Welcome to the forum! How many miles are on it? OE Spark plug gap is .043, I'm not sure if that matters with the aftermarket coil packs. It might be worth looking into further. Did you check fuel trim?
Cold Start Idle Misfire
Good morning my fellow trail pioneers,
I am having issues with my automatic 2017 JKUR. On cold starts(usually morning time) I seem to have a misfire or what sounds like a misfire. I hear it clearly in the engine and exhaust as it idles. It goes away after it warms up a few degrees(3-5 mins). It runs and drives fine but it never used to do this. I took it to a local tuner/dyno for him to hook it up and take a digital look. He mentioned how it retards the timing for warm-up and that's why I only hear it on cold starts. My concern is that it never did this before and hoping for community advice. I must advise all who read, I am a weekend warrior mechanic and have had the help of a professional mechanic/ friend with some of these tests. Maybe someone with a supercharger or even w/o has had similar problems?
-Things that I have tested and/or replaced-
Vacuum Test
Fuel LBS Test
Compression Test
Checked for exhaust leaks
New Plugs(20 miles ago)
New Coil Packs(10k miles)
New Ripp Map Sensor
New driver-side valve cover(back cylinder plug was leaking)
-Mods-
Ripp SC system w/ 11 lbs
Ripp Coil Packs
Ripp Oil Catch Can
NGK Iridium Spark Plugs(gapped at .032)
RK 4' lift(front and rear)
Diablo/Ripp Tune
The rear muffler was chopped off and replaced with a pipe
Bilstein 5100's
37" BFG KO2's
TF Ball Joints
Appreciate all the feedback possible! Planning to go back to the tuner on May 28th and take another look.
I am having issues with my automatic 2017 JKUR. On cold starts(usually morning time) I seem to have a misfire or what sounds like a misfire. I hear it clearly in the engine and exhaust as it idles. It goes away after it warms up a few degrees(3-5 mins). It runs and drives fine but it never used to do this. I took it to a local tuner/dyno for him to hook it up and take a digital look. He mentioned how it retards the timing for warm-up and that's why I only hear it on cold starts. My concern is that it never did this before and hoping for community advice. I must advise all who read, I am a weekend warrior mechanic and have had the help of a professional mechanic/ friend with some of these tests. Maybe someone with a supercharger or even w/o has had similar problems?
-Things that I have tested and/or replaced-
Vacuum Test
Fuel LBS Test
Compression Test
Checked for exhaust leaks
New Plugs(20 miles ago)
New Coil Packs(10k miles)
New Ripp Map Sensor
New driver-side valve cover(back cylinder plug was leaking)
-Mods-
Ripp SC system w/ 11 lbs
Ripp Coil Packs
Ripp Oil Catch Can
NGK Iridium Spark Plugs(gapped at .032)
RK 4' lift(front and rear)
Diablo/Ripp Tune
The rear muffler was chopped off and replaced with a pipe
Bilstein 5100's
37" BFG KO2's
TF Ball Joints
Appreciate all the feedback possible! Planning to go back to the tuner on May 28th and take another look.
1 - 8 of 8 Posts
Thanks @dermarpaintWelcome to the forum! How many miles are on it? OE Spark plug gap is .043, I'm not sure if that matters with the aftermarket coil packs. It might be worth looking into further. Did you check fuel trim?
It has roughly 63k. I called Ripp yesterday when I installed the new plugs to check what their recommendation was with their equipment. Tuner says the fuel trim looked good. I can also see fuel trim on my Diablo tuner but I don't know what is good or bad. The tuner is a big name in Jacksonville FL and many car communities(drag, offroad, street etc) recommended and use him. Im going off his knowledge expertise and wisdom.
You're welcome. Anytime you get into those kind of mods there's a lot of areas of gray, and OE specs can go right out the window unfortunately. Over the years I did troubleshooting for problems like yours and once or twice plug gap was the issue. Having said that your situation is different, I would ask around about the plug gap, and double check for vacuum leaks. Good luck!!
Thanks man! Ill double check. Im at witts end and willing to do anything. lolYou're welcome. Anytime you get into those kind of mods there's a lot of areas of gray, and OE specs can go right out the window unfortunately. Over the years I did troubleshooting for problems like yours and once or twice plug gap was the issue. Having said that your situation is different, I would ask around about the plug gap, and double check for vacuum leaks. Good luck!!
Ask around about the plugs gap and type first, taking them out is a bit of a PITA. But I do question the gap. Double checking for vacuum leaks is easy.Thanks man! Ill double check. Im at witts end and willing to do anything. lol
Update-
After leaving work this evening I kicked a little on the interstate. 45 mph to 75mph pull under moderate acceleration. It started to have a miss or skip. Still pulled but it was enough to feel it. Upon getting home I did a quick visual check under the hood with a flash light(it was late), checked my oil and antifreeze levels and condition. Nothing unusual. :/
After leaving work this evening I kicked a little on the interstate. 45 mph to 75mph pull under moderate acceleration. It started to have a miss or skip. Still pulled but it was enough to feel it. Upon getting home I did a quick visual check under the hood with a flash light(it was late), checked my oil and antifreeze levels and condition. Nothing unusual. :/
Got a fresh tune on it. I had some fuel cuts in the higher rpms range(3k and up) and the tuner tweaked some other supporting components to keep the tune at a moderate but safe level of aggression. I still have some idle misfire, skipping or stuter on cold starts but it seems to be less frequent and intense. It still does it every cold start though. :/. The tuner sees all the correct info and suggest everything is working as designed(digitally) so im pointed towards a minor mechanical failure somewhere. :/ The hunt continues.
1 - 8 of 8 Posts
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