I noticed something not too long ago that i get a ticking or pinging sound that sounds like spark knock almost. I never noticed it before because i never drive at 2500 rpm's i always drive in the city and im always 2k or under in the rpm's.

So i tested it some more while going up hills in 2nd gear and its deff doing it at around 2500rpm, it stops at 3,000 and below 2500 as well and doesnt do it all the time. I thought it might be the plenum is bad perhaps ? I looked inside the throttle body and used a mirror and i dont see oil anywhere, i do see some carbon spots tho more like black specs on the pan. I revved the engine with the throttle lever and i cant hear it standing there. Seems to only do it when driving under load

Since this is a Jeep its the 5.9 that uses 93 octane and i never put anything else in it. I have been using the cheap 93octane from sheetz tho and i've a few people tell me that causes check engine lights to come on there vehicles the guys i talked to about this have sports cars like a corvette so i assume the engines are more sensative ?

I tried the 2 tests i know of to check a bad plenum gasket. I sprayed carb cleaner all around the kegger and the rpm's didnt go up at all. I unplugged the PCV hose on the passenger side valve cover that goes into the manifold. Then unplugged the drivers side valve cover breather hose that goes into the airbox.. Turned the engine on and put my thumb on that breather hose and then let go and air pushed out. Maybe 1-2 PSI it wasnt much but it did PSSHH out. According to the service bullitin this means the gasket is good right ?

Then what could be causing the ticking at 2500 rpm ?

Here is a pic of inside the manifold. I know its not great but its the best i could get, and it looks like this from back to front side to side.


http://i1083.photobucket.com/albums/...HPIM1749-1.jpg

 

bounce your ignition wire routing off that published in the TSB (can be found in the FAQ section).. could be a wire grounding under a certain range.. electricity is lazy and will go to the weakest point, so if a wire is laid across a decent ground- even through good wires- it can momentarily pop.. and, it's been known to only do so in certain ranges..

when is the last time you changed oil? have you checked it lately? too much oil will froth the stuff, which under-loads lifters, which can popaticktick.. and, again, under certain loads and in a certain rpm range..

check your grounds..

check your coil..

in other words, are you sure it's a ping? and, about the plenum- hold on... jussssst a second... wait... wait... it's trying to tell me something.... oh, duh: "pay me now or pay me later, but pay me you will"..... God, I hate those things.. they don't have to be so friggin' arrogant about it, ya know?

edit: just looked at your pic... your plenum gasket is a goner dude.. it may only be slightly blown, but, give it time.. you're likely hearing pings indeed..

 

The plenum gasket is blown, simple as that. The Vac test is useless and spraying anything around the outside of the intake is as well. 93 octane will just temporarily mask the problem, until the cat clogs and the heads crack. Stop kidding yourself .

 

I've seen that picture on here before.

 

Ye thats mine lol thats why youve seen it before

 

Stop kidding myself ? The Jeep 5.9 uses 93 octane from the factory.. Im not putting it in there to mask it its required, if i put in 87 or 89 it will ping like crazy due to the higher compression of the 5.9 in the Jeeps.

All im asking is why it sounds like its pinging or spark nocking at 2500rpm, if your sure its the plenum. How much would it cost to fix this ? I would have to do this next year spring anyway i cant afford anymore repairs right now.

As for drewactual, its sounds like my mom's Mitsubishi Endeavour did when she used 87 in it when the engine requires high octane hers only made the noise during higher rpm's as well.

Sounds like this video altho not as bad. Sorry the anoying song he plays in the begging

http://www.youtube.com/watch?v=XiBzxxvy3FQ

Or like this video at 0:04

http://www.youtube.com/watch?v=Due7m...eature=related

 

120$ in parts

 

Ehh like 250 if you're fixing other stuff that's needs to be done. I spent $400 but I got a bunch of stuff

 

What other stuff ? The only other things i can think of that i would fix is the thermostat gasket and upper radiator hose which i know are going bad. This suck too you know i thought i finally had everything fixed on this thing..

Replaced the broken windsheild, both cv axles, the viscous coupler in the transfercase, the timing cover gasket, the water pump.. and so forth. I just dont want to fix something that possibly isnt bad. I dont remember ever hearing this noise until maybe a month or so ago.

 

The 5.9 in dodge trucks specifies 87 octane in the owners manual. I would've guessed they were the same motor. I'd try filling up with good name brand gasoline, maybe put some fuel treatment in there. I would try that first. If that didn't help, I'd try plugs, good plug wires, and a new cap and rotor if yours have over 50k miles on them. If that doesn't work, I'd do the plenum gasket. If that doesn't work, I'd sell it. (Kidding)