1990 Hardbody Pickup - Rough Idle

[Robert]

2.4L KA24E

Extremely rough idle (shaking, stalls when cold) but smooths out with
higher RPMs, but occasional misses.

Changed fuel filter, plugs and wires. Distributor cap contacts are
worn (will replace that plus the rotor).

Added iso-heet in case it was water in the tank. I use only Chevron
fuel, but also added a few bottles of fuel injector cleaner. Went
through another tank of fuel. No change.

For what it's worth, the ECCS computer reports no problems (I had to
take out the seat to get to it!)

EGR valve diaphragm moves easily, but I'm not sure if it is being
actuated though. I have not tested the solenoid controlling it. Can
I connect straight battery power to test it?

AIV valve WAS stuck - freed the plunger and reassembled...I heard
movement using a simple vacuum bulb after I put it back together. I
did not try hooking battery power to the controlling solenoid, instead
I hooked my DCV multimeter to the connector leads and only got about
1V. Should this be at 12V? Can I test the solenoid using straight
battery power? I really have no idea if a malfunctioning AIV would
cause this problem or not.

With so many possibilities, I'm just wondering where I should attack
next.

Any help is appreciated.

Robert

[reddave1999]

ya know the dealer techs would just start replacing parts. by the way have you
checked the timing?

[Al]

Timing is controlled by the ECCS computer on this one.

david...@cs.comnospam (reddave1999) wrote in
news:20031118220716...@mb-m23.news.cs.com:

[Robert]

Well, the problem has disappeared.

After I "unstuck" the AIV valve, I had tried just starting it up and
running it in the driveway, and the problem persisted. Tonight I took
it out on the freeway for about 30 minutes. I revved it pretty good
in a few stretches and by the time I exited to turn around, it was
idling nice and smooth.

I'm glad it's working again, but I have a feeling this problem will
return sometime. I wish I knew what it was. Hopefully I'll be on to
a new truck by that time....

[Andrew]

dl....@comcast.net (Robert) wrote:

Possibly a bad fuel injector?

Try pulling a plug lead while it's idling roughly and see if it gets
worse. If it gets worse, plug it back in and move to the next plug.
If it doesn't get worse for one of the plugs, that may be the bad
injector, or it could indicate another problem related to that
cylinder.

It worked for me in a similar situation.

Andrew
and...@hotmail.com

[N Todd Sides]

Not neccisarily... you can still position the distributor manually.... He
can retard or advance it easily with one screw..
Todd
"Al" <noe...@noemail.com> wrote in message
news:Xns9437C72...@216.148.227.77...