Engine RPM Governor

[Economist]

I have to get my M35A3 emission tested today to get registered in AZ. When I took my GMC and Hummer H1 in, they made me stomp the pedal to the floor several times. Both of the diesel motors have an RPM governor, so it did no harm. Does anyone know if the CAT motor in the A3 has the same, or might I do damage to the motor.

It just goes against all I was taught to mash the pedal and hear the engine scream like that.

Thanks for the help.

 

[nk14zp]

Yes it has one.

 

[Economist]

Thanks. I will head in this afternoon and see how she does. Anyone else have to pass emissions in AZ? Any problems?

 

[patracy]

FWIW, diesels don't have throttles. They have governors. Engine speed is controlled by fuel delivery in the absence of a butterfly valve in the intake path. So simply put, more rpm's = more volume of fuel injected. The governor is dialed in by flyweights and spring pressure to adjust "redline". (Course that only applies to mechanical diesels)

 

[JDToumanian]

If I knew in advance that they were going to do that to my truck, I would adjust the pedal linkage to not allow high rpm.

Why is this required? Are you registering it commercial?

Jon

 

[m16ty]

If I knew in advance that they were going to do that to my truck, I would adjust the pedal linkage to not allow high rpm.

Why is this required? Are you registering it commercial?

Jon

Going fast from an idle to wide open under no load is hard on an engine.

 

[Economist]

Non-commercial use, but in AZ it is required to have emissions to get registered (in Maricopa, Co.

If I had a choice, I would not do it on any of my vehicles, but to get registered, have to do what the "MAN" says...

 

[JDToumanian]

Are you registering it to the year it was rebuilt as an A3 (1990s?) or the year it was originally built (1960s or 1970s)..... I can't believe they would expect a 40-year old diesel truck to pass some kind of visible smoke emissions test. That's worse than California! It should be exempt.

Jon

 

[DieselBob]

Why is this required? Jon

The true answer is they needed a way to grab more money from John Q Public. IIRC they do this to check the smoke output, particulate in exhaust.

 

[DieselBob]

I can't believe they would expect a 40-year old diesel truck to pass some kind of visible smoke emissions test.

Jon

All we need to remember is we are dealing with the Gooberment so logic and doing something that makes sense never enters the mix.

 

[JDToumanian]

I expect that crap in California, I thought AZ was better.... Especially Maricopa County. Isn't that Sheriff Joe Arpaio's territory?

 

[armytruck63]

I have heard about this horrible part of the Arizona test (and I thought California was crazy).

I agree with the comment about limiting the throttle linkage travel. Do A3's have the same bolt under the gas pedal that can be adjusted. If so, I would set it so the engine wouldn't go over 2000 or 2100 rpm.

 

[patracy]

RPM's are actually your friend in diesels when it comes to exhaust typically....

The fueling curve is what causes the smoke.

 

[Economist]

The SF-97 says 1995, so I am kinda stuck with that year. I took it to emissions testing. Had to do the goofy rev deal. She passed with flying colors. Off to get titled and registered next week.

Thanks for the quick responses. This board is excellent resource.

Cheers!

 

[nk14zp]

congrats

 

[1983M35A2]

i agree money money us to death.

 

[lonegunman]

I took my A3 in for emissions testing here as well. The major areas of Washington state require it as a way of cheating you out of an extra 20 bucks a year.

The engine will rev only to it's preset limit, it is a mech diesel. I had Caterpillar check mine after I purchased it, the tac was correct and it limits at 2927, within two of the factory setting.

My truck is technically built in the 1999 model year, late 98 dates on everything including the engine. But It is considered a 1993 model truck by the military and I registered it as a 1993 so that it is covered under the earlier emissions standards.

It passed with flying colors by the way, well under the norms and very clean running. You will have no problems if you truck is running nice.