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stevedak
Dodge Dakota
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9/28/2006
09:33:37
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 Subject: engine ping
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Message:
I've been trying to eliminate an engine ping for a few weeks with no luck. My 92 3.9L was recently rebuilt, about 1500 miles ago. It runs great except for a ping that seems to be only on one side of the engine, drivers side. Seems to only be 1800 - 2000 RPMs and occurs while accelerating or steady load. The EGR seems to work, the egr passage (in the intake) has been cleaned. I've checked and changed the plenum gasket at the bottom of the intake (I have to 1/4 thick steel plenum from Hughes), I've changed the intake manifold gaskets, the plugs, cap, rotor and the wires. THe fuel pressure at idle is about 32 psi, it goes up to 39 or 40 when I disconnect the vac hose from the pressure reg. Engine temp is 184-188 deg. The compression is 135-150 psi (if I remember right). Engine vacuum is about 14.5 at idle.
I have an auto xray scan tool that shows (while driving) the o2 constantly swithching from rich-center-lean. The scan tool also shows the timing at about 32-34 BTC during normal steady high speed driving, not sure how accurate that is with the CPS mod.
I undid the CPS mod and still had the ping, I undid the ram air mod and still had the ping, I changed the IAT back to the intake and still had the ping.
There was no ping before the rebuild. The rebuild was done because I lost oil pressure on the interstate (the oil pump shaft broke), main/rod bearing were shot. During the rebuild, I replaced 1 piston due to a scarred cylinder wall and piston, I replaced it with a spare (used) piston. After honing the cylinder, the diameter was still in spec. When the machine shop swapped the pistons, the guy used a hone to clean the piston pin hole so the pin would rotate more freely, the piston rotation was kinda stiff. not sure if this would make a difference but who knows.
I could really use some help if someone has any ideas about my engine ping. SOrry for writing this long novel but this problem is killing me.
Mods: CPS, IAT, TPS, V8 TB, Fuel sync, Ram air, autolite 3923 plugs, 180 T-stat.
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?
Dodge Dakota
JOIN HERE
9/28/2006
17:20:48
| RE: engine ping
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Message:
Have you tried higher octane gas to see if it would reduce/eliminate the " ping " ?
If it does -you know it is a timing/compression situation .
If not , there may be something 'loose' .
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daddio
Dodge Dakota
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9/28/2006
17:31:54
| RE: engine ping
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did you raise compression with the rebuild?
that 14.5 inches of vacuum seems kinda low for idle. maybe you have leak somewhere.
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zzark
*GenII*
9/28/2006
19:50:45
| RE: engine ping
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I have a similar setup and mods.
I also had pinging that would not go away.
The last thing I did that fixed my pinging was to replace the EGR.
Before that, I had disassembled and cleaned the whole EGR and the metal tube. Still had ping.
So I spent the bucks on a new one, and that fixed it.
Curious, what is your BTC at idle?
zzark
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stevedak
Dodge Dakota
JOIN HERE
9/28/2006
23:13:00
| RE: engine ping
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Message:
I should have mentioned that I did try high octane fuel.
I'm not sure what the compression was before rebuild. Timing at idle is 10 BTC. It seems like my EGR is working, in other words, I can see the needle move but I can't tell if it opens enough or if it stays open long enough, I haven't gotten any codes set. The EGR definitely has not been changed, maybe its time.
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J and J Auto
GenII
9/29/2006
02:29:30
| RE: engine ping
IP: Logged
Message:
try a 1 colder plug like the NGK FR5
a reg stant 195 themo will run 185 188 the stock
thermo is a metered type and runs 195 200
If you live where it does not get that cold get
a 180 super stant
try yhese things
another thing if the o2 is not reading right it
will also cause a ping ngk.com order direct same
one mopar puts in at factory you pay the $108
for the box ngk.com $44
Larry
J&J Auto
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stevedak
Dodge Dakota
JOIN HERE
9/30/2006
20:09:36
| RE: engine ping
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Message:
OK...I replaced my EGR valve, most of the ping is gone but not all. I'll put some miles on it and see how it goes.
Thanks for the comments
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zzark
*GenII*
10/01/2006
10:27:35
| RE: engine ping
IP: Logged
Message:
At least it is better. I would have felt bad if the EGR made no difference.
Put some Seafoam in the gas.
And reset the computer.
Check for vacuum leaks.
Consider the O2 sensor, as Larry says
And reply with results.
zzark
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stevedak
Dodge Dakota
JOIN HERE
10/02/2006
10:25:01
| RE: engine ping
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Message:
Ahhhh....reset the computer
No matter what you know, you never know it all...thanks
I didn't bother with the O2 because it seems to be going thru the full range, like from 0.2 to 0.8, isn't this how the O2 should respond or is there more to it?
Can anyone shed some light on what they get for vacuum reading (at idle).
Thanks for the comments
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daddio
Dodge Dakota
JOIN HERE
10/02/2006
10:43:31
| RE: engine ping
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Message:
did you put some kind of performance cam in during the rebuild? that could be why you have low vacuum. vacuum should be about 20"@ idle
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xmr2
Dodge Dakota
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10/02/2006
12:15:05
| RE: engine ping
IP: Logged
Message:
the low vacuum could be a small vacuum leak somewhere or even a bad pcv valve.
