I bought a 2004.5 Ram Cummins truck one year ago, my first ever diesel vehicle. Saturday I took it to emission test it for the first time. They checked the emissions equipment, fuel cap, etc. Then for the run test, the emissions guy asked me to floor it while in Park on his signal, then release the accelerator on his follow up signal. I was kind of taken back by his request, so I didn't floor it, just tried to bring it up to the 3200 rpm redline and hold it there. That resulted in an unsteady rpm, so they told me that the readings will be all over the board if I don't floor it. I told him this engine has a 3200 rpm redline. He said the engine's governor will protect my engine. I was required to get the truck emission tested to renew the plates, so I reluctantly did as asked. I had to do the procedure for a few seconds each of three successive times. The governor did kick in, but the engine still exceeded the redline by several hundred rpm. This experience was in Maricopa County, Arizona. My questions are: Even though the procedure caused the engine to exceed its redline, is the governor truly protecting the engine? Are the governors reliable? I'm thinking if the governor failed during one of these tests, the result could be disastrous. Is this typically how the diesel emissions test procedure is done in every state or metro area that has a diesel emissions test? Or is it unique?

In PA, diesel trucks are exempt from this nonsense. They are kept busy destroying the gas powered vehicles.No way would I allow some jerk to abuse my property.

I have read many similar stories, so it seems normal. The ECM is programmed and will protect from overspeed, there is no external governor. If the truck runs normal it should limit rpms. That model ISB is rated to 4200 rpms for 15 seconds.

On Long Island, they follow the same procedure.

I just give it about 3/4 throttle and get it up to about 3k. If it doesn't work we do it over.It will exceed the red line and while the Cummins wont suffer any catastrophic damage until it gets to about 5K, I figure cylinder scarring from revving an unloaded engine is always a possibility.The 3200 RPM red line is just the top of the useful power band and not an indicator of where valves float or any other damage.

Our area also uses the "punch test" to test diesels for gaseous and opacity output. My 6.0 V8 Powerstroke had no problem revving since peak horsepower was developed at 3300 RPM. The I6 Cummins a has lower redline and peak horsepower RPM, so I would expect the test to take account for the differences. I do not have to take my Cummins in for testing until 2017, so I don't know what kind of testing will used. Monitoring was done through the ODBII port with a sensor at the tailpipe with my last Powerstroke test.

Diesel Emissions Test Question | Good Sam Community

20 Replies

AH64ID
Explorer
Mar 23, 2015
I have always liked the hillside conversions for the Palouse. I do miss living up there at times.
45Ricochet
Explorer
Mar 23, 2015
Turtle n Peeps wrote:
45Ricochet wrote:
Turtle n Peeps wrote:

And for those of you that are gloating about no smog test in your state. You won't gloat for long. Your gloating is almost over. :B

Good ole snap test... Reminds me of the dentists drill sound.

What do you mean the gloating is almost over Bob? You mean I need to find some items out in the barn :W

Well............in the land of fruits and nuts; "they" want to make sure all the other radical states fall in lockstep with their own ideas.

I have to admit they are doing a darn good job at doing that.

Help, I'm trapped in the state of fruits and nuts and can't get out!

According to the AQ manager I talked to "The oh snap test"; is coming to a state near you!!! :B

But don't fret. We in the land of fruits and nuts force contractors with tractors and ALL other diesel equipment to put DPF's on ALL of their engines no matter how old or young.

Need an older (06 on down is older to them) tractor or backhoe or any other piece of diesel equipment Rick? There will be a fire sale on this stuff in Kalifornia. Come on down!!!! :B

Interested in the firesale buddy. You guys have many of these around? Palouse hills can be tricky :W
BenK
Explorer
Mar 23, 2015
Over 50% of the adults here are from the other 49...please take them BACK !!!

