A drive cycle or two might help the ECU, might not. The coolant temp sensor would be chasing parts at this point, better to spend the cash on a diagnostic hookup and then go from there depending on what they find. You have a good IACV to work from, a base line. If you've downloaded the Rave another thing you can do is check your throttle linkage for slop and throttle cable for slack and remove it according to the book.....and of course your mechanical acumen......use common sense. You could probably lower your idle with just a linkage adjustment until you get it under the knife. I know this is your first ECU controlled vehicle that you can't crack easily.....but if there's a will, there's a way eh.

There is also a plug directly above your IACV. It has a bung that can be punched and pulled out. It's only for idle air amount (oxygen) but it gets carbon in it as well. It's basically shaped like a set screw, pointed and the point and bore can be cleaned. Count the number of rotations when removing and then reinstall the same rotations which will put it very close (close enough for hand-grenades) to get the truck to start again. It's only to be adjusted when hooked up to a diagnostic box. Very miniscule adjustment is in order so be careful when you count your rotations.

The ECU's coolant temp sensor only really controls the injectors, increasing the pulse time to allow more fuel to enter combustion until the coolant gets up to temp. Of course it keeps your idle up around 1k until that time but it acts like the old bimetalic spring choke pots to warm up the motor. Git er done....

Again, good luck, hope to hear some good news. You did lower your idle speed by 400 rpms so far without a hookup so it's looking up.

 

My linkage started acting up and go astuck a couple of times until I sperayed it really good a few times and adjusted it slightly. Mine would stick above idle and not allow it to return like it should, so take aa look at spraying yours down good...

After reading about people screwing up their IACV, I keep putting off doing anything associated with it, but mine is still running pretty good, idles right at 750, very steady, so I leave well eough alone.

 

If your OBDII reader will display live data, the engine coolant temp sensor is something that shows up. If mine is unplugged the display reads -40F, which calls for more gas. This is a common problem on some other vehicles, especially Fords. The coolant sensor is next to the thermostat on a little hill in the manifold. Square top two conductor cable. The one next to it with a single wire runs the temp gauge.

You could also read it with an ohm meter.

Same for IAT sensor, it is part of the air box, shows up on live data display, and can be read with an ohm meter.

There have been posts about adjusting the base idle and the voltages that can be monitored while doing it.

 

I've read write-ups on voltage adjustments on the 94/95 (14 CUX) models but not on the GEMS. Do you have those bookmarked SB?

 

At this point no, but I seem to recall it was an exchange bwtween an Aussie member and Spike. Not sure about the GEMS vs 94/95. Like you said, the adjustment is so sensitive that it is something I would save for last, plenty of other things to fix first. I'll hunt for it.

 

Ordinarily I would save it for last but the vintage of these vehicles, the lack of maintenance and most importantly......it's one area that I know gets overshot and overlooked when cleaning the IACV and port and it's soooo important to the idle characteristics. The caution blurb in the Rave would have most ignore it, too risky. You know me, no risk, no glory, no fun, bored to death. I'm a HALO sort of guy who enjoys a Mae West every now and again.

 

Or a Gumby suit... I did not find the adjustment voltage, did find that ptshcram usually advises against it, and certainly the TPS may be an issue.

 

And if you know PT like I do he's always going to err on the side of caution, it's his business, his reputation eh. I don't have either of those constraints. One man dynamite show and it only goes off once. He invited me to come join him once upon a time, more business than one Mohawk can handle.....I'd probably laugh too much to get any serious work done. That guy can get me to laugh out loud like no other. I laughed so hard one time I scared the heck out of my dog (chocolate lab named Bear) he just about pee'd on himself.

 

Thanks for the overall response!! Looks like I am going into full tech mode and bring in all that I have. I just got a cheap obdII reader and I will also pull my Scan gauge II off my tdi jetta to see what I can see. But that will be later on today. First play with the kids then Disco!

 

Your a good man Duckk, priorities in the right place.