Author Topic: Smog gurus  (Read 1279 times)

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Snowtoy

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Smog gurus
« on: May 30, 2019, 05:57:48 PM »
Smog numbers this year compared to 2017.  '17's numbers are in red.


The truck sat for about 30 minutes with a nice cool breeze blowing on the cat, then fired up to pull it into the stall and ran for about 5 minutes while the tech checked the timing, egr, etc., before testing the emissions.  My guess is the cat did not have time to warm up, but figured i would get some other input before letting it go until the next test.,
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

emsvitil

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Re: Smog gurus
« Reply #1 on: May 30, 2019, 06:08:39 PM »
What year truck and how many miles and what engine?
Ed
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86 SR5 XtraCab
22RE  W56B
31x10.50R15

Snowtoy [OP]

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Re: Smog gurus
« Reply #2 on: May 30, 2019, 08:18:51 PM »
'91, 22re, w/220k, engine rebuilt about 22k ago, and only 1,029 miles between the two smog checks.  Cat is the new CARB approved one with less than 500 miles on it.
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

emsvitil

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Re: Smog gurus
« Reply #3 on: May 30, 2019, 08:32:39 PM »
That does sound like a cool down problem.

I've always have kept the engine running at high idle with AC on while waiting...…………..  (After a high speed run before getting to smog place)
Ed
SoCal
86 SR5 XtraCab
22RE  W56B
31x10.50R15

Snowtoy [OP]

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Re: Smog gurus
« Reply #4 on: May 30, 2019, 09:05:42 PM »
That does sound like a cool down problem.

That is what I am thinking, no loss in mpg's or performance,

Quote
I've always have kept the engine running at high idle with AC on while waiting...…………..  (After a high speed run before getting to smog place)
That is what I used to do, but both the shops I use that are "no appointment", now tell you to turn the engine off while waiting, not sure if it is a CARB thing or the local ordinance.
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

emsvitil

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Re: Smog gurus
« Reply #5 on: May 31, 2019, 02:10:20 AM »
Where's the NOX column?

Ed
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22RE  W56B
31x10.50R15

Gnarly4X

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Re: Smog gurus
« Reply #6 on: May 31, 2019, 02:59:32 AM »
https://www.smogtips.com/failed-high-hydrocarbons-HC.cfm

So, your truck passed the test, right?

Gnarls.
1986 XtraCab SR5 22RE 5speed W56B, ~26,000 MI after break-in, DIM (Did It Myself) rebuilt engine - .020" over, engnbldr RV head, OS valves, 261C cam, DT Header. https://imgur.com/oACTHTR

emsvitil

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Re: Smog gurus
« Reply #7 on: May 31, 2019, 03:43:44 AM »
It just squeaked thru......
Ed
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sirdeuce

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Re: Smog gurus
« Reply #8 on: May 31, 2019, 08:53:09 AM »
With only a little over 1000 miles in 2 years it could be an issue with the fuel system. Injectors can get gummed up without being used on a normal basis. How much of the fuel was fresh? Old fuel burns slower after the lighter components boil off. Even in a decently sealed fuel circuit the more volatile chemicals escape. Unless you use the vehicle regularly a good long trip with fresh fuel and cleaner would be a good idea. Just throwing in experience with a friends car. The test results were similar to yours, even after the second test. His second attempt was after the car was driven about 20 miles on the freeway and straight to the sniffer. Our solution was 2 cans of Berrymans B12, fresh fuel and a drive to Cambria to go fishing(from Fresno).  We caught dinner and his car passed. We did not replace his cat or get the injectors cleaned for that test, but we did have the injectors cleaned for the next test and the car passed with flying colors. Just a thought snack.
 
Does sound like a cold cat though.
Sure it'll fit........ Just needs a little brute finesse.

Gnarly4X

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Re: Smog gurus
« Reply #9 on: May 31, 2019, 12:03:08 PM »
I’ve been using Berryman Chemtool B-12 for upteen years in all my vehicles.  It’s the best fuel additive/cleaner I’ve tried.

I usually dump a can in a full tank of gas about every 6 months.  You want to run that tank down, then immediately change oil and filter, because as it cleans, it deposits everything in your crankcase oil.  So I always put in a can in the tank of fuel right before my oil & filter change is due.

Stale or bad gas can cause all kinds of issues.  If the vehicle is not going to be driven much, you might consider putting in some Sta-Bil Storage fuel stabilizer.

Gnarls.
« Last Edit: May 31, 2019, 12:10:40 PM by Gnarly4X »
1986 XtraCab SR5 22RE 5speed W56B, ~26,000 MI after break-in, DIM (Did It Myself) rebuilt engine - .020" over, engnbldr RV head, OS valves, 261C cam, DT Header. https://imgur.com/oACTHTR

Snowtoy [OP]

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Re: Smog gurus
« Reply #10 on: May 31, 2019, 01:47:46 PM »
Where's the NOX column?

No NOX measurement requirement in my county, yet.

So, your truck passed the test, right?

Yes, by 2 HC's below the limit, which is extremely unusual for any of my vehicles, even the '86 22r w/300k+ only runs in the 50's with HC's at 2500rpm.

With only a little over 1000 miles in 2 years it could be an issue with the fuel system. Injectors can get gummed up without being used on a normal basis. How much of the fuel was fresh? Old fuel burns slower after the lighter components boil off. Even in a decently sealed fuel circuit the more volatile chemicals escape. Unless you use the vehicle regularly a good long trip with fresh fuel and cleaner would be a good idea.
 
