Sanity draining Smog 'Readiness' indicators [98 850] Topic is solved

[WhatAmIDoing]

The temp gauge is just a dummy gauge. It doesn't really mean anything. Really just tells you if the system is reaching operating temp or if the car is overheating. For serious readouts, it should be ignored. Use the temps on your OBD2 scanner.

[ToriWhite]

3 drive cycles later, 2 of which started 'At Temp' .. nothin

Calling the dealership to see if I've got an exempt VIN.. all my research says otherwise but I'm running out of options here..

Going to take the Volvo in anyways.. came across a passage in the Volvo readiness documentation

Readiness status cannot be read from a vehicle equipped with Motronic 4.3 using the VST, but the completion of two 'TRIPS' will establish readiness.

IDK what that means, but Smog guys give you a free retest if you fail, so I'm not opposed to giving it a shot

Anyone know what this means?

When interrogated using a generic OBD II scan tool the MY 1996 Volvo 850 equipped with Bosch Motronic 4.3 Engine Management System, may experience all of the Readiness Codes changing from 'COMPLETE' to 'INCOMPLETE' when the ignition key is cycled. This behavior applies to all 1996 M 4.3 850s and cannot be corrected. DO NOT turn the engine off until after the Enhanced Inspection/Maintenance OBD II check has been completed.

Also I took a picture from the OBD screen with a lot of info I don't understand.. please let me know if anything here makes any sense to you!

What is all this nonsense

The temp gauge is just a dummy gauge. (...) For serious readouts, it should be ignored. Use the temps on your OBD2 scanner.

That's my suspicion, thankfully the starting temp is a pretty big window to land in- Took fancy OBD with me, and even starting in temp- no dice..

Anyone have a clue whats going on? Anything helps!

[ToriWhite]

Tried contacting the local dealership, they were 100% unhelpful and even a little abrasive about it- the only "valued customer" is one they can take more money from!

Read earlier that someone had similar struggle getting codes to set because they had a small Evap leak- not large enough to throw a code, but enough pressure difference to severely interfere with their attempts to pass readiness. They found/fixed a hairline crack, all codes came green 50 miles later. (Could that be the reason 850's have such a bad rap? Picky Trip requirements meet ubiquitously degrading rubber hoses?)

Going to swing by friends shop for a smoke test, fingers crossed something comes up! Otherwise I'm at a loss, I've heard of someone having trouble with their Mass Airflow (valve? Something), don't know what that is or how that'd affect emissions though.

[ZionXIX]

I just finished patch a hole in my fuel tank and replacing to disintegrated hoses. My evap code cleared after 11 miles. I drove 500 miles before without out it passing. Now I just need the catalytic converter to clear.

[ToriWhite]

Finished the smoke test yesterday: no leaks along the lines: even at the most recent repair- however we DID find that my purge valve off the charcoal box was stuck open, and regardless of how we ran current across it- it wouldn’t close.
I’m not knowledgeable enough to know how that would affect the emission computer’s ability to perform tests, but I’ve replaced the valve with a working one now.
Just finished the flywheel adaptations (I hope, still no VST to check!) on my way back: I’m going to fuel up to the required window and try those damnedable drive cycles AGAIN

[abscate]

A stick purge valve , either open or closed , will cause an emissions Evap fail and pop a code.

Here’s how complex the Evap test is....courtesy of user lexia

The EVAP system consists of:

Fuel tank
To avoid the fuel tank deforming due to negative pressure it has a reinforcement plate screwed to its underside.

Roll-over valve
The roll-over valve is a safety valve which closes if the car tilts sideways by more than 45°, preventing fuel leaking in the event of an accident.

EVAP canister
Fuel vapor from the fuel tank passes a bed of activated charcoal in the EVAP canister. The activated charcoal binds the fuel and pure air flows out into the atmosphere through the vent at the top of the EVAP canister. 80-140 g fuel can be absorbed by the EVAP canister, depending on the volume of charcoal.

