I'm Lost
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I'm Lost
I think I'm in the right forum again. Let me try this question again here. I have an 86 5000 QT and I can't get the boost up to the normal 1.4 bar. 1.2 is as high as it goes. I have an O2 sensor fault code so I should replace that. Can't find any vacuum leaks. Changed plugs to platinum +4s. Re-soldered WOT.
My question is: What would happen if I went to a stiffer wastegate spring without modifying the ECU? Would the boost increase? Would I be doing damage to anything?
My question is: What would happen if I went to a stiffer wastegate spring without modifying the ECU? Would the boost increase? Would I be doing damage to anything?
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I'm no turbo genius...
but I think that if you were to only put in a stiffer spring you could only achieve 1.6 bar tops. The ECU would cut off any gas flow after that. This information is of course subject to my limited knowledge on turbo engines
For best results check out Audifans.com. Use the Google search bar on the main page and type in words like "stiffer wastegate spring" "low boost problems" etc. Use your imagination
As far as your low boost problems go: WOT switch was a good place to start. Confirm that when you resoldered it that it is functioning correctly. Also check the "michelen man" hose. It's the hose that runs from the intercooler to the throttle body. Take it off to look for cracks. They are hard to spot with the hose connected. Other things to consider: What grade gas are you using? Turbo engines like premium! For more info on turbocharged Audi's consult:www.sjmautotechnik.com
HTH!
Also, from past arguements, +4 Pltinums may not be the best plug to be using in the I-5 turbo...
Steve Ankney
88 5000
Holland, MI
For best results check out Audifans.com. Use the Google search bar on the main page and type in words like "stiffer wastegate spring" "low boost problems" etc. Use your imaginationAs far as your low boost problems go: WOT switch was a good place to start. Confirm that when you resoldered it that it is functioning correctly. Also check the "michelen man" hose. It's the hose that runs from the intercooler to the throttle body. Take it off to look for cracks. They are hard to spot with the hose connected. Other things to consider: What grade gas are you using? Turbo engines like premium! For more info on turbocharged Audi's consult:www.sjmautotechnik.com
HTH!
Also, from past arguements, +4 Pltinums may not be the best plug to be using in the I-5 turbo...
Steve Ankney
88 5000
Holland, MI
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Joined: Jun 2001
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Re: I'm no turbo genius...
Thanks for your opinions Stephen. Hey, I'd be beaming with 1.6 bar :-). I had checked the intercooler hose with it on and it was fine but now that you say the cracks are hard to find, I wonder if I missed it.
No problems as of yet with the +4s. Premium gas is quite expensive in Canada. It's about 90 cents a litre which is roughly $3.60 a gallon.
Any idea where I can get a wastegate spring? So far I haven't seen any price listings anywhere.
So far the cheapest O2 sensor I've found is $160.00 Canadian for the universal one.
BTW, I forgot my password and had to change my ID. I was Rob5000 last year. Ok, so maybe nobody remembers me :-).
No problems as of yet with the +4s. Premium gas is quite expensive in Canada. It's about 90 cents a litre which is roughly $3.60 a gallon.
Any idea where I can get a wastegate spring? So far I haven't seen any price listings anywhere.
So far the cheapest O2 sensor I've found is $160.00 Canadian for the universal one.
BTW, I forgot my password and had to change my ID. I was Rob5000 last year. Ok, so maybe nobody remembers me :-).
AudiWorld Senior Member
Joined: Dec 2000
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Need more info...
Need to know more about the baseline condition of the car: have you ever seen anything over 1.2? When I bought my sedan I never saw over 1.2 in the summer, but after I discovered the loose clamp on the Michelin Man hose and tightened it, 1.2 was much more predictable. And when the temps cooled in the fall, 1.3 was a fairly regular visitor to the dash gauge. Your engine likes cooler, denser air.
Also, check the crankcase breather hose to see if it is soft and "leathery" feeling, not firm and "rubbery" feeling. If it collapses this can affect the performance of the car. The hose is located at the back of the engine and connects to the metal tube that runs up to the three way rubber hose on the top of the valve cover.
If your engine has a bunch of miles, you may want to pull the rubber hose off the center of the turbo (check the hose clamp first and see if it is loose and leaking boost) and turn the turbo impeller by hand. It should turn freely with a minimum of lateral or axial play. Binding is not a good thing, you'll need to start saving for a turbo rebuild if that's the case.
By all means follow the instructions at Scott Mockry's to get the engine running well in stock form _first_, then go for the big boost.
Good luck!
-Steve Jensen
87 5kcstq
87 5kcstqw
Also, check the crankcase breather hose to see if it is soft and "leathery" feeling, not firm and "rubbery" feeling. If it collapses this can affect the performance of the car. The hose is located at the back of the engine and connects to the metal tube that runs up to the three way rubber hose on the top of the valve cover.
If your engine has a bunch of miles, you may want to pull the rubber hose off the center of the turbo (check the hose clamp first and see if it is loose and leaking boost) and turn the turbo impeller by hand. It should turn freely with a minimum of lateral or axial play. Binding is not a good thing, you'll need to start saving for a turbo rebuild if that's the case.
By all means follow the instructions at Scott Mockry's to get the engine running well in stock form _first_, then go for the big boost.
Good luck!
-Steve Jensen
87 5kcstq
87 5kcstqw
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Re: Need more info...
Thanks Steve. I replaced the collapsed crankcase breather hose last year. As you can see from my above post I've gone ahead and modified my wastegate spring and am now running 1.5 bar at max.
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