Faint detonation noise
05-02-13, 07:36 AM
#1
Lexus Champion
Thread Starter
Faint detonation noise
Fo the last two years, I've been hearing the faint detonation sound when starting off. The sound is more pronounced when I'm driving besides another car, or a road divider, which reflect the sound back at me.
It's more pronounce on warm days, and mostly when starting off. It goes away when driving at steady speed, and usually is not there first thing in the morning.
I know the knock sensors are supposed to adjust for that, but I'm not sure if they're just slow to react, or if that is normal.
No CELs, no codes in memory, and the car starts and drives fine. I normally use regular fuel, but I tried a couple of tanks of the highest grade fuel available, and from different suppliers, but it made no difference.
I dont think that im supposed to hear anything, but Is it normal to hear some faint detonation?
Car is a 2001es300 with about 100,000 miles. Timing belt was done last year by Lexus dealer.
Any feedback?
Thanks!
Phil
It's more pronounce on warm days, and mostly when starting off. It goes away when driving at steady speed, and usually is not there first thing in the morning.
I know the knock sensors are supposed to adjust for that, but I'm not sure if they're just slow to react, or if that is normal.
No CELs, no codes in memory, and the car starts and drives fine. I normally use regular fuel, but I tried a couple of tanks of the highest grade fuel available, and from different suppliers, but it made no difference.
I dont think that im supposed to hear anything, but Is it normal to hear some faint detonation?
Car is a 2001es300 with about 100,000 miles. Timing belt was done last year by Lexus dealer.
Any feedback?
Thanks!
Phil
Last edited by PFB; 05-02-13 at 08:32 AM.
05-04-13, 08:09 AM
#3
Lead Lap
Pretty common on these motors. My 01 ES does the same on 87 octane gas, if I use 91 or higher it does not for me. You might have some other issue if it does that on the high test.
The knock control on a 2001 vintage is going to be a bit more primitive, it will adjust for knock but controlling it on throttle tip in is difficult from an engine control standpoint. The latest cars have more long term feedback where if you use low octane gas all the time your car would anticipate it in a sense but I don't think our old Lexus has this sophistication.
The knock control on a 2001 vintage is going to be a bit more primitive, it will adjust for knock but controlling it on throttle tip in is difficult from an engine control standpoint. The latest cars have more long term feedback where if you use low octane gas all the time your car would anticipate it in a sense but I don't think our old Lexus has this sophistication.
05-04-13, 01:36 PM
#4
Lexus Champion
Thread Starter
Pretty common on these motors. My 01 ES does the same on 87 octane gas, if I use 91 or higher it does not for me. You might have some other issue if it does that on the high test.
The knock control on a 2001 vintage is going to be a bit more primitive, it will adjust for knock but controlling it on throttle tip in is difficult from an engine control standpoint. The latest cars have more long term feedback where if you use low octane gas all the time your car would anticipate it in a sense but I don't think our old Lexus has this sophistication.
The knock control on a 2001 vintage is going to be a bit more primitive, it will adjust for knock but controlling it on throttle tip in is difficult from an engine control standpoint. The latest cars have more long term feedback where if you use low octane gas all the time your car would anticipate it in a sense but I don't think our old Lexus has this sophistication.
What do you mean however when you say "controlling it on throttle tip in is difficult from an engine control standpoint"?
Phil
05-04-13, 05:12 PM
#5
Lead Lap
Without getting too technical just saying it's hard for the engine control to react to knock as you are putting the throttle down from a stop. A more recent or advanced control keeps track of ignition timing over time and anticipates the knock by dialing back timing. Think of it like the difference between reacting to low octane gas every time you push the throttle, and realizing you run low octane gas all the time and adjusting accordingly to avoid knock in the first place. I believe our old ES is the former.
05-04-13, 08:09 PM
#6
Lexus Champion
Thread Starter
Without getting too technical just saying it's hard for the engine control to react to knock as you are putting the throttle down from a stop. A more recent or advanced control keeps track of ignition timing over time and anticipates the knock by dialing back timing. Think of it like the difference between reacting to low octane gas every time you push the throttle, and realizing you run low octane gas all the time and adjusting accordingly to avoid knock in the first place. I believe our old ES is the former.
Thanks,
Phil
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