It's not a sweet spot; it's really more of a "must" spot. When my coolant gets over 200, my engine starts pinging under load. And, the hotter it gets from there, the worse the pinging gets. It gets REALLY bad in the 220 range - to the tune that I am scared I'm going to bend some valves or something, so I have to drive very gingerly, if I drive it at all, when it gets that hot. Good thing I know what causes it to get to 200+ and, more importantly, know how to remedy that problem.

 

What happened to your recommendation in 2009 to do this procedure at least once a year? Is this first time you did this since 2009? It sounds that way because you reference the amount of crap you got out this time versus when you did this in 2009.

 

What OCTANE fuel are you using and where do you get fuel?

 

To be honest, I had forgotten all about it, I guess because everything was fine for so long.

 

Using the highest I can get here in Nor Cal, as always. Tried all major brands, no difference. Always stay away from budget brands. Remember, I only get ping when the engine top-end gets too hot, as is evident from the clogged radiator fins.

 

Thanks, I appreciate the advice.

 

No codes after knock?

 

Nope.

 

Copied from a Bill Curlee post... looks like something you might want to check... PING= no-waynoo


The only way that you can verify that you actually have KNOCK and the engine is properly reacting to the problem and retarding timing is to DATA LOG the engine.

Do you know anyone with EFI Live or HP Tuners??

Several things can cause KNOCK/Pre Detonation. They are

High Cylinder temps
Poor Fuel Quality
Lean AFR
Timing to high
EXCESSIVE Carbon in the cylinders

-Clean the radiator and make sure that you have good air flow (fans working properly

How are you reading te DTCs???????????? Proper procedure listed below:

DATA LOG the PCM!


Your PCM should detect Knock and go into the KR mode and drop spark timing and or go into the low otcane spark tables.

 

I understand these things. But, like I said, it only happens when the coolant causes the top-end to get too hot. While easily duplicated, it is definitely not desired! :-) Of course, in my case, the resolution has been to remedy the overheating, as has been demonstrated the first time in July 2009, and again in June of this year. Nothing more needs to be done, because my engine doesn't ping when run in the proper temperature zone. Thanks for excerpting Bill's info. Anything from Bill is worth a read!

 

Cool... just doesn't seem like a NORMAL situation, I don't think I have ever heard of anyone else hearing ping or knock because their car got up to 230 ish...maybe most of us are so old and deaf we just don't hear it lol

 

I see your point. But, from what I'm experiencing, I'd be surprised if others did NOT experience ping when their C5s overheat.

That said, I believe that cars have a bit of individuality. What I mean is, my car's typical operating range is mid-180s on highway, and mid- 190s in traffic on hot days. So, 220-225 is definitely hot and starts to ping under load, like coming off a stop on an incline (I have an MN6). After parking, I smell coolant when it hits those high temps, whereas I normally don't smell coolant. Of course, my car is not supposed to run that hot, as we know by the temps it hits with and without clogged radiator fins.

Now, someone else's car may typically run 190 highway and 200 in traffic on a hot day, so maybe their "high" is 225-230. Either way, 30 degrees F is relatively "hot" compared to their normal temps. Not sure if there would be a difference between 6-speed and automatic (I wouldn't be surprised if there was a difference), but I would venture to guess that if that person also has a 6-speed, I'd be really surprised if it doesn't ping when theirs gets to their hot range.

Then again, how many of us actually experience our cars overheating like mine did in 2009 and then again just recently, you know what I mean? In fact, when it happened in 2009, it ran that hot for quite a few days before I finally figured out that it was indeed overheating, and what the cause was, and in the meantime the heat burned out my oil pressure sending unit.

BTW, what is yours, auto or stick?

Edit: I forgot to mention that when I got hot and had ping, I actually noticed a power loss from the pinging. Either that, or it was because I was alarmed and thus more conscious of how much lead I put into my foot!

 

04 vert 6spd... Ti cat back exhaust, Vararam CAI, Chuck CoW street tune, 160 degree stat, reprogrammed fans...runs 187 degrees hiway...
Now that were discussing it I think I do remember getting some detonation when we first got the car and were in OKC on a HOT day and the car was running pretty hot... was right after that, I pulled our radiator out after trying to blow it clean with air and NOTHING would go through it.. mind you this is a 20k mile car... Pulled the radiator and it was COMPLETELY blocked ... no grass, no seeds, no trash, the whole radiator was full of little tiny clay brickets between the fins.. it took several washings and rinsing with power washer and garden hose before I could see clearly thru the fins when I held the radiator up to the sun... hasn't been an issue since...

 

Aha! So, fin blockage is not an uncommon thing. And, neither is failure of an air compressor to blow out the debris. Well, at least you know now (from my experience x2) that you don't have to yank the radiator, just tap-tap-tap.

Why is it that you always feel so much better when someone else experiences the same problems you do? Oh, right... misery loves company!

 

Do you happen to remember your fan settings? Just curious. When I was having mine reprogrammed, I specifically requested 178 for low fan, but tuner talked me out of it, and insisted on 183. Hence mine are 183 and 188. While it bothered me to no end for quite some time, I think in the end 183 puts less wear on the fans for me, because my car usually runs between 180 and 183, so a 178 setting would mean much more "on" time for the fan, subsequently probably (two adverbs in a row?) meaning a shorter life.

 

I do not know how the fans were programmed I need to call Chuck anyway I'll ask if I remember...

 

It seems like you PCM could use a tune, T1 corvettes (stock Corvettes with saftey equipment) typically qualify at 230 degrees and after a 20 minute race the temps are around 250. That is using a stock radiator. When running HPDE's my oil temps usually run 265 and water is between 230-235. Around town I have a stock stat and have the fans turn on at 194 and 210 (AC) and the normal city temps (non-Air) stay at 206 and highway 199. Like it was suggested you should have a scan log run to find your problem.

 

if you suspect it was detonating at 230-240 degrees just driving normally I would definitely datalog the car to verify... I'm not sure how modded your car is but if the fan settings have been tweaked then there's a chance other things in the tune were tweaked as well... some tuners will program the car to pull a degree or 2 of timing when coolant temps get really high and that will help prevent detonation... if my car gets too hot it will go into "reduced engine power" and shut itself off, just depends how the tune is set up but I would definitely look into datalogging the car and having the tune adjusted if necessary

 

It only pings at those high temps at low RPM's, under load, like when coming off a stop on an uphill incline. When it gets into the higher RPM's upon acceleration, there is no pinging whatsoever. At normal temps I can't get it to ping, even if I tried (not that I would want to!).

 

That's when you HEAR it detonating... doesn't mean it may be doing some damage that your NOT hearing ... that would be my concern..
I believe your ping condition is very normal..Low RPMs, Under load, Uphill IF mine still had a audible ping I would data log and get it fixed.... but that's just me