RE:Code P0201 & P0301. Why are these coming up intermittently? on 2001 Jeep Cherokee

cold start,runs rough until norm operating temp reached. The motor will surge rhythmically when brought up to 2000/2500 rpm-when cold @ start-up. After warm the motor displays no other symptoms. @ present it takes appx 12-15 min to warm-up once warm........ok until it gets cold again, then repeat the warm-up. chg'd coolant sensor, 02sensors are good.MAT/MAP not ck'd yet. Any clues?

by in Bandon, OR on May 25, 2012
1 answer 4 comments
ANSWER by on May 26, 2012
The P0201 indicates an injector fault on cylinder #1. The P0301 indicates a misfire on cylinder #1. If the injector isn't spraying, it will cause a misfire, so concentrate on the P0201 and when fixed, the P0301 will go away. Causes for the P0201? Most likely a broken wire to the injector, poor connection at the injector or a bad injector. I have seen a few Engine Control Modules cause that code, but not as often as the other possibilities.
COMMENT by on May 28, 2012
ok, I fully understand these first fundamental steps for these codes and they have been considered and or checked. Everyone seems to skip over the part about "It runs fine when it reaches normal operating temp, the coeds will erase after three trips etc. Next time the engine gets real cold....dead cold, it runs rough and throws the codes." if you cannot address this part of the issue, please do not reply with all the basic stuff for these codes........it goes beyond that. Do you have any other possibilities I could explore?
COMMENT by on May 28, 2012
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COMMENT by on May 29, 2012
Hot or cold, a P0201 indicates an open injector circuit. The fact that it only does it cold, simply indicates you have a smaller window to perform diagnostics in. Have you ohmed the injectors cold and compared them hot? Have you used a noid light on that circuit while the engine was cold? The fact that it won't set that code hot, only cold, more than likely means you have a bad connection somewhere, that is temporarily fixing itself when it warms up. Could be a cracked solder joint in the ECM, weak injector coil, spread terminal in the injector connector, etc... You still have to perform the basic diagnostics, only it had to be done when its cold.
COMMENT by on May 30, 2012
Thank You.

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