jmartins

Hi!

I planning to get my car this month and I'm planning what to do first.

Once it's running rough, I think I'll try to tune the fuel system first.

I remember that one mechanic, trying to help, did several turns at mixture screw at both sides wile I was sited at driver's seat cranking the engine.

Reading the Bosch CIS manual, I was noticed that 1/4 of turn change the mixture a lot... I was wondering what several turns will make

Is there any way to return it at initial position, or there is some initial position?

I'm thinking to use one wide band O2 sensor to troubleshoot the engine, but I'm afraid that I can't have the car running even for a few seconds.

Any advice?

Thanks

JL

The Forgotten On

Turn it back to where you think it was and see if you can get it to idle, then see if you can carefully tune it.

jpitman2

IIRC I have read somewhere here that you slowly adjust towards rich ( I thinks thats clockwise?) with the pump running until you hear the injectors start to open then back a tiny amount. Pushing the airplate a little you should hear the injectors again, then it should at least run enough the fine tune mixture.
jp 83 Euro S AT 55k

checkmate1996

get a set of CIS gauges. Can't harp on it enough. Get a baseline of all of your hot/cold/hold pressure for the fuel system. Get a wideband 02 sensor to do the FINE tuning. BTW, you don't need to turn the a/f mixture screw more than a 1 mm or so (once you are in range). Right Rich - Left Lean. Get a book on Bosch systems. Search the forum for CIS. Don't forget your cam timing, iginition timing and idle bypass valve all need to be verified/adjusted too for final tweaking/tuning. Let the adventure begin!!

BisimotoSales

I agree with checkmate1996, a wideband UEGO sensor is a well worth investment to accurately monitor air/fuel ratio at a quick glance and a perfect tool for fine tuning. Personally, I have always utilized AEM Electronics wideband UEGO with digital display gauge for accurate and consistent readings. If you are in need of one, I currently have a hand full for $159 including shipping to the Continental USA. PM us for details for shipping else where.

jmartins

Thank you guys for the advices.

I have one set of CIS test gauges and a Innovate Wide Band.

I was wondering if there is some clearance between the plate and airflow body.

jmartins

I think I found what I was looking for.

I need to adjust the vertical and longitudinal position of sensor plate and it's clearances.

This guide will help a lot to troubleshoot my car's fuel injection.

http://jimsbasementworkshop.com/CIS/...%20Spiral.html


Thanks!

JL

Dennis Wilson

The only air sensor plate adjustments on the 928 is centering of the plate in the venturi. The lever from the control piston to the plate has a set length and mounting points. Have you tried adjusting the A/F mixture as suggested by Jpitman?

Dennis

jmartins

Hi Dennis

Not yet. My car is about 300 miles in another State/City but I think I´ll get it next week, close to me.

The procedure suggested by Jpitman, will be the first thing to do, but I think my flow mixture was serviced before in a wrong way, for curious and nonsense people.

This kind of injection is very rare down here, and only a few cars was imported with CIS K-jetronic (less then 100 cars).

I´m pretty sure my air flow plate is all wrong.

This page http://jimsbasementworkshop.com/CIS/...ages68-69.html has some information on how to check the lateral and vertical adjustment.

Thank you !

JL

Dennis Wilson

The procedure Jpitman described is the only way to set the A/F mixture on a non-running CIS system. Lateral and vertical adjustments may be required on other cars (MB, Audi or VW's) but the 924 and 928 only has an adjustment to center the air metering plate. This can be confirmed by pulling the fuel distributor and checking the set up.

Dennis