Yep


Yep



It will drop to normal idle within about 6 to 8 sec or when it makes a total of about 6 or 8 fluctuations. But it will always stop fluctuating before I get stoped.



Yep



Yep



And yep

OK, I no longer think it's the vac temp switch, cuz if it was that, it would do it when you were sitting still, at idle.

I'm thinking more about the VSS (Vehicle Speed Sensor) at this point, but don't really have an answer for ya. Lemmee consult my sources (who are out of town...)

Well that would make the most sense. Maybe some wire came loose ore something. <img src="/forums/images/graemlins/confused.gif" alt="" />

I might just have to put some miles on it and see if it continues. I think I have a total of 32 miles on it now.

drove it some more.

the fluctuation stops when speed drops to 5mph or less.

This is happening when you are coasting down from speed, with foot off the gas, and clutch in, yes ?

What does it do if you leave it in gear, and coast down with foot off gas ?

Any backfiring/popping ?

Yep



no back firing or anything.

But I did play with the timing and idle control again.

When I checked it today it was idling at about 1000RPM with 12 degree BTDC.

I slowed the idle about 100 RPM down to 900RPM, and I changed the ignition timing to match. I didnÆt change either very much, but the problem has gown away. (After one run) <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

IÆll drive it again abit later and see what it dose. But I think it might have just been too high of an idle. <img src="/forums/images/graemlins/confused.gif" alt="" />

Anyway well see how it runs for a couple days.

Thanks, Troopersphere <img src="/forums/images/graemlins/cheers.gif" alt="" />

GREAT! Glad to hear it...

Sometimes the ECM can get confused I guess, sorta like me, most of the time!

Yeah, on a new engine, it just sometimes takes a little time tweakin' stuff till it runs right. The ECM is expectin' to see certain signals within a range it can deal with, and if stuff is outside that range, it can play tricks. When the timing and the idle are both off to start with, you often have to go back and forth between the two until you get it "dialed in" .

Keep us posted on how she's doin' !

Ok that was short lived.

it seams not to want to idel down now.


i'll take a look at the timming and idle setting again.

Ok I checked timing again. <img src="/forums/images/graemlins/frown.gif" alt="" />

And it running about 24 BTDC. And idle is at about 1100 RPM.

The engine is warmed up to temp, and I go through the same procedure everytime I set it.

I must be doing something wrong. I can't figure this out. <img src="/forums/images/graemlins/confused.gif" alt="" />

IÆm going to have to kill the electronic advance. I havenÆt been up to this point. But I canÆt seam to find that plug in the above pic. Any sugestions?


Question; Is the computer supposed to advance the ignition timing when youÆre setting the timing? Or another way of saying it, when IÆm supposed to set the timing to 12 BTDC is the computer already advancing the ignition?

Also what is the timing with everything functioning, everything plugged in/ connected and the engine idling? ô0ö or ô12ö degrees? And what RPM should it be idling at?

I'm not sure if you've got that EST on your rig or not. Haynes manual says that's only on V6 engines .

I must confess that I'm not real hip on the newer rigs, my experience is with the gen1 engines, I've got several shop manuals that I've been blessed to borrow and memorize... well, use on a semi-permanent basis.

What year is the truck ?

Is the ECM original to the truck ?

I seem to recall that you pulled a 2.3 and put the 2.6 in, is that right ?

From what I could tell in all yer pics, all the systems are identical to my 2.6, so these books should "tell all".

The shop manual for my truck says:

Turn off A/C.
Verify idle is 900 RPM.
Adjust timing to 12 BTDC.

That's it! No hoses to plug, nothing...
The Haynes manual says:

Basically the same thing.

Are you sure the throttle cable/body isn't sticking ?
Will it idle down if you manually push the throttle closed?