So my jeep was misfiring badl at 3000+ rpms, replaced my distributor cam/crank sensors. Took apart the front end to check timing chain it was fine, took a scope into the cam gears they weren't abnormally worn...so I was completely stumped, took it to a local shop here and they told me the Reluctor Ring on my camshaft was bad and the cam needs replaced, does this sound accurate? And if I do need to replace my cam what should I get? An OEM replacement or is there mild cams out there that it would be worth getting since the cam needs replaced anyway. I am new to working on vehicles and not the most knowledgeable when it comes to things like this. I have an 05 jeep wrangler tj sport.
Here's something interesting. The link calculates dynamic compression ratio, among other things, based on various engine set-ups. I plugged in a whole lot of aftermarket camshaft options. The results I think I got are that the 2005-2006 factory camshaft yields the best dynamic compression if you have a 4.0L set-up, while the 2004 factory camshaft yields the best dynamic compression if you have a 4.5L budget stroker, using only the 4.2L crank and short rods with 4.0L stocker pistons.
So, the factory camshafts seem to provide better results than you can get from Comp Cams or any of the other aftermarkets that I found stats for. I still need to run the numbers on the Mopar upgrade cams. Never got around to it because I was surprised to see factory out perform aftermarket. I guess the aftermarket cams are designed for high rpms, while the calculator assumes lower rpms (for the kind of driving that I guess they anticipated for the factory camshaft?).
Wish I could find/ figure out the formula and/or assumptions that the calculator uses for dynamic compression. I ordered a whole bunch of highly rated engine math books from Amazon, and none of them included a formula for dynamic compression !
Thanks Pine Cat, very helpful information I am curious to see what the Mopar upgrade cams yield also, and Johnny I replaced the cam sensor first then when I bought a new distributor it had another new sensor on it also, I am thinking the chances of two bad sensors is unlikely. And yea they were OEM parts from an overstock company.
Have you checked the plugs themselves? Swapped injectors (I assume not all cylinders are misfiring) to see if the misfire moves cylinders? Done a compression/leak back test to ensure it's not a leaky valve?
Seems like there's lots of possibilities we haven't yet explored, unless you just haven't mentioned them.
Yea JSt like I said in new working on vehicles and engines is defiantly not my strong suite, the told me they ran tests and is positive the cam is bad, I guess I'll just wait and see what happens when I replace the cam and update you guys.