Rough idle after full tanking

I have been searching for awhile about the issue im having and i havent found any solid discussion on the topic.

For the past year whenever i put gas and full tank it the truck idles rough around 300 to 500 rpms for a minute or two before it smoothes out.

A little about the truck its a 2010 tacoma trd off road 4x4 long bed automatic with a trd supercharger. I bought it used from its original owner and it currently has 80k miles. Besides the supercharger its all stock.

When i bought it he mentioned about the rough idle when you full take it and he said he spoke to toyota and its normal blah blah blah with the supercharger when full tanked because the ecu is re-learning the fuel and what not. I knew something was fishy but its exactly what i was looking for in a truck minus the rough idle problem of course. Low miles, trd supercharged, long bed, 4x4 and with a sweet snug top sport camper. Deals bu deals.

Did my own research on it and it sprang up problems with the emissions. I dont have a CEL btw.

I already checked the purge valve solenoid located in the engine bay by the intake manifold. I checked its resistance with a DMM and it read 34 ohms. I read somewhere that between 10 ohms and 100 ohms is good. DAMN thats a large margin... oh well good right idk moving on, i also checked if it was clogged which it wasnt because I was able to blow thru both ends of the valve no problem also put 12 volts to it from the battery and heard it clicking indicating normal operation. Cleaned the trottle body because why not. Now I took off the charcoal cannister and that was a pain in the ass and im trying to figure out how to troubleshoot that but i dont have an emissions smoker thingy to check for leaks.

Soo with the above said.

1) has anyone with a supercharger heard of the computer re-learning after full tanks or was the previous owner full of shiet?

2) Anyone experiencing or experienced the same problems as me and fixed it?

Thing is annoying me because I am usually good at getting to the bottom of things when it comes to my cars problems but I'm not knowledgeable about emissions.

Really want to get this solved so i can throw on the 2.85 urd pulley and make some ponys. Any help is good help.

Mahalos

 

1)I'm no expert but there shouldn't be any re-learning coming from the fuel tank. Any re-learning should be stuff like throttle input, speed sensors, transmission shifts, etc.

2)I had this happening on one of my VW Golfs and I think it was the PCV valve, if I remember correctly.

 

SLiMbo4.0

Yeah the whole thing about it relearning when full tanked was pretty odd to hear but I never had a forced induction car so I wouldnt know better.

Ok those pcv valves are pretty cheapill try that soon. Gonna go junk yard and cut out a charcoal cannister while im at it too.

 

Your charcoal canister is probably full of gasoline from topping off the tank.

 

Fullboogie

Thats the thing i dont recall ever overfilling the tank. I fill it up and stop once the pump self stops.

I have the charcoal cannister removed and i dont hear any sloshing around of fuel.

Crazy thing is i dont have a Check Engine Light.

 

Bump

 

I agree with full boogie...previous owner probably ruined it by over filling. Canister problem not unusual for Toyota. I always advised customer to round off to nearest nickel after nozzle shutoff, IF they must have a even number.

 

Most of the time it seems it is the charcoal canister that gives problems.
But the EVAP Purge Valve maybe bad.
I’ll will say, I am not that knowledgeable on EVAP Systems, but my understanding is that the Purge Valve releases Fuel Vapors into the intake to from the Charcoal Canister.
The vapors that come from the Gas in the tank.

So, if the Valve is stuck OPEN. Would this cause issue shortly after fueling?
Where the intake is saturated with vapors from refilling?

I don’t know, I’m not that smart.
Maybe someone else will know?

 

TnShooter

I think your on to something. After reading that link you provided I read on the purge valve aswell. Seems like it should be closed with no voltage.

Like you mentioned if its stuck open while fueling it may be filling the intake with excess fumes makes total sense.

 

Goldfinger

Any tips on identifying a bad charcoal canister?

Thank you everyone for your input.

 

@Jimmyh

 

OP and Tn are already on the right track. Put 18-21 inches of vacuum on the manifold side of that purge valve and see if it holds or bleeds down.

It should be closed at all times unless commanded open. You could unplug it, put it on the bench and it should hold vacuum on the manifold side

If it looks like it's holding vacuum, tap it gently with a screwdriver. Sometimes they'll bleed down in increments when you shake it internally

 

Damn bros.

Just checked the purge valve pretty extensively. Ohmed it out 29 volts thats withing spec. With no voltage on it i wasnt able to blow thru it, applied battery voltage and then i was able to blow thru it.

Sorry b_r_0

I dont have a vaccum pump to do the test you suggested.

I want to say the purge valve is fine but, im heading to the junk yard tomorrow after work to source a new purge valve anyway. And maybe new charcoal canisters pretty sure I can score them cheap (fingers crossed)

 

Next time the problem happens clamp off the purge line with pliers and see if the idle improves

 

B_r_o

Yessiirrr. Thats my plan next. That should be the only way the evap system gets introduced to the motor am I right.

 

Not real into superchargers and such but it seems all are on the right track with the purge valve and the canister.

 

Found a few purge valves at the junkyard today one from a 4runner same plug and resistancr just different port placements and one from a nissan (i know its like mixing oil and water). The place has changed so much, before i could just walk around no questions asked pick what i want and pay at the end. Nowadays they ask whats needed and if they dont have it in their inventory, they rather you not walk around.

Put my original canister back because i did some checks and I just want to eliminate or confirm the whole evap system by putting gas and blocking off the purge valve when starting. If it works then ill change the purge valve first.

Thanks yall for another set of ears and brains towards my problem.