Knocking or pinging

[Dan]

I think that I am getting some pinging or knocking but it is unusual due to its somewhat diffcult nature to duplicate. I will do my best to describe it and hope that you guys can tell me more.

Basically, it only seems to happen when I undertake strong acceleration from a rolling start. When I floor it it sometimes has a very, very short duration knocking or pinging noise. It seems to occur between 35oo and 4000 RPM and, if I have to get closer I would say 3700 RPM.

It is kind of funny because I noticed this happening in the Trilogy SC when I drove it and it was attributed to bad gas.

Maybe this is the case but it still seems odd to me in that it is so hard to replicate. I can normally make a knocking engine knock on command.

Thoughts, anyone?

Best,

Dan

PS: The car is an 03 with 10K miles and the Supercharger MicroTuner. Otherwise it is stock.

[TripleTransAm]

Does it only occur at WOT? If you held it in 2nd and brought it up to that RPM, would it do it as well?

It could be pinging... I don't know how the Ford PCM handles bouts of knock, but it might be trying to dial back in some spark timing only to have it knock again... I'm thinking this could be a result of the more aggressive tuning of your MicroTuner? I can't say I've experienced this on my stocker.

Bad gas... seems a lot of this is happening lately, coinciding with the extreme price of fuel. Seems a lot of dishonest folks in our society may be 'bubbling' to the surface... sad.

BTW: local fuel price last week (all time high for my 94 octane fix): $3.13 US dollars per US gallon.

[Dan]

Steve,

I'll have to try placing it in 2nd and performing a WOT run and a part throttle run. I think that it is at WOT.

Dan

[woaface]

I've had a similar problem with my car. I tried a couple things but since I've "flushed" my tank...letting it go almost empty, then filling it to the brim with 93...and doing some more 93 at half a tank, and then rarely letting it get below 1/4 a tank...it works fine. Trying to stick to one brand of gas as well...

Although, I'm noticing a new ticking sound...you can only hear it when there is a wall to your left and the window is down (something for the sound to bounce back with) and this is ONLY at idle...it goes away with any amount of gas.

You know...there was an article in MMandFF I think, talking about the 3valve 4.6. They said something along the lines of "Ford has worked hard to prevent ticking and ping with this engine"...I bet ANYTHING Ford knows there's an inherent problem with all of the 281's out right now, 2 and 4 valve.

[darebren]

I have my groaning sound narrowed down to it only happens at low rpm's (like at idle) when i have it in drive and my foot on the brake? when it is in park, it does not happen.. the sound comes from the drivers side middle of car? when i was at the drive up ATM today, it was pretty loud...

[Dan]

OK. This morning I got a bit more technical in the hopes that you guys can help out.

The AM temp was around 60º. I got in the car and got under way immediately. About a half mile later, while rolling up from a stop (this is the point in the MM where it is doing all it can to climb to OD) and at about 20 I gave it some gas and the "clacking" noise came in at 3500 rpm and lasted less than 200 rpm.

Next, I slowed againt to 20 and place the car in gear 2. From there I nailed the gas and again, at 3500 the clacking occurred and went away withing 200 or 300 rpm.

The clacking does not accur at any other point of the RPM curve.

I have yet to test it with the car warm but I will do that next. I have some suspicions that it will be even more fleeting when warm but let me hold my hypotheses until I have more data.

Best,

Dan

[TripleTransAm]

But the real question is... does it still do that clacking if you hold the car at that RPM in a gear like 2nd gear or even 1st? Or in neutral? That will eliminate the chance of it being crankshaft or rotating-assembly related.

[Dan]

I'll check today and again tomorrow morning so as to determine if it is engine temp related, too.

Thanks,

Dan

[sailsmen]

I have never heard knock @WOT. I have heard tip in knock in OD Lock whcih was attributed to a software error and sub corrected.

Which software do you have on the tuner, was it bought from SCT, Lidio, Reinhart and what date was it bougth?

[Dan]

I don't know what s/ware I have on th tuner. It was apparently part of a "group buy" that was done here.

I heard the sound again today. The engine was warm and I hit the gas kind of hard to make a light, possibly full throttle. The ping was right there in the 3500 area of the range.

I did the test in other gears and it seems to always happen in the same RPM range.
Hmmm.

