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Engine light

897 views 8 replies 4 participants last post by  Digger84 
#1 ·
Well I am back again. This all started when all of the sudden my jeep started running rough and I got a engine light. I guessed the fuel injectors. Everything else has been replaced. I unplugged each one and the # 2 cylinder showed no difference when unplugged. The others did. As I drove it to my local shop to have the code read, the jeep started running real good again. No missing. The code was # 2 cylinder misfire. We cleared the code and after 10 miles or so, I got it again. Same code so we cleared it again. Then I disconnected the negative for 10 minutes. Now the engine light is back on. I did the system check that Jerry B taught with the ignition switch and the code came up 12. My haynes says that is battery power to pcm disconnected. I still have an engine light. And the jeep is running great. Do I need to just drive awhile? Will it clear itself? Thank you for your help.
 
#2 ·
Could also be no spark for that cylinder as cutting fuel has no effect if no spark

I don't recall which cylinder but lest say it is cylinder 3

Swap plug one and three
Swap spark plug wires 2 and three have to move both ends to keep firing order

Swap injectors three and four

If miss moves to one was spark plug
If moves to four was injector
If moves to two it was plug wire

If stays it is none of these

Then think dist cap or injector harness or mechanical like weak valve springs

And for what it is worth live data and reading pending codes gives much more info then displaying codes in odometer window
 
#3 ·
Thank you I have brand new wires, plugs and rotor and cap. Just might have to break down and take to a mechanic for a good code read. The jeep is running great. If I unplug any of the fuel injectors now, there is a noticeable difference. When it was running rough, there was no difference when I unplugged # 2. Now there is a difference so I think all is working. I just keep getting the code
 
#4 ·
The code read on the dash should always end with 55. It sounds like you are only seeing 12 (which you will likely always see), if you are not seeing at least 55 after that, then you are not seeing the whole enchilada. Maybe leave the key in/on for a longer period after seeing the initial 12 code.
 
#7 ·
flyngfsh - I assume you have a '97.
'12' is very common - my TJ displays '12' every time I check codes.
But '12' will not trigger check engine light.

wheeliemay is right - will always display '55' at the end to advise check is complete.
 
#8 ·
Thank you all again. The #2 cylinder quit firing again. Since I have already replaced the wires, plugs, distributor cap and rotors I am guessing it is the injector. The jeep has 245,000 miles and the injectors are the original ones. I was referred to the Bosch 4 hole in this forum and have them on order as we speak. Guessing is the key word here. I figure before I take it to a mechanic, I will replace things that should be replaced with the amount of miles I have anyway. Fingers crossed
 
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