Canister purge (CP) valve
The canister purge (CP) valve is located between the EVAP canister and the engine intake manifold, the valve is used to control the flow of fuel vapor from the EVAP canister to the engine. It is connected to a 12 V supply from the main relay and to the engine control module (ECM). The engine control module (ECM) opens the valve by grounding the cable.

EVAP canister shut-off valve
Certain markets require the engine control module (ECM) to detect leakages in the tank system, in these markets a leakage diagnostic has been introduced. In order to check the fuel tank system, cars in these markets have an EVAP canister shut-off valve. This is mounted in front of the left A-pillar inside the front fender or close to the rear right tire, depending on the model, and is connected to the EVAP canister vent. The valve is connected to a 12 V supply from the main relay and can be grounded by the engine control module (ECM). The engine control module (ECM) can close the valve by grounding the cable. The EVAP canister shut-off valve valve is normally open (turned off), it is only closed (turned on) when the engine control module (ECM) is checking the system.

Control
Normally the canister purge (CP) valve is closed and only opens when the engine control module (ECM) is emptying the canister. When the EVAP canister is emptied the valve is first pulsed, this pulsing increases to bring the mixture from the canister up to a value which varies according to engine load and speed. Because of the negative pressure in the inlet manifold, fresh air is sucked into the engine through the EVAP canister vent or through the EVAP canister shut-off valve. As the air passes through the EVAP canister, fuel stored in the activated charcoal is drawn into the engine and burned.

Vapor which evaporates from the fuel in the fuel tank is routed to and stored in the EVAP canister from where it is introduced into the combustion process via the canister purge (CP) valve and negative pressure in the intake manifold. A leakage diagnostic has been introduced in certain markets to ensure that the fuel tank system is not leaking. This diagnostic is designed so that the system will detect a leak/hole greater than 1 mm. The fuel tank system consists of the fuel tank, fuel filler pipe, roll-over valve, EVAP canister, canister purge (CP) valve and all hoses between these. It now also has a fuel tank pressure sensor and EVAP canister shut-off valve to allow the diagnostic test of the system.


LEAK TEST
The diagnostic test is divided into phases in which the various components are tested, if a fault is detected the diagnostic test is interrupted and a diagnostic trouble code (DTC) is stored for that component. The diagnostic test works as follows:

-EVAP canister shut-off valve shuts off the EVAP canister (valve turned on), the fuel tank system is entirely closed. Pressure in the fuel tank should be fairly stable, if the pressure in the fuel tank drops this indicates a leaking canister purge (CP) valve, and diagnostic trouble code (DTC) EFI-315 (Canister purge (CP) valve, leakage) is stored.

-EVAP canister shut-off valve is opened (valve turned off), the tank system is open.

-Canister purge (CP) valve is energized, and because of the negative pressure in the intake manifold the engine starts to suck air through the EVAP canister. Because the EVAP canister shut-off valve is open, pressure in the tank should drop slowly. If pressure in the tank drops rapidly, this indicates that the EVAP canister shut-off valve is sealed, diagnostic trouble code (DTC) EFI-614 (EVAP canister shut-off valve, flow fault) is stored.

-EVAP canister shut-off valve is closed (valve turned on), the canister purge (CP) valve is still energized, pressure in the fuel tank should now drop fairly quickly. If the pressure does not drop enough, this indicates a serious leak somewhere in the fuel tank system and diagnostic trouble code (DTC) EFI-611 (Fuel tank system, serious leakage, OBD P0455) is stored.

-Canister purge (CP) valve is closed (turned off), EVAP canister shut-off valve remains closed, there is now a negative pressure in the fuel tank. The negative pressure in the fuel tank has stabilized. If pressure starts to increase too quickly this indicates a small leakage in the fuel tank system and diagnostic trouble code (DTC) EFI-612 (Fuel tank system, small leakage) is stored.

