Evap. Valve Rubber Washers (taco tick fix) = Trac Off & CEL after.

Hi folks,

Yesterday I added rubber washers to both sides of the Evap valve bolt, which is supposed to help the "taco tick"...and it may help some. I used (what are sold as) faucet washers, 3/16 x 17/32 x probably 1/8 thick. FYI, 3/16 is a tad tight...you can make it happen, but if you go this route, get 1/4 ID.

Anyway, immediately after, BOTH the Trac Off light and the Check Engine light came on. I haven't pulled the codes yet (I know...that's step 1), but I will do that when I get home after work. I had not gotten gas in a few days, so I don't think it would be the gas cap.

Just wondering if anyone has any thoughts on the reason.

My first thought was that the valve had to be level...but that thought went away quickly because it doesn't make any sense, really. 1) IF it had to be level, it would either have 2 bolts or a "key" and a bolt to keep it where it should be. 2) The truck isn't always level.....so that shot that idea.

Then I wondered if that valve has to be grounded, and the rubber washers isolated it, and so that was the problem. If so, I can add a jumper from the engine side, around the back washer to the valve side....??.

I also wonder if I pulled too far on the wire and pulled something loose, but it didn't seem like I did...but ya never know I guess.


Any thoughts are appreciated. Thanks in advance. Take care

 

You do realize this is as absurd as someone swapping out their engine over an ABS engine code right?

we have no idea what problem you are trying to solve. You just start presented a “fix” for a problem yet to be diagnosed.

If you want help or helpful answers, at least, then come back with a diagnosed problem or indicators of a problem.

 

Did you happen to turn the key on with anything unplugged?

No the valve doesn't need an external ground or to be oriented in a certain direction as long as the hoses are hooked up to the correct ports.

Other than that without knowing the code(s)

 

In the spirit of helping but still confused as to why you installed rubber washers.

The EVAP system will purge without the ignition or ACC being turned on. It will trigger a fault during this period if it detects a large or small leak and then store codes once the ECU attempts a full diagnostic. It doesn’t trigger a purge immediately after shut off and the truck would have to sit for a bit. I’m not sure what the cycling period is but it will happen just overnight so nothing a whole day. My assumption is probably around every 4-8 hours.

There are many parts that make up the EVAP system. It will definitely trigger DTC MIL. I have never heard anyone associating an engine noise with the EVAP system though.

 

Yes, that is the EVAP system purging the fuel tank of vapors through the charcoal filter. While it is purging if there is too much drop in pressure then it will fault in the ECU.

I have a feeling this may be something to do with the PCV valve instead of EVAP, but I’m not really sure what is going on as I never tried to address or read about stopping the tick noise.

 

Got it fixed...although it was an un-diagnosed "guess" and I wouldn't want anyone to swap out their engine over an ABS code, so I probably better not report.

Thanks to all

 

K Flo has a video on the VSV valve tick washer mod. That shouldn’t cause any issues.

 

That's the video I was following

 

This is not correct. The engine has to be idling/running for there to be vacuum available to draw vapors from the canister. That is a purge cycle. Pcm usually likes to do that cold start up. Tap.. tap.. tap.. tap..tap..

If it purged when the engine was off, where would the vapors go? Out the throttle body and through air filter to atmosphere?

They get run through the engine while running with the rest of the air/fuel mixture precisely so the vapors will get consumed. And ultimately go through the converters in the exhaust..

The key off function at night that you're referring to is the leak test of the entire evap system. There's a vacuum pump back there that wakes up, draws a vacuum on the evap system, sits back and watches for a pressure drop that would indicate a leak. the pump generates its own vacuum, it doesnt need engine vacuum for this test. Totally different from a purge cycle

 

Yes. I meant to help out the guy with the mysterious problem that nobody knows what he was trying to solve that a pressure leak down of the system will occur without the ignition turning on.

I acknowledge it is a test of the EVAP system but it doesn’t purge while off.