I see there are a lot of these threads but after reading I still need some help. I keep having a misfire in cylinder 1 and 6. I have out in a new fuel pump, fuel pressure regulator, new plugs, wires, and distributor I do not feel the misfire and when hooked up to scan tool it only misfires at higher rpms any ideas?
Multiple misfires
- Thread starter Scott D
- Start date
Is it throwing any codes? Have you pulled the spark plugs to inspect them? That can often be telling.
Rubicon88
TJ Addict
Rubicon88
TJ Addict
It might not be causing you problems but you need to start at ground zero.
The MFG recommends using NGK...
ZFR5N
They're not expensive and consistently work the best in these old engines.
If you took this to a Jeep dealer or my shop and something wasn't blatantly obviously wrong like a damaged plug wire or the like...
The very first thing the tech will do is walk to the parts counter and get the oem plug for it. Install and reevaluate
Others have had misfires go away changing back to the OEM recommended plug.
Your iridium plugs are definitely not the problem if they are the correct model for your model year engine. And there's definitely no need to run specifically NGK spark plugs. The engine was not designed around any particular brand of spark plug even though one particular member likes to think it was.
What is your model year? It sounds like a 2000 or older but... At this point I'm almost thinking your crankshaft position sensor could be going T.U.
Yes its throwing codes I don't know the actual code but it continues to throw codes after reset
Pardon the absurd length of time it took me to have noticed the Bosch brand name. Bosch spark plugs (O2 sensors too) do not have a good reputation in our wrangler engines due to their limited heat ranges. Try swapping them for one of the following plugs that are well known to work well in older 2.5 and 4.0 engines with distributors like yours has. Champion 7034, Champion 3034, Autolite XP985, Autolite App-985 or Autolite AP-985. For others, not all of those are suitable for newer coil-rail equipped 4.0 engines.
Rubicon88
TJ Addict
Get a leak down test done, I just got done fighting a po301 and po303 and it ended up being something wrong with my brand new motor XD
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