Temperature sensor testing

[woodman]

the information That I have refers to the residence on pins 1&4, on a 4pin temperature sensor should be 2500 ohms at 20* cel.
My reading is 1342 @ 22.3*cel.

1) Do I have the correct information?
2) wouldn’t that tell ECM that the engine is warmer than it really is and as it warms up, if that trend continues, possible causing lean mixture ?

Failed CA smog again slightly elevated HC
Any help. Greatly appreciated


M104.992… Woodman

 

[gsxr]

2500 ohms at 20°C is correct for the 4-pin temp sensor on the engine.

Slightly elevated HC may be due to the catalysts not being hot enough. What did you do, if anything, to get the cats FULLY HOT prior to testing? Most of the time, that's all you need to get it to pass. Also, what was the HC reading?

 

[woodman]

Warmed up cats blasted down freeway in 2nd gear. Failed the 25mph test with 50ppm HC with the limit @ 32. Limits @15mph 57 and I was right at the limit.
Was wondering if the temperature sensor might have played a role in the fuel/air ratio.
Changed the 02 sensor since the test and ordered a temp sensor since it is out of spec.
Car runs great no othe

 

[woodman]

Warmed up cats blasted down freeway in 2nd gear. Failed the 25mph test with 50ppm HC with the limit @ 32. Limits @15mph 57 and I was right at the limit.
Was wondering if the temperature sensor might have played a role in the fuel/air ratio.
Changed the 02 sensor since the test and ordered a temp sensor since it is out of spec.
Car runs great no other issues other than passing the test.

 

[woodman]

I also suspected the smog guy took the hose off my EGR valve that would have created a vacuum leak.
He reached down where the egr is before and after the test.
No proof but it seems fishy.

 

[gsxr]

50ppm HC is excellent. Your test requirements are insane. Ah, you are in California... my condolences.

Might need to try some other tricks like additives in the gas tank, if the new O2 sensor and new temp sensor do not help. Make sure you do the 2nd gear freeway blast at >3500rpm for at LEAST five minutes, btw. Oh, and check the entire vacuum system for leaks, and make sure the EGR valve is working properly too.

Last question - are the catalysts factory, or aftermarket?

 

[woodman]

Yes I am in CA. Cats are original @190k. My NOX readings have always been in the teens so the EGR is not a issue.
4years ago I smoke tested the intake system and found the EGR was leaking from the stem and replaced it. The valve design makes it prone to a slight vacuum leak I don’t think it’s the problem this time. My co and 02 are very low and my co2 is 15.1.
I would replace the cat if I thought it would solve the issue but I really don’t think that’s justified with the other readings being what they are.
I know they lowered the allowable levels back a few years ago but I think the testing method and limits are insane like you say.

 

[gsxr]

I agree - DO NOT replace the factory cats! (And don't be surprised if the smog shop tries to convince you that it needs new cats.) The vast majority of aftermarket cats are garbage and won't last more than a year or two.

32HC max limit is just ridiculous.

 

[woodman]

It’s too bad that the fuel sold in CA makes you play chemist to get it to pass. Did get it to pass with fuel additives,but in the process of reaching the potential issues I found out some information that I was not aware of.
The ECM has a map in it for straight gasoline @ 14.7 to 1 ratio. The crappy 10% ethanol fuel we are forced to buy only requires 14.3 to1 for complete combustion. That makes for a lean mis and incomplete combustion. I burped the fuel tank just before the test to relieve the pressure and I believe that it reduced the fumes sucked in from the evap system.
It’s not the car’s fault that they fail but the testing and extreme limits that are set to get these old cars off the road.
They were not designed for what is expected from them.
The newer cars have way more complex controls and I would bet that if some of them were forced to run on dynamometer at the same emission levels they would fail
too.

 

[gsxr]

What mad scientist stuff did you need to do?

 

[woodman]

A big dose of Techron and Archoil 6200 and the addition of a couple of gallons of 87 octane gas to make the ECM retard the timming. That got the combustion temperature up. Right after the test,I filled up with best 91 octane that I could find!

 

[woodman]

P.S. pumped up the tires to reduce the rolling resistance.

 

[TerryA]

@woodman,
Why are you running 87 octane fuel? The M119 requires Premium 91 octane. I believe the M104 does also. Maybe NOT but it wouldn’t hurt. If you were using 91 all the time it may have passed without the additives. These cars are old and require all the help they can get to stay on the road.

I will add Techron to a full tank about once a year but only run Arco Premium 91 octane “Top Tier Fuel” fuel in my 93-500E. Along with an “Italian Tuneup” on the freeway to make sure the CATs are fully heated up before any CA Smog Test.

My car has never failed CA Smog in 21 years of ownership.

 

[gsxr]

Terry, it sounds like the idea was to add some 87 to try and force the ECU to retard timing slightly, hoping that might reduce HC during testing? And afterwards he filled with 91.

In this case, the max HC allowed (32!) was set ridiculously low. CA is just trying to force "old" cars off their roads.

 

[woodman]

CA emission testing is not the same in everywhere in the state. If you happen to live in a “enhanced testing area “ you are subject to dynamometer testing. Other parts of the state just require a idle and 2500 rpm test with allowable HC of 100 and 150 respectively! That just doesn’t seem like the state is not really concerned about emissions!

