Topic: Spark Plug Looks Bad

[GBJeep]

I have been having a problem lately with my Jeep stumbling on the highway between 1800-3500 RPM.  I would be going say 55 and give it some gas to speed up and it will stumble on me and lose power.

40k and 2 years ago I changed my cap, rotor, plugs and wires.  I went with Bosch Platinum +2 plugs.  In trying to fix this I took a look at the plugs and they look bad.  Very burnt with some crusty build up on them.  Only #4 had a little oil on the threads but nothing bad.  I do know I have a faulty O2 sensor that is getting replaced today (along with fixing a broken exhaust manifold stud).  What do you think about these?

**(first time posting pics, if they dont work the link on the bottom should)**



http://picasaweb.google.com/111221152534234309517/Desktop?authkey=Gv1sRgCJbi_uHRiM3ePw&feat=directlink

[sharpxmen]

I have been having a problem lately with my Jeep stumbling on the highway between 1800-3500 RPM.  I would be going say 55 and give it some gas to speed up and it will stumble on me and lose power.

40k and 2 years ago I changed my cap, rotor, plugs and wires.  I went with Bosch Platinum +2 plugs.  In trying to fix this I took a look at the plugs and they look bad.  Very burnt with some crusty build up on them.  Only #4 had a little oil on the threads but nothing bad.  I do know I have a faulty O2 sensor that is getting replaced today (along with fixing a broken exhaust manifold stud).  What do you think about these?

**(first time posting pics, if they dont work the link on the bottom should)**



http://picasaweb.google.com/111221152534234309517/Desktop?authkey=Gv1sRgCJbi_uHRiM3ePw&feat=directlink

color is good and i would say maybe a bit on the lean side (but that could be related to your O2 sensor). Replace that dist cap and wires and while you're at it replace the rotor as well - looks like you had bad connection between the wires and prongs. I would stick with the recommended spark plugs and nothing fancy.

[GBJeep]

color is good and i would say maybe a bit on the lean side (but that could be related to your O2 sensor). Replace that dist cap and wires and while you're at it replace the rotor as well - looks like you had bad connection between the wires and prongs. I would stick with the recommended spark plugs and nothing fancy.

Thanks for that.  I replaced the cap and rotor last night.  I was waiting to hear on the plugs til today.  I will change those tonight, and wires, when I get it back from the exhaust shop (they are changing the 02 sensors also). 

So standard plugs and .035 gap then, and I should be fine.

[Jeffy]

IIRC, stock are Champions but I've been using Auto Lites.  I agree with Sharp.

[sharpxmen]

IIRC, stock are Champions but I've been using Auto Lites.  I agree with Sharp.

i've had the best luck with NGK, but any of the good brands equivalent to stock will do.

[GBJeep]

Cool, thanks for all the input.  I got the 02 changed and other exhaust work done.  I bought the Bosch Platinum plugs (2.99 compared to 1.99 for the autolite, although the are proly made next to each other with a different name on them).

What does changing the gap to .045 do?  I understand the longer arc part which I assume would make it burn more fuel, but if I was running the +2 plugs and was running lean would that make much of a difference? 

I'm thinking I will leave them at .035 now and see how that goes with the new 02 sensor.

I hope this fixes the stumbling problem I had.  I will let you all know how it works.

[sharpxmen]

Cool, thanks for all the input.  I got the 02 changed and other exhaust work done.  I bought the Bosch Platinum plugs (2.99 compared to 1.99 for the autolite, although the are proly made next to each other with a different name on them).

What does changing the gap to .045 do?  I understand the longer arc part which I assume would make it burn more fuel, but if I was running the +2 plugs and was running lean would that make much of a difference? 

I'm thinking I will leave them at .035 now and see how that goes with the new 02 sensor.

I hope this fixes the stumbling problem I had.  I will let you all know how it works.

is not going to burn more fuel, the fuel burns progressively in the chamber, that's why you have ignition advance - the spark ignites the air/fuel mix and the rest is a controlled burn. With stock ignition just stick with the stock gap - if you go more than recommended you might have problems with misfires.

[linewrench]

number one and four cylinder has always ran lean on mine, to the point were my plugs foul out about every three months. I have tried just about everything to correct it but still lean. i have had better luck with the ngk v power then  the auto lite platnium that im using now. prolly in the up coming weeks i will also change the o2 sensor. as far as gap i have ran a .35 .45 and now im using a .50 and the only difference that i can tell is a bit smother idle and it seems it has more power in the high end.....but nothing to jump for joy over.

[sharpxmen]

number one and four cylinder has always ran lean on mine, to the point were my plugs foul out about every three months. I have tried just about everything to correct it but still lean. i have had better luck with the ngk v power then  the auto lite platnium that im using now. prolly in the up coming weeks i will also change the o2 sensor. as far as gap i have ran a .35 .45 and now im using a .50 and the only difference that i can tell is a bit smother idle and it seems it has more power in the high end.....but nothing to jump for joy over.

did you try replacing the injectors? if those cylinders are lean i cannot see any other reason for it (given that the other 2 are fine).

[Torch_Ind]

i've had the best luck with NGK, but any of the good brands equivalent to stock will do.

+ 1 for NGK's and also stay away from those mufti tabbed spark plugs like that. I have used them my self as well and they never seem to work properly. keep it simple!!

if you really want a better spark plug go platinum or something but with single conductor

[linewrench]

did you try replacing the injectors? if those cylinders are lean i cannot see any other reason for it (given that the other 2 are fine).

it has the tbi set up... i have ran in to the same problem on carburated six cylinders.... if the engine is slightly lean the cylinders farthest from the carb/tbi will be lean while the ones in the middle will be just fine....cylinder 2 and 3 are a beautiful redish brown shade..while one and four are lean enough to foul out lol .... and i thought it was the injector/ tbi set up so i cleaned it all up and replaced the o rings and screen on the injector....made it run better but still lean....

[sharpxmen]

it has the tbi set up... i have ran in to the same problem on carburated six cylinders.... if the engine is slightly lean the cylinders farthest from the carb/tbi will be lean while the ones in the middle will be just fine....cylinder 2 and 3 are a beautiful redish brown shade..while one and four are lean enough to foul out lol .... and i thought it was the injector/ tbi set up so i cleaned it all up and replaced the o rings and screen on the injector....made it run better but still lean....

got it - yeah, tough to fix that

[chardrc]

you could try upping the fuel pressure a bit if it is running a bit lean. although it would only make a difference under wot or closed loop whatever you call it. and from what soemone said on hear adjusting the fuel pressure regulator on the TBI isn't as easy as the FSM says it is. something about the access plug filled with pot metal that wont come out so you have to drill it out and make a new plug...

[sharpxmen]

you could try upping the fuel pressure a bit if it is running a bit lean. although it would only make a difference under wot or closed loop whatever you call it. and from what soemone said on hear adjusting the fuel pressure regulator on the TBI isn't as easy as the FSM says it is. something about the access plug filled with pot metal that wont come out so you have to drill it out and make a new plug...

wot=open loop,

closed loop is when is using the o2 feedback

i thought of suggesting the same but didn't say it for the same reason - closed loop won't make a difference, and that's where you spend most of the time.