FINALLY fixed my vacuum leak problems

So pretty much ever since I got the car I've been battling the dreaded p0171/174 code problems. I'd replaced pretty much everything you can think of relating to vacuum:

CCV (Valve and Hoses)
Fuel Pump and Filter
Upper and Lower tubes to the MAF
All SAP hoses
VCG
DISA seal
ICV seal
You freaking name it....

Finally I read a thread about one specific very small and practically free potential fix.

Back behind the Manifold where the SAP hoses goes next to the firewall there's an opening tubed up with a rubber cap. Pic below where the white cap is (not my picture)......



So that white thing on there is not what is stock. Its a black rubber cap that's apparently prone to get brittle and cracked thus allowing un-metered air into the system causing the lean codes. The cap is below (again not my picture).....



Well my cap looked almost identical to that with another small crack on the other side. Since I couldn't find anything around the house to replace it and didn't really feel like going out to a parts store to find something I decided to MacGuyver it.

I grabbed some Gorilla glue and generously applied it. Let it get tacky then held it till it dried. I then grabbed some electric tape and wrapped it up real good. Gave it a couple more hours to really cure and reinstalled it.

After putting everything back together, clearing my codes, and eventually driving over 1000 miles I'm glad to say this very simple fix solved my very annoying lean code problems. What a relief. Hopefully this will help some of you guys with the same symptoms.

Just thought I'd also include some of the symptoms I got because of the lean codes.....none. I literally wasn't getting any noticeable symptoms. No rough idles, hesitant or weak starts from stop, nothing. That's what made it even more frustrating. Everything was running just fine with the codes. The only thing I would probably say is my gas mileage was definitely taking a hit, and now I've noticed it getting generously better.

Later all.

I have the same problem but it only happens in the winter. here in nc when it gets cold i will get these two codes clear them and every winter it comes back has been happening for three years now. if i do this to my car and it fixes it, i will forever owe you a thank you!

Originally Posted by SHK&BAK3

I have the same problem but it only happens in the winter. here in nc when it gets cold i will get these two codes clear them and every winter it comes back has been happening for three years now. if i do this to my car and it fixes it, i will forever owe you a thank you!

Yeah my codes were definitely more prominent in the winter. They'd simply stay on. Once the warm weather rolled around it would be a lot more intermittent. Usually on for couple hundred miles, off for a couple hundred miles. Now its gone for good.

Haven't seen that part here described before. Nice work man

While the rubber cap you found will certainly cause the problem you describe when the cap is in the condition you show, I'm not sure fixing it with Gorilla glue is the right thing to do. You can buy those rubber caps at the auto parts store.

Originally Posted by jdstrickland

While the rubber cap you found will certainly cause the problem you describe when the cap is in the condition you show, I'm not sure fixing it with Gorilla glue is the right thing to do. You can buy those rubber caps at the auto parts store.

Yeah it was more of a temporary thing to see if it would solve the issue. I'm still procrastinating the search for a suitable replacement. Just been busy.

I'm having some vacuum probs as well, but I'm not sure where to find that plug/cap. Do you have to take off MAF and boot to ICV to see it under there? I cant find it otherwise. Thanks for your help!

Yes, you need to remove the cabin filter holder, airbox, maf, and boots at the very minimum. It would also help and give you more room to work to take out to separator between the brake components/ECU and the engine pictured below.

I just bought my e46 and it has the same lean code with no symptoms. tomorrow was my tear apart the intake day but now hopefully I can focus my search. great pics.U

46driver,

Suggest you read the first link below in my signature. I think you might find it helpful?

Good luck resolving your issue.

My Cap was barely cracked, replaced it and still got the codes. On to the links for further trouble shooting.

Originally Posted by jfoj

46driver,

Suggest you read the first link below in my signature. I think you might find it helpful?

Good luck resolving your issue.

If you follow his "process" in his link and you don't fix your problem, you either didn't read enough or shouldn't be working on the car period... His link is a gold mine of info and, if followed properly, will resolve any vacuum leak issue..... Just say'n.....

Is it part #11 61 1 437 560 ??

i guess we can assume that's not your crotch in the picture. lol

Ha. Definitely not my crotch.

Originally Posted by Quenotte

Is it part #11 61 1 437 560 ??

Probably. Not exactly sure from pics of the part. If you go to any major parts store you can find vacuum caps pretty easily.

Originally Posted by jfoj

46driver,

Suggest you read the first link below in my signature. I think you might find it helpful?

Good luck resolving your issue.

I am working through your extremely helpful link, but I am getting code P1192, and am having very "jerky" driving when the engine is cold that seems to mostly subside when it is hot... any advice on this code? Replaced all four O2 sensors and found that my fuel filter didn't even have a line attached to the f-connector! But honestly, after removing the DISA and inspecting, and fixing the line to the fuel filter regulator, the car has driven even rougher than before, but could be a coincidence since the cold weather really just hit. Thanks for any suggestions!

Originally Posted by eph6jonprice

I am working through your extremely helpful link, but I am getting code P1192, and am having very "jerky" driving when the engine is cold that seems to mostly subside when it is hot... any advice on this code? Replaced all four O2 sensors and found that my fuel filter didn't even have a line attached to the f-connector! But honestly, after removing the DISA and inspecting, and fixing the line to the fuel filter regulator, the car has driven even rougher than before, but could be a coincidence since the cold weather really just hit. Thanks for any suggestions!

Me too, when reconnecting the f connector hose to fuel filter, my car initially ran worse ! Has cleared up over time but still not perfect...

Originally Posted by Landlorder

Me too, when reconnecting the f connector hose to fuel filter, my car initially ran worse ! Has cleared up over time but still not perfect...

Turns out I was 3 quarts low on transmission fluid, which no one mentioned was not the "ATF" cap on the top of the engine... I'm sure this was a rookie mistake, but where was the logic in putting the initials for Auto Tran Fluid on the Power Steering reservoir? Anyway, off the rant, definitely check your transmission fluid, could have really ruined it if I had driven it that low much longer!

in for my search later today.

Originally Posted by eph6jonprice

Turns out I was 3 quarts low on transmission fluid, which no one mentioned was not the "ATF" cap on the top of the engine... I'm sure this was a rookie mistake, but where was the logic in putting the initials for Auto Tran Fluid on the Power Steering reservoir? Anyway, off the rant, definitely check your transmission fluid, could have really ruined it if I had driven it that low much longer!

It is confusing for people coming from other cars. The cap says "Use ATF only" and "ZF" if it's OEM. That's confusing since a lot of people know the cars have ZF transmissions. It should say something like "Power Steering reservoir USE ATF ONLY".