ErnieD

From a previous post:
"I have a 2004 coupe and it has always had a tendency to ping -- sometimes more than others. Strange thing, the tendency to ping subsided somewhat around April or May , was fairly decent throughout our hot Summer, then just started getting worse about the first of September, or so. Must be the gasoline blends. Any other thoughts?"

As I thought about the above performance, and did a bit of additional research, I discovered that California changes their blends between Summer (less volatile blend) and Winter (more volatile blend) in March and November, respectively ...except this year, they changed to Winter blend early, around mid September, due to hurricane Katrina and the gasoline supply issues. Sure does seem that my car's pinging is worse with the Winter blend, which is more volatile. The pinging doesn't seem to be affected much by changes in temperature, either coolant or ambient. Enough 100 octane racing fuel (mixed with 91 octane) to bring a tankful up to about 93 or 93-1/2 octane completeley eliminates the pinging, by the way.

The pinging is at it's worst in 2nd gear, heavy throttle, and mid rpm range -- I'm guessing that's about where we go from closed loop to the power enrichment mode. It's not as bad in higher gears, lower rpms, and heavy load, but still pings some under those conditions. Anyone seeing similar effects? Done any tuning, or whatever, to fix the problem?

I'm thinking of buying a Predator so I can experiment with slightly retarding the timing and slightly enrichening the mixture from stock settings. I'm guessing that one or both of those changes would fix the problem and also allow me to redo the settings should my dealer reflash the ECM during a future warranty or recall visit. Comments and ideas are welcome.

Thanks, Ernie

Dirty Howie

I just add a little Torco and ping is gone.........


DH

SLPRC5

DH...maybe not and maybe so.
Cali gas is :"RFG" Reformulated Gasoline for California. What brand gasoline do you use. IMHO Chevron works best in Corvettes. Try adding Techron to your gas. You also can use Sea Foam in the gasoline. Your car is too new for carbon build up in the cylinders. Have you tired adding an octane booster? This may help or at lease let you know it's low octane..maybe also there was a mix up in the tanks where you get your gas.Good luck
Rsty

blu00rdstr

Google ethanol and how it improves the RON+MON/2 octane number. In short, ethanol improves RON (low load ping resistance) and oil companies can skimp on the MON (high load ping resistance). Since the two still add up to 91, they can sell it as 91octane.

Ethanol has 70,300BTUs per gallon, gasoline has 104,000BTUs per gallon energy. An ethanol blend leans out the engine 5-10% which can cause pinging also.

WALLstAL

I have had my car since Nov. 99 and pinging has never been a problem even when it was stock. I have no idea what to tell you, 91 works for me. Even now with my compression at 11:1.1 have no pinging at all, I do add a quart of Torch to keep the PCM in the upper fuel tables for performance.

ErnieD

Thanks for the comments. I use Chevron 91, mostly, but have used a few other brands with very little, if any, difference. I have tried Techron with no change in the pinging. I suspect Torco would help, since the racing fuel does, and may try that.

I've heard, with no real substantiation, that the 2004's were tuned a bit leaner from the factory. I'm still thinking that a slightly richer mixture and/or a couple of degrees less timing advance at the critical areas would solve the problem. If I get a solid fix for this, I'll post the solution. If I decide to "spring" for the Predator, I'll post results, good or bad.

Ernie

BLOWN'NC

get with jbsblownc5 on here, he's in Cali too.

EVILNESS

have car tuned by a local tuner for crap **** gas we get here. Make sure he tunes it a lil rich just in case u get some bad gas. the part that interests me is that if u have read the manual it states that u can even run 87 in the car. if u are pinging on 91 I can't imagine with 87. get a tune or tune it urself u will be much happier. sorry about the spelling and punct. I'm trying to type from my phone

Dirty Howie

Rusty

I only use Chevron

My car has a little over 50K miles......90% freeway cruizing

SeaFoam in the gas never heard that before!