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stevedak
Dodge Dakota
JOIN HERE
10/02/2006
14:26:52
| RE: engine ping
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Message:
During the rebuild, I reused the stock cam.
The vacuum was only 15-15.5 before the rebuild.
I've searched for but have not found a vac leak, I also changed intake manifold gaskets with no change in vacuum. I've seen replies that suggest a vac leak could cause the ping but would low vacuum cause a ping if there is no leak? PCV valve was checked in good shape and then replaced....no need to debate a $3 part.
You guys have been very helpful.
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zzark
*GenII*
10/02/2006
16:30:07
| RE: engine ping
IP: Logged
Message:
Everyone told me that my vacuum was low.
I searched high and low, and did the propane and WD40 tricks. Never found a leak. I even bought a new MAP, but got no change. But the low vac is NOT affecting my truck. But while I was looking, I used black RTV to seal the ends of several tubes/hoses.
I did buy a DODGE pcv, and there is a diffrnence between the OEM and aftermarket PCVs.
I also installed a new NGK O2.
Then a new EGR finally stopped my ping.
So maybe it was a combination of my efforts that fixed the ping.
Keep trying stevedak
zzark
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J and J Auto
GenII
10/03/2006
01:44:55
| RE: engine ping
IP: Logged
Message:
18 to 20
are you reading with a guage or the map 15 is
very low
I have seen a few bad cams lobes
lobe lift off push rod .270
at valve .432
Do as was sugjested with sea foam drible down
throttle body while idling this will remove any
carbon real fast 5 min
A bad egr will cause carbon buildup
Larry
J&J Auto
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J and J Auto
GenII
10/03/2006
01:48:27
| RE: engine ping
IP: Logged
Message:
oh ya watch the o2 step on gas should hit
.9 to 1 volt
.1 to .9 it looks like its begaining to get lazy
ngk.com
I just orderd one fryday
$44
ground ship $10
3 day $15
2 day $15.96
stay away from the bosch
Larry
J&J Auto
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stevedak
Dodge Dakota
JOIN HERE
10/04/2006
09:05:49
| RE: engine ping
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Message:
Thanks Larry...I got a NGK on the way.
I don't remember what my cam lobe height was but I know for sure it was not .432 when measured at the valve. I had some very conflicting data from Hayes manuals. They make the manuals to cover a few different years. My manual covers late 80's to the mid 90's but somewhere in the middle, I think the cam spec changed. If I remember right, the hayes manual said .383 or .400, I don't have the book right now, loaned it out. My dakota is a 92'
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Chris
Dodge Dakota
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10/04/2006
10:07:44
| RE: engine ping
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Message:
My my 93 3.9 used to be noisy. I swore it was pinging as it "seemed" to be related to throttle load, and it would quiet down at about 2100-2200 RPM? The noise seemed to eminate from back in the middle of the engine - hard to hone in on. A new EGR didn't fix it. Finally, during a water pump R&R at about 160,000, I decided to go in and replace the timing chain. Bingo! That fixed it. I sometimes wonder if the noise really was a pinging, but caused by the ever-so-slightly retarded cam timing from the loose chain, rather than the chain itself making the noise. I don't know. Did you put in a new chain during rebuild? Also, you say someone honed the wrist pin hole on the replacement piston. I wonder if they might have over done it a bit, causing a rattle. And of course you're absolutely certain the new (old) piston was the same compression ratio as the other 5. I can't imagine anyone making that mistake, but a compression test for comparison should confirm that. Good luck.
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stevedak
Dodge Dakota
JOIN HERE
10/04/2006
13:53:48
| RE: engine ping
IP: Logged
Message:
got about 10K miles on the Timing chain and gears, compression is pretty even
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J and J Auto
GenII
10/07/2006
03:49:02
| RE: engine ping
IP: Logged
Message:
Why would you need to open up a pin hole
I think you are talking about the rod end to set
it up for a full floating pin
The 92 to 03 all have the same cam
.270 lobe int/ext
.27 X 1.6 ratio is .432 valve lift
what this would have to do with ping dont know
sure its not a lifter rattle or a very noisy
injector
Larry
J&J Auto
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stevedak
Dodge Dakota
JOIN HERE
10/10/2006
11:21:44
| RE: engine ping
IP: Logged
Message:
Looks like I found the source of the ping. I adjusted the fuel sync (move distrib CCW) and the ping is gone. Its kinda surprising because the rotor seemed to be at the mark ( 0 advance) before I moved it CCW.
Larry...we kinda got into the cam discussion somehow. It wasn't the cause of the ping but maybe the cause of low vacuum. I didn't replace the cam so there is some wear.
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zzark
*GenII*
10/10/2006
22:01:06
| RE: engine ping
IP: Logged
Message:
Great.
Now don't you feel better?
No sarcasm intended.
And the fuel sync was going to be my next suggestion. :)
zzark
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