Op.Temp.-temp: & 2ndry throttle

[Chas54]

I am still looking for my occasional engine revs dropping to near stall when pulling up or stopping at junctions etc.
I am about to take my plenum off again to check out the secondary throttle reservoir, solenoid and servo. Ive noticed the manifold vacuum shows a slight increase in pressure (absolute) that corresponds to my ignition timing advancing significantly. I was looking through Elanscan data for the energising signal to the solenoid at 4700 revs as the engine speed drops. I do think the vacuum loss appears at this point and so I am suspecting the solenoid vent to air may pass. I was wondering if anyone could tell me what the point is I should be looking for on Elan scan , and also , what is the reading Op.Temp.-temp: ? Mine goes from 0 to 3 at the same time my vacuum decreases and my ignition wanders around. All comments welcome.

Regards

charlie

[Simon_P]

Stalling when coasting to a stop is most likley a vac leak and the ECU not being reset. Check for vac leaks and reset the ECU.

Ignition timing is used to control the idle - you can ignore it as a cause.

[Chas54]

Thanks Simon.
I didn't realise the ignition timing was used to control the idle speed . Although I did realise that the MAP does enter the timing adjusting logic. Its sounds an odd way to control idling to me . .. I am still looking for vacuum leaks and have today received my plenum gasket so I am still considering the secondary throttle . I have a little hand Vac pump and the two areas I cant pull a vacuum on the pipeworks are the secondary throttle and the heating and vent control pipeworks.. Both seem open to air when testing from the plenum connections. I can easily plug the heating control pipework to remove that vac loss in the short term . The secondary throttle though is both essential and virtually unreachable. Having read the section in the manual on the secondary throttle, my initial test with the engine stopped and ignition off, would have the solenoid de-energised . This should have the actuator side of the solenoid vented, but I would expect the vacuum inlet to the solenoid to still be a closed pipework, mine , I cant pull a vacuum on so I think either the solenoid or the reservoir( or pipe work) is leaking. Once I have the plenum off, I am hoping to be able to disconnect the pipeworks from the reservoir and the solenoid inlet and outlet for testing the individual components.
I wish I had looked a bit closer last winter when I had the injectors out for clean and test.
Incidentally, I have looked at a few other peoples Elanscan data sets on LEC ,and have noticed a trend to have the hot engine idling faster than the 950 rpm book figure. Do you know if this is something people intentionally are doing?. It could be it gets round the stall problem albeit by hiding the issue.

Regards Charlie

[Chas54]

I may well have found the problem.
A self inflicted wound really.
I had the plenum and fuel rail off last winter and I did replace the clips on the vacuum hoses to the secondary throttle, but either the tubing was either already on the wrong connections or I mixed them up.

I have the solenoid on the bench now and can identify which connection would dump the actuator air, and which should remain under vacuum. The solenoid works perfectly and when the tube is on the correct connection, I can pull a vacuum through the reservoir and tubing back to the plenum.
With the solenoid pipes confused there would be a vacuum loss through the actuator vent when the solenoid was de energised but it would seal and provide a vacuum for the actuator when energised.


I bet somewhere on this forum somebody has already highlighted the importance of not mixing the tubes up.

I may change the oil filter while I can see it.

Regards
Charlie