4.6 stroker in 00' xj need help with pcm tuning and misfire

[SilverXJ]

2) the OBDII guys that are still living in the stone age and try to tune via manipulating map voltage.

Even w/o any form of tuning other than a MAP sensor adjuster to bring the AFR in line (if needed) his Comp cam would be fine.

[bandofthHawk]

Ok and what spark plugs do you guys recommend? And what gap?

[SilverXJ]

I was going to post the spark plug info earlier since you are running stock plugs, but I got side tracked. NGK 2756/BKR6E-11, or NGK 4291/ZFR6F-11(extended tip). Stock gap will work.

And progress on the misfire?

[bandofthHawk]

No progress yet. I was told i should have .35 gap. By the guys on pirate4x4. They told me champion plugs. But ill take it from you guys. As for the injectors ive never really messed with them before.
Just clean and unplug right? I replace the o rings? Again im just learning here....thanks again

[SilverXJ]

The 2000+ likes NGK plugs and are OEM. I also feel that NGK is a better quality plug than Champion. I think you mean .035" gap, which is stock. However, if you are interested in trying a .35" gap let us know how it works. LOL. Also, on the NGK don't use any anti-seize as the plugs are coated in an anti-seize like coating. Plus anti seize can change the heat range of a plug by not correctly transferring heat to the head.

It would be a good idea to replace the o-rings on the injectors. First, relieve the pressure from the fuel rail via the schrader valve. Remove fuel fitting from fuel rail, you will need a quick disconnect tool. Remove fuel rail, remove injectors, clean bores, install o-rings on to injectors, insert injectors into fuel rail using a little bit of oil or some other lube, insert injectors into intake manifold using some oil as well. Avoid damaging an o-ring. You can wiggle the injector a bit to get it to seat, but not a whole lot.

[bandofthHawk]

I'll go with your feedback since you also have a 2000 xj with a 4.6l lol also the guy on pirate told me i need 91+ octane. Ive been running 87. I always assumed jeeps didn't have high enough compression ratios for that fuel. But i suppose the high octane would prevent pinging. Can you tell me my CR based of my engine sheet? My old plugs were autolite 985.

[SilverXJ]

Its not a stock engine so you may need 91 octane. However, there is not enough information to determine your compression ratio and if you do in fact need premium. I would at least need to know your piston or piston dish CC and deck clearance. Do you hear any form of a rattle when under load?

[bandofthHawk]

I do hear rattle ...it annoys the hell out of me...i always try to ignore it. I would love for it to go away....how can i get rid of it?

[SilverXJ]

Put in premium and see if it goes away.

[bandofthHawk]

Its always rattled since ive had it. I never noticed it until about 3 months of owning the jeep. I hear it with the windows rolled up. Will try premium. Is the rattle detonation? And is it harmful othwr than annoying the crap out of Me ?

[SilverXJ]

Its hard to tell you if its detonation.pinging or not as I have not heard it. Pinging sounds like a metallic rattle (marbles in a can) with no pattern to the frequency. It usually happens when you put the engine under load.

Yes, it is harmful. Pinging/detonation can damage pistons, bearings valves, valve seats, etc.

[bandofthHawk]

Yea i hear it while im on the skinny pedal at all rmp ranges. Easy or hard acceleration its audible. I remember i did run a tank of 93 a while back but it made no difference. For a while i suspected exhaust problems because my banks header is made for a 00-01 xj witj the 0331 head where as i have the older style head. Ive looked at a pic of the new header vs old style and it appears the ports dont exactly line up with older header exactly. A friend of mine suggested the sound was turbulence in the header but i have always had that noise even back when i had no engine codes

[SilverXJ]

The banks header will fit the earlier head without issue. The runners are large enough to cover the ports in the head and seal correctly.

I ran your numbers through the calculator. KB only has one dish size for their Silvolite pistons 13.4cc. I specified a +.030 bore and stroker crank. Using the Comp Cam 68-231-4, installed straight up. Your Static compression ratio is 9.88:1, your dynamic is 8.62:1, and quench is .0725". Now, going with a 0 deck clearance and thinner head gasket you have a static compression ratio of 10.5:1, dynamic of 9.15:1 and quench of .044". Now, the general rule for dynamic compression is that 8.5:1 is about the most you can run on pump gas on an engine with an iron head.

Now, we don't know if anything else was done to increase the volume any such as polishing the combustion chambers or any extra material removed there. We also don't know if the pistons were dished and more or not.

Pirate mentions indexing the cam sensor. I don't think this is your problem as symptoms shouldn't be isolated to one cylinder. You also don't need a DRB tool to get it with in its window of working correctly. The DRB tool is needed when you want to get it 100% spot on, which is not necessary. However it never hurts to check, especially since you are experiencing pinging. See here: http://jeep.blackonyx.net/pdfs/jcss.pdf. Checking the wiring harness is also a good idea.

As for your pinging. It may be that the compression ratio is to high. First, change to the correct heat range spark plug. Stock plugs are to hot and aren't helping with detonation. Check your cam sync. Run the tank low and the fill up with premium. Your pinging should at least dissipate a bit. If the tank of premium doesn't help on next fill up add some octane booster and another tank of premium and see what happens.

How is the coolant temp? It should be around 210*, and if it gets hot that could also add to the pinging. What kind of air intake do you have? Hot air doesn't help either.

Now, running lean could be an issue as well. But you shouldn't be lean with those injectors. However, you don't have a wideband yet so we can't really tell for sure. However, since you say all RPM ranges I don't think its a lean issue until you get into WOT and heavy acceleration. I would also check the fuel pressure to make sure it isn't low.

[bandofthHawk]

Thankyou so much for the information man. I was afraid i would be at the mercy of the Stealer ship about the drb tool. (Im in NC there are no reputable shops around me ) Glad i dont have to mess with that. I do have a factory air intake. My temperature is good. I run less than 210. The flowkooler water pump i have helps a bit. I was told by my.friend thatif i were running lean i would feel like my motor was falling on its face at WOT. To me even with my slight issues itstill feels like the jeep accelerates like a rabid dog. Lol i filled her up with premium this morning. Well seehow that goes. Glad i dont have to mess with the headers. The guy who built the stroker told me it was one pf the best low end torque engines hes built. Ill see about the injectors too. Ill stick with the NGK plugs. Thanks again man id be lost without your guidance lol

[SilverXJ]

It would have to be really lean to fall on its face when accelerating. At WOT it will still feel fine even though its leaner than necessary. Also, if you look out the rear view while in WOT and you see black smoke that is a sure indication that it is rich.