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Discussion Starter · #1 ·
Having just had delivery of my JT exhaust and boost gauge (fantastic service from Elk, ordered 11pm Friday, delivered tuesday) I tried fitting the gauge to my 2.0 CSE LPT (1994). I connected it to the capped spigot on the inlet manifold next to the dump valve connection. It reads minus 0.5 bar at idle and when revved climbs to 0. Have I done something stupid and connected it to the wrong place?
Merry Christmas to all
Alan
 

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when your engine has no load on it or very little load (ie neutral and 1st gear) there isnt enough exaust gasses to spin the turbo up operating speeds. if you have the car in neutral, try bouncing it off the rev limiter and you will get about 1 psi of pressure out of the turbo.. thats the great thing about turbo's over superchargers.. you rev a supercharged engine, you get boost (in neutral you an blow a superchaged engine if not carefull) whereas a turbocharged engine needs load to preoduce exaust gasses needed to spin the turbo up, therefore less risk of damaging the engine.
 

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Discussion Starter · #5 ·
Having spent New Years morning fitting the exhaust (getting the old one cut out was the worst part), I could now do with some advice re resetting the base boost. I don't know how BillJ took those clear photos of the wastegate actuator but mine (2.0LPT) has several pipes crossing to impede access. Managed to grip the rod but the 10mm spanner seems to slip round the locknut. At the lever end the original rusted circlip (no R clip fitted) fell apart leaving sufficient in the groove to prevent removal of the end piece. I had bought a new ('seal'?) kit with clips from the dealer in anticipation and am now running with just the R clip fitted. Does anyone know an easy way to free the locknut etc?
The base boost has dropped to about .35 bar (although I do not have an intercooler I assume that it should be .45 bar). The peak boost (WOT in 3rd) has dropped from .6 bar to .5 bar. Can anyone advise what it should be for a '94 LPT? I cannot find a figure anywhere.
Thanks to all for advice.
Alan
 

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Alan, although it's not on my site, I seem to remember reading that base boost on the '94 2.0LPT should be about 0.30 or 0.35 bar. Lower than the intercooler-equipped LPTs because yours has APC while there is none where an intercooler is fitted. So yours sounds OK. Perhaps your actuator is a little weak and the greater pressure difference across the wastegate due to lower back-pressure in the JT exhaust is allowing it to blow open a bit more at high boost.

I took those photographs on a 9000 Aero with the Mitsubishi turbo, which is why it looks different (photos are taken from below). This turbo has the R-clip, while the T25 uses a circlip, although I believe there is also a hole there for an R-clip.
 

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Discussion Starter · #7 ·
Thanks Bill. But my car has lost performance which is dissappointing. The base boost was about .38 bar before fitting the exhaust. Will it do any harm to turn it up, assuming I can get the nut undone?
If peak boost is controlled by the APC (via the dump valve I assume) why should this also have dropped? What level of peak boost should an LPT achieve?
 

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Folks Ive recently fitted a new boost gauge and Im experiencing the same sort of issue as AlanG.

Trying find a solution Ive trawled thru previous posts and found AlanG's post something very similair to my situation.

Firstly, the car in question is a 1992 9000cs 2.0 eco, (manual) with intercooler fitted!. Im getting the same story with my boost gauge, even under load and hard accelaration my boost gauge does not budge beyond 0 and usually sits around
- 4/5 bar while cruising/idling.

Im not sure about fiddling around with boost pressure as I dont want to end up with a big pool of oil and smoke . Plus as far as Im aware the car seems to run ok.

Ive followed BillJ's instructions for testing the pressure on non trionic models and yet it still didnt budge over the 0. I assume it was the right procedure as my car is non trionic, however it kinda falls into both categories . And the addition of the intercooler has fudged the issue even more.

Im going to run all this by my local saab guy who should be able to shed more light on it but just wanted to see if any of you chaps have any tips?.

