Cold Air Intake Problem L4

[STR8BALLN]

2009 Malibu L4

Customer added a cold air intake.

After missfire on cylinder 4, DTC came.

When you drive the car DTC missfire code goes off, comes back when sitting at idle at a light. Also if you raise the idle to around 800+ missfires vanish.

Do a compression check, leak down, all within 120's psi.

Customer takes car to dealer, dealer says this is common and the only thing needs to be done is raise the idle to about 800-850rpm as the cold air intake messes with the cam actuator.

Dealer would not touch do to aftermarket CAI.


Sounds like the MAF tables need to be retuned?

Any thoughts on this or experience?

[Iam Broke]

No experience with it, just thoughts... but if the cross section at the MAF on the CAI is larger than stock it will show lower MAF hz, lower airflow and if untuned the cheap fix is to raise rpm to increase airflow at idle. Fuel trims are most likely skewed and a MAF tune is in order.

[MMGT1]

And he may have screwed the MAF, I saw this exact scenario when a mechanic at the dealership added one to his. He chased the problem for a week before trying a new MAF and problem gone. Never figured out "why", but it did fix it. If tuning doesnt fix, try a MAF