Misfire on cylinder #3 Not A Heat Soak Issue
11-26-2010, 07:18 PM
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Misfire on cylinder #3 Not A Heat Soak Issue
Hi, I am new to the Jeep world. I recently purchased a 2001 XJ sport and didnt drive it long enough before I bought it to know there was a misfire when it gets hot. My check engine light is on a nd I have a P0303 code(Missfire on cylinder #3). I read all about the TSB on the #3 injector and the first thing I did was put a rebuilt injector with the heat rap in and still I get a miss. I have read everyone elses complaints about the ruff running after they restart there engine but mine is different. The miss occcurs after i've been driving for a while and I dont notice it till i'm stopped at a light and can feel the car shaking. I took it to a local mechanic and he replaced everything, spark plugs, coil strip, and he also changed the injector on Cyl#3 and still the same problem. I'm frustrated now and dont know what to do next. Please Help!!!!!
11-27-2010, 05:08 AM
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If you have a single cylinder miss, you have to concentrate on causes specific to that cylinder.
Three of the "usual suspects" have been replaced, that being spark plug, coil pack and fuel injector.
The wiring circuit for the #3 injector is still in play though....
As mentioned already, you are losing pulse to the fuel injector on that cylinder so you have to start tracing it back to find out WHY. More often than not, this is a wiring issue, rather than the computer. Don't rule out the connector as well. It happens.
The fact that you are losing your injector signal is the red flag and what is causing it is also causing your miss.
Good luck and keep us posted!
Three of the "usual suspects" have been replaced, that being spark plug, coil pack and fuel injector.
The wiring circuit for the #3 injector is still in play though....
As mentioned already, you are losing pulse to the fuel injector on that cylinder so you have to start tracing it back to find out WHY. More often than not, this is a wiring issue, rather than the computer. Don't rule out the connector as well. It happens.
The fact that you are losing your injector signal is the red flag and what is causing it is also causing your miss.
Good luck and keep us posted!
Last edited by tjwalker; 11-27-2010 at 05:19 AM.
11-27-2010, 06:39 AM
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This morning I experienced something different. Started the car this morning and I had a ruff idle, proceeded to drive to work. After a few minutes she smoothed out and I thought all was well until while on the parkway the MIL light comes on (Not Flashing just Solid). I get to my exit and stop at the light and she is running smooth. I get to work and still all is well, I get my OBDII handheld and I scan the codes and get 3 codes. Random Misfire, Cylinder 3 Misfire and Cylinder 6 Misfire. I'm going to check all the wires to the injectors like you suggested after work today and we'll see what happens. Thanks for your input so far guys.
04-03-2011, 01:24 PM
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I am having the same problem with mine. Did you ever figure out what was causing you issue? I am being told I need to replace the computer but I want to know for sure before I spend that kind of money.
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04-03-2011, 06:29 PM
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Mine is definitely not heat soak, I have wrapped the injectors and even installed vents in the hood. Just replaced the injectors and coil pack and checked all the wiring for shorts. I am hoping someone has another suggestion before I drop a grand on a computer
04-03-2011, 07:17 PM
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If you reach the end of your rope and have ruled everything else out, try a "different" computer. A salvage yard is a good place to go for one of these as generally speaking, the computer is very hardy. Even if you go online and buy a refurbished (basically means verified that it works) one, it should be under $200.
04-03-2011, 07:26 PM
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