98 v70 NA P0455 - my most loyal friend

[98v70dad]

Yep the GN (Green Orange?) wire should have 12 VDC when the key is on. The ECU opens the purge valve by grounding it on the Blue Green.

Resistance measurement on BG wire won't be too useful

Voltage the on the GN should be 12 VDC to ground

Voltage across connector not useful - no one knows what load the ECU puts onto the wire in OFF state.

Yep. Voltage on the GN wire is 12 V to ground when the key is in the second position. Its 11.66 V in the first position. Both positions of the key are with the car not running.

[98v70dad]

So even though there are a couple of rubber items on top of the fuel tank that haven't been replaced I believe that the likelihood of them being bad is low. Building the smoker will be a pretty easy way to confirm that. The fuel pressure sensor could be bad but I know no way to troubleshoot that.

I had a chance to examine a fuel tank from a 98 off-the-car. Compared to an earlier 850, all the vac pipes on the 98 were HARD plastic instead of rubber. Also since I didn't see nor smell smoke from mine when smoked, I ruled out dropping the tank.

Fuel pressure sensor or Tank pressure sensor? Perhaps you meant the later? I knew mine was OK as I could see the readings change during the diagnostic testing.

Ease your pain & do yourself a favor...build a simple smoker next.

Tank pressure sensor is what I meant, sorry. Mine is located on top of the gas tank I believe and I think you have to drop the tank to get to it. I have not replaced the seal for the fuel pump or the sending unit. Parts for the smoker are sitting in the garage, my project for Saturday.

[sleddriver]

Here's some photos of a gas tank to give you an idea where things are. One is from a 98, the other, a 99.

[98v70dad]

Here's some photos of a gas tank to give you an idea where things are. One is from a 98, the other, a 99.

Thanks those photos are helpful. Is it possible that there was more than one configuration in 98? Mine has a tapered rubber hose that goes onto a blue plastic fitting that runs between the fuel pump and sending unit. I know this because I replaced it a few weeks ago. It required drilling access holes in the floor panel to loosen the screw clamps. I don't see it in your picture.

[sleddriver]

Here's some photos of a gas tank to give you an idea where things are. One is from a 98, the other, a 99.

Thanks those photos are helpful. Is it possible that there was more than one configuration in 98? Mine has a tapered rubber hose that goes onto a blue plastic fitting that runs between the fuel pump and sending unit. I know this because I replaced it a few weeks ago. It required drilling access holes in the floor panel to loosen the screw clamps. I don't see it in your picture.

Sure it is. After all, you charcan is up front and mine's in the rear. The sled was born in Aug 1997. So you DO have rubber hoses on your tank, eh? Interesting.....

Amazing how many changes, mods, and updates Volvo made to these cars during the same year and the following one before the P2 cars were released. One would have thought they'd have it all sorted for as long as the 850 was in production!

Once you get your smoker up and smoking, you may be surprised where you see smoke coming from. When smoking my engine intake, I found smoke coming out of the inside crook of a rubber elbow right off the intake manifold. Right in front of my face. The outside face was fine, but the inside there had crumbled! I also discovered all of the rubber caps on the vacuum tree attached to the intake were as hard as a rock! I sub'd short pieces of silicone tubing, with the ends clamped off. These were both downstream of the MAS too. Even the vac. tree gasket/seal was poor, so I replaced it and added some anerobic sealant as backup. That sure is a BAD place to have a vacumm/boost leak.....

Re: Your 6 month old PURGE valve. I wouldn't suspect it being that new. My two cents.....

[sleddriver]

Found this DIY Smoker in the TOOLS section. He used a bucket, a regulator on an air compressor and cigars:
https://www.matthewsvolvosite.com/forums ... 37&t=62821.

[98v70dad]

Amazing how many changes, mods, and updates Volvo made to these cars during the same year and the following one before the P2 cars were released. One would have thought they'd have it all sorted for as long as the 850 was in production!

Once you get your smoker up and smoking, you may be surprised where you see smoke coming from. When smoking my engine intake, I found smoke coming out of the inside crook of a rubber elbow right off the intake manifold. Right in front of my face. The outside face was fine, but the inside there had crumbled! I also discovered all of the rubber caps on the vacuum tree attached to the intake were as hard as a rock! I sub'd short pieces of silicone tubing, with the ends clamped off. These were both downstream of the MAS too. Even the vac. tree gasket/seal was poor, so I replaced it and added some anerobic sealant as backup. That sure is a BAD place to have a vacumm/boost leak.....

Re: Your 6 month old PURGE valve. I wouldn't suspect it being that new. My two cents.....

I believe that the large number of configuration differences is a big part of what makes this particular problem difficult to solve. Advice from one person may not apply to your particular problem.

