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23K views 30 replies 13 participants last post by  Texan4Life 
#1 ·
Vehicle: 2001 Cadillac Deville
Promblem: Failed Smog Emissions Test [HC (PPM) MAX=31 MEAS=50]
Recent Services: New Spark Plugs, Air Filter, Oil Change, Throttle Body Cleaning, Inspection of Idle Controllers.

Does anyone have any ideas what could be causing my car to fail? I've been having ENHANCED SMOG INSPECTIONS, would it pass if I have a standard smog?
 
#2 ·
Car not reaching temperature i.e. thermostat weak. car should run 205 to 220 degrees. EGR passages plugged? but I think that affects NOX more than HC. You can monitor temp thru the on board diagnostics. Should reach 95 to 98 degrees celcius in just a few min. Slow to react pre cat. OXY sensor. Again, it can be monitored thru on board diagnostics. I've seen a thermostat affect operation ( delay of going into closed loop) of the OXY sensor, so verify engine temp 1st.
 
#3 ·
All my Emission Control Systems passed according to my visual/functional check results.

But my ASM Emission test failed at 25 mph [RPM 1121, %CO2 14.8, %O2 0.1, HC (PPM) MAX 31 AVE 4 MEAS 50, CO (%) MAX 0.43 AVE 0.01 MEAS 0.11, NO (PPM) MAX 687 AVE 18 MEAS 24] FAIL

Also my 15 mph HC (PPM) test barely passed at MAX 47 AVE 4 MEAS 47

:banghead:
 
#18 ·
If anything was wrong w/ the TPS or any part it would throw you a code. Its OBD II system and their checks are really thorough.

Ya nox is EGR

HC is fuel mixture.

If there are no codes the O2 sensor is fine. If the car has a MAF sensor you can spray some throttle body cleaner inside the MAF sensor channel cause sometimes dirt builds up and causes your car to think its running lean.

I would go the full route and get hooked up to a true injection cleaning machine.

And I'm talking about a true machine like


Not one of those stupid upside down hairspray bottles.

If that don't work it might be a cat :(

But if you get a real motorvac fuel injection cleaning it should really work. Plus it will increase your gas mileage and performance. :)

JUST MAKES SURE after they run the cleaning you take the car for a good 1/2 hour ride and make sure he runs the car hot so the cat is properly ignited, all the gunk is cleaned out from the injection cleaning and your O2s are at proper temperature.

Your car should never be inspected cold. ALWAYS at full running temperature.
 
#4 ·
Hmmmm........Thought your car did not need the dynamometer test, just an OBD-II plug-in go/no go.

Do you have a Service Engine or any DIC messages concerning transmission or gas cap ?

Pull your Diagnostic trouble Codes from the car's built-in scan system. You don't need a scanner or outside help. Use the sticky thread at the top of this main page titled "How to pull codes", scroll to the OBD-II procedure, and then use the links to the P,B,U, and C codes to find what each (if any) means.

Curious that the car did not throw a "Traction Disabled" message and fail everything. (All wheel speeds not within tolerances for Stability Control.)
 
#5 ·
The car had an IDLE ERROR code appear a week ago, I took it into my local Dealer and they fixed the problem (Idle Screw Too Tight). Now there is no codes or lights appearing on the dash.

The first 2 smogs I had done were enhanced with dyno's. If I register it in Santa Barbara County first before I smog it again they, will perform a normal smog this time. Would my car maybe pass a regular smog test? :confused:
 
#9 ·
Those codes, will not light the MIL until the second time, they are both considered GM B codes in the sense that they do not affect emmissions right away like an o2 sensor would which is a A code. To properly diagnose these codes, you will need a BI scanner in order to control the IAC valve. It sounds like you have done the right things.

