Emission testing question

[AH64ID]

The rest of the gauges are fake... ... ... ... .

No, I doubt its accuracy period...

Yes some are. . But the tach always match's the OBDII readout. . I have no doubt of its accuracy.



The truck will rev that high, the neutral limit in the ECM is 3500, so you'll go over a little with a diesel unlike gas and the overspeed limit is 4200 for 15 seconds, but I am still not interested in going over 3200 without upgraded rods/springs.

 

[cerberusiam]

. . But the tach always match's the OBDII readout. . I have no doubt of its accuracy.

Yours does, but that is not true of every truck. The tach failures are common. Then again, how do you know the bus data matches actual?



What steved is trying to say is trust the tach, don't trust the oil pressure, trust the volt gauage, don't trust the temp gauage??? All the gauges are fake, set by the cluster controller, from data off the bus, sent by the ECU that interprets sensors readings and shapes the data stream.



Is 3500 rpms actually 3500 rpms, or, is it really 3200 rpms, or is it really 3700 rpms???



The ECU tells the cluster to set the gauges to what is expected, not neccessarily what it really is.

 

[AH64ID]

I know some of the 06's have tach issues but can't recall ever reading about other years having issues. I highly doubt many trucks have issues, and the ones that do are very noticeable.

Yes the ECM tells the oil pressure to be what is expected, but the voltage (except when in grid heater fires on some years), coolant (mine is 3° off across the range), and fuel (which is not designed to be linear for a more positive customer experience) do match the OBDII readings, which are what the ECM see's and should be within the normal gauge error.

I know my tach is accurate as I can compare mathematical rpms based on gears, tires, speed and a GPS and the difference is what's to be expected for normal tire error. . always within a few rpms.

 

[cerberusiam]

The tach readings have been questionable since before these trucks started using them. Its usbject to the interpretation of the ECU, ECM, SBEC, etc, what is output on the data stream. They have gotten better as the years have gone by, and they should because the ECU is after all sensing a digital signal from the CPS and not having to convert, but that does not mean variances cannot occur.



The 06's just have the most problems but all the rest of the years can\have had issues with the cluster controller.

do match the OBDII readings, which are what the ECM see's and should be within the normal gauge error.

On your truck they match, that is not an absolute for every single truck.



Also, what is on the bus is not what the ECM sees, it is what the EM says. The ECM interpolates analog electrical signals from the sensors to convert to digital readings and "says" its interpretation of what it "sees".



Yes, data bus and gauges should agree or there is a problem. How do you know if the data bus and actual readings do match? We get differences on boost, coolant temp, and trans fluid temp when we compare analog readings.



Even the speedometer is not always the same from truck to truck, so the questions do arise: are any of the readings correct, how correct are they, and is it the same for every truck?

 

[AH64ID]

You can have issues with anything, but for the most part I think its safe to assume they are correct, within a tolerance window.

There is zero reason to assume that a tach is hundreds of rpms off.

 

[lebar]

I just found out in Ohio vehicles over 10,000 lbs are exempt from our e-check program. I had to take the truck to a EPA office and they inspected the truck issuing a life time exemption.

 

[AH64ID]

Ironically I just got my 1st emissions notices today, and have lived here since 05. They were for both my gas rigs, when I went online and entered my trucks license plate it didn't find it... think that's all the research I will do on that!

 

[HBarlow]

I totally agree with you. I won't rev my engine that high. I'd just up and leave. Screw um!

That would be my response also.

Actually, I decided that was my response regarding the heavy hand of government that I sensed while living in San Diego in the middle to late '80s when I decided to move back to Texas. Screw all of them.

 

[Nyoest]

They made you rev it to 3575? I would tell them to kiss my #@$%!... There is no way they can require you to rev beyond redline!

How dare they make a truck you can blow up in . 08 seconds!



Governed speed is governed speed. That is the speed the oem has determined is safe for that engine and I'm sure they popped more than one coming up with that number.



Have you guys ever started a big genset? I mean a six cylinder John Deere powered one? They auto crank for five seconds then go full tilt. Regards of temp or oil pressure they snort about twice and then run a full wide open from there on out.



An oem is not going to build something that will self destruct this day in age. That being said I wouldn't LIKE to do it to mine. The only time it sees 3,900 rpm is in fifth gear.

 

[AH64ID]

Goverened speed on these motors is 3200, max neutral rpms are 3500 in the ECM. . just becuase it can take it doesn't mean I want to do it. .

Think about the guys under warranty, the ECM will record a max rpm of 3575 and we all know how happy Dodge is to void a warranty... so what do you think they will say when they see you ran it 375 rpms above redline?

 

[Bob4x4]

From The official Az site,There is no minimum rpm requirement for the test. It is just your standard snap idle,although the inspector may not understand what snap idle means



All 1967 through 2007 diesel powered vehicles registered within the emissions control areas of metro Phoenix (Area A) and Tucson (Area B) are required to be emissions tested annually. The only exception is for apportioned vehicles, which are commercial vehicles that are licensed in multiple states. Diesel vehicles pulling trailers will not be accommodated at the inspection stations.



Diesel emissions testing in Pima County and for light-duty (8,500 lbs GVW and less) vehicles in Maricopa County consists of loading the vehicle on a dynamometer and measuring the opacity of the exhaust plume. The measured opacity must not exceed the established maximum. In Pima County the maximum allowable is 30 percent opacity. In Maricopa County the maximum allowable is 20 percent opacity. (The maximum allowable is determined by the average elevation of the registration area).



