Random misfire

[coastierox]

I tried googling this issue first but couldn't find anything. I've been getting a random misfire code and sometimes I can tell it is misfiring. This is what I have: 4.5l with ford 24# injectors. I'm wondering if I am fuel fouling my plugs or if there is a possibility that the coil packs aren't hitting hard enough. Any place for me to start looking would be much appreciated. Oh, it only happens when I really get on the throttle, ie passing and such. Otherwise I'm not to heavy footed.

[SilverXJ]

Unless the coil rail is bad it shouldn't cause a problem. I would check your fuel pressure when this is happening to start with. What plugs are you running? Do you have a wideband? Besides 24# what is the part number on the injectors?

[wjtom]

If its obd2 make sure the cam sensor has been properly synced with a scanner.

[SilverXJ]

It has a coil rail so its oBD2. Good point.

[coastierox]

I can't remember what plugs I have right now, nothing fancy, but not cheap either. I'll check on the part number of the injectors. I just know that those are the ford racing 24 pound. As far as making sure my cam sensor is synced how do I go about that?

[SilverXJ]

I can't remember what plugs I have right now, nothing fancy, but not cheap either.

You should be using one heat range colder plugs search on here and I have a post about what NGK recommended.

I'll check on the part number of the injectors. I just know that those are the ford racing 24 pound.

They might be 24# at a different PSI and may be more at 49psi.

As far as making sure my cam sensor is synced how do I go about that?

http://jeep.blackonyx.net/pdfs/jcss.pdf

Do you have a wideband O2 sensor? It sounds like its going really rich or really lean.

[wjtom]

To do the cam sensor sync you need a good scanner any good shop should have one.There is a cam sync test so you can adjust it to + - 2 from 0. It will run without doing this but you will pull misfire codes if its off from those specs.Shouldnt take more than 10-15 minutes to do.Just make sure whoever does it checks it after they tighten it back down.Snap on modis has the test in it i cant say for sure about the otc or some of the other ones.

[SilverXJ]

A scanner is unnecessary for the cam synch. Using the toothpick method works fine.

[wjtom]

Not to argue with you that may work and is how you are supposed to install it.That is how reman ones come shipped, locked like that.Just install and pull pin.But that does not mean its right.You may get lucky maybe not but that is why the test exists in the scanners to get it right.+- 2 degrees is nothing as far as movement goes.

[SilverXJ]

Yes, maybe to be 100% perfect you need a scan tool. But it doesn't have to be perfect and the PCM is perfectly happy with the tooth pick method. There is a larger windows for the PCM to work with.

[coastierox]

Thanks guys! I'm on vacation for the week right now, but as soon as I get back to my Jeep I'll jump on this! I'm about 50% sure my scanner does read the cam sensor... Again, thanks! I'll try to remember to update this once I tear into it.

[wjtom]

I am going to have to respectfully choose to dissagree with you on this.Look it up on mitchells which comes from the oe manuals. The pin is for installinging to get it close so you can start it.Then you need the scanner to make it right.If close is good then just use the toothpick but it does make a difference in idle quality,performance and tuning just being off a couple degrees from the oe max spec say 5 degrees instead of +-2 from 0 as this is used for injector timing.Not going to argue this point. Anyone that wants to look it up for themselves can. Chrysler set that spec for a reason otherwise they wouldnt have wasted their time making the programming for the oe scanner.

[SilverXJ]

Not going to argue this point.

You already are. Just because its on a manual doesn't mean its actually necessary, I'm still looking for the section of the manual related to strokers. Also, what does Mitchells or the FSM say about setting the sensor with an aftermarket cam with different valve timing events? I'm also speaking from experience here that the scan tool is unnecessary. If it was necessary everyone wounle be running to the dealer to snych their sensors.

[FlyinRyan]

I have to interject here. Cam sync or fuel sync ABSOLUTELY MATTERS. It plays a significant role in making larger camshafts behave properly when done in conjunction with a proper PCM tune. Setting it to 0 is better than not setting it at all, but there is improvement left on the table.....

[coastierox]

Sorry for the long break guys, been crazy busy at work putting a helicopter back together. So with the live data feature on my code reader the spark advance bounces between 8-10 at idle. I m assuming I need to go get me a programmer to fix this. Also, what do I need for a fuel pump? I've purposely been avoiding that because I hate dropping fuel tanks. (Could be worse though, I have to get my helicopter 3-4 feet in the air to get the tank back in...)