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Need advise on boost gauge fu** up...

 
Old 05-22-2013, 04:47 PM
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Motosport
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Default Need advise on boost gauge fu** up...

So today it was time to start up my '89 TS for the first time after installing Vitesse stage 3 turbo, M-tune, Tial WG, new exhaust, MBC, Innovative WBO2, new silicone vacuum hoses all round, extra boost gauge and a few other bits and pieces..

She started up fine and after the initial smoke from burnt oil and grease had worn off, I noticed that neither my stock boost gauge or my aftermarket one worked at all, both just showing outside pressure at 1 bar..?!?! I did replace the old hardened KLR boost line with a new silicone hose, and did a T into it for the new boost gauge, but isn't that okay to do..? I guess when my new boost gauge doesn't show vacuum or boost, neither does the KLR..?!?

When I replaced my vacuum hoses and installed the Tial WG and MBC I used the vacuum diagram from Paulyy, so I believe that should be right..!?!

Next question is, where does the stock boost gauge get its reading from..? As far as I know, I haven't messed with the stock gauge but somehow I must have anyway, just don't know where..?!?

So I'm hoping someone smarter than me (doesn't take a lot I know..) could point me in the right direction as how to make both my gauges work...

The car seems to drive alright, even though I only did a very short test drive as the fuel rail had a crack at the fuel damper bracket and was leaking fuel ( So if anyone has a good spare fuel rail lying around at a decent price I might be interested..) I only went into boost very shortly as I didn't want to push it without a boost gauge, but she pulled fine and cleanly..

She does run a bit rough and lumpy at idle though, and sometimes also seems to stick at a high idle until I dap the throttle.. Can that be connected to boost gauge/vacuum issue or the fuel rail issue..?

I haven't had much time to investigate much into it yet, as I had to leave the car at the workshop where I've been working on it, but I thought I could use all the advice I could get before diving into it again..

Thanks - Alex.
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Old 05-22-2013, 05:09 PM
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pa951
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There is a hard vacuum line from the air intake to the klr computer under the dash. That signal gets translated to a low voltage signal that goes to the dash boost gauge.

You'd best check there again.

Oh and if it is giving 1bar it is getting a signal... Otherwise they would simply be down.
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Old 05-22-2013, 05:43 PM
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Thanks.. That explains why the stock boost gauge isn't showing anything either... But I don't think its getting any signal at all, as both gauges are pegged at 1 bar outside pressure, same as when the battery was disconnected during installation and general work on the car..

As mentioned, I did replace that hard vacuum line between intake and KLR with a new silicone vacuum hose, and I T'd the new boost gauge into that new vacuum hose. Is any of that a bad thing to do..??
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Old 05-22-2013, 06:01 PM
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The silicon hose could get pinched and that would cause the situation you are seeing (lack of boost gauge reading).

The intermittent high idle is a symptom of a sticking TPS / throttle body. Try adjusting the TPS. Also check to make sure you have sufficient slack on the throttle cable at idle.
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Old 05-22-2013, 08:15 PM
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Make sure the TPS is clicking just as you start to turn the throttle cam if not adjust. Still no click I would just replace it instea of trying to clean it so see if it will work. GL
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Old 05-22-2013, 08:38 PM
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+2 on boost like to KLR getting pinched. I would keep the plastic hard line just to go through the firewall. I've cut my plastic line fromt he KLR and put a silicone lie in place. Helps with removing the KLR & DME for any reason.

Same goes with the intake part. Just cut the plastic line and put a silicone line in place so you only have the plastic line going through the firewall so it won't kink
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Old 05-23-2013, 04:31 AM
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Thanks for all the inputs... It makes perfectly good sense of course that the KLR vacuum line is kinked somewhere, as its a straight hose from the intake to KLR so not much else can cause a no reading issue I guess..

Good point on the hard plastic line going through the firewall Pauly, only problem is mine was old and very hard so I tossed it already.. I'm thinking I could run the new hose through a piece of hard tube where it goes through the firewall instead, and also run the vacuum lines to the MBC the same way..

By the way Pauly... I ended up using your advise on the turbo water pipe modification and made a nice 90 degree bend with AN fittings, and there is not single drop of water to be seen anywhere on the turbo.. Bone dry and a happy owner... :-) Thanks...!!
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Old 05-25-2013, 02:22 PM
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One way or another, the vacuum line to the KLR that you Tee'd is not getting vacuum. Pull it off the KLR with the motor running and put your finger over it to confirm there's no vacuum. You can get the factory part brand new still -- see for example the 944online link below.

http://www.944online.com/cgi-bin/ASI...ystem-944turbo

Or you can probably do just fine with some 3mm I.D. / 5mm O.D. semi-rigid tubing from McMaster Carr or your local hardware store (look where they sell tubing for ice makers...). http://www.mcmaster.com/#5958K12
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Old 05-26-2013, 04:21 AM
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Thanks Tom, I'll try and do that as soon as I'm back from work... I didn't even know it was possible to get the stock hard pipe anymore, so I might end up doing that if I can't find something suitable locally...

But since I also have the vacuum hoses going to and from my interior mounted MBC, it should be possible to run them through the firewall without getting pinched, or do I also need to replace those with hard pipes just to be sure..?!?
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Old 05-26-2013, 11:10 AM
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You should be able to get away with rubber hose. It's actually quite difficult to pinch a hose so completely that you get zero signal. It's possible if you've sandwiched it between bolted items -- like between the block and bell housing. Assuming nothing like that happened I'd be inclined to guess that your hose has a tear in it somewhere or is disconnected somewhere.
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