Evap charcoal canister question 94 volvo 850

hanzbe420 · Post by **hanzbe420** » 09 May 2018, 16:52

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I got a 94 volvo 850 turbo and getting evap and fuel trim code. my question is this clip supposed to be letting air in or is it supposed to block it of Completely. I capped it off completely and the code hasn't returned yet. This is the cap that lets in air in the picture below, or its a vent. Does Anyone Know. And when I capped it you can see the bottom of the canister raise up and stay raised. Some kinda valve.

hanzbe420 · Post by **hanzbe420** » 10 May 2018, 06:32

Anyone

hanzbe420 · Post by **hanzbe420** » 10 May 2018, 20:26

I put it the cap back in so now the cel is back on. I'm thinking maybe its the purge valve but the vacuum hose going from manifold to valve is really crappy but I'm not sure if its leaking I don't see any holes. Just weird how I block the nipple for the fresh air and the cel stays off.

Post by **MadeInJapan** » 11 May 2018, 04:34

I got your private msg. I really don't recall that clip. My canister was broken open... I siliconed it and never had a code for the EVAP.... hmmm. Do whatever works!!

hanzbe420 · Post by **hanzbe420** » 11 May 2018, 08:23

The vacuum diagram shows it with the cap on. So I guess that's the way its supposed to be. So I'll have to check the Hoses and the purge valve. The hoses are old and crappy but it could be the purge valve cause it was running fine, but then again I did just replace the radiator, so maybe I hit the lines and cracked one or something. If the canister is fine the next step would be the purge valve and the vacuum line's correct?

Post by **abscate** » 11 May 2018, 09:37

You generally can't see holes large enough to fail the EVAP.

A large leak is regarded as a 1mm hole, so something 10x smaller than that will fault as a low leak but won't be seen.

Smoke testing is the only way to efficiently test EVAP hoses - otherwise it is remove and replace.

hanzbe420 · Post by **hanzbe420** » 11 May 2018, 10:35

Its probably the vacuum lines there in bad shape so I need to replace them anyways, and if that don't work I'll replace the purge valve. Are there any bad effects running your car with a evap leak. will the mpg suffer from it? I heard in another post a guy bypassed the canister and he got alot more mpg, so do they go bad or did the charcoal go bad or the diaphragm. I notice it squeezes up when I blocked the hole, same thing if purge valve went on it raises like an accordion.

Post by **abscate** » 13 May 2018, 05:57

It will not affect mpg at all, it opens something like 10% of the time with partial throttle load.

The evap code takes several evap cycles to be set so probably the correlation between the plug and code is weaker than it looks. It’s not like pulling the MAF plug , where the ECU looks for MAF signal every Fraction of a second so that will code instantly. I believe on my p80 the code fault has to be read at least three times on drive cycles.