P0455 and P0442 Return... '98 V70 GLT

[sleddriver]

Forgot to mention previously that if the tank pressure sensor is Toes Up, out-of-spec, or 'thrown a wobbly' then this could also cause problems. Being able to monitor this sensor while pulling a vacuum on the tank or pressurizing it would be very useful! Once either is done, then seeing the pressure/vacuum change over time would give some idea how bad it is.

I wonder if any of the OBDII tools (like Torque) are able to monitor tank pressure in real-time? Will VADIS? I have VADIS on an old laptop but no DICE box.

This is great info from fellow member lexia. Explains the sequence used and how the tests are carried out.

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.

[bmdubya1198]

I will have to check if I can do that in Torque. Being that there are so many PIDs, it should be possible.

[sleddriver]

....What other places could there be a leak? The only thing I can think of right now that could possibly be leaking is the fuel pump seal, which I already replaced when I replaced my fuel pump. When I removed the fuel pump access cover, I can smell a hint of gas (nothing TOO strong) but I figured it was from the little vent on the fuel pump housing. Is that normal or is that reason to re-seat the seal? I've re-seated it multiple times, and I don't think I can get it any straighter than it is.

I finally decided to do a tank drop in order to examine the top, hoses and to pull both the fuel level sender & fuel pump to verify both gaskets are OK. I also disassembled the FLS, inspected the internals as it's been hanging up from time-to-time.

I followed the instructions in VADIS. I placed a large roll of carpet under the tank as both a stop & cushion. Here's what I found. First photo shows two plastic T-fittings, all connected by hard plastic pipe that looks shrunk into place. I also found one of those small pinch-to-release-connectors on the right T. Very similar to the one found on the char. can (which I cut off years ago and replaced with silicone tubing.) I disconnected it and turned it around. Inside I found a dried-up brown substance, like grease. I swab'd it out with a q-tip, noticed both o-rings inside appeared to be intact, so I lub'd them with vaseline and reconnected it. I'm still suspicious of it though...especially after 20yrs.

Notice the rigid plastic pipe just to the back...appears to be no clamp on it. Odd that. Could be leaking air there as well. This line is the tank vent line. It runs all the way to the char. can and connects with another one of those push-to-disconnect-inner-o-ring connectors. Might be a good idea to replace the entire pipe with silicone tubing and proper clamps.

Volvo_Gas Tank 001.JPG (183.52 KiB) Viewed 1530 times

Here the first connector has been turned back around and attached.

Volvo_Gas Tank 003.JPG (182.7 KiB) Viewed 1530 times

Notice here just how tight the vent hardline is around the FLS collar. Right there it showed signs of being abraded a bit and well as pinched. I didn't remove it for inspection due to time and not having a suitable replacement, however I'm suspicious of it as well.

Volvo_Gas Tank 003.JPG (182.7 KiB) Viewed 1530 times

Both collars on the FLS and the FP were easy to remove using a cirved oil filter wrench that looks like a pair of pliers. VADIS noted it's important to replace these collars soon after removal to prevent the tank necks from expanding. I found the FLS gasket a bit grey and dry but no signs of rot. I cleaned it with Mequiar's VLR and reinstalled and tightened. Ditto for the FP except I used ReGrip instead. VLR would be fine as well. I also lub'd the FP connector o-rings with vaseline per VADIS before re-installation.

BTW, this is the tank/vent filter that's tied to the fuel intake line. I didn't bother taking it apart.

Volvo_Gas Tank 006.JPG (153.7 KiB) Viewed 1530 times

Lifting the fuel tank into place was eased by the roll of carpet. I also used a long 2x4 as a lever to raise the tank. I had better luck with a simple floor jack. The two rear tank bolts were a pain to line up as the weight of the tank had bent the steel tank straps, changing their connection geometry. A bit longer bolts would have really helped.

I buttoned it all back up, reconnected the batt. terminals and drove off the rear ramps. No leaks. Time will tell if this did anything to solve the P0-455 DRAGON.

Anyone else replaced all of these pipes & hoses in an attempt to slay the dragon? I suppose I could drop the tank, then smoke it and observe for leaks.

[bmdubya1198]

Wow, thanks for posting this update! This is such an overly complicated system. Hopefully your P0455 will disappear after doing this!

[sleddriver]

You're welcome. Note that the top of your GLT tank might not look like this at all. I posted my photos on CN90's link to compare & contrast.

What we all need is a diode-delete for P0-455!

[abscate]

I notice that the test only runs at 0 mph/kph , and after 17 minutes of running. That leads me to the long reset time on my freeway 1999, which hits 65 mph after 7 minutes and doesn’t stop for 2 hours on most of its trips.

I need to move somewhere with stop and go traffic.

I’m at 2700 miles now with EVAP NOT READY condition.

[sleddriver]

Something odd happend yesterday with regard to the fuel level sensor reading on the dash. The night before I put in about 4 ga. Afterwards, the gauge read 6ga total. There was some gas in the tank already. Yesterday morning, the gauge read fine. While driving later, I noticed the 'fuel low" light come on! Yet I'd only driven about 25mi so far. (I reset the trip meter when I gassed up). Thought I must have a leak so I looked under the back. Smelled no gas and saw no wet area. Thought maybe the fuel level sender was stuck. So I added 6ga from the pump. Level is now back up, so the sender unit did not come apart (very unlikely).

I've noticed lately the sled using more fuel than I remember. All in town driving. Something is up. I noticed someone mention that P0-455 can cause a drop in MPG due to the ECM adjusting for it. I'm very skeptical on this. Built in MPG penalty for ignoring -455? BTW, I did recently replace the air filter. It had been in there too long. I also disconnected the battery long enough to reset everything that's electrically resetable.

Thoughts?

[abscate]

Something is up. I noticed someone mention that P0-455 can cause a drop in MPG due to the ECM adjusting for it. I'm very skeptical on this

Yeah, that one is fake.

[wizechatmgr]

It sounds plausible - unmetered air entering the intake. That said, I wouldn't expect a drastic change in consumption.

[bmdubya1198]

It sounds plausible - unmetered air entering the intake. That said, I wouldn't expect a drastic change in consumption.

I thought the same. But I agree, you probably wouldn't even notice the drop.