Idle Speed

[RangieMatt]

Hi there,

to update from my previous thread, I no longer have a problem with my coolant temperature sensor, and I appear to have solved my overfuelling / poor running issue.

I had some new brake lines fitted to the front of the car about 2 months ago, and now I think of it, it's been about since then that I've had issues. The garage mechanic obviously slipped while doing it, and sliced into the main ignition lead from the coil to the distributor cap, and rather than replacing it, has just black taped over it. I didnt notice this until last night, as the connection to the coil is also black taped, just for a bit of security, and I hadn't notice the extra, however last night when I popped the bonnet in the dark, the ignition lead was arcing over onto the brake line every few seconds and popping. I'm willing to bet this is what killed my alternator recently too, and would have caused my misfiring

Anyhow, I now need to adjust my idle speed, as it is too low, but my engine (3.9 EFI) has a metal blanking plug over the top of the adjustment screw. Does anyone have any good tips for removing this? I've tried all kinds and I cant get it to shift at all, I've tried wd-40, the lot. The Haynes manual helpfully tells me "unhook blanking plug, and adjust screw"

Sorry for the long post!

[ramon alban]

Is it possible to drill a small hole from the top, screw in a self tapping screw and pull the plug out with a pair of pliers holding the self tapper?

[RangieMatt]

I think thats going to have to be the plan, I just wondered if there was a special knack to it that I'd somehow missed.

It's the typical Haynes manual lingo "unhook plug = spend hours losing knuckle skin and swearing blind at plug"

[ChrisJC]

I thought that with the hotwire, the idle speed is computer controlled.....

Chris.

[RangieMatt]

Someone else has said that to me, but the Haynes manual for my car clearly describes a procedure for raising or lowering the idle speed. I'm going to attack it with a hammer and a screwdriver later on.

[katanaman]

3.9 idle is controlled by the ECU , There are adjustments that can be made but if the ecu thinks its right then nothing will change it. I would recommend stripping the stepper motor out and all the tubes that go with it as odds on its these that are blocked/gummed up causing your problem.

[RangieMatt]

ok, cheers for that, what's the easiest way to do this, is the stepper motor basically the same as an idle control valve.

I had a 1988 Daimler that had an idle problem, I cleaned back the throttle body, and had to go through a few steps to wind the idle valve shut, then set the idle correctly, stepper motor sounds a bit different, and without wanting to sound daft, it's not something I've done before.

any tips etc?

EDIT : I've found this in my Haynes Manual now, it's evidently very easy to remove, how should I go about cleaning it? Can I damage it in anyway

[katanaman]

Yes its an easy job and usually is gummed up. Just unbolt it along with the tube attached to it and clean it with something like kerosene or paraffin, basically any light solvent like that. Not sure but if you actually dismantle the valve you will probably have to set it all up again so the ecu knows where its at. Give the bit the tube is attached to on the plenum a clean out as well.

[RangieMatt]

Thanks for all your help with this. I now have a perfectly idling truck. I cleaned the stepper motor, and then set it up using an emmissions machine to get the fuelling right, adjusting the AFM as necessary. She runs better than ever now, thanks a lot for your input once again.

[Coops]

glad the forum has come to your aid mate,