I've noticed a slight miss when sitting at idle. Its not a steady thing, but rather sort of sporadic. I first noticed it as something like a little bump, I felt it through the seat because it seems to torque things a bit when it happens. I've also noticed that the RPM's wobble by about 100 or so when it happens. I've noticed it in drive and in park, with and without A/C, and always while I'm stopped. Under power, everything is fine.

I've done some reading and have started troubleshooting. Throttle body seems clean, PCV valve works fine. I didn't feel like getting in to checking spark plugs tonight. I've read where people have tested their coil packs, but how exactly do you do that? Any other ideas?

 

Try opening the butterfly on the throttle body up and looking inside of the intake plenum itself to see what sort of shape it's in and I'd suggest taking a look at the plug wires as well.

 

Yeah, plugs and plug wires will be a job for this weekend.

 

Check the resistance in the coil packs and see what the specs are. I've not done it myself on my Toy, but I'm sure its the same principle as GM. You diconnect the plug wire and put the ground side into one terminal and the positive on the next terminal.

 

Anyone know what the specs should be?

 

That definately sounds like an ignition problem.

If you haven't changed your plugs in a while I would do that first and also look at the boot on the coils (I have seen some where they begin to arc around the boot causing a misfire). You can clean the throttle body but that shouldn't cause the blip in idle you are talking about.

Here is a good thread to follow (be sure to also check out the links throughout):
https://www.yotatech.com/forums/f2/help-hunting-idle-1997-4-runner-3-4-liter-54059/
https://www.yotatech.com/forums/f2/1996-4runner-v6-check-engine-light-misfire-31969/

It could be quite a few things: Plugs, wires, coil packs, MAF, TPS, IAC valve
Simple Haynes manual will have resistance values for the wires, coils and sensors.

 

Plugs have gone about 50K since I've changed them. At the same time I put on Magnecor wires. I should have my old ones around somewhere, maybe tonight I'll swap them and see if it goes away. Otherwise I'll probably change plugs this weekend.

 

Good idea about the wire swap. Also, if you do the plugs, be sure to buy one of these (see below) and gap them right. I don't care what anyone says, the OEM plug gap needs to be checked and often adjusted, even if they come from the dealer who says "they are pre-gapped."

This tool makes it easy. Autozone had them for about $3. They are a must for these type of plugs.

 

Well I did pull the coils tonight and tested them, primary and secondary resistances were all within spec. Plugs and wires on that side looked good too. I can't find my old set of wires, not sure what happened to them but I thought I had them when we moved. Oh well.

For whatever reason, I couldn't get the plug wires off of the driver side. They are really on there. I'll have to fight with them tomorrow I guess, I had enough for tonight.

 

No OBD II codes either.

 

tom,

sounds like the prob i had when one of my plugs (just ONE) was not pre-gapped correctly.

bob

 

I remember that Bob. I will have to check that tomorrow or this weekend, or as soon as I can get those stubborn plug wires off!

I've been looking for threads on testing/cleaning the TPS and IAC too.