Detonation is killing me, why????
Thread Starter
Drifting
Joined: Jan 2001
Posts: 1,332
Likes: 0
Detonation is killing me, why????
I can hear pinging when im in top gear, A4, and hit the gas to go a bit. I cant understand why all of a sudden its doing this, any suggestions? Shouldnt the computer adjust for this?
thanks,
Chan
thanks,
Chan
Burning Brakes
Joined: Jul 2000
Posts: 936
Likes: 13
Re: Detonation is killing me, why???? (whip383)
You live in California and our gas went to 91. That caused it on mine. Now I try to get to the station that sells 100 octane race gas, and put in 1 gallon race gas for every quarter tank that I need. No more detonation.
Some 93 would do it, just isn't around anymore.
Some 93 would do it, just isn't around anymore.
Thread Starter
Drifting
Joined: Jan 2001
Posts: 1,332
Likes: 0
Re: Detonation is killing me, why???? (DanC5)
yea i thought about that and may have to do it, but the 91 has been around for a while, it just started. the vette has become a dailer driver as of 2 months ago, maybe that has to do something with it, poor car isnt used to so many miles :)
chan :eek:
chan :eek:
Le Mans Master
Joined: Jan 2001
Posts: 6,429
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From: God's Replica
Re: Detonation is killing me, why???? (whip383)
sitting around heating up in traffic will get tha tcarbon sticking more...hmmm 91 octane I guess you could use a lil more. When it is hot and humid these things will ping. It has been HOT and HUMID in the midwest and I have been putting 93 octane and a booster to keep me from pining.
Race Director
Joined: Jun 2000
Posts: 14,537
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From: I don't have to show you any stinkin' badges
Re: Detonation is killing me, why???? (whip383)
Same thing is happening to my car. :(
I assume it is the lousy 91 octane plus the increase in summer temperature. I bought 5 gallons of 100 octane and put it in on a run up to Medford OR recently. The car really liked the added octane, but at $35 for 5 gallons, that won't be happening again real soon. I'm going for a 172 degree thermostat to see if that helps any...
I assume it is the lousy 91 octane plus the increase in summer temperature. I bought 5 gallons of 100 octane and put it in on a run up to Medford OR recently. The car really liked the added octane, but at $35 for 5 gallons, that won't be happening again real soon. I'm going for a 172 degree thermostat to see if that helps any...
Safety Car
Joined: Jan 2000
Posts: 4,965
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From: Midlothian, VA
Re: Detonation is killing me, why???? (NYtoCA)
I found a gas station that has 100 octane in my county. Just wondering if this is a no no with NOS? I'm hoping it doesn't matter.
Frank
Frank
Le Mans Master
Joined: Oct 1999
Posts: 8,205
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From: Tucson AZ
Re: Detonation is killing me, why???? (whip383)
It would be nice to blame it on the gas, because that COULD be the cause, but I suspect the MAF readings producing a lean condition. I have an A4 and run all over the country in the heat and frequently find that the best gas I can get is 90 octane. I have never had a detonation problem. However, when I screwed around with an aftermarket MAF I did! Otherwise, our set-ups are pretty mucch the same. Good luck. :yesnod: :)
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Safety Car
Joined: Sep 2000
Posts: 4,035
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From: Sands Township, Marquette County, Michigan
Cruise-In II Veteran
Re: Detonation is killing me, why???? (whip383)
Pre-detonation (gas dentonating spontaneously before the spark plug firing) is caused by gas with too low of an octane rating. There is no other cause. Octane among the gaoline molecules has the desirable characteristic of a high flash point.
Somehow you need to get your octane rating up. As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane. I have never personally experienced that phenomenon with pump premium.
[Modified by SMFCPACFP, 1:40 AM 7/2/2002]
Somehow you need to get your octane rating up. As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane. I have never personally experienced that phenomenon with pump premium.
