Pinging under light throttle - JeepForum.com
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post #1 of 16 Old 11-11-2013, 06:11 PM Thread Starter
timandsam
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Pinging under light throttle

Hi All,

I am getting some pinging under light acceleration. FYI, this is a 95 ZJ w/ a 5.2. I have replaced managed to fix everything that was throwing all my CELs (O2 and EGR transponder) and the pinging is still there.

The pinging happens more often than not. It seems to happen more under light (20% or less) throttle and low RPM (1500 or less). Going up hill seems to intensify this problem. Also, it seems to be worst around 45MPH ish.

If i get out of the throttle a bit or get on the throttle a little harder, the pinging seems to clear up.

BTW, i have already done the spark plug wire re-routing TSB.

I am currently getting about 16MPG, I can see a bit of oil when i look down the throttle body. I have never noticed oil smoke out the exhaust.

Since this happens at such low throttle, does this really sound like plenum gasket?

Thanks in advance,
Tim

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post #2 of 16 Old 11-11-2013, 06:12 PM
PolkaPower
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http://dodgeram.info/tsb/2000/09-05-00.htm

Open the throttle body and shine a flash light down there and see if you see oil or brown burnt oil. The plenum pan should be clean metal. This is a very common factory failure on magnum motors.

This is the fix

http://www.hughesengines.com/Index/p...p?partid=27091
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post #3 of 16 Old 11-11-2013, 06:19 PM
JasonStebbins
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1. Plenum
2. Running lean
3. Faulty plugs
4. Bad EGR
5. Crappy gas

Poop
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post #4 of 16 Old 11-11-2013, 07:12 PM Thread Starter
timandsam
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PolkaPower
I can see oil down the TB, its hard to tell how dirty or clean the pan is though. I will have to take another look.
I read that the Hughes kit came with some pretty shoddy gaskets. Is that still the case?

Jason
I plan on hooking up a vacuum gauge to do the definate test for the plenum gasket.
I have suspicions about the TB gaskets since the intake looks damp all around the TB.
I haven't checked the plugs yet.
I have tried gas from different places and even tried mid-grade 89

Is it possible to have a dead spot in the TPS that would cause this?
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post #5 of 16 Old 11-11-2013, 07:25 PM
PolkaPower
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The hughes kit uses fel pro now I believe so they fixed that issue. If you see oil in there it's the plenum and the cause of your pinging.
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post #6 of 16 Old 11-11-2013, 08:12 PM
ZeeJay1997
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post #7 of 16 Old 11-12-2013, 05:58 AM Thread Starter
timandsam
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Quote:
Originally Posted by ZeeJay1997 View Post
i'm throwing in a cat.
Why do you say that?
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post #8 of 16 Old 11-12-2013, 06:09 AM
ejschultz
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Quote:
Originally Posted by PolkaPower View Post
The hughes kit uses fel pro now I believe so they fixed that issue. If you see oil in there it's the plenum and the cause of your pinging.
This. If there's oil in there, you need to replace the plenum gasket. Your best bet is to buy the Hughes kit previously mentioned because it replaces the stock plenum plate with a 1/4" aluminum plate that won't flex and allow the gasket to blow out like the stock one did.

97 ZJ - 5.2L, 242, 4" IRO lift w/short arms & adj. TBs, JKS Discos/BPEs, DT3000s, Aussie'd 44A, sliders, bumpers, bunch o' skids, 31" Duratracs on 15x8s
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post #9 of 16 Old 11-12-2013, 06:17 AM Thread Starter
timandsam
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Alright, well i will start ordering the parts when i get paid this Friday. Thanks. I guess i may as well do a 180* thermostat, plugs, wires, cap, and rotor right away.

Is there anything else easy to do while it is apart?

I am trying to figure out what ZeeJay1997 means. Can a clogged cat really cause any of these issues? I am not losing any performance.
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post #10 of 16 Old 11-12-2013, 06:37 AM
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I don't know first hand what the kit comes with. When I did mine, I purchased my plenum plate from a guy over on thespeedfreaks.net. I sourced my gaskets and everything else separately. I see you're going to do the thermostat. That's good. I'd also recommend doing the coolant bypass hose. Other than that, I can't think of much. I know a lot of guys say don't reuse the intake bolts. I did. I don't think it's an issue to reuse them, but then again, I'm not responsible for your vehicle.

97 ZJ - 5.2L, 242, 4" IRO lift w/short arms & adj. TBs, JKS Discos/BPEs, DT3000s, Aussie'd 44A, sliders, bumpers, bunch o' skids, 31" Duratracs on 15x8s
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post #11 of 16 Old 11-12-2013, 07:51 AM
PolkaPower
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Don't worry about the cat just fix the plenum. Nothing indicates a bad cat so far. I would replace all hoses while you're at it. A 180* t stat in a cold weather state is not the best idea IMO. It will just keep the motor from reaching operating temp longer and your heat may not work as well when it gets really cold. WHat ever you choose, get a good brand T stat. Do not use a Failsafe.

Other things to consider are the crank shaft sensor, cam shaft sensor, valve cover gaskets, injectors, and after you get it back together adding an oil catch can in the pvc line to catch the blowby from getting into the intake after it's been cleaned.

Also when you are doing the repair, toss the front and rear molded gaskets and use Permatex right stuff or something like it instead. Lay a thick bead of it in the shape of the gaskets and let it set for 20-30 minutes before you drop the intake back on. It's not easy to get the stock gaskets to stay put when you put the intake back on and you may have a leak from them afterward and you don't want to do this twice.
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post #12 of 16 Old 11-12-2013, 08:12 AM
ejschultz
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Quote:
Originally Posted by PolkaPower View Post
Also when you are doing the repair, toss the front and rear molded gaskets and use Permatex right stuff or something like it instead. Lay a thick bead of it in the shape of the gaskets and let it set for 20-30 minutes before you drop the intake back on. It's not easy to get the stock gaskets to stay put when you put the intake back on and you may have a leak from them afterward and you don't want to do this twice.
Truth. Ask me how I know... Better yet, ask my driveway.

97 ZJ - 5.2L, 242, 4" IRO lift w/short arms & adj. TBs, JKS Discos/BPEs, DT3000s, Aussie'd 44A, sliders, bumpers, bunch o' skids, 31" Duratracs on 15x8s
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post #13 of 16 Old 11-12-2013, 08:20 AM
PolkaPower
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Quote:
Originally Posted by ejschultz View Post
Truth. Ask me how I know... Better yet, ask my driveway.
What you had an oil water fall? Or was it coolant?
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post #14 of 16 Old 11-12-2013, 08:21 AM
ejschultz
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The rear cork slid and I have a very small leak. I get about a drop a week from it. A drop a week over time adds up pretty quickly. My ZJ definitely marked it's territory at my new house. I'm assuming it's that because I can feel the cork behind it sticking out and everything in that area is covered in oil.

97 ZJ - 5.2L, 242, 4" IRO lift w/short arms & adj. TBs, JKS Discos/BPEs, DT3000s, Aussie'd 44A, sliders, bumpers, bunch o' skids, 31" Duratracs on 15x8s
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post #15 of 16 Old 11-12-2013, 12:52 PM Thread Starter
timandsam
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Thanks for the tips! I'll be picking up some Right Stuff as well!
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