 

[TerryA]

@woodman,
The MB 500E is exempt from dynamometer roller testing in all of California due to the ASR affecting the test. Other MBs may not be so lucky as to qualify for this exemption, I know my car has never been on a roller.

 

[woodman]

@woodman,
The MB 500E is exempt from dynamometer roller testing in all of California due to the ASR affecting the test. Other MBs may not be so lucky as to qualify for this exemption, I know my car has never been on a roller.

And what are your allowable emission limits?
I don’t think the ASR effects the test. The test has effects on the ASR and can cause damage to it.
The limits and testing should be the same throughout the state if emission levels were the real concern, regardless of ASR equipped or not. I realize not all limits are the same for all engines.
If you spend $600 or more at a “licensed repair station “ you can get a exemption regardless of the test results. That just doesn’t sound like it is consistent with being concerned with the environment. Out of that $600 I would bet most of that would be labor paid for what good of the environment? You would be lucky if you find a reputable shop to look at and repair your MBZ for $600!
Just my personal opinion.

 

[gsxr]

124's with ASR are exempt from dyno roller testing, because the ASR cannot be shut off to allow the car to "drive" the rollers.

Totally agree the limits should be the same throughout the state. I was not aware of the $600 buyout if the car continuously fails.

 

[TerryA]

@woodman,
This was the only test I could find on my phone from 2016 but they’re all just about the same. I’ve used the same Smog Tech for 22 years.

 

[emerydc8]

If you spend $600 or more at a “licensed repair station “ you can get an exemption regardless of the test results. That just doesn’t sound like it is consistent with being concerned with the environment. Out of that $600 I would bet most of that would be labor paid for what good of the environment? You would be lucky if you find a reputable shop to look at and repair your MBZ for $600!
Just my personal opinion.

Arizona mentions some sort of Voluntary Vehicle Repair Program where you can get up to $900 to fix the car (bottom of attached page), but anytime I’ve ever looked into the details of such free programs they never seem to apply to me. Just the fact they don’t publish information on the paperwork they hand you when you fail emissions but instead direct you to inquire in-person means they don’t want people to know about it.

 

[gerryvz]

When I moved to Texas I had to do emissions testing for a few years on my E500. It always used the "sniffer" test because of the ASR being present on the car, but my other non-ASR cars used the dyno/roller setup. I had to tell the techs a couple of years that I had ASR and that I couldn't use the roller - they didn't give me any problems with that.

When I lived in Oregon they didn't use a dyno test, only sniffer for all of my cars, so ASR was never an issue there. And tests were every other year. Texas made me do them every year, every car. Until they aged out.

 

[emerydc8]

And tests were every other year. Texas made me do them every year, every car. Until they aged out.

I’ve been waiting for my E420s to age-out for years. I think Arizona did away with that long ago. Speaking of Texas, Gerry, do you ever see yourself moving back there?

 

[Bogeyman]

I guess a benefit of living in "flyover land" - no testing. We just go forth and pollute...

 

[gerryvz]

Speaking of Texas, Gerry, do you ever see yourself moving back there?

No. I loved living in Texas, but have to be in a coastal area given our love for boating. So that means likely South Carolina, northeast Florida or the Florida panhandle. Probably South Carolina, as I want to be on the ICW.

 

[emerydc8]

I think the Intracoastal Waterway is a much safer alternative than the deep sea. It sounds like it would be a lot of fun. I worked with a guy who said he took his boat from south Florida all the way to Lake Michigan on various waterways starting with the ICW.

 

[woodman]

CA had program they will pay you a $1000 to retire your car BUT it must have a current smog certificate. Go figure.

 

[nocfn]

I still live in Texas, about 26 mins from where GVZ lived. We boat on Local lakes and also in the gulf of America. Growing up in NE Ohio, having lived in LAS, SFO, SNA (airline industry at age 19 for 11 years) and IAH all things considered - I am still in Texas and will not be moving.

Enjoyed all of the places I lived but TX is a self contained Republic. Yes I own boots, I wear them to Go Texas day at the club once a year during the Rodeo Wine dinner. HA viva la Tejas! Also, I never shoveled any rain out of my driveway over Easter weekend as I did SNOW - many times in Ohio.

 

[emerydc8]

Texas has the best BBQ restaurants in the country.

 

[gerryvz]

Texas has the best BBQ restaurants in the country.

There are several cities around the US who would loudly dispute that statement......

 

[gerryvz]

I think the Intracoastal Waterway is a much safer alternative than the deep sea. It sounds like it would be a lot of fun. I worked with a guy who said he took his boat from south Florida all the way to Lake Michigan on various waterways starting with the ICW.

Yes, the ICW will take you a good part of the way up the East Coast. Heck, I bought my boat in northern New Jersey and brought it down to Annapolis, much of it on the Atlantic. Fueled up in Atlantic City and Cape May NJ. Not a huge deal, as long as the weather is good. About 2 miles offshore is perfect for transiting south or northward.

The Chesapeake Bay is pretty much a boater's paradise, though. Having grown up on the cold and deep (and much smaller) Puget Sound in Seattle, I do prefer the Chesapeake for its summer boating culture, and longer boating season than in the PNW. My friends up in New England pull their boats out of the water right after Labor Day. We go fully through Halloween and even a bit into November. And you can splash the boat as early as April 1 here if you want to, though ours won't be going in until the first weekend of May.