Bob_98SR5

Guys,

I changed my spark plugs and wires today. Took and hour 1/2. The 1/2 was to document everything as usual.

I used genuine Toyota spark plugs and wires. I also used dielectric grease on the boots and anti-seize on the spark plug threads. Oh by the way, I did some research on dielectric grease: it is not conductive but rather, it is used on spark plug boots to seal the plugs from moisture as well as allowing the boots to have a "barrier" to allow the boots to be pulled off easily.

Anyways, it drives much better. Better pickup. However at idle, there is an occassional, sporadic "pulse". It is not rhythmic, but sporadic. I feel the "pulse" in my hand while I have it on the gear shifter (5 speed). It's not a huge pulse that reverberates throughtout the vehicle, but in the gear shifter.

My guess is that maybe I didn't seat one of the plugs all the way? Or maybe a few? I'll check to see if I seated the spark plug boots all the way down later this evening when it cools down, but anyone with advice on what the cause is and how to fix it would be greatly appreciated.

Thanks,
Bob

Addition: Toyota 98 3.4L spark plug # is 90919-01192 (K16TR11)

AgRunner06

That really sucks Bob.

Is this "pulse" that you are talking about a miss? Can you see the motor shaking when it "pulses"? If it is missing you should also be able to hear it coming out of the exhaust pipe. It will sound like a puff of air. You will know what I'm talking about once you hear it.

The only suggestions that I can make to fix it would be to:

1. Make sure that all your wires are properly connected. Be sure that you hear/feel the snap when you push the wire onto the plug. Sometimes it can be kind of hard to push it on there. (this is probably the problem)
2. Check for any arching out of the wires. (I wouldn't think Toyota parts would be defective but you never know.)
3. Those plugs should be pre-gapped but if you still haven't found the problem I would suggest pulling the plugs and checking the gap.

That's about all I can think of. Good luck finding the problem.

PhxTRDRunner

Any chance the computer has to re learn the ignition timing now that it runs so much better? Try resetting the ecu.??

89-4run

Man, sometimes I wish I would take the time to understand cars/trucks :\ I read all these threads a feel completely helpless :cry:

On the other hand, did you get the memo Bob? The TPS memo? If not I can send it again

Bob_98SR5

Phx and AG,

I'll try what Phx said and then try to re-seat all the boots. If that does'nt work, I'll pull one at a time and check. If that doesn't work, I'm gonna have to check each plug like AG suggested. Don't wanna but I gotta do waht I gotta do. Errghh...I wish this would've just gone smoothly like the other mods.

Bob

Cebby

Did you gap the plugs or were they multiple electrode?

kwando

This might not help, but i had this same problem with my 86. It doesn't happen when it's cold, once it warms up it starts to miss. You can definatley hear it in the exhaust note.

Here is what fixed it on my car. I did the normal spark plugs, distributor, wires, PCV, etc. That did do the trick.

I read a post on here about cleaning the throttle body. Did it one afternoon (without removing the TB) and it didn't help much. I noticed a slight improvement, but it was still there.

I decided to take the entire TB off and clean it. Along with the TPS. You will be in for a surprise once you see how much crap builds up in there. After cleaning it completely, it's smooth now.

There is still a slight (you wouldn't even notice it) slutter. WHen i had the TB off i noticed a layer of grime in the intake manifold also. So when i have some more time I will take the entire manifold off and clean it again. It would be a good idea to change the dreaded fuel filter also.

Hope this helps.

Bob_98SR5

Cebby and Kwando,

I didn't check the plugs w/ the feeler gauge. I talked w/ the service and parts guys at partznet and they said that they come pre-gapped. If worse comes to worse, I will have to.

Kwando: Yes, I noticed that the TB was pretty dirty. In fact, I opened up the butterfly valve and ran a clean cloth through it. It came out black. I thought about cleaning it but I didn't have enough time today. I think it'll have to wait until I get back from my biz trip in late September.

I listened to the exhaust note and you can here a sporadic "skip" like AG said. Its not a big hiccup, but enough to know exactly what AG was saying.

I'll check/replace the other items. Hopefully that will help too.

Also, what's a TPS?

Bob

AgRunner06

Throttle Position Sensor

I wouldn't mess with the TPS. First because this problem started after replacing the plugs and wires. Second because (at least for the 2nd gens) you need a feeler gauge and ohm meter to reset it after you take it off.

Also, did you by any chance get any anti-seize on the washer on the plugs? I was thinking that might give it a bad ground.

If you still can't get the miss to go away you should probably have your timing checked. I've done a tune-up before and had my truck run horribly afterwards only to find out that my timing was off because of my TPS. It ran fine (except for a slight miss) before the tune-up. Afterwards it would hardly idle. I feel your pain.

It makes you wonder how doing something so easy and trivial could make your truck run worse.