Cheers
Michael
 

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Micheal,

If you now have a boost guage and you are seeing vacuum's (-ve bar on idle / overun) then that is good.

If you can't get the guage any higher that 0 (and it should sit at 0 when the car's switched off), the you have one or more of a number of problems

1. You don't have a Turbo
2. You have a failed or disconnected wastegate
3. you have plumbed the gauge in after a 1 way valve or some such
4. You've plumbed the guage in before the turbo
5. the 3mm vacumm pipes are leaking badly under boost.

Also, remmeber that petrol cars will not produce boost unless under load (i.e being driven).

Does the car feel as if it is boosting?
How and where is the guage plumbed
check the wastegate/wastegate rod/any pipes or APC bits you have.

Andrew
 

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Cheers for the quick response Andrew much appreciated. Will answer your questions as best I can

1. You don't have a Turbo[/b]
yep theres one there alright

2. You have a failed or disconnected wastegate[/b]
Not sure about this can check to see if its connected ok in the morning. (im working nights at the moment:)

3. you have plumbed the gauge in after a 1 way valve or some such
4. You've plumbed the guage in before the turbo[/b]
I can answer the two of these at once, as I have plumbed the boost gauge into the port (at the back of the inlet manifold on the left hand side)
Have used the Y piece as specified, and Ive also replaced the vacuum hoses with the ones I got from elkparts along with boost gauge/di cassette.

5. the 3mm vacumm pipes are leaking badly under boost.[/b]
Im going to check new the pipes to make sure they are home ok. Ive noticed no major change in performance after fitting boost gauge/new hoses but if anything its got a little better . I can send pics if it will help pinpoint any issue?.

Does the car feel as if it is boosting?[/b]
Yes I think so, it can accelerate ok the power
seems to be smooth and the guage seems to be active moving up towards the 0 mark when I drop the revs off she goes back downwards.


Cheers again Andrew hope to get to the bottom of this one sooner or later
 

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Ok, Spoke to my local saab guy today, he said that because I recently fitted an intercooler that the pressure on the system would be different due to the increased volume of air in the system.

He suggested that I wind the boost up a wee bit in order to get the proper base boost, and that should do the trick.

Does this sound right?

Regards
Michael
 

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Only in part.

The intercooler will have lower the boost a little and cooled the charge, but it the gauge only gets to 0 at full throttle / load then you have no turbo boost at all (or no reading of it).

Are all the intercooler and all other intake pipes fitted securely? If it's a Trionic car it will still run OK if they are not.

If it's going OK as you say it is, then it a little odd if the paipes, wastegate and gauge are all fitted OK.

I'm assuming that the turbo isn't siezed or missing it's exhaust turbine (I think 1 or 2 here over the years have had siezed turbo's, but normally on tweaked Full pressure turbo's, LPT's are not that strained.

Andrew
 

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Andrew thanks again for the replies,

Im finished my last night shift tommorow morning so Im going to give all pipes a check over just to make fully sure. The car isnt trionic its the bosch management system.
Before I replaced the vacuum pipes I had a problem with the vacuum pipe to the dump valve which caused the car to die out when the revs dropped off.

So I get the feeling that if there was a leak somewhere, she'd be dying out and Id be seeing even stranger readings on the boost gauge.

Im hoping to find something loose or not in its correct place, a ceased turbine would not be fun thats for sure. From time to time I can hear a whining,whistling under load. Anyway Im going to have a good look at the car tommorow and make sure theres nothing amiss.

Anyway Will keep you posted Andrew, and thanks for taking the time to help me out!. Much appreciated!

Cheers
Michael
 

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I think it may have been down to a loose pipe,
checked it the other day and found them to be nearly off the Y piece connector...

Sadly broke the Y connector when putting them back on, the pipes where faily subtle as the engine was pretty hot, the Y piece just snapped off.. Im getting another one sent over, just going to have to be very careful and give the pipes a good soak in boiling hot water before doing any work.

Will let you know how it goes.

Cheers Again.

Michael
 
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