Anybody here know how to adjust the idle on a 308??????? My Bosch Book by author Charles Probst says to start by turning the throttle valve stop screw out until there is clearance. Then, place a piece of paper between the screw end and the throttle lever and tighten the screw until it contacts the paper. Remove the paper and tighten an additional ½ turn. From this point on, you use the idle air by-pass screw to adjust the idle. My problem is that if I do this, the idle air by-pass screw is backed out about 4 turns in-order to get 1000 RPM. If I leave it this way, every time I back off the throttle while driving, and put in the clutch to slow down, the idle stays high for way to long before coming back down to 1000 rpm. If I re-adjust the air by-pass all the way in and set the idle to 900 rpm using the throttle screw, then adjust the air by-pass for the additional 100 rpm, The car seems to run fine. The idle comes down like you would expect. Is this the proper way to adjust the idle or could there be something else wrong? I have been checking for vacuum leaks until I am blue in the face and found none. Also, I am checking the A/F ratio at the tail pipe. I am seeing 14.1:1 AFTER the Hyper-Flow CATS. Anybody have experience with AFR? Any help would be appreciated. Jeff
AFAIK, this is the recommended (and easier) method, but 900 RPM seems too high for the air bypass screw fully-closed condition. On a KE-Jet TR, the target RPM with the air bypass screw fully closed is 700 RPM, and I'm having a very vague recollection that someone once posted it's 450 RPM for a 308 K-Jet -- but someone please post the WSM spec for one of the K-Jet F. What RPM do you have when you've done the Probst mechanical twiddling of the throttle plate and have the air bypass screw fully closed? PS A post-cat AFR measurement with a running air injection pump won't really be meaningful -- you really need to make the AFR measurement before the cat and without air injection.
This may be a long shot... but there is a rubber gasket in the throttle bypass screw, and over time it cracks and lets in more air.... you may want to check that... mine did that a long time ago and the ilde was hi all the time... very annoying ... especially in a parking garage... way too loud. the other thing may be the coolant sensor on your catch tank... may be bad.. its a $10 part, and very easy to replace.... it sends a signal to the FI to lean out the mixture... hope this helps.
Someone had plugged the vacum line to the digiplexes on my car when I first bought it . . . thing is it wasn't completely plugged so the vacum signal was delayed going to the box . . . .symptoms were kinda like what you're describing. Good luck! Sean
On the right side of the engine, there is the Aux Air Valve and a Cold start air valve. They both tie into the manifold. It appears that vacuum is supplied by the manifold through both valves and then ties into the fuel distributor. I think that the Aux Air Valve has given up the ghost. It looks like it is still partly open even though the engine is completely warm. I removed the entire system and plugged off the manifold and distributor. I have to sit in the car and hold the rpm at 1000 RPM until she warms up, but after that, everything runs great. So it looks like I have to replace the AAV. Bosch Part Numbers are 0280 140 129. Anybody have a source for this.
