Engine ping under light throttle

nis350

Ok.. motorkote may take care of the vvel noise.

Let's get back to the engine ping condition....

Optimiser

ZoomZ

I did: I don't know the answer.

Back to the engine ping.

ZoomZ

Are you able to get higher than 91?

Do you know any airport that sells Auto or "MOGAS" at small airports? They are (Should be) Ethanol free and usually 92 Octane or higher.

Don't worry, it's not jet fuel or Avgas, but plain old car gas. Just no Ethanol and usually higher than 92. Not sure if it's possible in California. But check.

Maybe a quick drive to Oregon, if they sell higher than 91.

Jhill

Use whatever you wish it's just my opinion to buy and oil and pay more to add stuff to it when you could just buy a top grade oil that you can ensure all additives are blended to work together.

Just doing some light digging there is some speculation that there is chlorinated parrafins in motorkote (from independent lab test on bobistheoilguy) which can cause corrosion.

https://www.expeditersonline.com/for...bricant.49273/

Scroll to existenz post for links to other relevant data.

If you believe in it and think it works then great go ahead but I'll just rather stick to something developed with all additives working together and have multiple long term test data to back up claims.

FERRARI

Have you guys ever gone to an airport to get very high octane fuel ? That is what is causing your ping........low octane fuel..................

RadioFlyer

To the OP, about the pinging -

Do you have a cold air intake? I do, so I'm not sure how this applies to the stock intake, but if you monitor your Intake Air Temps, (on something like the Torque app for android or Dash Command for iOS) you'll notice that when you sit in traffic for a while, intake temps skyrocket. Other times when I've noticed this was when I'm running errands and I park the car for a couple minutes and get back in it.

What happens is the intake pulls from the front of the radiator, or somewhere in the front of the car. It's designed to pull colder air when the car is moving, but when you stop in traffic, all of the underhood heat spills out wherever it can, and ends up going into the intake. This is heatsoak. I've seen intake temps in the 120* range in traffic or in a drive through on a 70* (ambient) day. It sometimes takes a minute or so to drop back down once you get moving. So your pinging is probably because of a +50* difference in air temp. If this happens enough, then your ECU will adjust to the temp spike under those conditions, and adjust the Long Term Fuel Trim, so it should go away eventually.

Jhill

Ok this post has gone far enough I think and is becoming a bigger deal than it really is. As others have said if you want to "test" if it is pre ignition there are stations in California that will sell 100+ Lead free octane, it's super expensive but if you just want a test to confirm it will work. If it is pre ignition the pcm will not "learn" and adjust long term fuel trim for it, fuel trim is strictly an adjustment based on AF sensor feedback. PCM won't "learn" a timing advance, they have a base table with modifiers based on IAT/ECT and other variables but will always try to go to that "calculated" base timing, if severe enough knock is detected it will reduce timing to a certain degree determined by another table and then creep back to the calculated base map when the condition is no longer present. It will keep doing this dance and is constantly fluctuating much more rapidly than any LTFT.

RadioFlyer

Interesting - I'm basing my post on first hand experience with an 08 G37, is the ECU different on the Z? If it's det/preignition, increasing octane isn't the fix, it just let's you know that it's a combustion problem. What happens if the octane booster stops the pinging? It will only stop it until the tank is empty again. And unless the OP wants to run octane booster at every tank, it'll come back on the next tank. ...Unless the ECU has a way of adjusting for it. And the ECU isn't going to adjust for it unless it sees the problem, which it won't if you're running octane booster.

Between STFT, and LTFT, the ECU has a VERY wide range of compensation. So first it adjusts the STFT, and then if it keeps riding the same compensation when the same conditions are present, then it starts turning that into LTFT. And as far as ECU compensation, my understanding is that it pulls timing based on the knock sensor (so knock pulls timing, while closed loop adjusts fuel based on it targeting stoich). The conditions described by the OP - light throttle, idle, light load, all point to closed loop operation. So the ECU would be adjusting fuel if it's lean. At least that's what I've seen.

ZoomZ

Who ever said increasing Octane was a fix? I said TRY IT!! and who said use Octane booster? Not me. I said get higher octane gas. Stuff that will always be in the tank unless you run dry in which case the car won't run!!!

Please read the whole thread/comment.

ZoomZ

keep drinking your Kool-aid.

I don't see you coming up with suggestions otherwise don't criticize others.

nis350

the car is completely stock and it is an 09 g37s with 7AT.

you're correct about running higher octane (race fuel). it only masks the potential issues and certainly impractical.

It's pita because it is intermittent and can't be reproduce at will. Some of the explanations made sense about engine is tuned for 93 octane and with higher mileage, perhaps it is near the borderline with the highest available 91 octane fuel here in socal.

Are you saying that the ecu should adjust for the lean condition eventually? We have this intermittent ping issue for a long time now.

Jhill

It has compensation for fuel trim based on AF sensor feedback (not knock) but it is a much slower learning process and once learned it will store and save that memory untill reset. This is why it would not be a fuel "trim" issue as it would have been learned already and would have to be running pretty damn lean to cause pre ignition (more than likely DTC set). This is why it is more than likely normal and just the ign map pushing the system to the edge of efficiency and having to pull back a little when/if it knocks as timing is not a "learned value" and constantly changes and tries to stay in the base map.

All the higher octane recommendation is to either proof true or faulse if it is pre ignition. It is a test not a long term fix, unless you wish to run higher octane all the time. Cheaper route is to either go with a custom tune for 91 or just accepte that it is pushing timing to the edge at light throttle tip in.

RadioFlyer

In my experience, it should. If it's intermittent, then my guess is that it's related to the change in weather, and it will adjust to it. My car is doing that here in Socal. If it's taking a long time to make those adjustments, then maybe you have a front O2 sensor beginning to go bad. When it runs in closed loop, it reads off of the front O2 sensors, so if it's getting slow readings, then it would make slow adjustments. But again, this is just my experience and what I learned when I tuned my car. Some folks here are getting all heated about it, so take my suggestions as just another fella on the internet. Best of luck!

Optimiser

Cheaper route is to either go with a custom tune for 91 or just accept that it is pushing timing to the edge at light throttle tip in.[/QUOTE]



I've accepted my similar condition and am not worried or believe it's causing any damage at all to the engine.