New Plugs = Lower Idle?

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Jul 16, 2002
I'm a new owner of a 94 TLC, with 120,000, and have a two part question. I installed Toyota plugs/wires/cap/rotor a couple days ago and now the idle is down to 400 RPM. I simply raised the idle using the adjusting nuts on the cable. Why do you think the idle lowered from 800 to 400 RPM? The old plugs did need to be replaced (big gap and worn), but the remaining components looked good. My other question is a newbie one, does your 80 series idle up to about 1500 RPM at cold start-up and eventually idle back down after several minutes? My 88 FJ-62 never did this. Thanks!

 Idle speed is not adjustable. Put the cable back where it was. The IAC(idle air control) sets the idle speed. Did you have the battery disconnected maybe? Or perhaps unplugged anything on the throttle body during your repair? It takes several ignition on-off cycles for the idle to re-set properly.
(Sometimes as many as 10 or 12)
 Cold fast idle on a 1FZFE is normal. With the cable tightened up it may take a bit longer to come down.
 Oh, BTW, Welcome to the forum.

     Regards....Dan :beer:
Thanks for the reply and yes I did disconnect the negative battery terminal.

 Easy fix. Back the cable off to where it was. Start the engine and let it warm up. Maybe go around the block or something. shut it of. re-start and idle for about 20 or 30 seconds. repeat. each time you do it you should see the idle creep up some. It'll stop somewhere around 600-650.

  Good luck with it, report back.

    Dan :beer:

Oh, forgot, if you have started it a few times already, it may be back where it needs to be and all that would be required is to re-do the cable. It may have tried to over correct if the cable was opening the throttle plate too much. It will be able to figure it out in the end.

This thread caught my eye for a similar idle reason. Most of the time my '94 (only 109K on her) idles just fine. Cold start (if you can call anything in SoCal really cold) idle at 1500 and warm she idles just fine at 600-700. Recently when I start her she idles at 400 or just under and whole truck shudders just slightly like the engine is about to stall. Last time plugs, etc. changed was around 82/85K if memory serves. Wife driving truck at the time was noticing a rough idle and did the plugs, etc. earlier than the 90K major service recommendation. That service eliminated the rough idle at the time. Wonder if this new symptom is just telling me the same thing? Frustrating thing is that there is no consistency to the low idle. Any suggetions?

Doug - Welcome!!! You have a great cruiser with your '94.
Brent & Doug,

I'll let Dan cover the specific questions. If you just want to reset your ECU so that it relearns the fuel settings, idle speed, etc, you can remove the EFI fuse under the bonnet, in the black box to the rear of the battery. Leave it out about 10 seconds then put it back in.

This doesn't affect the radio if you or the PO set the security code.

Everything was 'reset' when the starter and alternator were replaced last month. They did say things may run a little different until the system 'relearned' everything. This problem has crept up in the last week or so.

Thanks Beo. Your info is always right on and helpful.

I'm pretty excited about this 94. It's exactly what I've been looking for...white, leather, diff locks, and in excellant shape. My previous rigs were a 85 FJ60 and 88 FJ62, both awesome trucks but the 94 is luxury and incredible off road capibilities. Wife says I can't start pouring money into it until next summer :'(, thats the only way she let me buy it!
Sounds exactly like my truck. White, gray factory leather, lockers. Only thing it did not have when I bought her in '94 was a hitch and I added that myself several years ago. Enjoy!
It's possible that the IAC is binding up. Does the idle kickup when the A/C compressor engages? You may try the Wulf's suggestion of a re-set to see if it knocks things loose.

Ok - stupid question - what's an IAC? Will turn on the A/C and see what happens.

I guess you didn't read the whole thread :tear: .

That's Idle Air Control. It's the roundish Widget on the throttle body that has a motor driven plunger that varies the ammount of air bled past the throttle plate in order to vary idle speeds. The further open it is the faster the engine idles.
The ECU senses idle speed and opens or closes the IAC as required to maintain the programed idle speed.

Oh, it's Ok if you didn't read it all. Sometimes I don't do it either...... :slap:
Duh - with add'l explanation and a reread of your original post, I understand what you meant to say. :stupid: Yes, my idle does kick up a little when the A/C is turned on, so that isn't the problem.

If the low idle gets any more frequent or worse the beast stalls, I'll take here in for a little tlc for tlc(tender loving care for Toyota Landcruisers :G). She had given me some early warnings before the starter/alternator failure. Just hope this isn't another forewarning of the checkbook deflating again! Jeez, I give her a loving pat on the dash every time I ride her hard, subject her to boy scouts and put her away wet. What more could she want?

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