Valve Pinging
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Senior Member
Joined: Dec 1999
Posts: 954
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From: Annandale, VA
Car: 1991 Formula Firebird
Engine: 2001 LS1 Modded
Transmission: 2001 4L60E Yank SS3600 TC
Valve Pinging
Recently I started hearing pinging on a regular basis. Could it be bacause of a bad knock sensor?
The car had a complete tune-up last year with new o2 sensor and clean/flowmatch injectors, etc. EGR was clean. Car is run on 93 octane. Anyone thoughts?
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91 Formula 305 TPI Stock
88 Formula 350 TPI Stock
The car had a complete tune-up last year with new o2 sensor and clean/flowmatch injectors, etc. EGR was clean. Car is run on 93 octane. Anyone thoughts?
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91 Formula 305 TPI Stock
88 Formula 350 TPI Stock
TGO Supporter
Joined: Aug 1999
Posts: 14,811
Likes: 1
From: Jackson County
could be the senser, but not likely. i'd change fuel or look at timing
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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM
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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM
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Joined: Jan 2000
Posts: 19,655
Likes: 309
Wm,
The ECM and EST (including the detonation sensor) should control any preignition/pinging. If what you are hearing is indeed spark knock or preignition, the system is apparently not functioning. This can be caused by a failing detonation sensor, failing EST/ESC, excessive base timing setting, or an extremely lean mixture that the ECM cannot detect.
If you are cetain it is not mechanical noise or an exhaust leak (which can sound like a ticking or pinging under load), check the base timing setting. After the timing is set correctly, reconnect the EST bypass connector and monitor the timing marks again. The idle timing should have advanced significantly.
You can try to induce a knock retard by lightly tapping on the metal body (cup) of the sensor with a screwdriver handle, but it is pretty difficult to reach and watch the timing marks at the same time. The sensor is buried in a nice, tight, hot spot on the engine. Sometimes you can monitor the timing marks and detect a retard by the EST when tapping on the sensor.
The other common causes of detonation are a failing EGR (which you already addressed), excessive carbon in the chambers causing high static compression and hot spots, excesively lean mixture (which the new O2 sensor should prevent or at least detect), low fuel octane, excessive fuel volatility from additives, or driving a Mitsubishi and expecting any kind of performance.
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Later,
Vader
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Justice and Freedom will Prevail
Adobe Acrobat Reader
The ECM and EST (including the detonation sensor) should control any preignition/pinging. If what you are hearing is indeed spark knock or preignition, the system is apparently not functioning. This can be caused by a failing detonation sensor, failing EST/ESC, excessive base timing setting, or an extremely lean mixture that the ECM cannot detect.
If you are cetain it is not mechanical noise or an exhaust leak (which can sound like a ticking or pinging under load), check the base timing setting. After the timing is set correctly, reconnect the EST bypass connector and monitor the timing marks again. The idle timing should have advanced significantly.
You can try to induce a knock retard by lightly tapping on the metal body (cup) of the sensor with a screwdriver handle, but it is pretty difficult to reach and watch the timing marks at the same time. The sensor is buried in a nice, tight, hot spot on the engine. Sometimes you can monitor the timing marks and detect a retard by the EST when tapping on the sensor.
The other common causes of detonation are a failing EGR (which you already addressed), excessive carbon in the chambers causing high static compression and hot spots, excesively lean mixture (which the new O2 sensor should prevent or at least detect), low fuel octane, excessive fuel volatility from additives, or driving a Mitsubishi and expecting any kind of performance.
------------------
Later,
Vader
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Justice and Freedom will Prevail
Adobe Acrobat Reader
Senior Member
Joined: Jun 2000
Posts: 781
Likes: 0
From: Palm Bay, FL
Car: 2007 Corvette Z06
Engine: LS7
Transmission: 6 speed
"or driving a Mitsubishi and expecting any kind of performance."
I know some DSMs around here that would consider thems fighting words. Mid 12s w/o touching a valve cover. Sounds pretty good to me.
Anyways, ESC counter, in a typical 1/4 mile run I get like ~80 counts, Is this normal? 93 octane, 4-6* timing, SLP chip. I'm getting a little worried since I just started N20 and although air/fuel looks good...Rich, same as w/o N20 at WOT, but I don't want to mess up too much stuff. The clutch already is complaining. I'm doing some major work soon(cam/ported stock heads) and I was thinking about changing the knock sensor as well. Suggestions.... 100,000+ miles
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14.62@96mph headers, muffler, chip, ghetto stuff, duct tape
89 GTA 305 TPI 5 speed 3.42 gears
I know some DSMs around here that would consider thems fighting words. Mid 12s w/o touching a valve cover. Sounds pretty good to me.
Anyways, ESC counter, in a typical 1/4 mile run I get like ~80 counts, Is this normal? 93 octane, 4-6* timing, SLP chip. I'm getting a little worried since I just started N20 and although air/fuel looks good...Rich, same as w/o N20 at WOT, but I don't want to mess up too much stuff. The clutch already is complaining. I'm doing some major work soon(cam/ported stock heads) and I was thinking about changing the knock sensor as well. Suggestions.... 100,000+ miles
------------------
14.62@96mph headers, muffler, chip, ghetto stuff, duct tape
89 GTA 305 TPI 5 speed 3.42 gears
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