The dealer can turn back timing 2 degrees with the push of a few buttons...

 

Hope it works out for you... The consult will allow you to pull up to 2 degrees off the car but that's a band-aid fix if its something that is wrong that is causing it besides bad gas in your vicinity.

Hopefully you get a Serv Writer that is willing to listen. Most always jump to the conclusion that you are not using premium which after reading Q's statistic above I can now see why...

But I still feel like they should give us the benefit of the doubt if that is what we're saying. I mean, I own a coupe and sedan bought new with thousands in upgrades and putting 87 in would be my last consideration.

 

Have you noticed that premium use to only command a 20 cent increment, now that sales are half to 1/4 volume it has gone up to 30-40 cents to just maintain gross margin difference.

Those premium tanks are getting cob webs waiting to empty especially in low volume stations.

Just because of low turnover Every other tankfull is now 89 octane, at least I know the 50/50 premium is not totally rotten from sitting evaporating all the good octane away.

 

What do you mean Q45tech? Are they mixing 89 into premium tanks? I couldn't quite follow what you stated above.

 

^^^
Two things...

1) I've never seen him/her/it respond to anything directly to his/hers/its post... only to existing posts... (research, its true)

2) the post he/she/it made isn’t accurate in my area... the difference between 87 and 89 is .10 across the board everywhere around here - and the diff between 89 and 91 .10 (90% of the time), .12 (10% of the time) - for the math wiz's that’s .20-.22 from 89 to premium in 90% of So Cal... but never .20-.30 ever.

Q45tech usually has decent info - almost always is too obscure to be of benefit and this time isn’t accurate at all in So Cal.

 

89 is usually 50/50 reg plus premium..........or some percentage depending on how they feel that day.
The numbers posted on pumps are set by the marketers, not the refineries so they may or may not be real and can change from batch to batch day to day.
Some states actually measure [ randomly sample a few dozen batches per year] octane but not to a specific number just to check that generally Premium is better [higher] than Regular otherwise the charging more would be consumer fraud...........unless Premium is 0.5, 1, 2, 3 points higher.

I live in ATL so my post concern ATL and Georgia and the South in general.

A good read is to study pipeline transport specifications and what happens in the 1-2=3 weeks from refineries to service station tanks.

 

Good info on the gas oct subject. I use Shell V-power 91 exclusively and ping on hot days. Especially when VQ has become completely heat-soaked from sitting for a short time after reaching normal op temps, then drive again. Just b/c it's Shell's V-power doesn't mean their hopeful 91 in storage isn't old and has degraded to who knows what.

91 imo is border-line sufficient for the 298hp rev-up VQ anyway. Hotter advanced timing compared to the 280hp non revups, but don't quote me on that; only an assumption as I've only seen revup VQ timing degree numbers. Compression ratios are the same though.

Another possibility I've concluded over the years on my Cali emission 2006 6mt G, is the lean AFR's from factory OEM tuned ECU maps. My dynos have proved that in the low to mid rpm ranges. Lean = not okay in my book. Saw a 2004 stock Z same dyno day....AFR's not lean.

Knock sensors are audible sensors, then retard timing to stop detonation or somewhat reduce = less power = again, not okay in my book. Sometimes wonder if my sensors even work. Mine will continue to ping if I keep the same load on engine and not left off. Only when I let up on the load, then it'll stop pinging. WTH!!

Can't do much about hot ambient intake temps or guaranteed fuel quality, but can tweak my AFR's to be in check with a custom tune, which is in my horizon after my replaced VQ hopefully proves to be healthy with no more oil consumption as it continues to break in.

Oil consumption also kills oct rating, so there's another one to add to the detonation recipe mix.

 

What about the increase in ethanol content over the last couple years?

 

Interesting comments...we have the same prob with the detonation. I have always believed that it is a combination of excessive heat, and poor gas/inadequate resistance to detonation. I have since reduced my coolant mix to about 40/60 water to increase my coolants "wetness". i have noticed an increase in hp, and a small reduction in pinging...I do mean small. I'm considering reducing my coolant mix another 10% to about 30/70 and see where that gets me. all this because there is not much I can do about the gas, unless I want to buy additives every time I fill up which is not an exciting prospect at the cost of fuel these days! Has anyone solved this problem by re-flashing their ecu/re-adjusting their timing. I notice the z's don't seem to have this prob?

 

I've had the same exact problem for years. Took it to the dealer a few times and they said everything checked out fine. The check engine light (multiple cylinder misfire) would occasionally come on but soon go away before I could make it to the dealer. I have a z-tube and stillen intake. My car is now out of warranty so I just avoid heavy throttle at lower RPM's.

 

Wow...great service...OK...well, I have reduced my % of coolant to water and have added a "wetting" agent. So far I only have ping after the engine is warmed and I park for awhile and then restart. All the other pinging has gone away. Not a solution, but an improvement!

 

Just learned that the EGR system can cause detonation if not operating up to pare and won't neccessarly throw a MIL.