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Ping time. (Not carbon buildup)

alexgalexg

NAXJA Forum User
Location
Connecticut
Been doing some digging on my own and even commented on someone else's recent thread on pinging. My 98 4.0 may be pinging at other moments but when I hear it is under heavy load (up hill) at low revs (45-55) in 4th. I tried to record it but there are other noises in the cab that totally muffled the light pinging sound.

I tested the o2 sensors with live obd2 date you can see this here it's unlisted on YouTube
https://youtu.be/YBL2ujQnR_w

This ping has been going on since 2016 and I can't figure it out. I know it's not carbon build up since the top of the engine is brand new. The engine runs at 200f all the time so it's not abnormal. I am going to try premium fuel to see if that narrows down the possibilities. Anyone have some advice on what to do next?

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It needs to be shifted to third gear for the conditions you listed to keep it from pinging.

My TPS on my Renix was bad and was causing the AW4 to not down shift under that kind of load, thus making it ping.

Is it automatic?
 
It is the auto. And it does downshift when it is supposed to. I know this because I have two Xjs and they both shift the same yet the other one does not make this noise.
However speaking of tps I noticed something on the live feed. I tested it while the engine was off and when I pushed the pedal to the floor it only read 79% on the feed. Is this normal?

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I'm thinking 87% is WOT, but I do not recall for sure, check an FSM or old posts. When my TPS was bad it went from 30-50%, idle to WOT on the TCU side (Mine is a renix that had the duel side TPS). My ECU side was perfect, but hung slung me into 4th gear with a lock TC before I got past 1200 rpm at 20 MPH LOL

Is the TC unlocking at high throttles like it should? If not it could be TPS span you just posted not going high enough

Yours uses the same data for the TCU and ECU/PCM

I think mine at 17-87% span.
 
I'm thinking 87% is WOT, but I do not recall for sure, check an FSM or old posts. When my TPS was bad it went from 30-50%, idle to WOT on the TCU side (Mine is a renix that had the duel side TPS). My ECU side was perfect, but hung slung me into 4th gear with a lock TC before I got past 1200 rpm at 20 MPH LOL

Is the TC unlocking at high throttles like it should? If not it could be TPS span you just posted not going high enough

Yours uses the same data for the TCU and ECU/PCM

I think mine at 17-87% span.
Do you mean is it kicking down a gear when the pedal gets closer to the floor? If so then yes. I could be misinterpreting what you are saying

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Yes, but if it is in a climb, and that speed, rpm, and under a load it should be in third gear. Manually shift to third and see if the ping stops.
 
Yes, but if it is in a climb, and that speed, rpm, and under a load it should be in third gear. Manually shift to third and see if the ping stops.
As I said the shifting behaves exactly the same as my other xj and yet the other jeep does not make this noise. It does downshift if I push a little but the ping isn't very loud so between the off road tires and super 44 exhaust I couldn't tell you if it's doing it ijn other gears. Doesn't sound like it. Seems like just that low rev part of 4th but hard to tell

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Gearing and tire size differences?
 
Fuel pressure, or flow rate problem?
 
Fuel pressure, or flow rate problem?
I checked this when my head blew to confirm an absence of lean conditions and it was good. Also plugs look normal so I'm inclined to believe nothing has changed.

Just want to say thank you taking the time to help trouble shoot this with me. It's greatly appreciated

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UPDATE:
Put premium in the tank. So far I have not been able to get the vehicle to ping. Will try a few more extremely steep mountrain roads and wait for it to be in low revs in 4th on my next day off to be sure. But assuming premium fuel stopped the ping, what is causing this?

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I didn't see the status of your "readiness monitors"? Have you tried to reset your ECU and give it enough time to establish "open loop" with all the monitors ready? Your fuel trims and timing don't look good. You definitely need data under load!
 
You reset it by holding the positive and negative cables together right? I can do a more thorough live feed on Wednesday to show you everything.

I figured if the timing was off it would run rough while cold at the very least but it always runs smooth

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Following this thread as I have a similar problem. Thought it noise was a loose timing chain (it was pretty loose) so I changed that out but no change. Premium fuel seems to help but ping always comes back under heavy load uphill. Did premium fuel in your case eliminate the ping all together? Keep us posted.
 
Following this thread as I have a similar problem. Thought it noise was a loose timing chain (it was pretty loose) so I changed that out but no change. Premium fuel seems to help but ping always comes back under heavy load uphill. Did premium fuel in your case eliminate the ping all together? Keep us posted.
It's hard to say. My jeep has a flowmaster exhaust and beefy tires so it's loud. But it is at the very least inaudible as opposed to my prior situation where steep mountain roads once it switches into 4th would cause the ping.

Tomorrow I'll be doing a more thorough recording of the live feed under load, idle and shut down. Hopefully someone here will see it and have am answer on what's going on

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I still say loading the engine that hard in 4th gear is causing the pings!!!!
 
I still say loading the engine that hard in 4th gear is causing the pings!!!!
Normally I wouldn't disagree. But I have a 99 Xj with the same 4.0 automatic setup and it does not do this. I filmed my obd2 live feed in more detail today I'm working on getting it uploaded tonight or in the morning

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