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Discussion Starter · #1 ·
Hi/.

As of yesterday, turbo needle is settling down to a steady 12 oclock on gauge ( i.e just a little bit into the orange section), whereas before, it would settle just past half-way in the green.
(1994 , L Reg APC Gauge, 2.3T FPT blah blah).

Secondly, when pushed, turbo needle would normally go off the red scale, and stay there (
), but no matter WHAT I do, it will now only reach the broken orange/red in-betweeny line.
When easing off again, needle sits back to the same position just inside orange section. Once engine hots up after a few miles, neelde sits back a tiny bit more, still just in orange though.

Everything is running OK, and turbo still seems to be playing OK (within these strange new parameters), no nastiness that I know of, or can feel.
I have replaced rubber feed pipes recently from dump valve, and from back of engine block, all except the final one that dissapears into the bulk-head.

If this pipe needs looking at, so be it, but could there be any other problem lurking that I dont want anyone to tell me about
.

( as you know, I have got Abbott dump valve, and bleed valve cut into rubber pipe, but I haven't been fiddling, honest !! )

Cheers, Andy.
 

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Andy, sounds like you have a leak somewhere. Possibly in the vacuum pipe going to the gauge (that's where that pipe goes that disappears into the bulkhead). The clue is that it isn't showing much vacuum. Even if the turbo wasn't working, the engine would still produce vacuum with your foot off the throttle.

I've found that the part of the pipe that goes from the bulkhead to the dash tends to be OK as it doesn't live in the engine compartment. However, that last bit of pipe you didn't change (it goes through the bulkhead into the "aquarium" and onto a plastic union in there) might be your culprit, especially if you have disturbed it recently.

Another possibility is a leak somewhere near the throttle body. A couple of days after I fitted the Maptun ECU to my Aero, I ended up with similar symptoms to yours, accompanied with a "whooshing" noise on acceleration. It turned out that one of the hoses to the idle control valve had been blown off the throttle body by the huge boost pressure. I'd forgotten to tighten it weeks before after I'd had the valve off. It must have been leaking a bit even then, because the boost gauge hadn't been working quite right (neither went as high as before nor as low), but hadn't been making any noise. Refitting the hose and tightening the clip properly allowed me to see the gauge go almost to 3 o'clock for the first time ever.

You say the turbo is playing OK. Do you mean you are still getting the same gut-wrenching performance, or just that it is still boosting somewhat.

I don't think it's a problem with the turbo.
 

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Discussion Starter · #3 ·
BillJ/.

Gut wrenching performance !! Thanks Bill, and roads were wet that day too

Had that "whooshing" sound a few weeks ago. Not being a techno, it turned out to be a bigger pipe that had dropped down by virtue of a loose jubillee clip, my mechanic didn't tighten properly when having gaskets changed etc.
This was right-side of engine, looking from bonnet, around and below the brake fluid reservoir ( you know I'm not techno minded
)

This time it isn't whooshing any more than usual, and performance still holding up pretty much, but feels diferent somehow, due to different parameters of the needle movement prehaps ?.

Is that throttle body thing what I was trying to mention, or something else. If the latter, can you please explain in "idyut-guide" terms where it is, and what it looks like.

Thankyou,
Andy
 

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Originally posted by Andy Bowles:
[qb]Gut wrenching performance !!  Thanks Bill, and roads were wet that day too[/qb][/b]
At least you seemed to have decent tyres on. Mine were almost bald and all I got was wheelspin!

Was that a big pipe with right-angle bend and an enormous Jubilee clip on it (bigger than any other ones in the engine bay)? If so, that's the inlet hose that goes onto the throttle body (the end with that huge Jubilee clip fits onto the throttle body). There are quite a few other pipes that fit around there, and a leak in any one of them could produce that problem to a greater or lesser extent. However, my betting would be on the vacuum pipes you disturbed. For the gauge to read almost no vacuum, then either it's not reading right or your throttle is partly open all the time and you would definitely notice that!

Bu66er it. I'll do a picture.



That's actually a photo of Alan B's Aero engine with traction control. If you don't have traction control, the throttle body will look a bit different and you'll have fewer vacuum hoses to sort through.

One vacuum hose to check that would probably give your symptoms would be the one under the left-hand side of the plenum chamber that comes from the plastic "Y"-piece on the right of the engine. If that's not connected to the plenum chamber (or the "Y"-piece), it wouldn't pick up any vacuum (so the boost needle wouldn't go below yellow), but you'd get some boost showing because the vacuum hoses are still connected to the pressure side of the inlet, although some of it would be leaking out of the open pipe so the boost gauge wouldn't see all the pressure that's being made.

Also, your bypass valve wouldn't be working properly (it would probably start opening with only a bit of boost so you wouldn't be getting full boost anyway or at least it would build up more slowly - "feels different somehow"?). I imagine if you opened the windows, you wouldn't hear the bypass valve hiss as you let your foot off the throttle after being on boost.

If you have any hose left, I'd do the other one that goes through the false bulkhead - you need to take off the plastic cover by the windscreen, and the hose goes in there and onto a plastic union on the "real" bulkhead inside.
 

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Discussion Starter · #6 ·
BillJ/.

Dont worry, sorted it out

Thankyou for pic, and yes, the previous problem with whooshing was the inlet hose, sussed out from your pic and description.

For this problem, I traced down under the throttle body, and found the t-joint. Hose from dump valve, and hose to back of the "plenum body" (new name on me) already replaced, but found hose on the t-joint going towards bulkhead was perished, almost hanging of joint.
Cut half and inch off, relocated and bingo !!

Obvious really, but too dark to check yesterday, and it should have been the first thing I checked today before "Saabscening", but foggy head ( ), didnt think etc..

Sooner or later, whole hose will need replacing, cannot get around dash removal for too long now, if that is whats required ??

Vrooom

Thks again,
Andy
 

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When I did this recently on a '96, I found the hose went onto a plastic union under that cover, and doesn't go all the way into the dash. The hose under the dash joins to the other side of the union and it was fine anyway (took the dash top off to fit an alarm). So no, dash top removal shouldn't be necessary, unless your car is different.
 
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