Took gasser smog controls about 20 years to mature...hope diesel smog takes less time...
Turtle_n_Peeps
Explorer
Mar 23, 2015
45Ricochet wrote:
Turtle n Peeps wrote:

And for those of you that are gloating about no smog test in your state. You won't gloat for long. Your gloating is almost over. :B

Good ole snap test... Reminds me of the dentists drill sound.

What do you mean the gloating is almost over Bob? You mean I need to find some items out in the barn :W

Well............in the land of fruits and nuts; "they" want to make sure all the other radical states fall in lockstep with their own ideas.

I have to admit they are doing a darn good job at doing that.

Help, I'm trapped in the state of fruits and nuts and can't get out!

According to the AQ manager I talked to "The oh snap test"; is coming to a state near you!!! :B

But don't fret. We in the land of fruits and nuts force contractors with tractors and ALL other diesel equipment to put DPF's on ALL of their engines no matter how old or young.

Need an older (06 on down is older to them) tractor or backhoe or any other piece of diesel equipment Rick? There will be a fire sale on this stuff in Kalifornia. Come on down!!!! :B
We_Cant_Wait
Explorer
Mar 23, 2015
In NY the Dept of Environmental Protection will and can pull you over on the side of the road and do a particulate test right there on the spot if the officer fells that you are blowing to much black smoke on acceleration. I know this for a fact because I had it happen to me with the Semi I was driving. It failed the test and the company had 30 days to fix the problem, and was still fined $700. So all of your with these tuners that crank up the fuel to the motor a word of warning, it won't be long till all the states EPA start this.
45Ricochet
Explorer
Mar 23, 2015
Turtle n Peeps wrote:

And for those of you that are gloating about no smog test in your state. You won't gloat for long. Your gloating is almost over. :B

Good ole snap test... Reminds me of the dentists drill sound.

What do you mean the gloating is almost over Bob? You mean I need to find some items out in the barn :W
hone_eagle
Explorer
Mar 23, 2015
Turtle n Peeps wrote:
Yes this is how it's done. As stated above it's called a snap test.
(Kind of like, "oh snap, you want me to do what?)

All modern throttle by wire engines are safe at WOT. You can actually put it to the floor and let it bounce of the rev limiter on gasoline engines and on diesels it will just pull fuel and rev to the limit. That's why on most engines there is no longer a red line on the tach. No reason for it anymore.

And for those of you that are gloating about no smog test in your state. You won't gloat for long. Your gloating is almost over. :B

^^This
I have had the same test done on the 12 liter in the volvo,coming soon to your state if you want to ever sell your truck it has to pass.
Dont f*** with it.
Turtle_n_Peeps
Explorer
Mar 23, 2015
Yes this is how it's done. As stated above it's called a snap test.
(Kind of like, "oh snap, you want me to do what?)

All modern throttle by wire engines are safe at WOT. You can actually put it to the floor and let it bounce of the rev limiter on gasoline engines and on diesels it will just pull fuel and rev to the limit. That's why on most engines there is no longer a red line on the tach. No reason for it anymore.

And for those of you that are gloating about no smog test in your state. You won't gloat for long. Your gloating is almost over. :B
crcr
Explorer
Mar 23, 2015
Thanks to all of you for your informative responses.

In a year when tag renewal time comes up, before I go in to get tested, I will research how long their specs specify a hard throttle is required. I don't like this test, but since I would like to keep registering my truck every year, I'll have to deal with it.

I had emission tested many gasoline engines over the years, and that test is completely different from what I experienced Saturday for my Cummins diesel.
goducks10
Explorer
Mar 23, 2015
rhagfo wrote:
Lynnmor wrote:
In PA, diesel trucks are exempt from this nonsense. They are kept busy destroying the gas powered vehicles.

No way would I allow some jerk to abuse my property.

In Oregon if over 8,500# GVWR also exempt! :)

Portland and Medford are the only cities in Oregon requiring EPA tests. The rest of the state is exempt. But yes 8500# and over are exempt.