[BillyGman]

For what it's worth, sometimes other problems can sound like pinging. For instance, my brother's Buick Roadmaster always sounds like it's pinging badly. However it's just an exhaust rattle. Something is loose down there, and it only makes the noise when you're on the gas pedal, and it soends like pinging, but it isn't.

So if filling up the tank twice w/93 octane at different stations doesn't remedy your problem, then I think you should have someone put your car on a lift to checkout the entire exhaust sytem to make sure even nothing minor is loose like a bolt on a clamp os something of that nature. Funnier things have happened. it can be something as simple as that. And if it is, then it won't be revealed until that's checked out.

[David Morton]

I have always wondered about how backing off timing helps "preignition" pinging.(?) If it's caused by bad octane, preignition means the cylider fired before the plug did. I don't get it. I think this type of pinging is not related so much to octane as it to engine load and the PCM running too much timing for the load involved even if octane can help it run more timing. I relate the true 'knock' back to those carburated engines that wouldn't stop running when they had bad gas in the float bowl and you turned the key off. That's the sound that worries me. On this engine, I'd be thinking carbon build-up on the piston, if your using the proper grade gas. Run some top-engine cleaner in your gas for one tankfull and then run it in first gear to the redline for a half mile or so. Just kidding.

Is it a ping or a knock? And did I hear somebody say 'clack'?

[BillyGman]

pre-ignition, and pinging(aka "detonation"), are actually two different things. Pre-ignition is the run-on you get after turning the engine ignition off like you've described. Pinging or detonation is the air-fuel mixture burning either way too quick, to a point that it's actually an explosion rather than an expansion of heated air like it's supposed to be(thus the term "detonation"), or it's because of carbon deposites heating up and igniting the air/fuel mixture in the combustion chamber so that the flame front of the ignited air/fiel mixture is actually on two sides of the chamber. On one side from the spark of the plug, and on the other side from an overly heated carbon deposite which can act like a glow plug. In the latter case the two flame fronts in the chamber collide w/a harsh percusion into the piston head. NOT good.

In newer engines w/low mileage which usually will not have such excessive carbon build-up, providing the air/fuel ratio isn't way too rich, the likely cause of pinging would be the former case. The air/fuel burning much too rapidly, and expanding too quickly before the piston reaches Top Dead Center("TDC"). If the timing is too far advanced, then even w/high octane gasoline which will not burn as quickly, or "detonate" as easily, the airfuel mixture is ignited too far in advance of the piston reaching TDC.

So therefore the flamefront of the Air/fuel is expanding too soon before the piston is headed for it's downward motion during the power stroke. The piston is still on it's way up, while the air/fuel is at it's height of this expansion process, and there's no where for the pressure to go but to crack against the piston top, and that's when you hear the pistons rattle, or "ping". Again, not a good scenario.

An overly lean air/fuel ratio can cause exccessive heat build-up and make this whole nasty scenario more likely to happen. And yes, a lower octane fuel will also burn faster and be ignited easier, and is more prone to pinging or detonating in the first place. So pinging can be the result of a combination of problems. The most common ones being an improper ignition timing curve (which would allow the ignition to become too far advanced at any point in the RPM scale, and therefore fire the spark plugs too early, and too soon before the pistons are at TDC), and /or an air/fuel ratio that's much too lean which being excessively lean the air/fuel mixture gets hotter.

All of this is especially critical in a S/Ced engine since "pinging" or "detonation" (same thing) is the one most dangerous possibility to the S/Ced engine. It can melt or crack pistons, and blow head gaskets in short order (even if they're forged pistons), which BTW are the two most common occurences in S/Ced engines that are tuned improperly, or tuned too agressively.

On a side note: this is one of the things that sold me on the Trilogy S/Cer kit, knowing the the chip that comes w/the kit is burned by Lidio, who stresses a conservative approach to engine tuning when it comes to air/fuel ratios, and especially the timing curves in S/Ced engines. Now let me point out that I'm sure that Lidio isn't the only good engine tuner when it comes to this stuff, but he's known by many to be one of the best, and there are other engine tuners who are more concerned w/getting maximum power out of your engine than they are w/engine durability.

[sailsmen]

Dan, if you bought the tuner from Reinhart he did a recall to correct the s/w error, call him.