|
06-29-2009 | #1 |
Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,193
|
Knock Sensor; What happens if its disconnected
Could not get this answered on the other forum, if the knock sensor is disconnected does the ECM retard timing?
__________________
LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
06-29-2009 | #2 |
Join Date: Jun 2005
Location: pittsburgh
Posts: 4,632
|
Re: Knock Sensor; What happens if its disconnected
no the ecm does not retard timing since it doesn't detect knock. disconnecting it does nothing positive for you and can only end up hurting, at least according to Haibeck
__________________
It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B" |
06-29-2009 | #3 |
Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,193
|
Re: Knock Sensor; What happens if its disconnected
I did not disconnect, it was disconnected when I put it up to change the clutch. 101 projects for your corvette says it retards timing at WOT, when it is not hooked up.
If ECM does not detect resistance it retards a precaution...per the book. Checking to see if this is accurate.
__________________
LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
06-29-2009 | #4 | |
Join Date: Jun 2005
Location: pittsburgh
Posts: 4,632
|
Re: Knock Sensor; What happens if its disconnected
Quote:
__________________
It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B" |
|
06-29-2009 | #5 |
Join Date: May 2007
Location: Chicagoland, IL
Posts: 9,700
|
Re: Knock Sensor; What happens if its disconnected
Lee,
Looking at the FSM and reading the Diag Charts and reviewing of Code 43, the ECM only retards timing when it receives an AC signal produced by the KS. There's no indication that the ECM goes into a "default" timing if it doesn't "see" the knock sensor. If there's an open circuit, as in your case, then a voltage of either >3.62v or <1.44v will cause the ECM to set a code 43 after 24 seconds. I don't have an answer as to why you don't have a code set. There's a second test the ECM will run under the conditions of Coolant at > 93C and High engine load. If the ECM does not see a response from the ECM, a Code 43 will be set. I also remember that the GN guys would pull the knock sensor connector to avoid KR (Knock Retard). Of course, the LT-5 ignition could be different but the GN ignition is close as it uses Waste Spark. Last edited by XfireZ51; 06-29-2009 at 11:17 PM. |
06-29-2009 | #6 |
Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,193
|
Re: Knock Sensor; What happens if its disconnected
I guess we will find out when the clutch goes back on, I would think there would be some kind of protection for the engine in the event the wire came off.
__________________
LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
07-01-2009 | #7 |
Join Date: Jul 2007
Location: Bartlett, IL
Posts: 7,161
|
Re: Knock Sensor; What happens if its disconnected
C'mon guys..
If you unplug the Knock Sensor.. then the Knock Sensor does not work
__________________
1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
08-07-2014 | #8 |
Join Date: Sep 2008
Location: Speedway, IN
Posts: 132
|
Re: Knock Sensor; What happens if its disconnected
The ECM does check this circuit periodically by advancing timing to trigger spark knock and checks to see if the sensor detects it. I had a bad pigtail connector and was getting a code 43 about every other drive. Replaced pigtail with OE AC Delco part from Advance Auto Parts and no more codes.
|
Thread Tools | |
Display Modes | |
|
|