Heavy-duty (8,501 lbs and greater) diesel vehicles in Maricopa County are tested using the Society of Automotive Engineers J1667 test protocol, commonly referred to as the "snap-acceleration test. " The test consists of measuring the opacity of three, wide open throttle, no-load accelerations from idle to maximum governed engine speed with the transmissions in neutral. The average opacity for the three accelerations cannot exceed the applicable standard for the model year of the engine. The maximum allowable for engine model year 1991 and newer is 40 percent opacity, for engine model year 1990 and older the maximum is 55 percent opacity.



All diesel vehicles are subject to a tampering inspection at the time of emissions inspection. Tampering inspection includes the presence of properly fitted fuel tank caps as well as the operation of any emission control devices required at the time of manufacture of the vehicle.



Diesel powered vehicles may be tested at any of the vehicle emissions inspection stations in Maricopa County. In Pima County, heavy-duty diesel vehicles (26,000 lbs GVW or greater, or any truck with tandem drive axles) must be tested at 6661 S. Renaissance Dr. ,

 

[HBarlow]

Bob,

"snap-acceleration test. " The test consists of measuring the opacity of three, wide open throttle, no-load accelerations from idle to maximum governed engine speed with the transmissions in neutral. "

You are a dealer tech - what is your opinion of running a Cummins engine up to governed engine speed with no load?

In neutral with no load the engine will exceed max governed engine rpm before the ECM defuels won't it?

I have seen Cummins literature that refers to engine redline as high idle speed or something similar but the concept has always been troubling to me. I do not want to run any engine belonging to me up against the rev limiter in neutral.

 

[AH64ID]

Technically speaking (not common jargon) high idle is rated rpm at no load, 2900 on the HPCR 5. 9 and 3013 on the 6. 7. Fast idle is what we all use with the cruise control, and is commonly refereed to high idle.

Rated rpm, Governed rpm, and max rpm in neutral are all different, 2900, 3200, 3500 are the respective rpms for 04. 5-07 5. 9s, not sure of all 3 numbers for the 6. 7 or older 5. 9s.

The 04. 5-07 5. 9's have the Neutral soft limiter at 3500 rpms, and at 4200 rpms they will drastically shutoff fuel to try to get back around 3400, at 5200 the ECM will cut power to the CP3.

 

[K3RACE]

emission test in Arizona

We probably are over concerned about this. I think that these RPM's could be more harmful to belts, pulley's, waterpumps etc. However I do wonder what is happening with the high pressure side of the injection system. Rail pressures, limiting valve, etc. As more of the commonrail trucks start going thru these tests we may have a better idea how harmful it may or not be. Also the wide open throttle is only for 2 or 3 seconds, so unless something is ready to come a part all should be good. My suggestion is do not look at tach, because that is the worst of it all.

 

[Bob4x4]

WOT is different on a gasser than diesel. The gasser would worry me the diesel does not. On the 12 valve the first test for a low power concern was to go wot to be sure it would reach 3k. With the electronic controlled engines the controls hold the engine speed to a safe level,some of the aftermarket programming alters the hi idle significantly under load but until recently they could not run up to an unsafe rpmprogrammers just kept searching for the magic

Think back a couple years ago. there was a recall to test core plug fit. The Cummins test consisted of running a stone cold engine to max rpm a number of times. Not something I would like to do to my own but Cummins says no problem.

The truck repair shop at the north side of the grapevine sees injection pump damage from big rigs over-reving coming down the steep grade there by in-experienced drivers but after a new pump they are good to go with no engine damage-in most cases:-laf

 

[Bob4x4]

We probably are over concerned about this. I think that these RPM's could be more harmful to belts, pulley's, waterpumps etc. However I do wonder what is happening with the high pressure side of the injection system. Rail pressures, limiting valve, etc. As more of the commonrail trucks start going thru these tests we may have a better idea how harmful it may or not be. Also the wide open throttle is only for 2 or 3 seconds, so unless something is ready to come a part all should be good. My suggestion is do not look at tach, because that is the worst of it all.

The rail presure is not an issue,it is well contolled.

 

[HBarlow]

Bob,

Thanks. I think I asked Bill Stockard the same question years ago and received a similar answer.

Intellectually I believe what you and Bill told me. Emotionally it goes against my instincts. I'm glad we are not testing like that in Texas.

 

[Bob4x4]

In Cali they came up with a procedure to avoid going above red line in the test. The inspector is to get a feel for the response on some practice snaps before doing the official test

 

[retirednak]

I don't think I would be too worried about the test,but before I go, I'm going to test fit some balls of cotton under the floor mat and see if I can keep from going over the last couple hundred RPM no matter how hard one pressed down. I've not run my truck to the red line yet,and damn sure don't want to pay someone to do it. If for some reason something grenades during the test,I don't see the state saying sorry and paying for parts. Is there any Smarty settings to limit RPM's?

 

[Fistfull]

I don't think I would be too worried about the test,but before I go, I'm going to test fit some balls of cotton under the floor mat and see if I can keep from going over the last couple hundred RPM no matter how hard one pressed down. I've not run my truck to the red line yet,and damn sure don't want to pay someone to do it. If for some reason something grenades during the test,I don't see the state saying sorry and paying for parts. Is there any Smarty settings to limit RPM's?

That's another quirk of the az snap test ... U are mashing the pedal. The inspector will watch as you accelerate to governed rpm, he is watching the tach. After he verifies the truck is reaching a stable governed rpm he will have you watch a monitor, it will tell you when to mash the throttle and when to let off. Been doing this on my 97 since 2002 (they make you pay but don't test em for the first five years) it's actually gotten to be a simpler test. Haven't had the joy of it all with the 2004 yet, not looking forward to it. Oh and they have a data base they consult for cat requirements. If your truck originally came with one, it will need to still be in place. If it didn't come with one, don't sweat it.