[Modified by SMFCPACFP, 1:40 AM 7/2/2002]
Burning Brakes
Joined: Jun 2002
Posts: 767
Likes: 1
From: Noble OK
Re: Detonation is killing me, why???? (Mickyd747)
I use Sunoco 93.5 with no problems, but as it gets hotter you do need higher octane to keep from detonating. There is a good article about this by the people at Vette magazine at http://www.idavette.net/writers.htm read article called gasoline digest. PS they don't recommend av gas. :reddevil
Safety Car
Joined: Jan 2000
Posts: 4,965
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From: Midlothian, VA
Re: Detonation is killing me, why???? (SMFCPACFP)
Pre-detonation (gas dentonating spontaneously before the spark plug firing) is caused by gas with too low of an octane rating. There is no other cause. Octane among the gaoline molecules has the desirable characteristic of a high flash point.
Somehow need to get your octane rating up. As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane. I have never personally experienced that phenomenon with pump premium.
Somehow need to get your octane rating up. As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane. I have never personally experienced that phenomenon with pump premium.
Safety Car
Joined: Sep 2000
Posts: 4,035
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From: Sands Township, Marquette County, Michigan
Cruise-In II Veteran
Re: Detonation is killing me, why???? (C5Noir)
Pre-detonation (gas dentonating spontaneously before the spark plug firing) is caused by gas with too low of an octane rating. There is no other cause. Octane among the gaoline molecules has the desirable characteristic of a high flash point.
Somehow need to get your octane rating up. As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane. I have never personally experienced that phenomenon with pump premium.
Pre-Detonation is also caused by hot spots that could be present in the combustion chamber, also.
Somehow need to get your octane rating up. As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane. I have never personally experienced that phenomenon with pump premium.
Pre-Detonation is also caused by hot spots that could be present in the combustion chamber, also.
Safety Car
Joined: Jan 2000
Posts: 4,965
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From: Midlothian, VA
Re: Detonation is killing me, why???? (SMFCPACFP)
A hot spot is an tiny piece of metal or an unfinished by-product from the machining process that gets super hot, to the point of glowing, thus igniting your combustion mixture before the spark plug fires. Read my Combustion write up in my sig for more info.
Safety Car
Joined: Jul 2000
Posts: 3,596
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From: Orange County CA
Re: Detonation is killing me, why???? (SMFCPACFP)
As some of the other guys have mentioned, get some higher octane gas (like avation gas) and mix with your regular premium gas to boost the octane.
[Modified by SMFCPACFP, 1:40 AM 7/2/2002]
[Modified by SMFCPACFP, 1:40 AM 7/2/2002]
Good luck,
Advanced
Joined: Sep 2001
Posts: 55
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From: Miami fl
Re: Detonation is killing me, why???? (Charley Hoyt)
Everyone is commenting on the Octane Rating of Fuel used but I wondering if this is symtomatic of a problem with the older C5 Auto's which have built up some milage. Could a specific problem be developing with these cars that is now causing the problem. Could it be more than an Octane problem but rather an engine problem.
Just Wondering
Mike
98 Vert Torch Red
Just Wondering
Mike
98 Vert Torch Red
Safety Car
Joined: Jan 2000
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From: Midlothian, VA
Re: Detonation is killing me, why???? (Mickyd747)
Everyone is commenting on the Octane Rating of Fuel used but I wondering if this is symtomatic of a problem with the older C5 Auto's which have built up some milage. Could a specific problem be developing with these cars that is now causing the problem. Could it be more than an Octane problem but rather an engine problem.
Just Wondering
Mike
98 Vert Torch Red
Just Wondering
Mike
98 Vert Torch Red
Advanced
Joined: Sep 2001
Posts: 55
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From: Miami fl
Re: Detonation is killing me, why???? (C5Noir)
Quote
>If boosting the octane doesn't help<
I'm not saying that boosting the Octane will not help but that its masking
a problem with the engine. The A4 will shift into fourth as low as 1500 RPM and 35 MPH. That's fine if the engine is running strong, but if for some reason your starting to lose horsepower, I believe you will run into a situation where your engine will ping. Now the question is, are we seeing a drop in horsepower as the mileage acrues.
Mike
98 Torch Red Vert
>If boosting the octane doesn't help<
I'm not saying that boosting the Octane will not help but that its masking
a problem with the engine. The A4 will shift into fourth as low as 1500 RPM and 35 MPH. That's fine if the engine is running strong, but if for some reason your starting to lose horsepower, I believe you will run into a situation where your engine will ping. Now the question is, are we seeing a drop in horsepower as the mileage acrues.
Mike
98 Torch Red Vert