misfire without cel

ShannanC

ShannanC

Member
I have a 98 limited v6 automatic. As of late it has a terrible vibration when I accelerate and the truck is in gear (smooth as silk when in park or neutral). I have recently changed all plugs with ngks, slave wires, o2 sensor (was throwing a CEL) and the fuel filter was changed around 6 months ago. One coil boot is only 1.5 years old and another one was replaced by my girlfriend's mechanic before I met her. She doesn't remember which one it was and the two older ones look quite similar in color.

Process of elimination seems to be the old spark plug boot.

But if the boot is bad and the engine is misfiring won't I get a CEL?

Thanks in advance and I'm sorry if I overlooked this while searching the forum.
 
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It can miss without setting off the CEL. Once it misses a certain amount of times in a cycle, it will turn the CEL on (but I'm not sure how many times that is - I've read 40 but I don't know if that can be confirmed or not??). If it's intermittent, the CEL may flash just while it's doing it or you may get no CEL at all. It will come on eventually if you let it go long enough though. I would check to see if there are any stored codes in the computer (often it will store the code, but still not turn the CEL on). That may help you figure out which hole is missing.
 
The only stored codes that it has (as of December) was misfire on #6 (which is a slave wire closest to the firewall I believe) and the o2 sensor. CEL went off after I changed the o2 sensor.

It's got me pretty dumbfounded. I'm thinking the stupid spark plug boot is bad but I have to figure out which one. :(
 
Along with checking for stored codes, I'd focus on #6 since that's what the code said last month. I would pull the plug and see if it's fouled or if the the gap is off, inspect the wire, and use a dab of dielectric grease in the boot when you put it back together. There are other things it could be but I would start there. #6 is the hardest of the cylinders to get to, maybe you didn't get the wire on all the way, it could be that easy.
 
ShannanC said:
The only stored codes that it has (as of December) was misfire on #6 (which is a slave wire closest to the firewall I believe) and the o2 sensor. CEL went off after I changed the o2 sensor.

It's got me pretty dumbfounded. I'm thinking the stupid spark plug boot is bad but I have to figure out which one. :(
Click to expand...

Just change all the wires, solved my misfire.
 
You can test the voltage/resistance of the injector, but you can't test if it's partially clogged without removing and inspecting it. I think you should go one thing at a time - If the wires don't take care of it, then it may be an injector, but it could be a head gasket too, or it could be a cam issue, timing issue, maybe a burnt valve or it needs to be adjusted, etc... It's always better to start with the cheapest stuff 1st. The wires won't cost you as much as the labor for a compression and/or leak-down test and not near as much as removing the intake plenum to pull the injector. The wires are good maintenance to change anyways and you've got a really good chance that will solve your problem.
 
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brian2sun said:
You can test the voltage/resistance of the injector, but you can't test if it's partially clogged without removing and inspecting it. I think you should go one thing at a time - If the wires don't take care of it, then it may be an injector, but it could be a head gasket too, or it could be a cam issue, timing issue, maybe a burnt valve or it needs to be adjusted, etc... It's always better to start with the cheapest stuff 1st. The wires won't cost you as much as the labor for a compression and/or leak-down test and not near as much as removing the intake plenum to pull the injector. The wires are good maintenance to change anyways and you've got a really good chance that will solve your problem.
Click to expand...

x2 injectors are your last bet, they are the most expensive, start with plugs, the wires, then coil packs then injectors when chasing this stuff down, from cheapest easiest to more difficult and expensive.
 
ShannanC said:
Thanks to everyone that has responded. I will post my progress as I find time to work on the truck
Click to expand...

you can thank mainly brian and the rest of us with the gay unicorn rep button under our names....it's like a heart or some other gay care bear stuff like that...
So Gay

let us know how it goes !
 
ShannanC said:
Ok...gay unicorn rep points given. Lol
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Be careful when you give the gay unicorn rep points out, my number went down, I think you may have given me negative points (as you would for a bad response).?? Not that it really matters though, I don't even know why we have them, you can only see your own point anyways, I can't see other member's. What good is that to have points if you can't see othere's scores? Or am I missing something??
 
How weird!! I made sure it said positive and even typed in "very helpful" in the comment box.

I don't think that you're missing anything. Seems like a flawed system to me. :)
 
ShannanC said:
How weird!! I made sure it said positive and even typed in "very helpful" in the comment box.

I don't think that you're missing anything. Seems like a flawed system to me. :)
Click to expand...

Could be a glitch. Oh well, I saw your comment so thank you!
 
OK i had the same thing happen on my 98 4Runner. first off is what i did was i replaced spark plugs and the wires. then it came back on and i a cylinder 4 misfire. well i asked my father about it (mechanic for Toyota for 30years) and he said we need to switch a coil so take the coil pack from the cylinder thats misfiring and switch it with one has the same wire connected to it. if the cylinder misfire changes cylinders then its the coil. if not its most likely the fuel injector. ok i work for O'Brien Toyota as a parts salesman. ive seen this alot and you could have gotten a bad coil pack new from the dealer or where ever you got it. ok first switch then like i said if it changes take the coil back to where you got it from and tell them its bad.
Good Luck getting it fixed I know its a pain but you got to what you need to.
 
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