Re: [DML] Question about the Oxygen sensor and Bosch adjustment

[Martin Gutkowski <martin@xxxxxxxxxxxxxx>]

Stephen Jones wrote:

>I just got my car back from a shop and was told that the oxygen sensor 
>was
>disconnected because it was not needed.  To compensate the mixture 
>control
>unit was adjusted.  
>
Get your money back.

Doing this will put the Lambda system ito "limp" mode and will run rich. 
Specifically it affects the gradient of the fuelling curve (it Air to 
fuel ratio). The mixture adjustment screw adjusts the offset of the 
curve - the two are not mutually exclusive but must be balanced. Get a 
new lambda sensor in there.

If your engine stalls when you rev it then it's likely the idlespeed 
motor is not centred properly - this is quite common and the way -I- 
compensate for it is as follows. And yes I know this is not the way the 
manual tells us to do things but the manual doesn't account for 
variations in the idlespeed valve.

With the engine hot and idling, but minimum load on the alternator (no 
AC, stereo, fans, anything) back the rearmost two brass adjustment 
screws off by 2 turns each. These are the two that don't have a flat 
screw head in them. They're 11mm BTW.

Then unscrew the front one - the one with the screw head. Keep undoing 
it until the idlespeed starts to increase. When this happens, screw it 
back in until the idle returns to normal, then another 1/4 of a turn. 
Your engine will now no longer stall.

Martin





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