So my 98 has a misfire on cylinder 6. Spark plugs were changed last year and it still is running good. I would think with a misfire I should be experiencing some rough idle or engine running rough at times. Any ideas?
Cylinder 6 misfire
- Thread starter Kevin E
- Start date
A misfire can be vague and intermittent.
I cured a cyl#3 misfire on my 97 recently due to a bare spot on the #3 fuel injector wire, arcing to ground.
One thing to try is switch #6 plug with an easy to get to spark plug, and see if the misfire duplicates.
Are any other codes thrown?
A good engine code scanner/diagnoser would really be useful.
Beautiful jeep, nice half doors !
Thanks for the reply. No other codes. I'm going g to get a code scanner. I'll check things out this weekend and see what I can find. Thanks for th compliment on my Jeep.
I've had this in my minivan before. It's eather the plugs, spark plug wires, distributor, or fuel injector. If it's a fuel injector that could be a bear. However in the case of my minivan after I replaced the plugs and wires it ended up being the dustributor. Which was fairly simple. Just note with some tape and sharpie the location of all the wires to make sure they go back where they belong.
Here are the steps to troubleshoot a misfire (look for changes or abnormalities after each step):
1 - Swap plug wires between #5 and #6
2 - Swap plugs between #5 and #6
3 - Replace distributor cap
4 - Swap injectors between #5 and #6
5 - Use a Noid Lite to watch injector firing signal. If signal is bad or intermittent, find wiring problem (possible bad computer).
6 - Perform a compression test (all cylinders should be within 20% of each other). If #6 is low, squirt some oil into the spark plug hole and redo test. If #6 numbers go up to normal you have leaking rings. If numbers stay low go to next step.
7 - Perform a leak down test to determine where compression is being lost (head gasket, valve, cracked head, etc.).
1 - Swap plug wires between #5 and #6
2 - Swap plugs between #5 and #6
3 - Replace distributor cap
4 - Swap injectors between #5 and #6
5 - Use a Noid Lite to watch injector firing signal. If signal is bad or intermittent, find wiring problem (possible bad computer).
6 - Perform a compression test (all cylinders should be within 20% of each other). If #6 is low, squirt some oil into the spark plug hole and redo test. If #6 numbers go up to normal you have leaking rings. If numbers stay low go to next step.
7 - Perform a leak down test to determine where compression is being lost (head gasket, valve, cracked head, etc.).
Last edited:
Thanks for the detailed post. If I replace distributor cap and plug wires should I stick with Mopar or are any other aftermarket brands do any better?
Tstewart1
Member
Did you find out what this was? I'm having the same issue currently. Jeep drives great, no issue. Check engine light for cylinder 6 misfire.
John Scoggins
TJ Enthusiast
If, by chance, you have Bosh plugs, throw them out and put in something else, Autolite seems to be the best here.
Tstewart1
Member
I have Mopar wires and copper champion plugs which is what OEM used. Less than 5,000 miles on them. Hoping it's just injector wiring or injector. Would it be distributer if it starts right up no issues ?
John Scoggins
TJ Enthusiast
Tstewart1
Member
Good to know, thank you. Are there test I can perform to see if it is the cause or just replace it?
BrunoPizz97
TJ Enthusiast
Its either your injector or the gaping of the spark plug in cyl 6 trust me I had this issue too. Was driving me crazy for months, I pulled my fuel rail and there was something clogging cyl 6 injector so I blew out the fuel rail cleaned it with some brake cleaner. To this day I had no idea what it was. I replaced all injectors with Siemans and it runs great. I said to check the gaping as well because the gaping on my plugs were off so i changed plugs wires rotor and rotor cap all together.
Tstewart1
Member
I changed my plugs in February, I gapped them correctly. The engine light just popped up a few weeks ago. Does the gap change over time?
I'm sure my fuel rail and injectors could use a cleaning. 21 year old jeep now.
BrunoPizz97
TJ Enthusiast
I don't believe that the gap would change over time but I may be wrong about this. But it certainly does not hurt to take a 3/4 socket to them and check them out. I would pull your fuel pump relay and give your motor a couple cranks to drain the fuel rail then pull the throttle cable bracket off to buy some room when pulling the rail off. You don't need to disconnect the rail from the main fuel line just need to check out whats inside maybe it would be a good idea to get a clear cup and get a sample of what your fuel looks like from the rail. There will be residual fuel inside of it so might as well get a sample and see if you see any sediments. Also inspect the intake of the injectors make sure they arent clogged.
Similar threads