Conditions For Running the DTC
DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0335, P0336, P0340, P0341, P0385, P0386, P0401, P0403, P0404, P0405, P0440, P0442, P0443, P0446, P0449, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122, P1336, P1372, P1404, or P1441 are not set.
The engine coolant temperature (ECT) is greater than -40°C (-40°F).
The intake air temperature (IAT) is greater than -18°C (-1°F).
The ignition voltage is between 10.5-16 volts.
The barometric pressure (BARO) is greater than 6 kPa.
The engine run time greater than 40 seconds.
The transmission gear state has not changed for 3 seconds.
The torque converter clutch (TCC) state has not changed in 3 seconds.
The TPS less than 1.5 percent.
The spark advance is less than 12.39 degrees.
The spark retard is greater than -13.79°.
The vehicle speed sensor (VSS) is less than 3 km/h (1.9 mph).
The above conditions are present for 3 seconds.
Conditions for Setting the DTC
The actual engine speed is 100 RPM less than the desired engine speed.
The above enabling criteria must be met and fail the diagnostic 3 consecutive times to set this DTC.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
Inspect for the following conditions:

A restricted air intake system
Proper operation and installation of all air intake components, for example, collapsed, clogged, or loose air intake ducts, a clogged air filter, and proper operation of the mass air flow (MAF) sensor, if equipped
A tampered with or damaged throttle stop screw
A tampered with or damaged throttle plate, throttle shaft, or throttle linkage
Objects blocking the IAC passage or throttle bore
Excessive deposits in the IAC passage or on the IAC pintle
Excessive deposits in the throttle bore or on the throttle plate
Vacuum leaks
A low or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by the IAC valve. Refer to Symptoms - Engine Controls .
If the problem is determined to be intermittent, refer to Intermittent Conditions in Symptoms.
 
#10 ·
Pull the IAC (Idle Air Control) valve out the side of the throttlebody and clean it with TB cleaner. Clean the TB as posted several times in here, Seville, Northstar Performance and technical down below.

"Idle screw too tight" ?????? No idle adjustment screw on a 2001 that I know of...........
 
#12 ·
Your idle, in D, should be about 650 rpm.

When you removed the IAC to clean the tip, what did it look like?? Nasty black or clean ???

If it was nasty, then you need to go back and carefully remove the intake ducting, block the thottle wide open and use throttlebody cleaner, rags, and a toothbrush to scrub the butterfly (both sides) and TB bore until they're absolutely clean. Stuff a lint-free rag into the TB past the butterfly in order to prevent liquid cleaner from pooling in the manifold. Remove the rag carefully with long needlenose pliers. .......or be very careful with the amount of cleaner you spray/use.

You may also want to remove the EGR valve, just behind the throttlebody, and scrub that and the gas passages also. A dirty/stuck EGR will screw up an emissions test, too.
 
#14 ·
mcdominguez,

95C is 203F. Normal Northstar everyday temperature.

F = C x 9 / 5 + 32

C = F - 32 / 9 x 5

As carnut posted, your engine should reach 200F within 2 miles or so - a few minutes of town driving.

EDIT carnut, are you looking at the possibility of the engine not going to closed loop ?
 
#16 ·
How many miles you got? You know, I posted something in the N* section about the throttle position sensor. If its going bad it can throw your idle off and kill mileage as well because it tells the pcm wrong throttle settings so the pcm is sending the IAC valve wrong settings. It will also throw a code. Well it did on mine, P0121 I believe. My check engine light did come on too. It's a $30 part. Can't hurt to take a look at that as well.

Hey Sub, we're both in MD. I have to do the dyno emission test. You dont? They put it on the maching and drive it for like 15 minutes on the machine. Maybe they hook their scanner to the car and that disables it from throwing codes. I know when I enter diagnostic mode in my car while I am driving, I never throw a code, but as soon as I exit diagnostic, whatever code is nagging, will sure enough pop right up.
 
#17 ·
Our County Commissioners bought into the phony green EPA "opt-in" program, so although Queen Anne's County air is far cleaner than EPA mandates, the county gets some sort of Federal kickback and the California (contractor) testing company gets megabucks...................The entire emissions testing system is the biggest scam ever foisted on the car driving public, but it keeps the greenies happy - at our expense.

There's no more dyno test over here; it's all OBD port plug-in. The state test stations removed the dynos 8 months ago.

DO NOT go into diagnostics while driving - the load and temp fluctuations screw things up royally - best to do it in the driveway, engine OFF, ignition switch ON..................and DO NOT "clear codes" within two weeks or more of a test; the system needs a bunch of start-run cycles to present a "ready" code to the test set........... reset the system on the way to the test station and you will fail, guaranteed.

