Yet another knock sensor ECL thread
Thread Starter
Teching In
Joined: Jun 2024
Posts: 5
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Yet another knock sensor ECL thread Vehicle background - the car is a 2000 Firebird Formula - a bit of a Frankencar
Bought with an unknown history ...
had to do an engine swap - got a 6.0 to replace the 5.7 - paid to have that done
102 mm throttle body moved over
FAST intake manifold moved over
ECL was on - both knock sensor codes, when the car came back from the shop - they said "when you take it to the tuner, that'll fix that" ... ignorant me ...
took it to a "tuner" - tuned - but still ECL - he said "need knock sensors" - once agin, ignorant me ...
in short - chasing an issue that has existed since I got the car.
----------------------------------------------------------------------------------------------
fast forward - read many threads here - especially this one:
https://ls1tech.com/forums/pcm-diagn...ow-voltage.htm
-replaced the knock sensors and harness, reset code. codes came back within 50 or so miles.
-tested new sensor "tail" to ground - 100.1K ohms resistance, both sensors - so they look good.
-created a test harness with (2) 100K ohm resistors (thanks @Rob WS6 ) - connected between the sensor => PCM plug and ground. codes still popped after < 50 miles.
-unplugged the c1 connector from the PCM - tested resistance to ground from pins 11 and 51 - 100k ohms - disconnected test harness and retested - open circuit - so I have the right pins, and the harness is good.
-c1 pins all look clean, no corrosion
So - if I interpret all this right, there is a PCM problem? Or, could the tune have something that doesn't match?
what should my next troubleshooting step be?
Thanks
Bought with an unknown history ...
had to do an engine swap - got a 6.0 to replace the 5.7 - paid to have that done
102 mm throttle body moved over
FAST intake manifold moved over
ECL was on - both knock sensor codes, when the car came back from the shop - they said "when you take it to the tuner, that'll fix that" ... ignorant me ...
took it to a "tuner" - tuned - but still ECL - he said "need knock sensors" - once agin, ignorant me ...
in short - chasing an issue that has existed since I got the car.
----------------------------------------------------------------------------------------------
fast forward - read many threads here - especially this one:
https://ls1tech.com/forums/pcm-diagn...ow-voltage.htm
-replaced the knock sensors and harness, reset code. codes came back within 50 or so miles.
-tested new sensor "tail" to ground - 100.1K ohms resistance, both sensors - so they look good.
-created a test harness with (2) 100K ohm resistors (thanks @Rob WS6 ) - connected between the sensor => PCM plug and ground. codes still popped after < 50 miles.
-unplugged the c1 connector from the PCM - tested resistance to ground from pins 11 and 51 - 100k ohms - disconnected test harness and retested - open circuit - so I have the right pins, and the harness is good.
-c1 pins all look clean, no corrosion
So - if I interpret all this right, there is a PCM problem? Or, could the tune have something that doesn't match?
what should my next troubleshooting step be?
Thanks
If you're giving the PCM exactly what it wants to see and it's still throwing the code, then unfortunately it's probably internal to the PCM. Only think I would try first is to reflash the the tune file if you have the ability. 411 PCM?
Thread Starter
Teching In
Joined: Jun 2024
Posts: 5
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Thanks for the fast response! I don't have a tune file or software ... looks like that is next to acquire.
It looks like I can pick up a refurb ECM for about $100 from flashmasters - would a stock tune "run" and act OK with this car? forgive my ignorance, but I'm not sure which mods require a change. It's a quick swap that I could use as a troubleshooting tool.
It looks like I can pick up a refurb ECM for about $100 from flashmasters - would a stock tune "run" and act OK with this car? forgive my ignorance, but I'm not sure which mods require a change. It's a quick swap that I could use as a troubleshooting tool.
Last edited by FraidKnot; Jun 28, 2024 at 08:14 PM.
Do yourself a favor and just have your tuner disable the codes for the knock sensors. This does NOT disable the sensors themselves, just prevents it from throwing a code because it thinks the sensors that you have now are bad. From what I've found all of the "new" versions of the old single wire LS1 knock sensors are just different enough that the PCM thinks something is wrong even though it still picks up knock.
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