Hey guys,
Had this issue the past few days.

Start the car and idle goes to 1400rpm, steady and consistent. Good!
Start to drive and when I go into neutral or clutch in ar a stop sign etc, the idle bounces from 0 back up to 1400rpm repeatedly.
Engine does not die but is probably close to it. Under load the issue seems to not be present.

After probably 4 mins of warming up the issue disappears.

Thoughts?

It's 60 degrees here in the PNW in the AM so I don't think it's the cold start valve, but what the hell do I know! Lol

1.7 d jet 1970
Thanks!!

the aux air valve is not closing smoothly enough, maybe start by lubricating the recolving door inside with some wd 40.

of course there could be several other things contributing to it, but if everything else is perfect then that is it

Thanks George, I will try that. I may have a spare as well if that doesn't work.

D jet has a lean hunt if the idle mix isn't rich enough during warm up. Your symptoms are classic.

Check pbanders website for more info. Skip to the bottom: https://members.rennlist.com/pbanders/djetfund.htm

Later cars have an idle mix adjustment knob on the ECU. If your car has the stock 70 ECU, quite unfortunately, you don't have the knob and therefore you can't directly dial in your idle mix.

Bottom of page mentions the CHT spacer which may or may not help. You can also add an inline resistor or potentiometer which might help. Very well detailed on this forum.

You should also check that your throttle position switch is properly adjusted, so the ECU "knows" when you are at idle. Probably not the whole issue but if it is set too far counterclockwise the ECU will think you are still at part throttle when at idle.

Your symptoms are classic.

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Mine would do this all the time
Fixed it with a pair of carbs

But for 40 year old system i take my hat of to djet

Usually fails but car is still driveable
Thats craftsmanship

I've got 2 aux air valves soaking in WD 40. If they fails I'll go down the CHT road. Thanks guys!

I had an extra Aux valve in a box from the PO. Soaked in WD40 all last night. Tested the ohm reading which was pretty close. Installed and did not have the issue today. Cautiously optimistic that this has solved it. I'll find out more this weekend when I can drive some more.