cc260E

hello everyone.

I have messed up the adjustment screw of throttle flap stop.
Does anybody know the procedure to adjust it correctly.

Can it be done without electronic equipement?

any info is welcome.

thanks in advance

cc260E

Nobody ever had to adjust that famous stop?

bicylindrico

If I remember correctly, the switch is just that....an on/off or open/closed switch. I believe there were two circuits involved and they would alternate open and closed between the two when the throttle was at rest and off idle. With that being said and you never moving the throttle switch itself, you could adjust the plate to bring the switch back into the correct function. You should be able to confirm this with a simple DVOM and adjust accordingly. I don't remember there being a spec. for the plate adjustment as it's never supposed to be adjusted or moved. Was there a paint mark on the adj. screw? If there is no running issues after adjustment, I woudn't be too concerned.

shdoug

This is a fairly easy adjustment. The purpose of the stop adjustment is simply to prevent binding when opening the throttle. If the plate were allowed to fully close, then it would bind when opening from that position.

Simply back the screw out until the plate is fully closed. You will know because when you try to open it you will feel it break loose and open. Turn the screw in until it just barely breaks and there is no resistance felt when opening the plate from fully closed.

bicylindrico

Keep in mind the air being pulled past that throttle plate will have an effect on the "airflow sensor" portion of the fuel distributor. I would think there is more involved with the factory setting than just bind prevention of the linkage. At idle you can see the air flow plate being drawn down and effecting the fuel pressure to the injectors. The idle air circuit will do the fine tuning to achieve the correct idle speed but this adjustment may have an effect on idle quality as well. This level of movement or effect on fuel quantity is what you are adjusting when you perform a Lambda adjustment. I would assume this plate being out of adjustment may cause hard starts and intermittent stalls. I would start with shdoug's recommendation and fine tune from there until there are no problems with starts or stalls. The switch portion of the throttle plate is crucial to correct idle function, so make sure it is operating correctly.

cc260E

Hi, all, thanks for replies
bicylindrico,
I concurr with your explaination, the throttle flap controls the air quantity swallowed by engine. at idle, the ICV makes the fine tuning of the air.
I did some adjusments (stop screw and rich and lean adjust) by "trial and error".
Now when starting the engine at cold, starts after two cranks with very low idle (below 500rpms) then when temp raises idle increases slowly to 700rps.
I am sure I am very close to the correct adjustment , but I am not yet there. That is why I would like to know the procedure.

bicylindrico

Should I guess you attempted to adjust the flap for an idle problem? What prompted the adjustment screw fiddling? Do you notice a change in idle when unplugging the idle air valve? I was able to correct a few cars by cleaning out the valve with some intake cleaner but most required replacement of the valve itself. I also came across some cars with the tube from the valve to the flow sensor assy being split or very loose fitting causing a vacuum leak.

I think you really need a on/off ratio guage to correct set the Lambda correctly. If you know anyone at the local dealer or shop, you could ask to use the guage out in the parking lot maybe and then know that the mixture is correct. The idle air valve has the ability to send the RPM's pretty high so it should be doing more to bring that idle up. 500-700 is too low, especially on a cold start. Check that overvoltage relay also. Keep us updated on your progress and hopefully we can help you out.

cc260E

Yes I had idle problems some times ago, and at that time I did not know that idle was monitored by the ICV and is not adjustable (I thought it was like old cars with carburettors) and unfortunatley that prompted the adjustment.

Much later I learned more on injection cars through the forums (it is my first one).

The throttle has been cleaned (it is almost shiny) after fuel distributor has been removed, vacuum holes on throttle as well, ICV has been cleaned also.

When unplugging I notice little change in RPMs

Hoses on ICV have been changed

I have no chance to found a on/off guage.
On my car there is no Lambda sensor( no catalysator).

The manual says Idle should be 650 +/-50 Rpms at
overvoltage relay and fuel pump relay are new.

Any further info is welcome. Will keep you posted.

shdoug

The ICV (EHA; Electro-hydraulic actuator) may be defective if unplugging it does not cause a significant drop in idle. If idle is too slow when cold, and yours is, that almost assures that the EHA is not operating. The EHA controls the idle speed. It bypasses the throttle plate and that is why I say that the plate position is not that critical. The EHA will compensate somewhat for a plate out of adjustment. Even if the plate were completely closed, in my mind the EHA will still bypass enough air to allow the air sensor to control the fuel metering to the injectors.

cc260E

EHA is different from the ICV, as far as I know, it is on the side and attached to Fuel Distributor.

EHA is new. unplugging it gives also little change in the RPM at idle

shdoug

My bad, you are correct. I meant ICV. The EHA fine tunes the mixture. Concentrate on the ICV.