2001 bmw z3 tank leak diagnosis with DMTL error

[Conrad]

Guys,
Need some help and hoping I can get some from my mates across the pond.
My check engine light came on a few weeks and my diagnostics reader pointed me to the fuel evap system. I checked my hoses and found that the main pressure hose had a huge hole in it. Changed it no problem. Reset the light and it came back with a fuel trim bank 1 and 2 error and also misfire error in all cylinders.
Found a bad hose coming from the MAF, changed it, pulled cleaned and reseated all the coils. Misfire gone and fuel trim error gone. Reset the light and thought I was good to go. One week goes by and the SES light comes on again. Now I have a Tank-Leak Diagnosis with DMTL error. What is that??
Some folks say that my gas cap (which is new) wasn't on properly.
I cleaned the cap reseated it tightly and reset the light. Three days later, the SES light is back on again.
Can anyone help me find what's causing this error?

 

[BMBabe]

@Lee @t-tony maybe able to help

 

[Conrad]

I'll take any help I can get. I think I'm close but can't exactly put my finger on it. I've come too far to give in and take it to the shop. How can I contact these two zed gurus?

 

[Mint]

Now Bmbabe has tagged them, they'll be on later

 

[t-tony]

Hi Conrad I'm afraid I can't help here, but wish you well in your quest.

Tony.

 

[Conrad]

I'll keep you posted on what I find.

 

[BMBabe]

Now Bmbabe has tagged them, they'll be on later

Who else is technical? @Stevo7682 @5harp3y @Mnbrennan @Sean d

 

[Mnbrennan]

It sound alike an air leak to the tank to me (assuming it works on pressure). Is your tank cap OEM?

 

[Stevo7682]

@Mnbrennan. Ha you beat me to it .Check the tank venting system and charcoal filters for split hoses etc .
Yours being a USA market vehicle could be slightly different to European due to emission regulations.

 

[oldcarman]

Sounds like you need to go over all your hoses and connections especially to your TB. If two have been degraded the others aren't usually far behind. Even the slightest crack can let in air which will start throwing up all kinds of codes. I can't help with the vapour canister or hoses unfortunately as my car is from the UK. Good luck! JIM

 

[t-tony]

Buy yourself a can of carburettor cleaner. Start the motor and spray around all vac. pipes and hoses that you can see and listen for any change in engine note. If it's a vacuum leak it will suck in the carb. cleaner and burn it as fuel.

Tony.

 

[5harp3y]

This many warning codes to me sounds like you might have wiring / waiting problem rather than the actual faults

I.e why would you suddenly get a misfire on all cylinders?

 

[Conrad]

It sound alike an air leak to the tank to me (assuming it works on pressure). Is your tank cap OEM?

Yes,
Took it to the dealer originally for the SES light. They said I needed a new gas cap so they sold me one. I walk our of there with a $200 bill and 3 days later the light is back on. So yes I have a $200 OEM gas cap.
I just bought one on line coming off a wrecked z for $12.00. I'll try that. Can't go wrote g with a price that cheap.

 

[Conrad]

This many warning codes to me sounds like you might have wiring / waiting problem rather than the actual faults

I.e why would you suddenly get a misfire on all cylinders?

The misfires are all gone. Engine purring like a kitten. Only error left is this tank leak error.

 

[Conrad]

Buy yourself a can of carburettor cleaner. Start the motor and spray around all vac. pipes and hoses that you can see and listen for any change in engine note. If it's a vacuum leak it will suck in the carb. cleaner and burn it as fuel.

Tony.

Thanks Tony,
I will put that on my list for this weekend. I'm determined to have this fixed no later than Sunday.

 

[Conrad]

@Mnbrennan. Ha you beat me to it .Check the tank venting system and charcoal filters for split hoses etc .
Yours being a USA market vehicle could be slightly different to European due to emission regulations.

Is the charcoal canister accessible from the engine bay?

 

[t-tony]

Thanks Tony,
I will put that on my list for this weekend. I'm determined to have this fixed no later than Sunday.

Hi Conrad, I'm sorry I can't be any more help but this is a trick we used back in the day to find inlet leaks. Do hope you get to the bottom of the problem. Good luck.

Tony.

 

[Conrad]

So I bought the carb cleaner and sprayed everything I could see. Took the top panels off and sprayed all the hoses I saw there also. No change in engine idle so I'm assuming no leaks. I have another gas cap coming so I'll see if that does the trick.

 

[Conrad]

ok,so here's the latest. I ran a home remedy test today. I parked the car in the sun so the gas tank could heat up real well. When I got home from work, I checked the gas cap and the rubber seal was wet with gas. My guess is that there are fumes escaping and then turning back to a liquid. I have a gas cap coming so I'll know soon.

 

[t-tony]

A good idea Conrad, you certainly wouldn't have got that effect over here in the UK yesterday. Man I wish we were your side at the moment, I see a warm up on the way! Hope you nailed the fault mate.

Tony.