-EVAP canister shut-off valve is opened (turned off), the diagnostic test is concluded.

The pressure in the fuel tank system is determined for its various phases by the following factors:
-the volume of fuel in the fuel tank.
-height above sea level
-fuel temperature and evaporation.
The system can calculate this information. Because of this, it is difficult to say how fast or much the pressure can rise or fall in the various phases. To carry out the diagnostic:
-engine temperature must be above -10° C when the engine is started
-engine coolant temperature (ECT) must be below +107 °C
-there must be no permanent faults stored for the throttle position (TP) sensor, vehicle speed signal (VSS), canister purge (CP) valve, idle air control (IAC) valve, mass air flow (MAF) sensor, battery voltage, fuel tank pressure sensor, EVAP canister shut-off valve, engine coolant temperature (ECT) sensor and the engine must not be misfiring
-the engine is idling and load (Tl) must not exceed 2.7 ms (automatic) and 2.3 ms (manual)
-speed must be 0 km/h
-the concentration of fuel vapor in the canister must not be too high
-there must be more than 11 liters of fuel in the tank
-the pressure in the tank must not be too high.
-fuel trim must be active.
-the car must be below 2700 meters above sea level.

The diagnostic test starts at the earliest 17 minutes after the engine has started when all conditions have been fulfilled, and takes approximately 30 seconds. If the diagnostic is interrupted it will try again when all the conditions have been fulfilled again. The engine control module (ECM) makes a maximum of 3 attempts in one journey. If the diagnostic test is interrupted all three times it will not try again until the engine is started again.]

[ToriWhite]

Thanks for the info Abscate.. good explanation on the difference between the canister shut off vs purge valves!

As for the 850’s status since replacing the sticky purge valve- one generous set of flywheel adaptations and 3 drive cycles across 2 trips; still no codes! Even following the specific instructions to flip one monitor-

DTC/EFI 233 - Adaptive Idle Air trim. After completing the trip and the function is not set, idle the engine for 60 seconds, press the accelerator and rev up the engine above 1500 RPM for a few seconds, return to idle for 60 seconds. Continue this until EFI 233 is completed

didn’t flip a single monitor.. really troubling. Same for the rear O2 sensor:

DTC/EFI 425/436 - Rear oxygen sensor, Accelerate to at least 45 mph, drive for 5 minutes at 1800-2200 RPM.

I must have fulfilled that 5 minute RPM segment 4 times today... still flagged as unready!

Have been reading about the greater emissions system as a whole over this ordeal, and came across the MAF part of the system. Apparently the MAF sensor can get dirty over time, and need cleaning. A bad MAF means inaccurate readings for the airflow, which I imagine could cascade down and mess with the fuel trim and O2 sensor diagnostic routines (maybe other monitors too)

Lo and behold, one Robert DIY video later- and I realize something. That big black box, the Air Filter box- isn’t supposed to be empty, like mine is. Like the name implies- that big empty box is supposed to hold an air filter.. What component is immediately after the air filter box? The MAF sensor! I don’t want to prematurely jump to conclusions, but I think my MAF may eligible for a really good cleaning.. going to crack open the hood after buying some cleaner spray (and a filter insert!) and see what the damage is..

[erikv11]

Just a naysaying note up front: cleaning the MAF almost never does anything, unless the MAF is visibly dirty with oil or debris on the sensing wire. Certainly won't hurt as long as you are very careful to not touch the wire, but mostly it is a way to sell MAF cleaner ...

[WhatAmIDoing]

If you've been driving hundreds if not thousands of miles without an air filter, I'm surprised you do not have more problems.

[abscate]

AC off?
Do not exceed 60 mph
Throttle in range 1/4-3/4 only
A good scan gauge can monitor tank pressure so you can confirm the purge valve is pulling the tank to the correct pressure.

What other monitors aren't ready?

I forgot fuel tank 1/2 full. Range is 1/4-3/4 or so, less if it is hot out.