1987 16V Turbo idling problem

Did you set the idle after cleaning the TB? What often happens is a car starts idling poorly because of a crudded up TB, so someone adjusts the idle to compensate. You come along and clean the TB, car idles too fast.

thanks for the reply Grunff. No, I didn't reset the idle. Not sure how to and the Haynes book of lies I have isn't very clear on how to do so. Can you help?

Cheers

Mike

Look at the lever (pulled by the throttle cable) whick opens and closes the throttle butterfly. Open and close it - you will see that there is a little screw which stops it from closing all the way. That's the screw to adjust.

You slack off the locking nut around the screw, and unscrew it by say 1/4 turn at a time (with engine running).

Thanks - all sorted and idling nicely now!

Just out of interest, what's the other adjustable item to the right of the throttle lever? It's also got a locknut on it, and needs undoing with a 10mm spanner? It seemed to adjust the idle speed as well, but not by as much. I fiddled with this first! But I marked it before I fiddled and put it back before I reset the idling speed.

Cheers

Mike

Good.

Do you mean the dashpot? About 40mm diameter, looks like a flying saucer?

No, it looks like a 10mm bolt coming out of the TB. It's near the top of the TB . Further back than the idle screw -ie the "other side" of the butterfly spindle.

If that makes no sense, blame beer, rugby and rallying. sorry :-)

Mike

The bolt is perpendicular to the throttle body, right?

Yes, top of TB, about 5cm in front of the cold start valve .If you have the Haynes maroon coloured manual for the 90,99 and 900 1979-87 manual, the bolt is on page 79, diagram16.18, but the manual doesn't say what it is.

Thanks

Mike

Throttle valve air bleed screw. It allows you to adjust the amount of air which bypasses the throttle plate. Discontinued on later models. You can use it to set the idle in exactly the same way as the throttle stop screw.

So as long as it's idlingOK, it doesn't matter what either the air bleed screw or throttle stop are set to?

Thanks a lot for your help

Mike

in article snipped-for-privacy@damia.uk.clara.net, Grunff at snipped-for-privacy@ixxa.com wrote on 09/11/2003 20:25:

Interesting. Is this what the AIC valve does? I'm sure I *didn't* have one of these bleed screws on my '85 though.

Paul

Ok, by the book if your TB has an air bleed valve, that's how you should adjust the idle. In the real world, it doesn't make any difference.

Yes, but the AIC does it dynamically. The air bleed screw is for setting the idle.

In article , snipped-for-privacy@ixxa.com spouted forth into alt.autos.saab...

Which managed to dismantle, clean out, and reassemble and check it springs closed properly using carb cleaner the other week, without breaking anything else.

in article snipped-for-privacy@news.cis.dfn.de, MeatballTurbo at snipped-for-privacy@bouncing-czechs.com wrote on 09/11/2003 21:17:

Unlike me - I managed to break mine while cleaning it. Replacement from Bosch was about 80 UKP. Still, it's nice to have a least one shiny new thing in the engine bay :)

Paul

I'd like to caution you guys about which screws are used to adjust idle.... You can achieve the 850-900 rpm by either means, but the CORRECT method after cleaning the plate (assuming you have changed the original setting), is to first back off the 8mm nut and turn the slotted set screw out to allow the throttle plate to completely close....then turn it back in until contact just barely starts to move the plate. Go one quarter of a turn in, and secure the 8mm locknut. This set screw not only sets the initial plate clearance, but if you do not have the very small bypass gap (i.e the actual plate NOT touching the bore of the housing), the plate will start to 'wear' a groove into the bore over a period of time. Start the car and allow it to idle, until the radiator fans cycle at least once....loosen the 10mm locknut on the 10mm bolt protruding from the throttle housing. Adjust the screw in or out to achieve the idle rpm, and lock the 10mm nut.You will only have to do this one time EVER unless the vacuum somehow changes or engine wear occurs. Over a period of time the idle will deteriorate....just clean plate and idle will fall right back to where you set it this time...Good luck.Keep 'Saabing'.

TR.

All good advice, except that the 10mm air bleed screw was in fact not present on later models. In that case the only adjustment is using the throttle plate stop.

Also worth adding is that the "correct" way of doing it involves connecting a dwell angle meter across the AIC, and adjusting the idle until you hit the correct dwell angle (can't remember what it is - 25deg?)