Fault Code O0201 - rough idle

[ltd02]

Also, as this is an intermittent "hot only" problem, it makes wiring checks difficult

Yeah, I see what you mean about the intermittent issue. Seems like a wiring issue would be more consistent. I saw your post on the other forum too but I got a specific code when my TPS went a few years back. Doubt it would trigger the codes you are getting.

Is you KJ making any knocking noises before or when it is in this loss of power state? Don't know if it applies here and haven't heard much of this on these KJ forums, but the "limp" mode you experience when the "misfire" occurs could just be a knock sensor doing its job. They should ****** timing if they sense knocks or detonation.

Of course this doesn't help the cause of your situation. Maybe check the continuity of the wires from the PCM to the #1 injector connector? Do it cold and then run it until hot and flaky and try it again. Heat can exacerbate all sorts of things.

I really thought the new injector would do it. Might not be a bad idea to swap the injector from a cylinder without a code. I know you said you put in a "new" injector, but what if the "new" one was bad from the box. It's happened to me before.

I think I've exhausted my list of suggestions. :shrug:

 

[branny]

Thanks. A bit clueless and ready for a jeep dealer diagnostic for $99.

Are there any wiring diagrams available?

It does sound like the timing was ********... But why only the cylinder 1 code?
Anything to do with it being the first cylinder the fuel gets to on the rail?

 

[CactusJacked]

Ok, i fitted a new injector in cylinder 1.
After a few short trips in succession, nice and hot engine. I got the check engine light and it started refusing any more than minimum throttle.
It is not a 'typical misfire'. The engine is jerking in time, almost like it must be electrical.
Does anybody recommend anything else?

Did you use an OEM/Mopar fuel injector, or an aftermarket one? When changing out only one injector, you want to use the same kind as the rest. Aftermarket injectors don't necessarily have the identical flow rate as the OEM, so that can actually make matters worse than when you started. Been there, learned that.

 

[ltd02]

Thanks. A bit clueless and ready for a jeep dealer diagnostic for $99.

Are there any wiring diagrams available?

It does sound like the timing was ********... But why only the cylinder 1 code?
Anything to do with it being the first cylinder the fuel gets to on the rail?

The diagnostic test might be a good idea at this point.

Also, maybe the injector #1 issue is causing the problem that is then causing the driveability (******** timing) issue. If that is what is happening. I'm not sure if this is really what's happening. In any case, your injector #1 issue is still the main problem.

I'm not sure what year your KJ is. Might want to put it in your signature line. That helps everyone out. Check these FSMs out for wiring diagrams:

Index of /manuals/Jeep/KJ

 

[branny]

Jeep is 2004 3.7 4x4.
I used aftermarket parts, but really can't believe any combination of things could cause exactly the same issue.

 

[CactusJacked]

Believe it. I had a misfire issue, not the Jeep, but still the same. I diagnosed the issue to being a bad injector. Replaced the injector with an aftermarket one, and the engine ran even worse...had no balls. On a whim, I figured as long as the old injector was out, I'd soak it in carb cleaner to see if the issue was it sticking due to varnish. Put it back in place of the aftermarket one, and sure enough, the engine ran like a top. By the way, a couple tanks of gas with injector cleaner did absolutely nothing, but a good soak did the trick. Using mis-matched parts isn't always a good way to go.

 

[branny]

Thanks, I'll bear it in mind, maybe try a deep clean of the old injector.

However, the jeep runs great, lots of power smooth tickover, then at a repeatable 20min point it suddenly throws the check engine light and only then does it refuse to accelerate.

Here is more info, the CEL was flashing yesterday and I smell fuel after stopping. Probably injecting fine just not igniting.
I just learned that flashing CEL means possible CAT damage, is that true?

 

[CactusJacked]

From your fuel rail clip thread:

Hi,
I replaced a fuel injector on my 3.7, which involved removing the right hand fuel rail....

Your fuel injector issue is with the #1 cylinder, front one on the left hand side (drivers side), not on the right side. Did you (oops) replace the wrong injector, or make a right side/left side clerical error?
And yes, a flashing check engine light means have it fixed NOW, or other damage may occur.

 

[branny]

^ sorry, i wrote that on my phone and was a little lazy.
I meant right side as i look in the bay (from the front).

It is currently being diagnosed locally.

 

[branny]

Ok, after diagnostics from a local garage, this appears to be a bad ecu.
It only occurs when extremely heat soaked, then the throttle does not respond.

What kind of cost would I expect?

Almost certainly will be trading this car in as it is becoming very costly.

 

[ltd02]

I was afraid of that. I have seen them for a couple to a few hundred bucks but they have to be programmed for you vehicle and keys. Dealer will probably be involved no matter where you get it. I think I saw the Mopar varieties are >5-600. Never had to replace one so hopefully someone with experience will be along to help soon.

 

[branny]

Apparently the lack of throttle position output is symptomatic of a bad PCM.
It certainly fits my case of severe 'all or nothing' symptoms.

Note that when the problem was evident there was a strong smell of fuel and it just wouldn't run, but when i turn it off and straight back on, the problem is gone and it runs ok.

 

[Rowlette]

I am having a similar issue with my 2005 Jeep Liberty 3.6 Limited 160,000 miles on ODO. It very noticeable when it first started it is running rough but runs fine at normal speed. This process started a couple of weeks ago and at the present time it is running fine but probably will happen again. This escapade comes and goes but I been having problems with my ECU for years throwing out erroneous O2 sensor errors etc. Years ago The Jeep Service Center diagnosis that my ECU is faulty but it was not worth the cost for replacement until it on its last leg and the prices would dropped once more Mopar makes the Junk yard. I have looked at this many times....

http://www.ebay.com/itm/2005-JEEP-L...ash=item1ea4a0b8bd:g:DAYAAMXQLs5Rq1qO&vxp=mtr
Or
http://www.ebay.com/itm/ECU-ECM-COM...ash=item233daf1409:g:NgwAAOSwiCRUl-oU&vxp=mtr

Just wanted to know if any have purchased this or anyone knows another places and any regrets. The Prices range from around $50.00 to $400.00. My Jeep I purchased new in 2004 and it now just my Toy to take to the beach, trail and mild off roader and Lowes runner.

Thank You in Advance.

 

[ryamkajr]

I have had this problem 3 times but on my #3.

Occurs about every two years. Replacement of the injection coil fixes it until the next time.