Engine Ping (Ignition Knock) a Pre-Cursor to HG Failure? (1 Viewer)

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Joined
May 22, 2007
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23
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172
Location
Seattle, WA
I have done quite a few searches on engine pings, or ignition knock, that I am experiencing in my LX. It seems to be a common problem, especially on the 95 - 97 models, once they reach anywhere from 100k to 120k miles. Please pardon the generalizations but here is what I have deduced:

Many of the threads start off and discuss the topic but I have yet to see any definitive resolution short of the guys who have replaced their head gasket. Many of you have otherwise well tuned vehicles (that I can tell, anyway) and the pinging does seem to get worse over time. This also seems to be inflicting the later model LC's and LX's more than earlier models. Nobody that I can deduce has solved the pinging problem before a head gaslet change?

Maybe I am reading into this wrong, but could it be that the pinging we all hear is a pre-cursor signal of an impending HG failure? Not that this is the actual reason, but maybe a scenerio is that part of the gasket starts protruding into the cylinder #6 and causes both a change in compression and/or a restriction in the water passages causing localized hot conditions?

-Craig

Here is some background on my vehicle. Ping started at 120k...has gotten progressively worse now at 134k. I have done the following:
-Replaced wires, plugs, cap, rotor, PCV, valve cover gasket, PCV hoses, filters, ERG modulator.
-New fan clutch, radiator, thermostat, all hoses (had an overheating issue due to partially blocked radiator).
-Checked valves...all within spec but on the loose side
-Run fuel injector cleaner (Techron, Redline)
-Had injectors professionaly cleaned at my mechanic
-Timing in spec
-O2 sensor replaced at 100k miles by PO with OEM.
-No codes.

Nothing has helped. Pinging is at light to moderate loads off idle and around 2200-2400RPM.
 
Howdy! Are you running premium fuel? Lower octane may cause the pinging. Also can be caused by timing being advanced too far. John
 
inkpot,

Thanks for the reply. No, not running premium fuel as I thought the engine was designed for 87. Tried all different brands and currently have Chevron in the tank. I have read of a few guys going premium and reducing the ping for a short period of time but I am hesitant to do so since the engine theoretically doesn't require it.

Also, it only pings on a warm engine on at ~70F outside.

Timing checks out at 3 degrees in service mode.

-Craig
 
Adance the octane level. It should solve the problem
 
Adance the octane level. It should solve the problem

I might try that, but I was really wonding if this is a sign of HG issues. My understanding is that this engine should not ping using 87 and going to premium is only masking some sort of issue within the engine.

I guess I am looking for some folks to chime in that have had pinging issues and then seem to have had HG problems thereafter. Not that this is any sort of scientific poll, but maybe some anecdotal evidence that said...yes, Craig you may be on to something or...no, nobody seems to be having this sequence of events. Either way, I just wanted to pick the brains of some of you with your experiences.
 
FWIW, here's my pinging info:
-occurs during the summer months. Definitely was there during hot days with A/C on.
-seems to occur during wheeling in hot weather on slow, hard climbs in 4low.

-hi octane fuel didn't help.
- hi octane boost additive didn't help
-performed the usual additive flushes - Sea Foam green (about 10 times), tried water in the intake, Red line fuel conditioner, etc
-played with IGN timing
-coolant system is top notch.
-nothing helped

When I pulled the head off, I found
- HG in good shape. No sign of imminent failure.
- lots of carbon buildup on tops of pistons. Required scraping. :eek:Probably the source of pinging :hmm:
- lots of carbon oily residue on the intake (upper, lower, TBI). :crybaby:
- lots of varnish on cam shafts, timing chain, etc.
- all injector have a good spray pattern with closely matching volume. Even better numbers after injector cleaning.
- some of the vacuum hoses had split ends.
-spark plugs were in great shape for the age, 35k miles.

I hope by taking care the above items, the pinging should disappear or at least reduce tremendously and some of my hp should return. I also deduced that all of my additive Tx didn't do crap with an engine that's 165,xxx miles old. That oily residue and combustion chamber crud really need to be cleaned the old fashioned way using elbow grease.

From this point forward, regular TX of fuel additives and intake cleaning should actually help.

HTH.:cheers:

#6 cyl
IMG_5006.jpg


#1 cyl
IMG_5010.jpg


all cyl
IMG_5007.jpg


cruddy intake
IMG_5022.jpg


cruddy TB
IMG_5024.jpg


cruddy combustion chamber
IMG_5017.jpg


varnish on everything that's lubed by the oil
IMG_4998.jpg


all cleaned up
IMG_5047.jpg
 
Last edited:
You think using 91 octane would reduce carbon buildup?

