The dreaded idle droop

slomo · Postby **slomo** » Fri Oct 07, 2016 4:58 pm

For the last 9 months or so my na6 with bp engine had developed a nasty habit of stalling or near stalling when hot and approaching a stop sign or intersection, after going from coasting to neutral / clutch disengaged.
After researching the issue both here and at the MX5 miata forum, I found that the blue plug that pushes on the clutch switch when the clutch is engaged,
(open circuit, otherwise the switch is closed circuit when the clutch is disengaged) fixed the problem. I would never have pickup this problem up in a million years without the forums accumulated knowledge.
The fix is an 80 cent trim plug.
For those with similar symptoms, this is a great and easy place to start troubleshooting.

Noddycar · Postby **Noddycar** » Sat Jan 21, 2017 9:58 pm

I am experiencing the same issue, having twice now had the car stall as I am coming to a near stop. Just before finding your post, I replaced my ignition leads (no difference) and then my plugs. While my spark plugs looked OK (visually they looked reasonably clean, if maybe a tiny bit on the ashen side), when I changed the plugs my performance changed quite dramatically. The plug gap was way too high. Not sure if that was contributing to the poor performance of the car, but some new NGK Iridium plugs (correctly gapped out of the box) made a huge difference to output and the smoothness of the power delivery. Where there was a little hesitation when you put your foot down hard, the power just now pours on without a hiccup.
I will go hunting for the trim plug in the morning, as this may be the culprit causing my idle drop. Regardless, the new plugs have produced a great result so far! Really surprised the mechanics servicing the vehicle had not done anything with the plugs. Going over the service records, the plugs have not been changed for a very long time.

Ruffian147 · Postby **Ruffian147** » Sat Jan 21, 2017 11:24 pm

Can you expand on the trim plug slomo. Having the same problem, it was a hot day 40 degrees plus. Next day AFR gauge did was not displaying and experienced idle drop. Runs fine, heat might have damage some circuit/fuse/plug.

93_Clubman · Postby **93_Clubman** » Sun Jan 22, 2017 9:04 am

viewtopic.php?t=71780
viewtopic.php?t=60434

BlackLeaf · Postby **BlackLeaf** » Sun Jan 22, 2017 12:33 pm

Ruffian147 wrote:Can you expand on the trim plug...

As per following pic, a black carpet plug has been inserted where the blue thingy used to sit before it broke. This stopped the clicking clutch. I vaguely recall having idle droop at one point but don't recall whether it was fixed as a result of this, or whether it just stopped being an issue.

Ruffian147 · Postby **Ruffian147** » Sun Jan 22, 2017 6:27 pm

Thanks BL

slomo · Postby **slomo** » Mon Jan 23, 2017 6:21 pm

Well presented as above photos show. Definitely fixed the problem for me.
Post your result esp. if it fixes your problem.
The above plastic trim plug in photo replaces a blueish plug that seems to crumble to dust after 20+ years and is not for show....

Noddycar · Postby **Noddycar** » Mon Jan 23, 2017 6:24 pm

Are the plugs something you can pick up at a hardware store such as Bunnings?

Edit: just found something similar on the Autobarn site. Asked and (self) answered!

slomo · Postby **slomo** » Mon Jan 23, 2017 6:32 pm

Supercheap, Repco etc just needs to fill hole as in photo so switch button (white) comes in contact and is pushed in when clutch pedal is pushed in.
The original plug (blue) face thickness was about the same as in photo so the switch should not need adjustment.
The replacement is just a trim plug.