I've got an immaculate 1989 200 QT. with the MC two knock sensor engine 48k miles on it. What is stock boost at idle?

 

My 88 5000 tq gets 20 psi vacuum for reference if that helps

 

20 psi vacuum? Vacuum is measured in inches of mercury. Or do you mean 1.3 bar? You would not pull a vacuum on the boost side of a turbo.

 

Sorry I didn't clarify. I'm taking a reading from an after market boost gauge with a unit of pounds per square inch. I could be mistaken but I don't believe you will make any boost at idle as the engine will be pulling air in, regardless of where a reading is taken in the intake tract. Audi always shows a positive bar reading even in vacuum, true. I think 1 bar is a perfect vacuum (zero) and I believe you will see .8 bar at idle.

 

http://www.sjmautotechnik.com/troubl.../10vgauge.html


There we go. But ill still check my bar readout after work.

 

0.3 bar at idle from the dash. Between -15 and -16 psi vacuum from boost gauge.

 

Excellent! so 0.3 bar on the dash is normal at idle. Cool. I'm getting a real rough idle for like the first 20 or 30 seconds after it starts. It starts quick but rough afterwards for that first 20-30 second. Leaky injectors maybe? Should I try some cleaners first before I pull them. The car has been sitting for a year but only has 48k original miles on it. Thanks for the input.

 

Before you pull them... Get a spray can of brake cleaner or something else and spray it on the injectors where they go into the engine head. Bad seals manifest in bad low end torque and extended cold start (can't recall but maybe hot starts).If there is a bad seal you will see a change in the idle speed. Is the tank of gas a year old? I would siphon it out if possible and put new in. Or add dry gas. What the idle behave like during cold start enrichment as you were saying? Is it rough during hot start too?

 

Hot starts are ok. just cold start, starts quick but rough for the first 20-30 sec, real rough. Thought about the dry gas. It's possible there is moisture in the tank. Was stored for a year with little fuel in it. I sucked it out but still could have been some water in the bottom. I'll check for vacuum leaks and add dry gas or octane boost this weekend. I'll let you know how I make out, thanks.

 

Pull your spark plugs and check them over. Might need replaced. Search that Sjm site concerning testing your various temp sensors lastly. Could be over enriched.