Mississippi-Mud Forums

my truck has been drinking more gas lately, i usually get 215 out of a tank but my last two tanks ive got about 185-195. i ts got pretty good acceleration for what it is, but lately i ve have to gas it pretty good to get it up to speed, enuff that i can tell it seems to have lost some power. i stopped by auto zone today to get them to run codes even though my CEL is not on, and it came back my knock sensor is bad, and also shows low fuel pressure. ive done some reading and some say the sensor is impartant and some say its not. just wanting ya'lls opinion on that i guess. to change it ive got to take off the supercharger, intake, fuel rail and exhaust manifold. would a bad sensor cause these symptoms?

With a super charger, i would think you need that knock sensor. Maby Ben will put his 2cents, he knows all that stuff.

i'd say its probably important especially on a forced induction engine. the knock sensor notifies the computer when detonation occurs. detonation is not good for an engine. it generally occurs when running too low octane fuel or incorrect timing etc. if it happens enough cracks can form in the pistons etc. with that said we've been running my boss's toyota 22r without the knock sensor hooked up for about 6 years and its still running. but being that you have a supercharger i'd change it.

i knew youd have some good input thanks alex,......all ive ran is 87 octane, 93 bout 5 times but doesnt seem any different......i think its been out for awhile

This is all too common on the v6. It is a PITA to change.

With the KS not working, the ECU goes into a fail-safe mode, which is what you are experiencing.

There is an affordable alternative, however. You can add a resister to the circuit that tricks the ECU into thinking that teh KS is working. I don't have the experience to fully reccommend that, though.

Here ae some threads on the subject:
http://www.clubfrontier.org/forums/f46/k...ion-35769/

http://www.xterraownersclub.com/cgi-loca...0;t=001103

http://www.nissanoffroad.net/messageboar...7#msg22417

no prob. the knock sensor not working properly could be hurting your mileage. the knock sensor lets the engine run as much timing as it can without pinging(detonation). with it working properly you will burn the fuel more efficiently therefore more power and better mileage. with it not working properly the computer probably resorts to a safer timing curve to prevent damage but is less efficient.

Reserector Wrote:This is all too common on the v6. It is a PITA to change.

With the KS not working, the ECU goes into a fail-safe mode, which is what you are experiencing.

There is an affordable alternative, however. You can add a resister to the circuit that tricks the ECU into thinking that teh KS is working. I don't have the experience to fully reccommend that, though.

Here ae some threads on the subject:
http://www.clubfrontier.org/forums/f46/k...ion-35769/

http://www.xterraownersclub.com/cgi-loca...0;t=001103

http://www.nissanoffroad.net/messageboar...7#msg22417

i thought about that res, but i read thats not wise a sc'ed motor, but if it was NA it would be fine

Yeah. Probably best to bite the bullet and replace it.

Reserector Wrote:Yeah. Probably best to bite the bullet and replace it.

x2 with the sc bad things can happen

ping...ping...knock...KAPOW!!!!!!!!!!!!!!!