Calgary Jeep Association
4x4 Related Groups => Tech Talk => Topic started by: afb on September 10, 2013, 06:37:25 PM
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I'm at a loss... I took the head off to get at a lifter back in put it all back together and drove for 2 days. this sterted when it was raining like crazy last weekend. My yj 2.5 idles fine but when i rev it in neutral it has a popping sound to it. In gear it sputters almost raspy sound starting at 2000rpm and a loss of power happens but it does rev up. Its popping codes 21 24 and 25. Aic, tps, and o2 sensor. All were replaced 5k to 15k ago. The parts guy instantly said with all those 3 codes he bets the pcm. Any ideas on what it could be?
Thanks in advance.
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Timing?
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It seems fine.
The jeep idles smooth and revs with a hiccup in neutral and under load it revs smooth to 2000 then the popping happens as you gain rpm.
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Vacuum lines?
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Probably a funky 02 sensor. My 4.0l did the same thing.
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Vacuum is good and I unplugged the o2 but no change.
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Have you checked the plugs/wires yet? I had a car do that, it turned out when I removed the wires I broke one and it only showed up under load and when wet.
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Cap rotor and wires are good. Unplugged the tps and she died for a second and ran again. All sensors are working. An one know how to check the ecm?
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Vacuum leaks tend to only show at idle. Wide open throttle there is no vacuum. Lean mixtures cause popping out intake esp under load. Leave o2 unplugged and clear codes. Drive it for awhile and see if its better. Only check for PCM is try a different one. Don't have a spare but drive a '94 two fiver... Might be the same to try
Double check ignition. When in doubt, throw it out and put in new stuff. Chased cracked plug/poor wire/bad cap misfires way too ma y times
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I erased the memory and unplugged the o2, same. Tps unplugged, ran but low idle and engine changed for worser checked connections and wires, all good. Craaaaaaaaaap.
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Since you've had your head off, you checked the timing?
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I spent a few days chasing similar issues........ after going thru all the sensors, vacuum leaks, gaskets, it ended up being a plugged cat.
If you can drive it see if it will "bottom" out under load and limit your revs and speed to ridiculously low amounts.
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It has a new banks header and new 2.5" pipe to the back with no cat. Lots of pressure coming through her. Timing is good and the idle up to 2k is real smooth then goes to crap. The codes now are 21, 23, 24, 25. I've been popping off every electrical plug I can find.
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Check your ground ::)
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Also what voltage are you getting at idle vs high rev from the alternator? Still think it's a ground.
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I'll check tomorrow. I have an ecm coming this week so i can also see if its that. Almost 2 weeks without my baby...... I also ran out of beer..
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I also ran out of beer..
Well you might as well quit life now :'(
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The wife tried to hide my jack when the jeep died. It wasn't a good day for anyone that day.
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ever check the fuel pressure? test it when it's crapping out.
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Brand new pump, new injectors, new regulator, new sensors, new exhaust, rebuilt head, new alternator, new plugs, new wires, new msd, new lifters, new dent. All wires (ground and power) are good.
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Computer was a no go. The codes are gone now but runs like crap. Back to the ohm meter again.
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"New MSD" as in the aftermarket ignition box? If so take it out and run off the stock stuff till you figure it out. Did you try a different coil?
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Was it an exhaust lifter you changed? If so, if something got screwed up and the lobe got wiped off the exhaust lifter that could cause your problems as well. Pull the valve cover and make sure all rockers are opening/closing the same amount.
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I'll check. I had 3 seized lifters and couldn't take the noise any more so I replaced them all. The jeep ran great for 2 days after replacing them,then when I was waiting for my kid the jeep started with the popping and lack of power.
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My quad just did this. Had it for 2 years now. Last trip out it started losing power near the end of the trail. Put it on the trailer, brought it home, fired it up and it started popping. Pulled the valve cover thinking it had a broken rocker arm(there was also a rattle from the top end) nothing broken but one rocker didn't move as much as the others. Turned out the cam lobe was wiped out. Apparently Polaris had a bad bunch of them in the late '90s. Mine is a 2001, no idea why it lasted so long. Most went while still under warranty.
Maybe the seized lifter took the hard outer coating off and then the new lifters wore it out?
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The new lifters only have 50 min of runtime on them since putting them in. I'm going to strip everything off again and go one by one checking every frigging wire/sensor/ valve.
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Compression 115 to 120 replaced tps to be sure. Naaa. The plugs were black on 3 of them and #1 was tan. Valve cover comes off tomorrow . I'm starting to think engine swap time... Damn! :o
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Exhaust valve on #4 lightly tapped the piston. The guy that helped me finally told me when he bent the pushrod, he had the lifter in sideways and cranked down on the rocker with the piston up and when the valve wouldn't move anymore the pushrod bent. Geez do you think valve bent a bit? Off with the head again....
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"...when he bent the pushrod..." you left that part out in your original post.
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That happened 2 weeks before I replaced all the lifters.
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If its just a "dimple" in the piston you can get away with just soothing it out with some sandpaper so there are no sharp edges that can cause pre-ignition. I think you probably should think about a new head though.
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If the valve is done I'll replace it and the seat if need be, it would be cheaper than trying to find another one and rebuilding it.. The head only had 8000km on it since rebuild.
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Valves is out and doesn't seem bent. When rebuilt it was a 3 angle job but only one is sealing on every cylinder This is a pic of the one with the bent pushrod. unclean and wiped clean.
(http://i217.photobucket.com/albums/cc93/trialsguy99/20131001_170200.jpg)
(http://i217.photobucket.com/albums/cc93/trialsguy99/20131001_170145.jpg)
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The head pressure tested fine after the carbon was cleaned off.... I did find out what was wrong.... Clay is the winner !!!! 50km on these babies...
# 2 intake is at a 45 angle with chips off the side (#4 exhaust was the one with a bent pushrod) the rest have the beginnings of massive failure.
(http://i217.photobucket.com/albums/cc93/trialsguy99/1378608_10153291427820464_1845891733_n.jpg)