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I need to get my X (2008 Offroad, 6MT, 4x4) smogged in California. The issue I'm having is:

-The manual says not to put a 4WD vehicle on a 2WD dynamometer, such as those used by some states for emissions testing, even if the front wheels are lifted off the ground, as vehicle damage may occur. (Page 5-7)

-California exempts some AWD vehicles from the dynamometer requirement, and lets them just be smogged while in neutral with the engine revved. The Xterra is not on the list of exempted vehicles.

-I can't find a smog check place with a four wheel dynamometer

Does anyone know of a place in Orange County/Camp Pendleton/San Diego County that can smog my X without putting it on a 2wd dynamometer?

Link to the 2008 X manual: http://cdn.dealereprocess.com/cdn/servicemanuals/nissan/2008-xterra.pdf
 

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They should still be able to test it just switching the vdc off leaving it in 2wd . Correct me if im wrong but dont they do a OBD2 plug in for the smog test there ? We dont dyno anything 96+ its get a plug in check .
 

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X owner, CA resident.
We dont have AWD, we have a transfer case that has a true neutral (disengaged), i have had my X smogged a few times now. You're fine!

All wheel drive or BMW, Benz etc. that have wheel speed sensors that even though they are 2wd vehicles change the performance of the vehicle depending on what speed all 4 wheels spinning are the only vehicles that have an issue with this.
 

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Yeah vehicle damage will occur if you engage the 4x4 on a 2wd dyno lol. damage when it drives through the shop wall. just safety lingo for the idiot that somehow switches it into 4x4 while on a 2wd dyno.
 

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Discussion Starter #5
I've read all the warnings about not towing an X with two wheels on the ground-- I thought that only having one set of wheels turning overheated something in the 4x4 system. Wouldn't the same thing happen if the front wheels are stationary and the rear wheels are turning on the dyno?
 

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No different scenario. Engine not running causes lack of lubrication in transmission due to no pump.
 

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When I was still living in California, I never had to dyno-smog either my Xterra or my Bronco ... both are true part-time 4wd vehicles. In fact, I can't recall ever hearing of anyone I know of needing to use a dyno to get smogged ... is this a new requirement?

Having said all that, I'd be looking for a 4-wheel dyno as well. Our front drive-line, while it is not powered, is still designed to rotate (albeit passively) when in 2wd; the front diff/hubs/t-case output still spins, even when disengaged and running in 2wd.
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When I was still living in California, I never had to dyno-smog either my Xterra or my Bronco ... both are true part-time 4wd vehicles. In fact, I can't recall ever hearing of anyone I know of needing to use a dyno to get smogged ... is this a new requirement?

Having said all that, I'd be looking for a 4-wheel dyno as well. Our front drive-line, while it is not powered, is still designed to rotate (albeit passively) when in 2wd; the front diff/hubs/t-case output still spins, even when disengaged and running in 2wd.
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It won't make a difference, as long as the vdc is turned off. even though the hubs don't disengage, the transfer case is designed to be able to not turn while in 2wd.
 

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It won't make a difference, as long as the vdc is turned off. even though the hubs don't disengage, the transfer case is designed to be able to not turn while in 2wd.
Yes, I understand that there is a clutch in the t-case that allows differential rotation between the front and rear outputs ... but that does not mean that I would be happy letting that differential be a matter of ~1k rpm (or more), even for the 15-20 minutes a dyno smog test would take.

1k rpm is not a number I pulled out of thin air, either, if anything that's a conservative number. A 32" tire has a circumference of roughly 100"; at 50mph, that tire's going to be spinning at 528rpm ... with an axle ratio of ~3.6 (OP has a manual trans, so either 3.54:1 or 3.69:1 in the axles), the driveshaft would be spinning at 1900rpm.

Now, if the rear is spinning at that rate, and the front is stationary; is the t-case going to instantaneously lockup and explode? No. Let's not forget our common sense; but it's an added stress that I'm not sure is even required ... as I said, I don't recall ever having to do more than a sniff test when I was having to deal with CA smog, and I still have more than a few friends and family who live in CA - many of whom are gear heads - and I don't recall any of them saying anything about needing to run their vehicles on a chassis/wheel dyno for the purposes of smog testing ... which is why I was asking the OP if this is a new requirement.
 

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Yes, I understand that there is a clutch in the t-case that allows differential rotation between the front and rear outputs ... but that does not mean that I would be happy letting that differential be a matter of ~1k rpm (or more), even for the 15-20 minutes a dyno smog test would take.

1k rpm is not a number I pulled out of thin air, either, if anything that's a conservative number. A 32" tire has a circumference of roughly 100"; at 50mph, that tire's going to be spinning at 528rpm ... with an axle ratio of ~3.6 (OP has a manual trans, so either 3.54:1 or 3.69:1 in the axles), the driveshaft would be spinning at 1900rpm.

Now, if the rear is spinning at that rate, and the front is stationary; is the t-case going to instantaneously lockup and explode? No. Let's not forget our common sense; but it's an added stress that I'm not sure is even required ... as I said, I don't recall ever having to do more than a sniff test when I was having to deal with CA smog, and I still have more than a few friends and family who live in CA - many of whom are gear heads - and I don't recall any of them saying anything about needing to run their vehicles on a chassis/wheel dyno for the purposes of smog testing ... which is why I was asking the OP if this is a new requirement.
:scratch:

A plane is standing on a large treadmill or conveyor belt. The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?

