Hello all, I've been fighting with my truck for the last 6 months. I have a 2002 Nissan Frontier Crew Cab SC 140K miles. My battle is with the boost. Everything elso on the truck is great. When the truck is cold I will get the full 7 lbs of boost. When the truck warms up, max is 3 as indicated on the gauge I installed. I live in Wisconsin and last week we had a day where the temperature didn't rise above -7. During that day my truck engine temp gauge inside the cab indicated the truck was up to temp. Weird part was I had 7 pounds of boost with lots of power the entire day!
I don't want to live somewhere where it is -7 all year long to get the boost LOL! Any suggestions on where to go from here. Here is what I have done so far.
Replaced boost actuator, relocated knock sensor, replaced all vacume lines, timing belt, plugs, wires, cap and roter, .
Thanks for your time in reading this. Any guidance is appreciated.
Relocating the KS is not a good idea on the SC. If you placed in on or near the SC then you are picking up noise from the SC and retarding the timing. Timing does get changed by the ECU until the truck warms up.
Did you check for error codes? A bad KS does not display the CEL.
BTW: A bad KS and or KS picking up knock will retard boost.
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2003 silver CC LB V6 SE non-s, leather, SPAL e-fan controller, nismo wheels, bed extender, alarm, e-fan, Nismo CAI, sunroof, nerf bars, knock sensor mod, interior courtesy lights, Rockford Fosgate Audio, oem trailer harness, Nismo CAT-Back, *My Best truck mod* children seats in rear.
Thanks for your response. An error code led to correcting the problem with knock sensor After relocating, the truck actually ran better. I was experiencing the power loss before the knock sensor code popped up.
I still do not understand why the SC works great before it warms up, and after no boost. Makes me wonder if it has to do with another sensor. (temp or mass flow).
I think just like most vehicles the ECM doesn't really start doing fine tuning until the car is up to temp. If you take a look at the FSM the ECM doesn't adjust timing till the vehicle is up to temp. The timing then starts to adjust based on when you are in "D" and moving. However, your KS has to be good and measuring within range.
It's true that you could be having another issue somewhere else but as long as you have the KS hooked up some place else then that will always be the varaible and you could be chasing down non problems.
Grab yourself an Factory Service Manual online and read about the SC and see what other factors factor into boost. I know that some people have hooked up something manual to get boost right when they need it so I don't think that there is much that controls the vacuum boost outside the KS (unless you have a vacuum leak).
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2003 silver CC LB V6 SE non-s, leather, SPAL e-fan controller, nismo wheels, bed extender, alarm, e-fan, Nismo CAI, sunroof, nerf bars, knock sensor mod, interior courtesy lights, Rockford Fosgate Audio, oem trailer harness, Nismo CAT-Back, *My Best truck mod* children seats in rear.
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