BPT Idle speed adjustment

[Aaron]

Not a major issue, but since we'd gotten the other anreas of underbonnet tuning sorted on the Lynx (know as Stinky) I figured today I'd get the idle speed set.

Now I suppose I could have read the workshop manual, but that sounds like hard work.

So instead I winged it based on the readings on forums and the like.

So here's what I did, what happened and my dumb question at the end.

Stinky would upon being cold started ramp the revs up to 2000rpm, then drop within a couple of seconds down to 1500rpm. Once warmed up he would idle at around the 1100 to 1200 area.

This ofcourse doesn't make for the smoothest driving experience and ain't quite right. So I grabbed a screw driver and had a go. See there's a couple of places on a BP where idle speed can be set and it would seem that stuffing about with them in the wrong order creates all sorts of havoc.
So anyways I adjusted the base idle speed using the screw under the rubber stopper on the throttle body to a nice smooth 7-800rpm. Then to check if the little idle bump function worked correctly I switched on the A/C and loaded the crap outa the electrical system. Wed didn't get any dips in the idle speed but no real lift in idle speed.

So here's the dumb question, when the A/C is switched on should the little idle bump up thingo be adjusted to lift idle speed by 1-200rpm, or should it just be used to maintain the idle speed?

I guess the other question is (and remember we don't know what's been stuffed around with in the motors past) is there any dead certain way of setting everything back to a default and doing the idle settings from scratch?

Yes I have the manual, yes I should probably go and read it - but I have a sense it may just lead me to chase my tail around in circles until someone can shed some light onto a practical experience with these things?

BTW, I do intend on doing a de-carb on it just prior to the next oil change and this will probably involve me stripping off and fully cleaning the TB and related bits and bobs as well so I'll be revisting the idle adjustment again fairly soon I suspect.

Thanks

A.

[ROB-80E]

The operation of the ISC is to MAINTAIN idle speed. It's the BAC Valve on the front on the plenum that controls you're cold start idle up...it's done by water temp.

[Aaron]

Errr yeah, that doesn't exactly answer my question does it?

We're getting a much higher idle when cold, and a normal low (700rpmish but have already covered adjusting that) idle when warm. So we know the BAC function is working. Now is it possible (or indeed should I) adjust the cold idle speed to make it say 1200rpm instead of the 1500-1700ish it is at the moment?

What I was asking was whether bumping on the A/C etc should see a rise in RPMs or a consistent idle. We are getting a consistent idle at whatever I set the speed at when warm and starting when cold or warm is no problems.

Another related question.
On the Lynx the Fuel pump runs constantly whenever the ignition is on. Shouldn't it only run when the AFM is reading airflow? I would like to revert back to what the factory did. Should I be looking for wiring changes near the AFM or at the ECU?

A.

[Cosmo Dude]

Going by experience the idle should rise when:
A/C is activated
Power steering is in use
Rear demister is on
Radiator fan turning
Headlamps in use
and a few more that I can't remember. As a rule of thumb 'If it taxes the motor then rev it up'

[ROB-80E]

Maintain idle speed means that it won't change. Pretty much answers your question to me.

No you can't change the cold idle rate, because it will then effect your hot idle rate. Your best bet is to set the idle to what you want it, when at operating temp.

The wiring for the fuel pump can be done near the ecu...but that all depends on how the fuel pump has been wired now, and whether more wires have been cut. When fordlaser.com is working propperly, search the electrical section for a post by me outlining how it should be wired up. I'm sure I've posted the link to it on here at one stage before too.

[Aaron]

Yeah, I went and looked it up in the manuals, Stable idle no matter what load etc, set when warm.

I did notice today that the cold idle bump up dropped faster and held closer to the 1400rpm mark as well. So I suspect there's some magic going on in a black box somewhere.

Thanks for the tip Rob, I'll do a search when possible. I know this is going tobe a bit of a needle in a haystack job, but worth it in the long term I think.

A.

[Aaron]

I think I have a lead on the fuel pump issue.



I suspect there's something missing here, disconnect the jumper and the fuel pump stops. Re-connect fuel pump runs

A.

[Cosmo Dude]

Originally Posted by Aaron

I suspect there's something missing here, disconnect the jumper and the fuel pump stops. Re-connect fuel pump runs

A.

It looks like it's bridging the wires to/from the transfer pump (Section B-2 of the workshop manual electrical suppliment).
I can FTP it to you or burn it to CD and post it. Give me a bell tomorrow (I can send faster from work than home) it's 60+Mb

[Aaron]

Pretty sure I've got it

Now just to sort this out. At least we know the AutoSparky 4 years ago didn't hack into the wiring elsewhere.

[ongdennis]

for my idle speed, i set it around 800-900.
it actually quite hard to get a vey perfect idle rpm.
when u set it during day time, once at night u on ur headlight n A/C u will find that it being too low.
when u set it with both light n AC is on, once u off them then the idle speed become too high....

so best thing is to get between them