:laughing3:
 

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I know I may be a jerk for hijacking this thread, but with the path it was heading down with the 2wd dyno with a part time 4wd system, I just couldnt resist.
 

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How are you comparing jet propulsion with direct drive propulsion? What if I want to dyno my hot air balloon?
 

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Yes, I understand that there is a clutch in the t-case that allows differential rotation between the front and rear outputs ... but that does not mean that I would be happy letting that differential be a matter of ~1k rpm (or more), even for the 15-20 minutes a dyno smog test would take.

1k rpm is not a number I pulled out of thin air, either, if anything that's a conservative number. A 32" tire has a circumference of roughly 100"; at 50mph, that tire's going to be spinning at 528rpm ... with an axle ratio of ~3.6 (OP has a manual trans, so either 3.54:1 or 3.69:1 in the axles), the driveshaft would be spinning at 1900rpm.

Now, if the rear is spinning at that rate, and the front is stationary; is the t-case going to instantaneously lockup and explode? No. Let's not forget our common sense; but it's an added stress that I'm not sure is even required ... as I said, I don't recall ever having to do more than a sniff test when I was having to deal with CA smog, and I still have more than a few friends and family who live in CA - many of whom are gear heads - and I don't recall any of them saying anything about needing to run their vehicles on a chassis/wheel dyno for the purposes of smog testing ... which is why I was asking the OP if this is a new requirement.
What, exactly, do you think happens when you have the front hubs disconnected and go down the road in 2wd? Or if you lose a u joint and remove the front driveshaft? Have you heard anyone say "man I've got the front shaft off until I can put in new joints, so I gotta drive around in 4hi because the countershaft needs lubrication to be stationary"?

I'm giving you a hard time because its fretting over nothing and a waste of time. The front drive parts don't know what the rear is doing when in 2wd
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Skibum-
How old are you and how long ago did you live in CA? lol
I'm 32. Since i have been driving CA has been doing roller dyno smog tests. It is 90 seconds at approx. 1500RPM and I think 20 seconds or so at 2500RPM.

If you have all 4 wheels in the air and you spin a front tire will a rear tire spin?
Then you have FULL disengagement of front and rear differential.

Before the I know someone stuff starts...... In the last 5 years smog in CA has tightened down a lot and smog techs are now doing what they are supposed to be doing. Easy to get all sorts of smog for a price or techs who just did it out of laziness but those times have come and gone.

I have heard of some people talk about different regulations based on county (blew me away, makes not a lick of damn sense to me) but as long as you're not in BFE with a population of 7 people, everyone is dealing with the same thing in CA and you're stuck. If you want a $400 smog, find a 4 wheel dyno but you're wasting your money.

**DING DING DING**

You are correct sir..

Now, Can you smog a part time 4 wheel drive vehicle on a 2 wheel drive dyno?

FAIL.
Plane can't take off without forward movement to create lift :)
 

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Skibum-
How old are you and how long ago did you live in CA? lol
I'm 32. Since i have been driving CA has been doing roller dyno smog tests. It is 90 seconds at approx. 1500RPM and I think 20 seconds or so at 2500RPM.

If you have all 4 wheels in the air and you spin a front tire will a rear tire spin?
Then you have FULL disengagement of front and rear differential.

Before the I know someone stuff starts...... In the last 5 years smog in CA has tightened down a lot and smog techs are now doing what they are supposed to be doing. Easy to get all sorts of smog for a price or techs who just did it out of laziness but those times have come and gone.

I have heard of some people talk about different regulations based on county (blew me away, makes not a lick of damn sense to me) but as long as you're not in BFE with a population of 7 people, everyone is dealing with the same thing in CA and you're stuck. If you want a $400 smog, find a 4 wheel dyno but you're wasting your money.




FAIL.
Plane can't take off without forward movement to create lift :)
I have lived my entire life in CA And I have yet to see any of the smog shops in town with a dyno. So its not a requirement. Granted Sacto is a bit larger then Redding, but yeah. There are some municipalities with different rules regarding smog. But as everyone has agreed, aside from the plane, you are good on a 2 wheel dyno =)
 

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You learn something new everyday. I wish i lived in BFE somewhere that they just put a sniffer in and tested the car under zero load. That makes a world of difference.


DYNAMOMETER USED: Counties in California with greater smog pollution require vehicle owners complete the Enhanced version of California's emissions test. The Enhanced smog test requires your vehicle to be driven on a dynamometer while the smog machine collects emission samples from the tailpipe. The Enhanced smog test has been proven to retrieve a more accurate sample of a vehicle's emissions output, then it's predecessor, the Basic smog test. The Basic smog test requires vehicles to be tested, only at idle and 2500 rpms. No dynamometer driving required.
If your county is in the Bureau of Automotive Repairs Enhanced list, no need to worry. There is nothing to do on your part. The smog stations in your area will be equipped to handle your vehicle's emissions test. Only thing you should consider is insuring proper tire inflation and avoid smog checking on rainy days.
Counties that need smog: (pretty much all of them that have anything resembling civilization)
https://www.dmv.ca.gov/vr/smogfaq.htm
 
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