: 08 CTS - running rich after D3 CAI installed

05-15-12, 05:35 PM
About 3 months ago I installed the D3 CAI on my '08 CTS and instantly loved the difference it made. I wasn't looking to convert my CTS into a V, but the throttle response was noticeably improved. Despite the small whistle it made when gently pressing the gas pedal during acceleration, I was happy with the purchase. I also reset my MPG gauge and realized an increase in efficiency (21.6 versus 23.2 after installation).

Then about 2 weeks ago my engine light came on. Took it by the dealer, and the code it generated indicated the car was running "rich". This struck me as odd because if anything I would have expected the car to run "lean" after the installation. So I started to do some research....remembering back to the installation of the CAI, I forgot to detach the negative cable from the battery to reset the ECU. While this is recommended so that the system can instantly adjust to the new airflow pattern, it wasn't required. The learning curve for the ECU would have just taken a bit longer. Further, D3 indicated that this CAI was plug and play. The MAF size was not increased - the kit only came with a chromed tube and K&N filter. All the stock connector parts were still in place and functioning. The dealer noted the filter was a bit loose, so they tightened it, reset the computer, and sent me on my way.

Two weeks later the engine light it on again and is spitting out the same "lean" code. No failure codes are present.....not the O2 sensor, not the MAF. I quickly made a call to GoodSpeed (Dyno shop) to ask some technical questions as to what could be happening. They indicated just what I expected....if the CAI was plug and play, no tuning or parts swapped, the "rich" code probably isn't ECU related. More likely it is mechanical - possible a malfunctioning injector. I also called D3 and they indicated there has been no negative feedback on this system - the '11 CTS-V unit had issues, but not the '08 unit I used.

Has anyone else experienced this problem? My service tech advised me to put the stock unit back on and see if the code continued to be kicked out. If so, bring it back in and they could diagnose the problem. I still have the 5-Year 100K powertrain warranty in effect....and I know the dealer is going to try to tell me that the after-market CAI caused the mechanical failure, if that is what is happening.

Any feedback or experience you have with this issue and are willing to share would be greatly appreciated.


05-19-12, 11:03 AM
Since your code seems repeatable (2 weeks), I'd suggest swapping the original induction back on, clearing codes, and seeing if the code comes back before spending the time/money/effort to chase down possible O2 sensor or injector failures.
That will tell you whether it is the CAI or something else

05-21-12, 01:41 AM
hi, curious how noticeable is the whistle? is it throughout the rpm band? i recently tried out the vararam intake and unfortunately was not able to make it work due to the maf. So the only thing really left i may want is the d3, however i am very picky with noise. with this all said, hope u resolve your code issues though....

05-21-12, 11:22 PM
Just about any intake needs to be tuned for. These cars are MAF tuned and when you change the direction or velocity of the air hitting the MAF, you need to calibrate that parameter for it. It's very common to see check engine lights for lean or rich AFR with an untuned intake. Not trying to sell anything here, but we can correct it it you buy a tune from us.

05-21-12, 11:24 PM
If you have access to a scanner that can read all the different parameters, check the LTFTs and I bet they're outside +/-12, which will set a CEL.

05-24-12, 12:07 AM
Did you check the MAF sensor to make sure it was a) plugged in snugly, and b) clean?