[Ctrldinsanity]

I have a 2000 xterra 3.3 and recently replaced my knock and ckp sensor. I got it all back together and went to set the timing. While in the adjustment mode it reads 15 degrees BTDC (3rd notch from left) and idles at 725 rpm. I shut it off, reconnect everything and fire it up. Now the timing reads 30+ degrees BTDC and idles high about 1500 rpm. Could one of the sensors I installed be causing the high idle and timing? Do you have to sync the ckp sensor with the ecm? No check engine light, actually runs really good now aside from the high timing and idle. I appreciate your help.

 

[ryan42]

Oddly I have the exact opposite problem as you. With my TPS plugged in I idle low and at 15 degrees BTDC, but unplugging it makes it go to 1500 RPM and 35 or so degrees BTDC. Since mine works correctly in "normal mode" I have not chased the issue down yet.

One thing I'm confused about... you replaced your knock sensor but you have a 2000? I didn't think the knock sensor was equipped unless you had a supercharged model which only happened in 2003 and 2004. Are you sure about that sensor?

 

[RacerXXL]

One thing I'm confused about... you replaced your knock sensor but you have a 2000? I didn't think the knock sensor was equipped unless you had a supercharged model which only happened in 2003 and 2004. Are you sure about that sensor?

All Xterra 1st Gen engines, VG33E and VG33ER, have a knock sensor.

 

[Ctrldinsanity]

Ya unfortunately they do and I would like to slap the engineer who put it where they did. I know it's there for a reason but damn...

The problem was, the truck wouldn't tell me what was wrong (no CEL) no matter what. Pretty sure I got it figured out though, I finally said screw it and drove it the way it was -Got 2 blocks from the house and the CEL came on. Took it back home and hooked it up to the scanner and got a code for closed throttle switch and TPS circuit, here's how it went.

Hopefully this will save somebody some time one of these days.

The TPS has 2 harnesses. The top harness is a closed/wide open throttle SWITCH. The bottom harness is the actual positioning sensor.

With the throttle closed, the CTS (top harness) should be sending battery voltage to the ECM. When slightly cracked open (reving to 2000 rpm per manual), the voltage should be 0. At 2500 RPM I was still seeing battery voltage, which was telling the ECM the throttle is still closed.

Next I checked the positioning sensor itself (bottom harness). With a closed throttle I should be seeing .5 - .78 volts from the positioning sensor. Closed I was getting 4 volts which is telling the ECM the throttle is wide open. When I moved the throttle a bit it would drop back down to .80 volts but no lower. So bad TPS

I rigged/adjusted the TPS to get the numbers I wanted, it idled at 1100 but the issue and CEL went away. I bet your having the same problem just different extremes. I would check the numbers coming out of your TPS and match it to what the book says and SOON, apparently running it this way will destroy your Catalytic converts quick and the damn thing has 4!