Good Luck

Corey

iTrader: (1)

Bob, back when I use to do all of my plugs myself on my rigs, I never trusted the gap, even when they said they were pre-gapped, as they were way off on some of them.

I always set it myself with my gauge.

I'm willing to bet that your gap is off on them.
They can get wacked out of gap during shipping if they hit something.

Shane

He's talking about the memo concerning the TPS cover sheets... I'll make sure you get another copy.

hint: the movie your avatar is from

Bob_98SR5

hardy har har, guys. yeah, i know.

anyways, tomorrow is a new day and troubleshooting sucks.

bob

MTL_4runner

Hey Bob,

I think these 2nd gen guys are confusing you here!

First of all 3rd gens don't need to adjust the TPS (throttle position sensor) like a 2nd gen does. Second, we have dual electrode plugs which can be gapped (with some difficulty...needs a wire style feeler gage) but if you just replaced them (use the stock NGK or Nippondenso only!) they should be gapped correctly already and at least one of the electrodes should have the correct gap (I doubt this is the reason for your miss). I always threw my plugs in straight out of the box and have NEVER regapped my plugs...you have a higher chance of screwing them up than if you just leave them alone (just look for damage). I would pull the plugs one more time to make sure you did not damage them on install or that they weren't already damagaed when you installed them (look for any bent or damaged electrodes and cracked ceramics). Then check that all the wires are firmly seated (you should pull each wire and reseat it just to be sure you have good contact). You should feel a slight click or pop when the wire is seated correctly. The antiseize shouldn't affect it either unless you got it all over the plug tip....so when you pull them again make sure the plug tip is clean. I wouldn't worry about the timing because you have no distibutor to check the timing on! If I were to hazzard a guess, I agree with AgRunner06 in that I think the problem lies in the wire seating (and the wire is arcing sporadically to ground....hence the occasional miss) but you need to go through all the motions to get your truck back to 100%. Hope this helps.

PS I would also clean the throttle body because it will dramatically smooth out your idle but it won't help you solve your miss. When you do clean it make sure to open up the throttle butterfly plate, use liberal amounts of carb cleaner and an old toothrush to get as far into the intake as you can. Keep hitting it with the carb cleaner until it comes out clear. Car will be tough to start at first so hold the pedal down when cranking, then once it fires let off quickly. It will smoke like a mother$%$@# at first but then you will see the idle smooth right out.

rimpainter.com

Bob-

Make sure the plug wires are not touching. Yes, they are insulated, but they can still create a small miss if they are touching.

I would not re-gap multiple electrode plugs. The idea behind these plugs is that they last longer - that's it. There are no performance gains or any other benefit besides an increased service interval. The spark will automatically take the path of least resistance, which means it will "jump" the smallest gap out of the two.

My .02

AgRunner06

Good post MTL_4runner.

I remember now that the 3rd gens have coil packs and not a distributer. Is there no way to adjust the timing on a 3rd gen?

The other stuff is new info to me. You learn something new everyday.

Also, if by any chance you dropped any of the plugs you could have either broken the insulator or messed up the gap.

Bob_98SR5

Guys,

As you all suggested, I checked the spark plug wires first to make sure they were all seated. I started with the driver's side and I unseated them all and plugged them back in to make sure I heard/felt the "pop". I then started the engine. Still had the problem.

Then I moved to the passenger side plugs. These did not "pop" in so I thought...hmmm...that might be a problem. However, these don't pop in---they are each held down by a bolt for a better connection.

Then I removed each and every plug to check the gap. I started with the passenger side and they all looked normal. I checked the other side and sure enough, it was the frontmost spark plug (to the headlights) on the driver's side. One side was much closer to the tip than the other:



Though the pic doesn't make it look like the right side is off, it is.

Since I chucked the old plugs away in the garbage dumpster in the back, I had to do some dumpster diving. Luckily I had thrown them away in a small box which i easily recovered.

I put the best of the worst used plugs in. And viola, no more pulsing/vibration. I'm going to replace this one with a new plug, but for now, I got much to do so I'll replace them at the end of the month.

THANKS GUYS! Your advice saved me a ton of headaches.

Bob

Corey

iTrader: (1)

Hey, I was right...
I had a feeling Bob that the gap was way off.
Never trust a spark plug out of the box, my dad taught me that lesson 30 years ago.

Glad you got it fixed, and all is well.

MTL_4runner

Glad you got it fixed Bob, usually a good check with a calibrated eye right before you install the plugs will save you some headache. That plug was obviously damaged in shipping or something because the factory is very precise on their manufacturing tolerances (esp plug gap). I have changed quite a few plugs and never had a bad one but I do have a habit of giving them a quick eyeball check against one another to make sure they are at least symmetric between each other.

Back to 100%

Cebby

MTL_4runner

OK everyone gets a star on their homework!
You can all toot your own horn now....

In general though I agree with <96runner>.....multiple electrode plugs don't need gapping.
Check for damage before install peeps!