VCT Questions

[robomatic12]

Tonight as I was diagnosing a code 34 I finally realized the previous owner had done the detonation sensor bypass on the WRONG plug!!! The bypass resistor was placed on the VCT connector for the left solenoid and hooked up to the detonation sensor. As well as the detonation connector was being plugged into the VCT solenoid. I've heard this is quite a common mistake (mixing up the two connectors) but could that 1M ohm resistor on the VCT connector screwed something up? It worries me it's been like that for the past year. I'm also assuming I've been missing a little bit of power from the valve timing not working properly?

[es.biggs]

It shouldn't have damaged anything. VCT definitely affects performance and like you said it probably hasn't been running right the past year. But just switch them back and hope for the best; I doubt anything is damaged.

[marty1mc]

But, bypassing the knock sensor is dangerous! I would, at a minimum, buy a new sensor and harness and bolt it to the back of the plenum. There is a kit available for this. Then, when you pull the motor, you can install it in the correct location.

[es.biggs]

Just curious, what is the point in bypassing it? Just to turn the MIL/CEL off?

[marty1mc]

Yea, some due that just to make sure it's the sensor, but then fix it. It's rather dumb to do that and leave it.

[robomatic12]

But, bypassing the knock sensor is dangerous! I would, at a minimum, buy a new sensor and harness and bolt it to the back of the plenum. There is a kit available for this. Then, when you pull the motor, you can install it in the correct location.

It's not bypassed anymore now that it's hooked to the correct connector! I had bought a new harness and the knock sensor was good the last time I pulled the motor. It never tripped the 34 code until the last month because I'd checked before. Now it's running no resistor with the correct location det sensor. I agree if Nissan put the det sensor there, there's a reason for it.

[marty1mc]

It's not bypassed anymore now that it's hooked to the correct connector! I had bought a new harness and the knock sensor was good the last time I pulled the motor. It never tripped the 34 code until the last month because I'd checked before. Now it's running no resistor with the correct location det sensor. I agree if Nissan put the det sensor there, there's a reason for it.

Good. I doubt anything is screwed up due to incorrectly plugging the connectors. I would correct this and drive it. At first, drive it slow and through 3k rpm. The variable valve timing on a VG motor is actually engaged under 3k rpm (I think it advances timing 10 deg). The timing advance helps with low end torque. After 3k, it kicks out. So, you should see better low end response when you straighten this out.

[robomatic12]

Everything feels fine, I do notice the difference which is quite nice I had a bit of power to be found for free. Thanks guys for the info