3vze random misfire?

9

91'4bee

New member
Ok so I am baffled here. At 1400-1500 RPM there is a random misfire note out of the exhaust but not anywhere else in the rev range. This has been happening for a while now and so I thought I would come here. I have heard (and worked on)cars with dead cylinder misfiring but it wasn't like this or as subtle. What else shows symptoms of engine misfire besides exhaust note?

I have tried taking off individual spark plug wires but after getting shocked multiple times(distributor is really good!:jump:) trying to put the first one back on I dont really wanna try that method again. But hey at least I know #1 cylinder is not the problem:)

Spark plugs haven't been changed in a while but I think I have only put 20k miles on it since. The car doesnt shake and as far as I know there isnt a power loss(its my daily but I drive slower than my grandma). Gas mileage is pretty consistent 16-17 in the city but I just filled up so I will find out soon again.

This video is not the best quality(in fact it is really bad...stupid phone) But the sound comes through...kinda. I kept the RPMs below 2k mainly because any higher and the sound wont come through. It might not even help.

141008 0000 - YouTube
I also want to know (if possible) if I am misfiring at idle

Thank you for taking the time and any suggestions are greatly appreciated.
 
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Got new spark plugs but have yet to put them in. I am a little reluctant to put them in because I know that there can be problems and since this is my only car and daily driver I cant afford to have it go down. Also #5 cylinder is gonna be a PITA. At the time I didn't realize it but when I installed my headers the AS system couldn't bolt back to the block so I just left it floating/resting where it stays. It doesn't move and no leaks but it blocks getting to the #5 cylinder and I cant move the AS valve because I put it on before headers went in place and now everything is welded...(I am an idiot) So I gotta figure out how to do that.

Some new info...
the distributor cap and rotor have been changed a while ago. However the wires are the original yazaki 1990 date stamped wires. I am gonna test them but if they are good no reason to throw away good wires no matter how old.

Again any suggestions greatly appreciated
 
Make sure that when putting the new ones in they are gapped just check. And that you start the plugs by hand and just use the ratchet to finish it
 
Ok so...the new plugs are in and all the wires tested good(man these things are awesome 23yrs old and still workin!). Took her around the block to warm her up and...no more random misfire at 1500RPM!!

The old plugs were coated in white and some had a little build up but none were wet so they were all still working. Time will tell if this did the trick.

However when I hold the RPMs at the 1400-1500 range the revs fluctuate a little(but no misfiring) anywhere else I held the RPMs it didnt do that so anybody experience this before?

Thanks for taking the time.
 
KidVermicious said:
Check your TPS. I bet you've got a funky spot right there.
Click to expand...

I can test it or do the trick thing(unplugging it and seeing if Idle gets better) but since the throttle has to be open in a certain spot how would I know its bad there? Cause The FSM just says to test it with a multimeter...
 
Seems like I post this every day. :)

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Your TPS has a spring inside it, the resistance of the spring changes the tighter or looser it gets, which happens as you step on the throttle. If the spring is worn out it can touch itself at certain points between idle and WOT, shorting out and causing a funky reading to be sent to the ECU, which might dump or inhibit fuel at that particular throttle point depending on what it's seeing.
 
KidVermicious said:
Seems like I post this every day. :)
Click to expand...

Its cause you do:)...but that just means your an expert (no sarcasm!).
edit--The fluctuation only happens when the engine not under load

I can buy a new one and slap it on and see if it changes anything...as far as I know its the original one too so hope the screws aren't stuck.(I did one on a ford exploder and I had to tap them to get them out...such a pain!)
 
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^^Will do Kid...


Ok so I have a new array of problems I think...
1. hard to start when cold (longer to start than before)
2. I may have opened Pandoras box...the wires might be bad(maybe bad testing) but I am now random misfiring at idle(barely but I defiantly heard it!) So far it runs just fine(I think) but at idle(the misfire I heard) and the revving not under load at 1500 RPMs, still fluctuates.

So the to do list when I can...
1. test TPS and possible replace
2. New spark plug wires(The ones I have now are 23yrs old, they tested good but I might have done it wrong)

So question...What wires are best to go with? OEM(YAZAKI-- from the stealership) or OEM "style" from O riles?
 
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ltsr said:
What brand and type of spark plugs are you using?
Click to expand...

They are NGK platinum(The ones I pulled out were densos). Had to gap all of them to .31in but some might have been within+or- .02in, I couldn't get some of them just right, but I don't think that would cause these extra problems. Would it?


KidVermicious said:
I liked NGK wires on my 22RE. I've seen 3.0 guys use them with good results too.
Click to expand...

They look good in the pictures and I like the blue color! But I will see how much the ones from the dealership cost just for comparison (obviously they will be more expensive...but for fitment and longevity purposes)


I do want to add that I have mildly advanced my ignition timing(been that way for about a year now) for my tuning purposes but that wouldn't cause misfire would it? It didn't do this before new plugs with the tune so...
 
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Yes. We see it all the time at work. Customer comes in says he just put plugs in mis cleared up for a week or so and then it came back pull the plugs and they are often just black. The only time they work is when the engine is designed for it.
 
541joseph said:
Yes. We see it all the time at work. Customer comes in says he just put plugs in mis cleared up for a week or so and then it came back pull the plugs and they are often just black. The only time they work is when the engine is designed for it.
Click to expand...

Dang...I was really hoping I wouldn't have to do these again for a while. My hands are still cut up from Saturday. Can I return the platinums even though they have been used or no? Can I use the NGK copper core or whatever the NGK oem plug style? I dont think they sell v-powers at the o reillys next to my house(not in their computer when I looked). I can ask though...
 
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