Ray z

I went for my emissions test and failed due to the OBDII being not ready.Car is a '96 LT1 The check engine light has never come on sinnce I began driving this car about 1100 miles ago. I have never replace the battery either. Yes the bulb does light on start up. I bought from a Chevy dealer and it had a PA emissions sticker. I called the dealer and he said there was nothing wrong with the car and this happens from time to time. What must I do to get it to pass emmissions.This is what the Veh Ins report said:
Cat Conv-Not Ready
Heated Cat Conv-unused
Oxygen Sensors-Not Ready
Oxygen Sensor Heaters Not Ready
EGR Systems Not Ready
Secondary Air Inj Ready
Evap System Unused
Fuel System Ready
Engine Misfire- Ready
A/C refrig- Unused
Comprehensive Component-Ready Overall Readiness Result- Fail
Total codes present-0

Ray

redbullapril23

sounds like rear 02 sensors arent connected or are deffective...
a friend had a similar thing here in ga...



your friend
Sean

tjwong

Ray I can't remember exactly how it all goes. But apparently the IM240 tests have not all passed in your PCM. You may have to go to a dealer with a TECH2 to enable all the tests. I know that there is a procedure to get the PCM to pass all these tests. It does involve driving the car for X miles and at X speed and stops etc etc. It should be described in the manual somewhere if I get some spare time I can look it up for you as I have all the latest GM manuals on CD here.

TrackDayLT4

it seems the PCM got reset recently and all the drive cycles are not completed yet to set the monitor functions. Was the battery disconnected recently?

Cheers,

Lawrence

redbullapril23

but the weird thing is what he posted said zero codes read at the bottom.... thats what I dont understand... even if he dissconects the battery or whatever.... then it shouls still save the codes right...

Ray z

I have driven this car for 1100 miles and the battery hasnt been disconnected in those 1100 miles.
Ray

TJWONG, is this the procedure to complete a driving cycle. I find it hard to believe in 1100 miles all of these were not met.



General Motors Driving Cycle
A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:

Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.

Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.

Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.

Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.

Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.

Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.

Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.

Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
Reprinted on OBDII web site courtesy of General Motors Corporation
© General Motors Corporation

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© 2005 B&B Electronics The OBD-II Home Page is hosted by

TrackDayLT4

The PCM monitors various systems to detect if there are problems. When the PCM detects problems then it it stores codes and sets the Check Engine Light.

There are two types of monitors the PCM does;

Continuous - These are Fuel system, and Engine Misfire.

Non- Continuous - These are all the others.

When power to the PCM is cut or the PCM is reset using a scan tool, all the monitors are reset to Not Ready. The continuous monitors will switch to Ready during the first time the car is driven. The Non-Continuous Monitors will take several drives to switch to Ready. It looks like most of your Non-Continuous monitors have not set to ready yet.

Codes are set after a monitor switches to Ready and detects the appropriate problem to set a DTC

Don't worry about any that say Unused, they are not applicable to your car and do not effect the test.

It's entirely possible that the Inspection Tech reset your PCM while performing the test.

Cheers,

Lawrence

JCAIRE2

Was the car warmed up when you brought it to the station?

TBH94

I am a Certified inspection tech for PA and let me say that it can be a major headache to set readiness monitors. Some cars can take up to an hour and simple driving is not good enough. If you follow the procedure outlined above by another member it SHOULD, MABYE work. I have had cars where you drive them and all monitors set but two and you have to clear the PCM and start again. But don't get discouraged, once you set them they will be fine unless you unhook the battery or have a fault. What most likely happened in the first place is that the PA dealer cleared the codes because of a problem they did or did not repair. Good Luck

Mr Mojo

That was my first thought.

Ray z

Mr Mojo, I drove about 11 miles to inspection station I see you are in NJ. I drove from my house in Manalapan to the inspection staion in Freehold. About 11 miles on rte 18. Car was up to full operatining temp.



Ray

JCAIRE2

I'd say, drive it for an hour minimum and keep the rpm up. That's what I used to do with my '79 bronco when I lived in NJ, worked every time, even though that was the most foul-running POS I've had the pleasure of driving.

TrackDayLT4

Having the car warmed up or not does not make a difference here. The car did not fail a sniffer test, it failed for the PCM monitors not ready after being reset.

Ray listed the GM ODBII driving cycle in a earlier post. This is correct with the understanding that it may take two or three of these driving cycles to turn the Non-Continuous monitors to ready.

Since Ray also said, that he has driven the car 1100 miles with no check engine light, loss of power to the PCM, and not playing around with a scan tool. The only conclusion is that the Inspection Tech somehow reset the PCM during inspection.

If that was done and the car restarted, the Continuous monitors would almost immediatly switch to Ready and from the earlier post this appears to be true. Unfortunatly it takes two to three drives to reset the Non-Continuous monitors, there is no way around that.

The only thing I can recommend is to drive the car for a couple of days and find a friend that has a ODBII scanner (they are about $100 these days) or take the the car to an auto parts store where they will check your codes and verify the monitor status.

Cheers,

Lawrence

Mr Mojo

Oh I believe you, those are 11 hard miles. Traffic is horrendous on Route 9.

Aggravated4life

So you went to get it tested,it failed and the shop was no help?They couldnt fix it or suggest anything to try?If thats the case,they shouldnt be licensed to issue inspections.Im sick and tired of shops failing cars because of whatever reason but they have no clue as to why and what to get done to get it to pass.You posting on the forum tells me they didnt know what to do.Hopefully,all you need is a proper warm up procedure or something easy to do.Good Luck!

Mr Mojo

Public Inspection Stations don't fix anything.

Ray z

Lawrence, lots of good info here. THANK YOU! I will drive it for a couple of days and go for a retest.


Ray

SilverBeast

I think the tech probably reset without knowing it. Is there a different station that will do the inspection?

Ray z

I was thinking of trying the station in the next town. Dont want to deal with the same tech again.


Ray

bill_daniels

TTT

Ray z, I am having the same problem, and I am going to try the GM driving cycle you posted. It's rainy here in sunny Houston, but I'll report back whether this "driving cycle" cured my "not ready" problem.

Thanks,

Bill