but anyone can read.

Moderators: User administrators, Moderators

Post Reply
pirate-pete
Registered user
Posts: 232
Joined: 01 Nov 2009, 18:49
80-90 Mem No: 7945
Location: London

Need to reduce boost as get-me-home 1z engine

Post by pirate-pete »

On hols in France and all well until yesterday. Had the boost pipe to intercooler pop off seven times on our 300 km journey. On my conversion the pipe from turbo inlet side is connected to the black plastic pipe leading to the intercooler with a 2" piece of hose clamped with jubilee clips. Yesterday the joint to the intercooler pipe blew off first so I tightened it. A couple of miles further on the other side ( turbo side) popped off this time due to worn jubilee clip not tightening. So replaced that on went on my way. Few more miles and the first joint popped off again. Took a good look and it seems this pipe is getting deformed so hose won't clamp too well. It has been ok for last eight years since I have had the van. The pipe from the turbo inlet to this joint is fine as it has a metal ring inside to stop the crushing. As I am down in France near Rhone valley I have a fair distance to get back. What I would like to do if possible is reduce the boost to help keep the joint in place.

What I tried last night was to remove the electrical connector to the N75 boost controller to get the the last 25 km to the campsite and took it slowly. Anyone know if that will have right effect? Or will that just stop the controller from cutting off if boost gets too high? Any other bodges I can to till I get home and do a proper fix? The other thing I have tried is to cable tie these pipes on the intercooler inlet to the parallel outlet pipes to try to keep the joint together rather than blowing apart again.

This is a 1z golf engine and the pipes are from the donor but not the coupling which is just a bit of tubing of the right diameter to make the joint.
1983 Westy Joker HighTop, 1Z TDI Conversion

mm289
Registered user
Posts: 314
Joined: 31 Dec 2010, 22:00
80-90 Mem No: 9111
Location: Dover, Kent

Re: Need to reduce boost as get-me-home 1z engine

Post by mm289 »

Couple of thoughts.

Not sure on the effect of disconnecting the switch as mine doesn't have it!

Does your injection pump have the boost controlled LDA? (small tube going to the top of the pump). This uses boost pressure to alter the fuel when on boost, if you disconnected that it would "leak" boost from here, but equally would reduce power a bit. I ran mine for a day when it had come off and i did notice a slight drop in power but nothing significant

You could just be gentle on the throttle, boost comes in hard when the engine is under load and you plant the throttle above what feels like 2000+ rpm. I have a boost gauge on mine and it is surprising how much you can run "off boost" if you are gentle on the throttle.

Is there a chance the wastgate is stuck and it is not venting when overboosting? Not really a roadside repair but just a thought - are the pipes popping because they are old or because it is overboosting (which driving it more gently would help with) although doing that all the way back from France may be boring :shock:

I guess my preferred solution would be to try and find a replacement pipe.... local "proper" garage not a main deal and see what they have lying around that you mix and match? Not easy in a foreign land but possible :)

Cheers,

MM
'89 Autosleeper Trident
2.1 DJ
Member 9111

davidoft1
Trader
Posts: 2579
Joined: 27 May 2009, 18:56
80-90 Mem No: 16628
Location: hayling island

Re: Need to reduce boost as get-me-home 1z engine

Post by davidoft1 »

You can pull one of the small vacuum pipes off the boost control solenoid, n95 I think

pirate-pete
Registered user
Posts: 232
Joined: 01 Nov 2009, 18:49
80-90 Mem No: 7945
Location: London

Re: Need to reduce boost as get-me-home 1z engine

Post by pirate-pete »

Thanks for replies guys. Went for a short drive yesterday and looks like pulling the n75 electrical connector has helped. No vacuum connection on the pump with this engine and it looks like I need the n75 hoses connected or else wastegate stays shut giving me full boost and no protection from overboost. If I disconnect the wire from it that should just keep wastegate shut under spring pressure and restrict the boost to very low levels.

Pipes I think popping because they are old and I don't think I was getting any overboost. The problem pipe is the rigid plastic one which is mishaped. The rubber hose that goes onto this is in good condition.

Will head north a few hours tomorrow and will see how that goes. Will make sure I avoid the mountain passes my satnav likes. Next stop after that will be with some French friends in Belfort so if we need to find a garage hopefully a local can explain the problem better than I can.
1983 Westy Joker HighTop, 1Z TDI Conversion

Post Reply