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01' 4.0 wrangler misfiring

RayDaJeeper

New Member
Joined
May 19, 2019
Messages
5
Location
Indiana United states
Hello, I’m in need of some help with my 01’ TJ.
I’ve had an engine light for my Cat converters about 6 months now but was told by the auto parts guys it was nothing to worry about... well lately I’ve been having issues and I’m thinking I should have worried.

On cold starts it starts and runs T totally fine, but anything after that I’d i shut it off and restart it then it runs rough and shakes some. Had it worst today and the check engine light flashed at me a few seconds before the engin smoothed it self out and the light went back solid. After that it ran just as normal, no complaints or hiccups... nothing.
If anyone can help aid me as to what is causing this trouble I would greatly appreciate it!
Also if I left out details ask me and I’ll provide them.
 

ScottyZ

Member
Joined
Oct 1, 2018
Messages
98
Location
Buffalo, NY
If you can provide the actual trouble codes you are getting, you'll get more helpful hints on what to do. Doesn't sound like a misfire, more like a bad 02 sensor. Make sure to use OEM sensors or NTK brand.
 

Quigley

TJ Enthusiast
Supporting Member
Joined
Oct 20, 2018
Messages
267
Location
Kingston, WA
Auto part guys are not professionals they are home hobbyist getting paid $10 an hour. They guess... a lot. Our jeeps like Mopar, app985 autolight plugs, NTK o2 sensors, and bosch fuel pumps.

Get a OBD2 code reader off amazon they are like $40 or you turn your key off and on three times. The 01’s will give you your codes where the odometer is when done correctly. You need to do it fast. It will display codes and flash done when finished. I’d still get the code reader though.

I just went through all this myself in December so if you get us codes might be able to help you out more.

What led you to the cats ? Guessing I’d say upstream o2 sensors or your precats are rotten inside your front pipe.
 

Chris

Administrator
Staff Member
Joined
Sep 28, 2015
Messages
40,545
Location
Salem, Oregon
If you can provide the actual trouble codes you are getting, you'll get more helpful hints on what to do. Doesn't sound like a misfire, more like a bad 02 sensor. Make sure to use OEM sensors or NTK brand.
X2 to all of this.

The codes would be very, very helpful.
 
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RayDaJeeper

RayDaJeeper

New Member
Joined
May 19, 2019
Messages
5
Location
Indiana United states
Thank you for the quick responses, I got my codes checked today and here’s what I’ve got: P0303, p0432, and p1486.
In order that’s a Cylinder number 3 misfire, cat 2-1 efficiency and evaporative emission hose pinched.

I’ve read about people having trouble with the number 3 injector causing troubles when the little heat shield kinda goes bad. And I will say mine doesn’t look very good.

Could that cause my issues or is it something else, thoughts?
Thank you all.
 

Jerry Bransford

TJ Guru
Supporting Member
Joined
Nov 9, 2015
Messages
11,955
Location
Escondido California
A problem that doesn't exist when the engine is cold but appears once the engine has started to warm up is nearly always caused by a bad upstream O2 sensor. The computer only starts using the data from the O2 sensors to set the air/fuel ratio once the engine starts to warm up.

If you replace them make sure to ONLY use an NTK or NGK brand O2 sensor, don't use a Bosch!
 
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RayDaJeeper

RayDaJeeper

New Member
Joined
May 19, 2019
Messages
5
Location
Indiana United states
A problem that doesn't exist when the engine is cold but appears once the engine has started to warm up is nearly always caused by a bad upstream O2 sensor. The computer only starts using the data from the O2 sensors to set the air/fuel ratio once the engine starts to warm up.

If you replace them make sure to ONLY use an NTK or NGK brand O2 sensor, don't use a Bosch!
I had replaced the downstream sensor after receiving an engine light and code for the specific senor. Is there a chance that it would go bad and not throw a code?
 

Jerry Bransford

TJ Guru
Supporting Member
Joined
Nov 9, 2015
Messages
11,955
Location
Escondido California
I had replaced the downstream sensor after receiving an engine light and code for the specific senor. Is there a chance that it would go bad and not throw a code?
The downstream O2 sensor has NOTHING to do with setting the air/fuel ratio, its job is only to monitor the catalytic converter's function. It is the upstream O2 sensor, as mentioned above, that is responsible for correctly setting the air/fuel mixture which if wrong can/will result in misfires/poor mpg/poor performance.

And no, a bad O2 sensor will not always set a DTC since the computer is not always able to tell if an O2 sensor is telling the truth or lying.
 
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