Torco is sure fix for any pinging I have had. I get some from Joel (jbsBlownC5 here on the forum)


DH

C5-BRUCE

I'd like to ask if the engine has been modified, specifically a custom chip program? Another name for pinging is (as we know) pre-detonation. If 91 octane fuel is being used and pre-detonation occurs on a semi-regular basis, even if only under heavy load, there is every possibility for severe engine damage. This is NOT normal!

The computers (ECM and PCM) adjust for variations in octane and altitude, usually within 50 miles of driving. Combined with the knock-sensor, no pre-detonation should occur? Perhaps the knock-sensor needs to be replaced?

edensknight

Cali is notorious for switching blends throughout the year. Period. And, Californians subsequently suffer the annoying pinging during summer, and/or, heavy load. Personally, I have found that adding the large bottle of Techron II to a full tank of gas helps. Moreover, as stated above, you could add race gas to bring the Octane mixture rating closer to 93. Frankly, when I am travelling out of state, and, see a Sunoco with 93 Octane, I fill my car up to the max. And, the pinging disappears.

2KREDVert

If you can get a hold of some toulene, add it as an octane booster. That's what the oil companies use. Also, here in CA don't worry about the brand of gas, they all exchange supplies anyway just like banks do currency. I use Costco cause it is the cheapest.

C5-BRUCE

Guess I wasn't clear? An octane booster only masks an underlying issue. It doesn't matter whether you're in California or Brazil. The computer(s) adjust for octane and altitude, within limits of course, which is why I asked about a custom chip. Techron is not an octane booster, it's an injector cleaner and really helps to prevent contamination to the sender/sensor units in the fuel tanks. Last I checked, Techron was $7.99 for a 12oz bottle (Colorado-Pep Boys). Am I missing something here?

SLPRC5

"Sea Foam" is the product name. You can get it at Auto Zone. For more information on it put it in the forum search box and it will come up showing how other members use it. It can be poured in the PCV port or brake booster vacuum port. The can says you can add to your gas..I did the later. Come to find out my Superchips tuner was not calibrated for the CALI gasoline with "RFG". So I'm waiting for it to be returned with the proper calibration to see if it will still cause pinging with the new calibration.

Rsty

SLPRC5

big write up on the toulene used as an octane booter. I agree if need be use it.

SLPRC5

I would think the car is too new to have knock-sensor problems, BUT you never know. Again..it could be bad gas...advertised at 91 and might be 89, it has happended before.

C5-BRUCE

My car is a 2000 6-speed and I live in Colorado Springs (6,100 feet). I typically run the mid-grade (87) and it does just fine. When on sprited caravan runs through the Rocky mountains I fill up with premium, which here is only 91. Yes, altitude does make a difference.

GeorgeB

6 speed moded 2001 CA here too and I have yet to detect even the hint of a ping under any conditions. That is with 10.75:1. I guess the dyno tune was done right.

ErnieD

I appreciate all the suggestions. The car has 13,000 miles on it and is stock except for a GHL catback exhaust and a Z06 airbox cover (I even use a stock paper filter, for best filtration).

The car doesn't seem to ping at altitudes of 6,000 to 8,000 feet (Lake Tahoe and some of the No. Calif. passes), and in fact seems to run very well at altitude, but most of that driving has been on Summer blend.

The last three tanks of fuel have all been Chevron, from three different stations, and none of the three tankfuls has been noticeably better or worse than the others. I still think that the change to Winter blend has made the difference. On a hot day, with Summer gas, the engine would ping lightly a few times, then the knock sensors would come in to play and pinging would subside. Now, with Winter gas, it pings enough that I won't hold the throttle down long enough to see if the ECM will pull enough timing to finally stop the pinging. Maybe the solution is to run a few gallons of racing fuel per tankful in the Winter and just let it ping lightly on occasion during the Summer.

Thanks again, Ernie

debmwb

Be sure you add a PCV catch can on your '04. I have an '04, and have had pinging issues too. The 04's are tuned different from the factory, and the oil draw that occurs from the PCV system seems to have quite an effect. I have almost no ping since I added a catch can (that's on 93 TX gas with additional timing added via a Pred).

Just my $.02