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Re: 80 Turbo....hunting/erratic...at idle...
Posted by Gary Stottler (more from Gary Stottler) on Thu, 10 May 2012 10:11:42
In Reply to: 80 Turbo....hunting/erratic...at idle..., Slyde, Wed, 9 May 2012 15:25:58
Slyde,

While this could be a fuel problem, it sounds like it may be an air leak somewhere (engine is ending up running lean because all the air it's pulling in is not going through the airflow plate). I'd first go overall the hoses (both air intake and vacuum) as well as gaskets, clamps, etc. You might also check if your throttle blade is sticking and if it's correctly set (if someone has used the blade angle screw to set idle speed you'll be all messed up). If all else fails, try blocking off the port in the intake manifold that goes to the brake booster - a failed brake booster diaphragm can cause crazy and hard-to-diagnose symptoms.

On the fuel side, if you do elect to do a fuel spray test, please do it outdoors with a fire extinguisher standing by! You mentioned that "lambda is disconnected" - if you disconnect the sensor, the system will run at a fixed pulse relation, but the system still has to be operating, so make sure that the modulating valve is still buzzing away. If that is not working it will likely make the engine run lean.

Good Luck!

Gary


posted by 198.208.15...
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