they look fine, just tired and worn out, what did you replace them with?
my experience with MPG issues tends to center around the O2 sensors, engine temp too low, fancy multi-electrode spark plugs, and the time of year. here in New england they use oxygenated "winter" fuel from september thru april, and my MPG drops with the winter fuel.
agreed,,the electrode tip looks to be a little worn but thats just use....no colors no oil residue, no color changes from running to lean, they are pretty clean..i'd say they are in good shape and replacing them at the time you did was a good move
Awesome, I swapped them out for the double platinums. Forget which brand(NGK maybe?), but it was one of the most recommended ones for the 2000 4.0L with distributor less set-up.
Those ones have 20k on them, hoping the double platinums will last a little longer. No MPG gain from fresh plugs was noted.
I've got a real good hunch that the Bosch 02 sensor has a problem with the heater. The colder it gets, the worse the mileage is, and I am getting a lot of white smoke coming out of the exhaust during the winter. More than any other vehicle I see. Not loosing coolant and it has no smell.
I think the 02 sensor is at fault, going to drop in a NTK one pretty soon.
those electrodes are not worn. the ap985 platinum plug comes with those two step electrode tips. not the flat electrode tips that regular plugs come with. in all honesty those plugs do not look bad at all.
those electrodes are not worn. the ap985 platinum plug comes with those two step electrode tips. not the flat electrode tips that regular plugs come with. in all honesty those plugs do not look bad at all.
I agree, those plugs look barely used, but there is a huge variation in spark gaps between them!!!! Look at #6 and #4, the widest variation is between those two.
Did you gap the new plugs to .035?
Check for 12 volts at the wire to the O2 heater before you toss money at new parts. Also check to see if the T-stat is stuck open and slowing down warm up time!
I agree, those plugs look barely used, but there is a huge variation in spark gaps between them!!!! Look at #6 and #4, the widest variation is between those two.
Did you gap the new plugs to .035?
Check for 12 volts at the wire to the O2 heater before you toss money at new parts. Also check to see if the T-stat is stuck open and slowing down warm up time!
Good eye there, yes the gaps had huge variation. From barely gaped to over gaped. My dad put these plugs in originally. When I confronted him about the gaps, he basically said "I don't know". :laugh:
It ran fine for years anyways, and the new ones that I put in myself are gaped to .035".
I've got to get a meter to test voltage still....hoping to get paid soon.
Awesome, I swapped them out for the double platinums. Forget which brand(NGK maybe?), but it was one of the most recommended ones for the 2000 4.0L with distributor less set-up.
I thought the NGK ZFR5N copper plugs were the ones recommended for the 2000+ 4.0s, not double platinums. :dunno:
I've seen issues with people running Bosch O2 sensors in newer model Cherokees. Renix models came from the factory with Bosch but newer Cherokees came with NTK sensors. I replaced all 4 of mine (Cali emissions) with NTK sensors when I did the manifold cats and so far they are working great. You can get them fairly inexpensively from RockAuto.
Has anyone tried the "V-Power NGK 3459 spark plugs" used on the late model HO XJs (99-01), on the 87-90 Renix 4.0s?
The plug reach of the NGK FR5-(7373) (Renix) and the ZFR5N (3459)(99-01 HO) is very different and worries me just looking at them, but Cruiser54 says the ZFR5N works even better in his recent tests the last 2 or so years? The 3459 looks like a much hotter plug style?
