So we replaces all 4 02 sensors, replaced ignition coil rail, and installed new bosch platinum spark plugs. We are still having a misfire on cylinders 1,3,4 and 6. Dont know where to start and look for next possible issue. 01 wrangler 4.0. Any help appreciated.
Misfire after tune up
- Thread starter Fishingwarriors
- Start date
It feels like its running fine. No noticeable feeling. Not sure on compression. Have not done yet.
It too have a '01 4.0L and when I first purchased the jeep I replaced the NGK spark plugs with the dual platinum tips (recommended on the forum). Within a day the engine started throwing codes and receiving multiple engine misfires on all cylinders and YES... the sparkplugs were gapped properly.
I talked to a friend that has been a Jeep technician at the dealership for almost 30 years.
He looked the Jeep over and connected the factory troubleshooting console to the OBD2 port. Programmed a 200 second test window of the ignition and discovered >500 misfires in that time period. When he removed the sparkplugs.... the question asked was, " WHY the platinum tips were installed instead of the NGKs". I mentioned about the forum recommendation of the double tip platinums.
The explanation he gave to me goes like this.....
Around 2000 the Jeep Chrysler dealerships were having problems with numerous vehicles having engine misfires and the factory had determined the problem to be the sparkplugs. Replacing the sparkplugs with the NGKs resolved the problem.
The platinum sparkplugs were replaced with NGKs and the ignition test was performed again; now the misfires were down to only a few. Next step was to perform a Combustion Chamber cleaning with Mopar CC cleaner due to carbon build up in the chambers.
The misfires were gone.... so periodically (when I remember) I pour Seafoam High Mileage fuel system cleaner into the tank; this has taken care of my engines misfire problem.
There are members on this forum that swear by the platinum tips and members that swear at the platinum tips; the waste spark ignition system does not work well platinum tips in certain engines.
I talked to a friend that has been a Jeep technician at the dealership for almost 30 years.
He looked the Jeep over and connected the factory troubleshooting console to the OBD2 port. Programmed a 200 second test window of the ignition and discovered >500 misfires in that time period. When he removed the sparkplugs.... the question asked was, " WHY the platinum tips were installed instead of the NGKs". I mentioned about the forum recommendation of the double tip platinums.
The explanation he gave to me goes like this.....
Around 2000 the Jeep Chrysler dealerships were having problems with numerous vehicles having engine misfires and the factory had determined the problem to be the sparkplugs. Replacing the sparkplugs with the NGKs resolved the problem.
The platinum sparkplugs were replaced with NGKs and the ignition test was performed again; now the misfires were down to only a few. Next step was to perform a Combustion Chamber cleaning with Mopar CC cleaner due to carbon build up in the chambers.
The misfires were gone.... so periodically (when I remember) I pour Seafoam High Mileage fuel system cleaner into the tank; this has taken care of my engines misfire problem.
There are members on this forum that swear by the platinum tips and members that swear at the platinum tips; the waste spark ignition system does not work well platinum tips in certain engines.
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Your thread title is misleading. You already had a misfire and the tune up didn't fix it, is that correct?
your 2001 wrangler should use Champion spark plugs as o.e.
go to the parts store and get the correct plugs, then re-evaluate the concern.
Platinum plugs are going to cause issues in your jeep.
go to the parts store and get the correct plugs, then re-evaluate the concern.
Platinum plugs are going to cause issues in your jeep.
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If you want to run platinum tipped plugs, they will need to be the dual platinums since you have the coil rail.
Single platinums will cause issues.
Single platinums will cause issues.
There's some misinformation being passed around on this subject which is not uncommon. The wrong model platinum plugs will cause misfires in later 4.0 engines with the coil rail ignition, but the correct model of platinum plugs run perfectly well.
It's not whether they're platinum or not, it's whether the platinum coating is on both sides of the gap or not. A coil rail ignition system requires the platinum coating to be on both sides of the gap. This is due to the coil rail's extra waste spark firing in the opposite direction. These are known as "double-tipped" platinum plugs.
Only plugs with the platinum coating on just one side of the gap will cause misfires. These are commonly known as "single-tipped" platinum plugs.
Next, Bosch plugs are known to have problems in our Jeep engines. A Bosch engineer posted that it was due to their more limited range of available heat ranges as compared to other spark plug manufacturers like Champion, NGK, or Autolite. Where Jeeps are concerned, stay away from Bosch spark plugs.
Two known good double-tipped platinum spark plugs that run extremely well with the coil rail ignition system include the Autolite APP-985 and Champion 7034. Don't listen to anyone who claims they won't run well just because they're platinum... they don't know what they're talking about as those both of those two spark plugs have a great reputation among those who run them as I have. Plus those plugs typically have a 100k mile life.
Another plug with a superb reputation in the 4.0 is the Autolite XP-985 iridium tipped plug. Its life is typically expected to be 200k miles.
Again, only the wrong type of platinum plug will cause misfires and that's the single-tipped version that only has the platinum coating on one side of the gap. The right type of platinum spark plug with the platinum coating on both sides of the gap, or double-tipped, runs beautifully.
It's only those who don't truly understand spark plug technology who will claim we shouldn't run platinum tipped plugs.
It's not whether they're platinum or not, it's whether the platinum coating is on both sides of the gap or not. A coil rail ignition system requires the platinum coating to be on both sides of the gap. This is due to the coil rail's extra waste spark firing in the opposite direction. These are known as "double-tipped" platinum plugs.
Only plugs with the platinum coating on just one side of the gap will cause misfires. These are commonly known as "single-tipped" platinum plugs.
Next, Bosch plugs are known to have problems in our Jeep engines. A Bosch engineer posted that it was due to their more limited range of available heat ranges as compared to other spark plug manufacturers like Champion, NGK, or Autolite. Where Jeeps are concerned, stay away from Bosch spark plugs.
Two known good double-tipped platinum spark plugs that run extremely well with the coil rail ignition system include the Autolite APP-985 and Champion 7034. Don't listen to anyone who claims they won't run well just because they're platinum... they don't know what they're talking about as those both of those two spark plugs have a great reputation among those who run them as I have. Plus those plugs typically have a 100k mile life.
Another plug with a superb reputation in the 4.0 is the Autolite XP-985 iridium tipped plug. Its life is typically expected to be 200k miles.
Again, only the wrong type of platinum plug will cause misfires and that's the single-tipped version that only has the platinum coating on one side of the gap. The right type of platinum spark plug with the platinum coating on both sides of the gap, or double-tipped, runs beautifully.
It's only those who don't truly understand spark plug technology who will claim we shouldn't run platinum tipped plugs.
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