Infamous vacuum leak SES codes
 

My sweet 03 X5 6cyl has been dealing with a vacuum leak and p0171 and p0174 codes for a while now. Twice so far, I've gotten to a point where the engine was misfiring. The first time it happened, the car fixed itself after sitting off for 10 minutes. After this incident, I changed my lower intake boot which I knew was cracked and taped by me, as well as my Disa valve. The vacuum leak error came back immediately. Two months later, which was this past weekend, in very cold weather the misfire returned. The car was undrivable on Saturday morning. Figuring I had nothing to lose and since I had the parts, I changed my valve cover gasket, which was shot, and all 6 ignition coils. Car then ran fine after this, no misfire, but my check engine light came back on after 10 miles.

So - I still have a vacuum leak. Car has 167k miles.

1) should I bother to replace the oil filler cap?

2) I will spray the MAF sensor with cleaner for a cheap try.

3) I've studied up on the DIY to pull the intake manifold and replace the CCV system with new parts. I think the CCV works, but maybe one of the lines is cracked.

4) I'll replace the other vacuum hoses.

5) I recently replaced my secondary air pump and I don't have reason to believe that check valve is an issue.

6) I read it could be my oxygen sensors, but those are expensive and probably ok...

Anything else I should be considering???

I don't have a smoke machine to test.

Get a smoke machine to test or take it to a shop that does. The only way to approach this correctly.

Did you scan the engine again, or just assume it is the same code? Do you know what the short term and long term fuel trims are? What is the MAF G/S reading at idel?

Do you know what the engine data were when you got the Check Engine Light?

I know it's a lot to ask, but f you want some better guesses we need to know as much as possible.

I only have OBD2 code reader. I now just have the p0171 and p0174. When the misfire happens I get all the misfire errors.

Seems to me like of the crack is down under the intake manifold, a smoke machine on hand isn't going to help much.

There is the key. Sorry to be blunt but you are simply guessing. The smoke test will show you the leak immediately.

Yes, I know you are correct and I guess with the smoke machine creating positive pressure in the system, I could inspect under the intake manifold to see where the smoke is pushing out. Where is the best place to connect in the smoke on our 6 cylinders for this diagnostic.

In the absence of the smoke machine, I was hoping to address the most likely suspects and those that are inexpensive to replace. Most all of the items that could cause my air leak are due for replacement in my opinion. I'm the only one who has worked on my car and I never changed any of these parts.

Along those lines, I guess I'd change the MAF and oxygen sensors last. I think next I'll change the CCV system, the vacuum lines and the intake manifold gasket, and oil filler cap. All cheap parts and then they'll be new.

If you are using one of those OBD Bluetooth readers, you can get an App that provides all the info that I mention above. I have Torque Pro as well as OBD Fusion. Spend a little bit of money and get a better diagnostic or just shoot the parts cannon.

My OBD2 is old school action, plug it in.

I get it all, but my point is the parts to resolve this are basically cheap and in need of replacement anyhow. So might as well crack on with it. If I get to the end of the trail and still have my lean codes, then yes, I can bring it over to a BMW shop to get a diagnosis for $150.

Spoke to a bmw shop in my area, guy said, given what I already swapped it's most likely the CCV. He told me change that out and if still have problem, bring it and they will smoke test it for me for $165.

A single purchase of less than 150 USD will get you a Foxwell NT-510 or NT-520 and you will be able to scan as much as you want and get real codes not the generic p-codes.

The 165 you said for a smoke test seems pretty high to me but maybe that shop has hookers and blow in the waiting area.[emoji848]

Not trying to be a dick about it but if you want to keep costs down then throwing parts (even cheap ones) adds up quickly. There will be plenty of things that will need to be done and sometimes a few minor parts replacements can cause other parts to shit the bed at the worst time shortly thereafter.



Sent from my SM-A730F using Tapatalk