Don't forget that there are two code designations: C for Current, and H for History. There is a big difference.
 
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#19 ·
Several things about this thread concern me.
First I want to know why they are doing an ASM test on an OBD-II vehicle.
Next I want to know why a dealer told you they adjusted the "idle screw", that would be completely insane.
Granted on an emissions inspection they are subject to random ASM tests, but I have never seen it happen. You might call CARB and ask them why your inspection stations are doing an ASM test on your car.

Idle control problems have nothing to do with the "screw", if there is an idle problem it is a control problem and no amount of screw turning will fix it, the computer will just attempt to compensate for it and now your minimum air flow rate is trashed.

Were I you, I would clear all the codes, then drive it, then DIAGNOSE the codes properly rather than throwing parts at it until it goes away.
You need to find a competent tech who can properly diagnose the codes and find the root cause.
 
#22 ·
I know a lot more places are adopting "smog" programs. We only have it in certain counties in Northern Virginia, the rest of the state is not required to have them but DEQ is pushing the government to adopt it statewide.

All of CA has one, I know MD has some sort of program in place and some places in TX also.

The programs are usually similar. Some places use an I/M 240 dyno test but I know CA uses the same ASM test and OBD test program that we use.
Our regulations are that any OBD-II car would typically be an "OBD" test only with a visual on the catalyst and a gas cap check.
If the MIL is on and codes are current then it will fail. If the MIL doesn't work, it will fail. If the codes have been cleared by some sneaky pete trying to cheat, the flags won't set and it will reject from testing. OBD tests are subject to random ASM tests but I have never seen it.
Typically the computer tells you what to do based on the vehicle info put in to the computer.

I am just wondering why this car keeps getting an ASM test unless CARB has singled it out for some reason in the computer system.

I think this program is pretty good in major population centers to help with air quality. I think it should be expanded to more rural areas also.
Any amount of research will show that a very minor number of gross polluting cars contribute almost all of the airborne emissions. Most modern cars almost puff out cleaner air than they ingest to begin with... until people start jacking around with them.
I know it is an unpopular opinion but.... there you go.
 
#23 ·
A significant part of the country is not required to perform emissions testing OR dispense reformulated gasolines.

Go to www.epa.gov/otaq/rfg/whereyoulive.htm

The site is a bit old, but you will find links to other regional and state sites which have testing and gasoline information.

Bill, MD (around the Beltway and Baltimore) is emissions test - a couple of other counties have opted into the program because of the federal tax kickback bribe to use the program, and the California company that runs the test stations for MDOT lobbied heavily for the program. At $14 for the test, which takes a max of 5 minutes, that's a potential $166 an hour per test lane- not exactly peanuts for totally free state and contractor income.
 
#24 ·
Have they ever done I/M 240? That is a pretty intensive test.
So they do an OBD check now?
We get paid the same rate if it is a 2 speed idle, ASM dyno, or an OBD test.
Thankfully at a dealer we only see newer cars so most of them are OBD, but we get some old 4.9's that come in needing the EGR ports cleaned out.

I am a certified repair technician so I can do waiver repairs too. We don't see a lot of those though.
Biggest issue I have is knuckleheads clearing codes after a repair.. DOH!
 
#26 ·
I don't know about the Baltimore/Montgomery County area, but over here on the Shore the opt-in counties have removed the dynos from the test stations - it's all OBD now. $14 for a 5 minute plug-in is a ripoff. So simple even a caveman could do it.

Antique, resto, and kit cars are exempt anyway, so time has caught up with the system and it's all electronic now.
 
#27 ·
Even when we do an OBD we still have to do a visual on the cat, check the numbers on the car and test the fuel cap in addition to the OBD check.
I hate the old stuff, but sometimes they do pass.
 
#28 ·
You shouldn't complain about 14 bucks, ours is 29 bucks in Massachusetts every 12 months. Havent seen a fee less than 15 dollars since about 1985. Everything back to 1986 gets tested. Have to use the tailpipe sniffer on the pre OBD2 cars, so that takes a while for those cars to be done. My 69 just gets a safety inspection, lights, ball joints, parking brake, etc, no emissions.
 
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