P0455 and P0442 Return... '98 V70 GLT

[bmdubya1198]

Remember the city vs highway occurrence is not giving you good diagnostic info, it's just the nature of the drive cycle. Every time you go over 60, the evap drive cycle is cancelled, so you won't get the code with lots of highway driving.

Smoke is going to be your friend here. I still get a code on the 99 1-2 a year, but the leak is so small smoke isn't showing it. Thank goodness all my other cars use positive pressure evap test systems, they are a lot more robust

Interesting. That would explain why it only comes up every now and again. I very seldom drive somewhere and don't go over 60. With the rural roads and highways around here, it's easy to go a little fast. Especially when I "accidentally" find myself on a nice curvy back road...

[abscate]

If I Recall it correctly, the ECU will try to test Evap three times during each trip ( defined as both ignition being cycled AND coolant temp falling below some predetermined level) after which it gives up and waits for the next one. If you are driving on highways in heat and dusting BMWs you will kill the cycle with anyone one of these conditions: AC compressor on, full throttle position, and over 60 mph... it could be a long time to successfully complete the EVAP test and detect a code

[bmdubya1198]

I have not. Currently it just shows P0442.
Good to know, though. I plan on changing both of those hoses anyway, so hopefully that'll fix it. My other thought was the fuel level sender gasket.

[sleddriver]

The P0455 monster lurks in my 98 as well unfortunately. Abscate's explanation explains why it sometimes takes so long to return, other times within a week or so. What a PITA system....

I have plenty of posts on this both here and on BITOG. I used an Autodiagnos Volvo scan tool to run the cycle and watch the tank pressure sensor reading. It really bugs me when I can't figure something out and I've been working on this one for at least a decade. It'll evaporate for awhile, but eventually returns. Always returns.

Sure would be nice to remove the entire system from the car, lay it out on the driveway, hook it back up, then smoke it all out in the open! I'm tempted to do this partially by removing the gas tank, char can, hoses, fuel filler, shut-off valve...everything in the rear. Pressurize it all with Nitrogen, spray down with very soapy water and look for bubbles. While out replace both FP & FLS tank gaskets.

I wonder if the hard, plastic line that runs from the purge valve on the radiator, all the way back to the rear char can is at fault? It's mainly covered underneath the body. I think it's tucked in with the dual fuel lines.

I think it's time to remove the gas tank & fuel fill tube, bring it all into the daylight for a good LOOK. Beats knocking our heads in to a wall over & over.

[bmdubya1198]

The P0455 monster lurks in my 98 as well unfortunately. Abscate's explanation explains why it sometimes takes so long to return, other times within a week or so. What a PITA system....

I have plenty of posts on this both here and on BITOG. I used an Autodiagnos Volvo scan tool to run the cycle and watch the tank pressure sensor reading. It really bugs me when I can't figure something out and I've been working on this one for at least a decade. It'll evaporate for awhile, but eventually returns. Always returns.

Sure would be nice to remove the entire system from the car, lay it out on the driveway, hook it back up, then smoke it all out in the open! I'm tempted to do this partially by removing the gas tank, char can, hoses, fuel filler, shut-off valve...everything in the rear. Pressurize it all with Nitrogen, spray down with very soapy water and look for bubbles. While out replace both FP & FLS tank gaskets.

I wonder if the hard, plastic line that runs from the purge valve on the radiator, all the way back to the rear char can is at fault? It's mainly covered underneath the body. I think it's tucked in with the dual fuel lines.

I think it's time to remove the gas tank & fuel fill tube, bring it all into the daylight for a good LOOK. Beats knocking our heads in to a wall over & over.

Unfortunately it might come down to that one day... already dreading having to drop the tank on my Saab to replace the fuel level sender.
Who knows how long I'll even keep my V70 at this point... it knows just when to irritate me! One car gives me trouble, the other one has to jump in on the fun!
My brakes have been feeling odd and the stumble has come back pretty noticeably. The stumble seems to be on braking and on some shifts. I just don't get it...

[sleddriver]

Given my recent experience, dropping the tank isn't the big deal I read about, much less to be feared. Should have done it years ago rather than thinking "I've read it's difficult/frustrating/PITA/etc."

I'll be posting pics and notes.

[bmdubya1198]

I've found a lot of "big and scary" jobs to be actually quite simple. I'm not afraid to do any work on my own. A lot of jobs are over-hyped! Hopefully the fuel tank is one of those.

[sleddriver]

This may help:

When the EVAP canister shut-off valve is closed the fuel tank system should be sealed. When the EVAP canister purge valve is activated the fuel tank pressure must fall to a set negative pressure or it will be interpreted as a major leak. Then the canister purge valve closes. Fuel tank pressure must then remain within certain limits or it will be interpreted as a minor leak. DTC ECM-4308 is stored if the CM registers a minor or major leak.

Possible Source(s)

Major Leak
Leaking fuel tank, filler pipe, fuel tank filler cap, EVAP canister, EVAP shut-off valve or lines between these components.

Blocked EVAP valve.
Blocked hoses to the fuel tank pressure sensor or defective fuel tank pressure sensor. Does not react to changes in pressure.

Minor Leak:
Leaking fuel tank, filler pipe, FT filler cap, EVAP canister, purge valve or lines between these components.

Here's links to my other posts:
1. 98 V70 P0455 GROSS leak

2. EVAP System Operation Question

[bmdubya1198]

This may help:

When the EVAP canister shut-off valve is closed the fuel tank system should be sealed. When the EVAP canister purge valve is activated the fuel tank pressure must fall to a set negative pressure or it will be interpreted as a major leak. Then the canister purge valve closes. Fuel tank pressure must then remain within certain limits or it will be interpreted as a minor leak. DTC ECM-4308 is stored if the CM registers a minor or major leak.

Possible Source(s)

Major Leak
Leaking fuel tank, filler pipe, fuel tank filler cap, EVAP canister, EVAP shut-off valve or lines between these components.

Blocked EVAP valve.
Blocked hoses to the fuel tank pressure sensor or defective fuel tank pressure sensor. Does not react to changes in pressure.

Minor Leak:
Leaking fuel tank, filler pipe, FT filler cap, EVAP canister, purge valve or lines between these components.

Here's links to my other posts:
1. 98 V70 P0455 GROSS leak

2. EVAP System Operation Question

I'll look over those links!