KClight01

Thanks for checking. I am trying to understand MF CAT ACCUM CYL1, the count value has not changed since my first noticing it. But I haven't had the long crank either because I disabled the tip start. I am sure MF = misfire, but what do you think CAT means? It surely can't mean the catalytic converter. ACCUM probably means accumulator. What is curious is how can I have that many misfires but never have an issue or misfire code? Maybe it's because those codes are for when the engine is running, not during the cranking condition. I still have no explanation why it always starts immediately on the second crank. I am now wondering if there is a special parameter just for that, where the computer knows it didn't start the first time, so goes to some other setting for the second crank, just another theory.

I already replaced the ignition coil, I did this early on a few years ago now, it did not solve the problem. I never changed the plugs or wires though because I never saw a misfire (before now using Jscan) and it runs and idles so smooth. Yes, there are tons of parameters to watch and check. I am going to have to make a spreadsheet and try to track all of this.

Mr.T

"CAT" usually means catalytic converter, and miss-fires are bad for cats, but we're blazing new territory on this -- at least for me.

KClight01

I still don't understand how I could have that many misfires related to the CAT and no codes. Jeep reported to run and start good all week with the tip start disabled, not sure if there is a correlation yet. I started it today after ~45 min shut down and it started right up, which should have been within the typical window of the long crank. I ran scans and checked the same MF CAT ACCUM for the cylinders and all read 0. I never reset anything so not sure how that reset. I don't think I've solved anything but disabling the tip start seems to be working for now, it either starts right up immediately or on second try. I plan to look closer at the spark plug wires next.

Awamori

Think I'm reading this right...almost 3 years and still no solid resolution to this problem. Just subscribed to this JKForum to help hopefully solve this exact same issue you speak of with my 2017 JKU Sahara. I'm in Okinawa Japan with a RHD/EU version and completely on my own trying to fix this demon. Going to run down everything you have tried over the next week or so...to try and fix the issue. Not having a lot of faith after reading all the above attempts and certainly not interested in just tossing parts at it. Mine is actually failing and experiencing total shutdown when it does start with zero codes related when using JSCAN.

Staying tuned here and will certainly report back if I discover anything useful moving forward!

KClight01

Howdy. Jscan is definitely a good tool and I am still learning all its functions. For my case, part of the reason is that I am not one driving it daily, and it took a long time to figure out the exact conditions. I would check it after work for instance, and it would start right up fine for me. I never had a total shut down so that is definitely different, and I have the 3.8L engine so that is different. I would check battery and alternator. The cam and crank sensors are not expensive and easy to replace and seems to be the most common resolution for funny cranks, the MAP sensor is easy too (not necessarily saying to throw parts at it). I still think my issue is related to fuel, but others think its electrical, I may never know for sure. I still might change the plugs and wires. One thing that helped was disabling "tip start" function. Now it either starts right up immediately first time or it doesn't, but then it always starts right up the second attempt. No extended crank, no engine stumbling, or anything else that would help me figure out why. Wife calls it fixed because it starts right up almost every time (maybe 3 out of 4 times it is started each day is my guess). I recently had to replace the ABS module, I don't have enough data to know if it made any difference with the crank issue, I doubt it is related at all. Don't lose faith just because I am still dealing with this, I think most probably fix the issue, but just don't follow-up on what the fix was. I thought I fixed my issue a few times actually.

stephenspannn27

Add me to the list of people with this issue. My Jk is a 2012 with 180k on it. Automatic. I bought it in the fall. In addition to the intermittent long start, I have missfires on bank 2. The missfires may be #2,4 or 6. I’ve replaced the spark plugs but not coils or injectors. Like the OP my jeep will start right away if I turn the key to the run position for a few seconds before starting. It also always starts immediately on the second try. I replaced the drivers side cam position sensor even though my serial number didn’t match the TSB. No change. I did install an aftermarket remote start module a few months ago but I’m not sure if thats related. The problem occasionally existed before. The problem is worse more recently but temps are high as well. I’m wondering if it could be a vapor lock issue? It’s a return style fuel system but I suppose it’s still possible. Maybe it could be related to an oil pressure sensor? I know some ecm’s want to see oil pressure before it will allow the engine to fire.

stephenspannn27

Update and thoughts: I replaced the bank 2 cam position sensor, so both cam sensors have been replaced, no change. Three Ideas I've had. I want to determine if it's fuel of electronics related. I've thought about leave the key in the "on" position after shutting the engine off, maybe using a battery tender, and see if I ever have the long start. That would tell me if it's an issue with some electronic "going to sleep" and not waking up in a timely manner. Another idea I had is always raising the hood after shutting the engine off, this could tell me if it may be related to vapor lock... could still be an electornic issue. My third idea is to wire a momentary switch to the fuel pump, and each time before starting the engine, run the fuel pump for a few seconds to see if the issue goes away.

KClight01

I am now pretty confident that it is not a crank or cam sensor issue, although both can cause starting issues. I played with the position of the cam before and got it do a long fast crank which I could tell was different than my issue, if that makes sense. I think some have had the crank issue when the MAP sensor was failing, or its wiring was shorting. I doubt it is vapor lock, although it might be related to your fuel system not holding pressure, leaky injectors or something. Does it start right up on first crank of the day? Is it a consistent long crank after hot and sitting for a certain amount of time, that was my condition. I tried the battery tender crank before but honestly cant remember, I think it started up, but it took me a while to figure out the certain conditions to replicate. Also, I tried jumping the fuel pump already too, so the fuel pump would run continuously (and I tried waiting 10 seconds or so) but it still did the long crank for me under the right conditions. The oil pressure sensor idea is a new idea, maybe even coolant temperature sensor, I've never tried changing those.

stephenspannn27

I also want to look into installing an inline fuel pressure gauge... I really think that's a key troubleshooting step we are missing. I know it's not easy since there is no port. We really need to know what the ECU needs to see before firing the iginition and injectors. We know it needs crank to cam sync, but does it also need to see oil pressure? What is the list of conditions that must be met for the ECU to allow the engine to start?

stephenspannn27

UPDATE** I disabled the WCM (wireless control module, aka sentry system etc) using Jscan. With hit disabled... I went a few days with no issues. The TIP system doesn't work with the WCM disabled, so I was starting my holding the key until it fired. Finally, on day 2, I got a long start, I just held the key, and let it keep trying. I gave up at abotu 45- 60 seconds. As soon as I tried to start it a second time, it started immediately. This tells me this is not a leaky injector or fuel pump issue. Sometime is needing to be "reset" by trying to start it a second time. This has to be some kind of sensor or module that is preventing the injectors from firing or coils from firing.