Does sound like a cold cat though.

While only 1000 miles on it in two years, it runs at least once a month around my property hauling a trailer, and the occasional trip to the trail or town.
 
Not remembering when I put gas in it last, likely it was February, I went ahead and removed all but a few gallons then filled it with 16 gallons of 89 octane, and drove about 20 miles to the shop, so there should have been nothing but fresh gas in the lines for the test.

The only thing simple that it could be if it wasn't due to being cold, is that when I put the cat on, and fired it up, I thought I felt slight leak at the rear flange just ahead of the 2nd O2 sensor.  I couldn't hear a change in putting my hand on/off the top of the flange, but it felt like there was a slight puff-puff with the engine idling.  Being lazy, I just ran a bead of sealant around the flange, and after a heat cycle to cure the sealant, I couldn't feel the leak anymore.

I figure I will drive the truck more regularly and check the mileage, if there is a sensor or injector dumping excess fuel into the system it should be pretty clear in the mpg's, I know an aged coolant temp sensor in my 3.0 caused teh HC's to be a lot higher, nearly 3 times as much at idle and about twice as much at 2500rpms, compared to a new one that was installed between tests w/just 600 miles on it between the two tests.
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

sirdeuce

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Re: Smog gurus
« Reply #11 on: May 31, 2019, 07:26:04 PM »
I wouldn't worry about the second O2 sensor really. If 2 O2 sensors are employed the first senses the AFR and the second keeps tabs on the cat operation. If excess oxy gets to the second sensor it would be read as a bad cat, or O2 sensor.
Sure it'll fit........ Just needs a little brute finesse.

emsvitil

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Re: Smog gurus
« Reply #12 on: May 31, 2019, 07:37:56 PM »
Quite awhile ago I found the procedure for how they do the test.

It's been awhile, so my time intervals are probably wrong, but there are 2 dyno tests. (15 & 25)

For each test you have up to 300 seconds to pass.    The 300 seconds are divided into 30 second bins.   


The ECU adjusts A/F ratio based on the first sensor.    The second sensor measures the effectiveness of the cat.     
Didn't think a 91 had 2 sensors...…...…...…..


Once you pass a bin, you've passed.

So if the cat is warming up during the test, each bin would be getting better than the previous bin.      You got under the limit for a bin...….. test over you passed.
Ed
SoCal
86 SR5 XtraCab
22RE  W56B
31x10.50R15

Snowtoy [OP]

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Re: Smog gurus
« Reply #13 on: May 31, 2019, 10:08:59 PM »
No dyno test here in my area, all that is done is the tech runs the engine up to 2500 rpms, holds it for X amount of time, then releases the throttle, after it drops down to idle, if the machine gets a good reading test is over, if not they redo the test.

From taking a look at Rockauto, it looks like the 2.4 trucks, Camry, Cressida, and Previa CA smog equipped vehicles got the second O2 sensor for the '91 model year, with other models getting them over the next few years.

 If the rear O2 is just a nanny for the Cat, then a leak there wouldn't effect the mixture, which kind of puts it back to a cold cat.  Given how fast this test was done compared to those in the past, or possible a combo of a cold cat and aged sensor, might poke around and see what the sensors are reading ohm wise.
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

emsvitil

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Re: Smog gurus
« Reply #14 on: May 31, 2019, 10:49:43 PM »
Should be narrow band O2 sensor.
You check the voltage output of an O2 sensor while it's running. 
tap in a digital voltmeter and watch the voltage.

Should dither around .5 volts.
Ed
SoCal
86 SR5 XtraCab
22RE  W56B
31x10.50R15

Snowtoy [OP]

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Re: Smog gurus
« Reply #15 on: Jun 02, 2019, 01:49:49 PM »
Not sure if this would have effected anything other than the CO, but the tech left the EVAP line pinched during the smog test.
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

sirdeuce

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Re: Smog gurus
« Reply #16 on: Jun 02, 2019, 06:01:49 PM »
I've seen the techs pinch the evap hose for the test, It keeps the gas vapors from entering the intake manifold so the HCs don't go off the chart.
Sure it'll fit........ Just needs a little brute finesse.

Toyotadon

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Re: Smog gurus
« Reply #17 on: Jun 05, 2019, 10:46:39 AM »
The EVAP hose being pinched has nothing to do with the exhaust emissions. It's related to the Low Pressure Fuel Evaporative test which is used to ensure there are no leaks in the system up to the charcoal canister. Technically, they are not supposed to do that test while running the engine, but smog techs do it all the time.

Your numbers show you were running slightly lean at 2500 RPM, but an exhaust leak could also have been bringing in excess oxygen to skew those tailpipe numbers. At idle, you are very close to ideal air/fuel ratio. In short, the tech should have been running your truck for a longer period before checking emissions. The good thing is, if it had been too high, the machine would have forced him to do a "3-minute warm up" at 2500 RPM, then the numbers would have probably looked much better.

To check rich or lean status, enter your readings into one of these calculators:
http://www.factorypro.com/tech/Brettschneider,engine_carbon%20balance,AFR%20calculations.htm
http://www.smogstats.com/Lambda_CAT.aspx

 
 
 
 
 

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