I don't know...not sure if octane would help with the carbon buildup; someone with more knowledge can answer that. I think I may have oil leakage past the intake valve stem seals that are worn.

I also wonder if the usage of Rotella motor oil contributed to this varnish issue.
 
I would concur that using higher octane is only going to mask the underlying problem.

Sounds like alia's methodology might be more in line.
 
isn't there some sort of detonation sensor and auto adjustment? Can any of this get out of wack?
 
I'd be more worried about the pinging causing a head gasket failure. Detonation produces extreme pressure spikes in the combustion chamber that can cause a lot of extra stress. If it really is just light throttle it may not be a big deal. My 3FE had the common light throttle/low rpm ping until the bearings failed and I rebuilt it. Anyway I'd continue to try and get to the bottom of the root cause.

Good details on detonation here: Engine Basics: Detonation and Pre-Ignition: Streetrod Stuff
and here:
J&S Electronics • Tech Articles
 
I've been eyeing that J&S ultrasafegard for the Tacoma for a while.....
 
Well, it looks like we have at least one person here who has pinging (detonation) related to carbon without a headgasket failure. I'm sure if carbon buildup is causing detonation, with the associated pressure pulsations, that cannot be good for an already weak headgasket. Anyone else have any insight?

alia176, thanks for the thorough posting with pics:cheers:. Did things get better once everything was cleaned of carbon and buttoned up?

For me, I would like to solve the cause of the problem before it causes any other damage...but seeing as though I can only hear it on light-to-medium throttle, maybe it is just something to live with until it gets bad enough to warrant pulling the head? Maybe this really could be a pre-cursor that can be a factor causing weak head gaskets to fail?

I can see the ignition timing pull back when pinging happens using my Scangauge (although it is tough to say if it is really from the knock sensor feedback because it is always all over the place during normal drining), but there are places in the RPM band that the pinging never fully goes away if, say, climbing a moderate hill at partial throttle at constant 2400 RPM.
 
Well, it looks like we have at least one person here who has pinging (detonation) related to carbon without a headgasket failure. I'm sure if carbon buildup is causing detonation, with the associated pressure pulsations, that cannot be good for an already weak headgasket. Anyone else have any insight?

alia176, thanks for the thorough posting with pics:cheers:. Did things get better once everything was cleaned of carbon and buttoned up?

For me, I would like to solve the cause of the problem before it causes any other damage...but seeing as though I can only hear it on light-to-medium throttle, maybe it is just something to live with until it gets bad enough to warrant pulling the head? Maybe this really could be a pre-cursor that can be a factor causing weak head gaskets to fail?

I can see the ignition timing pull back when pinging happens using my Scangauge (although it is tough to say if it is really from the knock sensor feedback because it is always all over the place during normal drining), but there are places in the RPM band that the pinging never fully goes away if, say, climbing a moderate hill at partial throttle at constant 2400 RPM.
Howdy! Obviously, the knock sensor is working, at least to some degree, but is there a test for it other than just replacing it with a new unit? John
 
alia176, thanks for the thorough posting with pics:cheers:. Did things get better once everything was cleaned of carbon and buttoned up?

You're welcome; glad I could contribute to the cause. It's always nice to backup assumptions with pics to help everyone see the real picture. Unfortunately, I got called out of town for work so the engine is still in pieces :crybaby: I'll be home in two weeks to wrap it up. Remind me in a month or two about the Pinging reduction, if any.

One thing is for sure, doing a HG project like this usually brings back some power that's been slowly going away. I attribute this to carbon cleanup, injector balancing and vacuum hoses replacement. I've seen this on the wife's 80 and two buddies' 80s. I'm hoping/praying the same for my 80 :hmm:

Cheers.
 
I've been eyeing that J&S ultrasafegard for the Tacoma for a while.....

I run one on my built 3FE. I had mild detonation before the rebuild and wanted to make sure that if there were still problems after that I would have some extra insurance given the rebuild cost. No detonation after the rebuild so now I run more timing. The Vampire units are easy to set up and use. Tough to get hold of J&S though.
 
I run one on my built 3FE. I had mild detonation before the rebuild and wanted to make sure that if there were still problems after that I would have some extra insurance given the rebuild cost. No detonation after the rebuild so now I run more timing. The Vampire units are easy to set up and use. Tough to get hold of J&S though.

Nice to hear. Tacomas are notorious for pinging after installing the S/C. Even with fuel mods I had to pull more timing than I liked. Don't have the issue with the cruiser but you never know.
 

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