Same kinda plug as in the O2 wiring harness. It has a snapon piece/cap that looks like 2 wires should be comming out. Take the cap off and there is only one prong. I bet it's along the firewall, probaby where the main harness comes thru the firewall.



Thanks - I looked around on the firewall but perhaps I missed it - I'll look this evening again if I can get out there. If someone knows - please chime in. And thanks Dave for looking if nobody else chimes in.

One thing I did notice was that during the advance stage during warmup, as the engine got warm (nearly ready to idle down), the rpm's were going up and down (cycling). I had the timing light on it at that time and it was cycling between 20 and 5 BTDC. I'm thinking that was because, at that time, the timing was at 15* BTDC, but I don't know. I'll pay attention next time it's warming up and see if it cycles again. Especially after I find the plug to ground and get the timing right again.

Incidentally, does anyone have a source for the idlers for the serp belt? I thought I had a solution, as there were two on a Montero at the local yard, but they were both dry too. I thought I might be able to pry a seal off (I've done that in the past on Toyotas) and repack, but I can't figure out how to get into these. The bearings are good, for now, but they are dry and making quite a bit of noise. Any suggestions?

Thanks, Wayne

Pulley replacement is Goodyear 49075, IIRC, plus 5 flat washers to space it out right.

Idle problems may be a bad ICM or an out of adjustment tps. I'd readjust all that stuff, and the idle bypass screw and idle stop, and test the icm, a known problem spot. New late model icms from dsmisc.com are known to work.

You must ground the lead to time the motor correctly, and that wire has to be somewhere. I've grounded the lead at the ecu successfully, and sometimes the ground wire plug is at/near the ecu, but it's somewhere. An fsm is needed here. Since you used all original engine accessories, you have to use the stock timing and timing setting method, too.

Like Fasteddy said,
I think you said that you loosened the idle screw. If so you do have to go thru the proper proceedure for the TPS/IS and the screw. You need the right feeler gauge and an analog ohmmeter. you probably know this already...
You might have a bad conection at the ECUs water temp sender

If so you do have to go thru the proper proceedure for the TPS/IS and the screw.

No, I don't know the exact procedure...care to share it or post a link? I might have to end up doing that...

The solenoid on the idle control didn't test right for resistance, according to my book. I think it was supposed to be 28-33 ohms in four checks. Two fell in there, but the other two were way off. I'm wondering if that's the problem. I think I'm going to try to get one from the yard today (after I check it) and try that.

Oh, and I didn't mess with that throttle screw - BUT, I also don't know if someone else has done just that before me. I simply backed out the throttle "stop", or "return", or whatever you might want to call it. I didn't gain much there, though.

I'll check back in a few hours if you guys have any more suggestions...

I'd download the factory shop manual from MontyMcV's site for the 89 montero, both volumes, and the procedure is there in the fuel injection section, IIRC. Can't fix these things right without it. The surging idle sounds like a tps problem, and you have to get the idle plate set all right before you set the tps and the idle position switch (in the tps).

The isc is also part of the problem with two coils bad. Good luck in the JY for a used one, most have a failed coil or two. It's possible to take them apart and make a good one with good coils from a bad one soldered in. Replacement is $130ish for the second improved model from dsmisc.com.

Do that idle stop setting and idle speed setting to base idle (have to ground that same mystery wire for this too, I think) and adjust the tps right per the manual, then fix the isc. ISC's are notorious for going bad in these, especially if somebody sprayed tb cleaner into the tb without plugging the idle air hole in the bottom of the tb. Or, just having the coils die because they want to.

I was able to get the whole throttle body at the local pick n pull so my first step is going to be just changing the whole TB. Maybe that will work...if not, then I'll start on the TPS and solenoid, etc. By the way, thanks for the heads up for the page with all of the manuals - great deal!

I changed the throttle body and everything seems to be fine now. Cost me $5 at the local yard! Anyway, things are looking good. Got the idle set and the timing fine-tuned. Nice quiet running engine (I think it did indeed only have 65K on it). I'll try to summarize the entire process with some photos and stuff within a few days...

Now, it's on to other things - rust repair on rear frame, resealing the steering box, new shocks, install stereo, some selective use of bed liner, et.al....

Thanks everyone for the help so far...

Bringing this back from the dead:

Engine is running perfect. No noise and no smoke. I'm still working on some other things with the truck, but it's coming together.