Low Idle Issue

[Mr Blue]

As above. Throttle switch.

hold the revs just above idle by hand, press the switch in.
.revs should drop. That indicates its working.


also check the oil breather bung under the oil breather. If bad condition...can would likes its running on 3.5

[Santiago]

Yep, looking like a cheap fix.

With engine warm and idling, unplug the two-way connector from the top rear of the throttle body. Any change?

If not, now try shorting the two connections on the loom plug with a bit of wire/paperclip etc. Any change?

If there's no change with either of these actions, you need to continuity-check the wires between that loom connector and the ECU connector (pins number 6 and 11 here I think).

If the first action doesn't make any difference but the second does, you need to check the wiring from the connector on the throttle body to each of the microswitches, and make sure that the idle one (underneath) clicks when the throttle is closed.

Let me know if a photo or two would help.

[TomSan]

I shall try and give that a go, much appreciated. Isv is well cleaned out now!

If you could provide the odd pic Santiago, and it's not too much trouble, that would be great.

[Santiago]

Here you go. Two way connector location:



The contacts to try shorting together:



A visual inspection of the wiring coming to that connector may reveal the problem if you do find that neither unplugging nor shorting changes anything. If you still can't see anything, time to continuity-check up to the ECU connector.

[borax]

OK, so my ISV was not buzzing at all. So last night took it off and gave it a good clean. Started buzzing. Reconnected it all now the idle constantly goes between 850 rpm - 2000rpm11. I have disconnected ISV. I am suspecting blocked throttle body/butterfly?? Next job is to take off throttle body and give a good clean.

[Santiago]

OK, so my ISV was not buzzing at all. So last night took it off and gave it a good clean. Started buzzing. Reconnected it all now the idle constantly goes between 850 rpm - 2000rpm11. I have disconnected ISV. I am suspecting blocked throttle body/butterfly?? Next job is to take off throttle body and give a good clean.

Try what I've suggested above, in post #11, first. It's easy, it's quick, and it's free.

[borax]

So I unplugged the top connector and the engine revs to about 3000 what does this mean?

[Santiago]

So I unplugged the top connector and the engine revs to about 3000 what does this mean?

This means that your ECU is seeing the idle switch correctly I think.
Sorry, it was a waste of time for you, but not much time.

[borax]

I am new to water cooled engines, so it is all fun poking around. I did have a quick look in the throttle body and it is full of grit and oil, I will strip this down soon and see if it helps.

[TomSan]

So I unplugged the top connector and the engine revs to about 3000 what does this mean?

This means that your ECU is seeing the idle switch correctly I think.
Sorry, it was a waste of time for you, but not much time.

I did not get the same response. I got a small increase in revs after disconnecting the plug, for about a second, then they settled back down to 800 rpm. Annoyingly I searched around for ages for a paper clip - nothing suitable. I'm away for a week now so won't be able do what you said properly.

Something I did try, was turning the idle screw anti clockwise, 1 whole turn. This brought the revs up to around 875 when the engine was warm and it sounded just sweet. Also the isv stopped buzzing when the revs came up.

Really appreciate the help. I think you've got me onto a likely solution. Also just noticed I didn't follow Mr Blues suggestion properly, so I will check that again also.