Anyhow, I agree the new OEM purge valve is low on my suspect list but I can easily get at it and check it. I replaced it 6 months ago because the P0455 code popped up again after almost 2 years and replacing it fixed the problem. Now the problem is back a few months later so that's why I suspect it at least a little. As you know the other big valve behind the drivers front wheel well is a pain to get at. I haven't looked at it. It may be stuck in the open position. I am planning to hook up a hose and do a blow test through the charcan tomorrow.

I've decided that on an 18 year old car I need to start keeping records of what I replace and when. I'm pretty sure I replaced that valve 2 years ago with and OEM part due to the annoyance of getting at it when I replaced all the rubber hoses up front. BUT I'm not positive and I stupidly didn't keep a record of it. The dealership has changed their computer set up so they aren't able to tell me either. I do have a vivid memory of one of them having a yellow plastic cover on the air filter and the other having a purplish color ... both OEM, so that's why I'm pretty sure I replaced it.

Other than these little tweaks the smoker is my next step. I'm not that gung-ho about putting even regulated air from a compressor into my car. My air compressor is a $35 special from harbor freight. I trust the regulator up in the 50 to 90 psi range but not in the 1 psi range. 1 psi doesn't concern me its that the pressure gauge on the cheapo compressor might tell me I have 1 psi when I actually have 10 psi.

I plan to buy an aquarium air pump and use that. That said opting for much less pressure and airflow will reduce the amount of smoke produced and the likelihood of finding leaks.

What sort of pusher pump did you use and have positive results with?

[abscate]

I have to think the purge valve is date coded like everything else nowadays. Look for a circle with a year in the middle and a month indicated on it elsewhere

[sleddriver]

I believe that the large number of configuration differences is a big part of what makes this particular problem difficult to solve. Advice from one person may not apply to your particular problem.

Anyhow, I agree the new OEM purge valve is low on my suspect list but I can easily get at it and check it. I replaced it 6 months ago because the P0455 code popped up again after almost 2 years and replacing it fixed the problem. Now the problem is back a few months later so that's why I suspect it at least a little. As you know the other big valve behind the drivers front wheel well is a pain to get at. I haven't looked at it. It may be stuck in the open position. I am planning to hook up a hose and do a blow test through the charcan tomorrow.

I've decided that on an 18 year old car I need to start keeping records of what I replace and when. I'm pretty sure I replaced that valve 2 years ago with and OEM part due to the annoyance of getting at it when I replaced all the rubber hoses up front. BUT I'm not positive and I stupidly didn't keep a record of it. The dealership has changed their computer set up so they aren't able to tell me either. I do have a vivid memory of one of them having a yellow plastic cover on the air filter and the other having a purplish color ... both OEM, so that's why I'm pretty sure I replaced it.

Other than these little tweaks the smoker is my next step. I'm not that gung-ho about putting even regulated air from a compressor into my car. My air compressor is a $35 special from harbor freight. I trust the regulator up in the 50 to 90 psi range but not in the 1 psi range. 1 psi doesn't concern me its that the pressure gauge on the cheapo compressor might tell me I have 1 psi when I actually have 10 psi.

I plan to buy an aquarium air pump and use that. That said opting for much less pressure and airflow will reduce the amount of smoke produced and the likelihood of finding leaks.

What sort of pusher pump did you use and have positive results with?

Re: Config diff. Indeed. Results in MUCH confusion when trying assist someone else.

Re: "Big valve behind drvrs front wheel". The SHUT-OFF valve? Mine's in the rear, where it's easier to get to. It's mainly open all the time, except when the confuser wants to run an EVAP LEAK test, then it's closed. If even the slightest bit of grit gets in there AND the rubber/foam seal has degraded, it'll leak. I temporarily revived mine by cleaning with alcohol, then spraying inside with silicone lube. P0455 disappeared for about 5 months, then returned. I eventually replaced it with a Pierburg. And then later....P0455 returned! Thus I had multiple faults/leaks causing the problem.

Re: Keeping Records. I sure do. I keep a maintainence log. Always have. The shortest pencil is far longer than my aging memory....

Re: Compressor. Regulators work pretty well. You can even use a bicycle pump! Indeed it doesn't take much. Mity-Vac has a hand pump that will both compress & pull a vacuum. Mine will only pull a vacuum however. The gauge reads in inches of Mercury, which is quite high compared to inches of water and Pascals.

Re: "Pusher Pump" I don't understand. Perhaps you mean aquarium pump? If so, I used a 30yr old Second Nature Whisper 600. I was lucky mine still worked! I got rid of my aquarium a few decades ago. I looked for a spec on how much air it'll move, but no joy. You need one big enough to supply enough air flow so you're not waiting too long for the system/tank/intake manifold/etc. to pressurize. A little one would take too long.

Smoke on.....

[abscate]

Ive got the nice turbo adjustment gauge which runs off tire pressure which would be perfect for this app. I keep promising it to Matt when Denver wins the SB.