Oil in Air Intake

[TheBugster]

I have a 2007 ZO6 with about 7500 miles on it. I just experienced a problem with engine oil getting into the air intake and onto the mass airflow sensor. This occurred while accelerating to about 6500 rpm. The engine lost power and ran erratically. I got to a friend's shop where we removed and cleaned the sensor and the intake and the car ran fine coming back home. Oil also got onto the air filter so that has to be replaced.
As of today the car is at my dealer's and they are unable to determine what caused the problem. They say there is a technical service bulletin about intake oil contamination but it is not relevant to this instance.
Has any one experienced or heard of this problem? I would appreciate any help you can offer.

The Bugster

 

[c4c5specialist]

Hi there,
A few things.
First, the oil level must be correct and NOT overfilled.
Then, the entire PCV system should be inspected for restrictions or misrouting.
Then, proceed with normal diagnostics, but this should ALWAYS BE the first course of action.
Allthebest ,c4c5

 

[NORTY]

1. Since your intake has been "oiled", please check the carbon stickers that are mounted just before the MAF. They can come loose and lodge in the intake. Even if the bottom one comes loose and "flaps" it can cause drivability problems.

2. The MAF sensor is VERY sensitive to any foreign matter. Try to clean it as best you can. Isopropyl alcohol 99% might be the best here. (not the store bought 70% junk.)

 

[TheBugster]

Hi c4c5
Thanks for your reply. I don"t think the max oil level has been exceeded as I've been very careful about that. The dealers mechanic has checked the other items and has found nothing wrong at this point. He has changed the oil and ordered a new air filter, which was not in stock. Although this is covered under warrenty I am amazed at the cost of a new air filter (about $150.00). Is there a cheaper after market source?
The Bugster

 

[TheBugster]

NORTY
Many thanks. I didn't know about the carbon stickers. Are they simply pressed on? What is their purpose?
TheBugster

 

[NORTY]

NORTY
Many thanks. I didn't know about the carbon stickers. Are they simply pressed on? What is their purpose?
TheBugster

Bugster, yes, they are pressed on. They are located before the MAF and after the filter element. If you remove the air bridge and look down towards the element, you'll see 2 stickers (one on the upper and one on the lower surface of the intake tract.) These are to "absorb any hydrocarbons" that may leach out the TB just after shutdown. (Think of the HC's that fill the chamber but the valve doesn't close all the way.) These vapors will travel back to the aircleaner.

Anyway, back to your question. If the oil is "over full OR spirited driving takes place", some oil can travel up into the intake tract. If (when) this happens, the oil loosens the glue that these are attached with. When this happens the MAF sends erroneous info to the computer. Drivability issues result.

The good thing is that they are easy to remove and then the problem goes away.

 

[TheBugster]

NORTY, thank you again for your very helpful response. I had seen those carbon strips when we were cleaning the intake, but neither of us knew what they were. After receiving your info, I talked to my dealer's mechanic and he said that one of them had been partially loose and he had pressed it back in place. I'm going to take your advice and remove them.

 

[catbert]

CRC makes a MAF cleaner that works well, and won't mess up the system.

 

[TheBugster]

Many thanks for the info. I picked up a can today at the local auto parts store.

 

[WNH]

Hi c4c5
. He has changed the oil and ordered a new air filter, which was not in stock. Although this is covered under warrenty I am amazed at the cost of a new air filter (about $150.00). Is there a cheaper after market source?
The Bugster

I must've missed something. :ugh

 

[TheBugster]

You didn't miss anything except the facts. Please read my initial thread a little more carefully.