Boost leak test caused an oil to leak from dipstick
 

Hello everyone on this forum. It's my first post and nice to be here for when I need some help. I tried doing a boost leak test and followed the corksport boost leak test video for instructions. I made a device and stuck it to the front of my turbo inlet pipe. After I pressurized it to around 4psi the dipstick popped out and oil started leaking everywhere. The video mentioned to block off the line going from the turbo inlet to the valve cover. I didn't understand what this line is. I think it might be capped off, I attached a picture to show you guys. Anyone know what's going and what I did wrong? Thanks for any help

Ok, no one is chiming in.

I'll give it a try. First, I want to understand something.

It blows the dipstick out when you apply boost from an external source (boost leak tester and compressed air source) of only 4 psi? Right?

But, it does not blow the dipstick out when the turbo is making its own boost of well more than 4 psi - normal boost of up to 15 psi? Right?

These seem contradictory.

If you are achieving normal boost levels while driving the car and not blowing out the dipstick, that makes me wonder if your compressed air source may be much higher than you think. Either that or you are not achieving much boost under operating conditions. The two do not seem able to be reconciled to me.

Do you have a boost gauge to connect to the vacuum line (Tee'd where it goes into the bypass valve, or have an electronic gauge that can measure boost from your OBD 2 port? How much boost are you developing?

Can you data log the car? What are your fuel trims? That can point to a boost leak.

Have you tried testing with the cap off of the valve cover? Can you hear air escaping?

Perhaps your PCV valve is stuck in the closed position?

Classic for excessive pressure coming back through the dipstick where there is no other explanation is . . . engine blow by from worn rings. You might want to get a compression test followed by a cylinder leak down test. Worn rings may be the culprit.

If you send pressure on the factory inlet pipe and do also pressurise the pipe going at the VC breathing it is like pressurizing the oil pan....And yes doing so may makes the dipstick to pop out...


Usually people remove the filter intake tube including that connection to VC to do the pressure test. it isn't useful to check for leaks before the maf anyway....

Well, it turns out that I was being foolish. I figured out which line goes to the valve cover from the inlet pipe (all the way at the back of the TIP near the clamp where it connects to the turbo). I was using the accessport to monitor how much pressure I was applying and sadly using a bike pump to pressurize it (maybe this caused excess pressure?). I have attached logs below, maybe if someone can look at them to see if the boost leak test is even the right step.

https://docs.google.com/spreadsheets...it?usp=sharing



https://docs.google.com/spreadsheets...it?usp=sharing

i thought i was the only one who could blow a dipstick on a boost leak test, so thanks for that.

why are you doing it though

I had my dipstick pulled and was blowing into my valve cover port with my mouth to check my PCV functionality. Oh boy, what a mess. I blew oil out of the dipstick tube.

You can post your .csv format logs directly here. You do not need a third party host.

okay here is the .csv posted. If someone can take a look and let me know if the boost leak test is the right move. My LTFT are pretty wonky. At idle its usually around -13. And the STFT can jump to -20 at idle. Where would the leak most likely be?

You may well have a boost leak, but you may just have a poor tune for your modifications.

At below 3000rpm up to about 4100rpm, your car is actually running lean and the ECU seems to be OK with this (LTFTs are in the -2.5 range while STFTs are in the 2-3 range - roughly balancing out at 0). A healthy engine with a good pump-gas tune and everything correctly hooked up should be in the 11.0-11.8 range at WOT all the way to redline. On the stock tune, these numbers are a bit different, but if memory serves, they drop down to around 10 or 10.5:1 by redline.

However, your AFRs quickly drop into the 10:1 range and then all the way down to 8.3-ish by the end of the WOT portion of your log around 6100rpm. This definitely seems to indicate that you have a fairly substantial boost leak OR a tune that is not appropriate for your modifications. The reason I say this is that if air that is metered at the MAF is disappearing from the system before it gets to the combustion chamber, your ECU will still add fuel to match the amount of air it thinks is being drawn into the engine. Furthermore, your boost pressures seem quite low. I would expect the stock turbo to hit 15.5psi +/- about 1.5 psi at peak load (around 4000rpm). Your car is only hitting 12.3. At redline, even on the stock tune, I think the target boost pressure is above 12psi as well, and you're down in the 8.25 range.

I would check for split or incorrectly mounted boost tubes.

Thank you all for the help! The car has no mods so I guess it would just be the boost leak then. I will correctly try to do it this time.

If you bought the car used, it might still have someone else's mods that might not be visible. A lot of guys "stock out" by selling their performance parts and returning the car to stock before selling it. Sometimes some "go fast" parts get left behind.

Not saying that's the case, but unless you know the history on the car, you really can't be sure about some of the less visible mods. Looks like you are running Cobb's equivalent of the stock ECU tune, though. That should be good enough for testing.

It probably is a boost leak somewhere. What is your altitude? That may have an effect on how much boost you can actually get from the stock tune.

Thanks, everyone for the help. I ended up getting the boost test done by a local tuning shop. This is what they had to say. I just wanted a second opinion from you guys. In case the image is unclear they said:
Boost leak tested from the throttle body. Air leak through oil cap. Suggest replacing PCV valve and retesting.

Need to remove air filter and hook up the pressure there to test the whole system.

they are probably right for PCV, if it was a good leak, it flow thru the pcv but it shouldn't

As said above, testing it there, by-passed the test of all other parts...you need to connect it at the filter and remove and cap the small pipe going back to the VC. (or connect it at the TIH after the maf if you are sure that lenght of pipe isn't leaking

Hello everyone. This problem is still ongoing for me. I am about to give up. I tried tightening the clamps myself and even took out the TIP and put it back together. I took it to 3 shops so far and spent money on them saying that nothing is wrong. They did a boost leak test and said that everything seems ok. I decided I will try to do this all myself, but I am new to working on cars, so it might be tough. Here is a recent log. The car doesn't lean out in the beginning or go rich near the end like it used to. But the boost still ranges from 14-12 psi. What would you guys recommend I take a look at first?