Rough Idle After Fillups - Yes I Searched

i12drivemyMP5

i12drivemyMP5

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-- 03 P5 / 23 CX-5 --
Don't recall what resolution people came to when they reported having issues after filling up their gas tanks. Was it the pump, the dirty sock on the filter, other? Searched for over half hr on different things & couldn't find it. Not happening on mine but may be problem a buddy is having. Anyone remember or been thru this?
 
It could be that the gas cap isn't tight enough or that it is defective and not holding enough pressure.

I've just read this and never experienced it.
 
I'm experiencing it. Not so much a rough idle as more a start, studder, and stall. Then I get a CEL.

Last cel I got after it died was "Running rich"

I'm just driving it for now. I was already without it for 2 weeks. I got it back and it's still doing this. Maybe in the next month I'll take it in to the mechanic to check it out

Tylor
 
Checkin ze plugs! I had the same stuff going on before I changed them, then the problems went away. I went with the NGK V-Power {ZFR5F-11} Spark Plugs. They reach in a little deeper than the regular plugs. If you go this route, you might need to add mid-grade fuel to avoid some knocking though. The MPG increase is worth the extra $ per gallon
 
I'm talkin about every time after the tank is filled not the whole time. Yeah, aware of the zfr5s, just doesn't make sense for plugs to do it just after filling the tank, it would do it all the time. What is the correlation between filling up your tank with gas & the functionality or performance level of the ignition system? The ignition system doesn't like a full tank of gas? Sounds like maybe the ecu should do something to adjust performance based upon fuel tank level then. lol. There's already a sensor for that.
 
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Yeah, it's only for afew minutes JUST after filling the tank. Then it goes back to normal. Well,normal for my car which is still crappy idle.

Mine is a super crappy idle after startup to the point of stalling about 3 times before I can keep it running long enough to get the rpm's above 1000
 
Pro5x2 said:
Yeah, it's only for afew minutes JUST after filling the tank. Then it goes back to normal. Well,normal for my car which is still crappy idle.
Click to expand...

Some substance in the tank heavier than gasoline? Perhaps water? When you fill it up with gas that stirs up and mixes that substance (whatever it is) with the gas so some of that gets sucked in until it settles again. Most gas tanks have an intake which is a bit above the bottom of the tank so that they won't vacuum crud off the bottom. If it is water then adding seafoam to your tank at the next fill up may help, they claim it is good for getting water out of gas.

http://www.seafoamsales.com/motorTuneUpConsumer.htm

If that does not do it the tank will probably need to be removed and cleaned out.
 
Main causes of most of these problems:

EGR valve

Coil and plug issues

Fuel pressure issues (which may be related to your theory on the fuel filter and sock)

MAF

Carbon can build up on the valves, causing a serious problem with idle and power. Very common.

Vacuum leak

That's the primary stuff. It will cause stuttering, stalling, rough idle, etc.

Always test each theory instead of buying parts though!

EGR is cleanable, and you can test it by disconnecting the line
Fuel pressure can be measured real-time while running the car
Compression tests can tell you if carbon buildup is possible
The MAF can be measured in voltage

and so on.
 
Been covered. Didn't see anything in that list that wasn't done with same thing happening. Closest you came was fuel filter sock. There's not water or other s*** in the tank. We looked. None of the other stuff even relates to the filling up of the gas tank. What else ya got?
 
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i12drivemyMP5 said:
There's not water or other s*** in the tank. We looked.
Click to expand...

How?

Just for giggles, what happens if you drive the car to the point where you would normally fill it, then "fake" a fill up? That is, do everything you would normally do EXCEPT actually put gas in the tank. If you do not see the rough idle after a sham fill up the only variable left is the gas actually going into the tank, and the only reason that should ever cause problems is if there is some kind of gunk being stirred up.
 
could it have anything to do with the charcoal canister? I know that its supposed to do something with the fumes, but ive read that it can fill with gas (liquid) if the check valve is bad, and maybe that causes some kinda vac issue? Does the pump stop when your trying to fill (stop as in clicking off like its topped off?)?

Im just guessing though. Other than that id guess gunk being stirred up.
 
pasadena_commut said:
How?

Just for giggles, what happens if you drive the car to the point where you would normally fill it, then "fake" a fill up? That is, do everything you would normally do EXCEPT actually put gas in the tank. If you do not see the rough idle after a sham fill up the only variable left is the gas actually going into the tank, and the only reason that should ever cause problems is if there is some kind of gunk being stirred up.
Click to expand...

lol thats just funny. a sham fillup.
 
Well, i did topoff when I only had half a tank and it only idled to near stall for about 30 seconds, so, I do think it's stirring something up.

Tylor
 
i12drivemyMP5 said:
When the pump assembly was out checking/cleaning the sock. The tank was less than 1/8 full. Saw no gak.
Click to expand...

Did you stir it up? If a couple of millimeters of water was sitting on the bottom of the tank it might not have been very easy to see. Still, it looks like you ruled out rust, dirt, and other easily seen contaminants.

If the "sham fill up" does not trigger the issue, you might also want to wait 10 minutes or so on the next fill up, between closing the tank and starting the car. The idea being to try to determine if the issue fits "something settling in the gas tank". If you wait as long as it normally takes to resolve the problem in normal driving, and then start the car, and the problem happens anyway, then you have pretty much ruled out the "gunk in the tank" theory. If after the delay it has no issues that favors the gunk theory, even if you did not see anything in the tank.
 
No stirring but did have buddy shake the car back & forth while peekin in there. Didn't look like anything but gas. Told him to get a new gas cap to eliminate that possibility. He hasn't said anything about it lately so I guess he's just dealin with it or both things fixed it. I'll ask him next time I see him.
 
I'll be dropping my car off with the mechanic when I have a day I don't need it and he's gonna look into the rough idle and stalling after adding gas.
 
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