Posted: Apr 14 2008 at 2:26pm | IP Logged

 I need some advice folks! New to these forums and new to my 2000 nissan frontier v6 4x4.  It's been running hard shaking the whole truck especially at stops while the engine is still running. Sometimes it will even shut off.  My bro suggested a tune up which is no problem for me to get done, but I took it to Advanced Auto parts and they gave it a diag and said it was a "knock sensor" and then another code said "system to lean".   Super!  What does that mean and what do I do now???  I don't think this is something I can take on myself.

Please some advice!

Posted: Apr 14 2008 at 6:16pm | IP Logged

Dave, just a small clarification.  Knock is usually caused when fuel of too low an octane rating is used.  The knock occurs AFTER the spark fires.  The spark sarts to burn the fuel around the spark plug.  This in turn raises the pressure extremely rapidly in the cylinder which in turn sets off the fuel right above the surface of the piston.  This is really an explosive pressure-induced combustion in a second flame front which we hear as a knock.   Higher octane fuels can resist this secondary detonation much better.  So if the timing is retarded a bit, the pressure buildup is less severe and the lower octane fuel will not normally do this under the retarded timing conditions.  The site below will show diagrams of this for both deposit-induced knock and compression-induced knock.  Hope this clarifies knock.

It also helps to understand why higher octane fuel is a better insurance against knock than just depending on the engine retarding the timing.

Google Image Result for http://www.thor-racing.co.uk/images/what_is_detonation.jpg

Posted: Apr 14 2008 at 10:31pm | IP Logged

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toriolmo;

The knock sensor is #22060P same as the xterra

http://www.courtesyparts.com/betasite/frontier-d22u-1998-200 4/genuine-nissan-parts/engine-electrical/226-engine-control- module/-c-2129_2130_2160_2164.html

http://www.courtesyparts.com/betasite/knock-sensor-2000-2004 -xterra-p-104.html

Have a good New Year while you can still laugh about it.. Don S..

Laws such as the use of corn ethanol are driving up the cost of living (have you been to the grocery store lately) without driving up wages. This equates to a lower standard of living thanks to Agro-lobbyists and corrupt and ill-informed lawmakers

Posted: Apr 15 2008 at 1:30am | IP Logged

Hey thanks you guys so much for your knowledge it is much appreciated.  One question I must ask though.  Should I change my plugs first then see if the sensor should be replaced or should I just do both.  It's going to be hell if I have to change out the knock sensor so if I don't have to do it I really rather not.  Thanks again!

Tori

Posted: Apr 15 2008 at 6:35am | IP Logged

I think the two items that are most likely are the O2 sensors and the MAF unit.  I don't know how far they can drift without throwing a code.  personally, I would look at the O2 sensors.  If they are some years in age, they do gradually deteriorate which usually shows up in worse gas mileage.  However, withoout codes, you are in for a lot of expensive diagnostic testing. I would not go down the road of throwing in new parts, though, as that can be even more expensive, especially if you have a shop do it for you. 

Lakota's part number for the knock sensor is good to have, however.  You can save a ton by doing repacements yourself instead of paying labor.  Perhaps the knock sensor might be a worthwhile replacement.  O2 sensors are usually burned out after 8-9 years and are just reasonable replacements in a truck of that age. 

Posted: Apr 15 2008 at 1:33pm | IP Logged

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... Always keep in mind when dealing with engine management and computer  problems check the wiring plugs (first) for good conductivity. Also recheck body, battery, and engine ground cables. A little corrosion goes a long way

Have a good one and see you later… Don S..

It would be nice if our members would add their vehicle information to their signature (similar to mine) plus add their City and State . A member in the same town might be willing to drop by and help you with a problem. Or drink all your beer ...