dtibbs

Hello,
I just replaced all the spark plugs in my 2007 GL450 two days ago and had no issues following the replacement or yesterday. However, today while driving, I have been experiencing what can best be described as RPM spikes. While accelerating, my RPM gauge spikes quickly, causing my car to jolt forward. It accelerates alright, though a little shakily. When braking, the RPMs also spike, causing a shaky deceleration. I didn't have any dash lights come on, but read the codes anyways. I received two, P2188- "System too rich at idle bank 1," and P2190- "System too rich at idle bank 2." My first thought was that there's a correlation from my spark plug replacement, but it ran just fine afterwards and yesterday. Some quick research said the air intake connections could be loose, which I double checked and everything seems to be fine. Any diagnosis advice would be greatly appreciated, thanks all.

eric_in_sd

Betcha you dislodged the throttle body from the intake manifold when removing or reattaching the air cleaner. The throttle body is not mounted very firmly to the intake manifold. Take the air cleaner off and re-seat the throttle body - be gentle - and then apply some silicone greaase to the rubber ring at the top so it fits easily and snugly in the air cleaner. Also lubricate with silicone grease the rubber buttons that the front of the air cleaner sits on. When you reinstall the air cleaner, be gentle. If you are using force, you are doing it wrong.

A leak at the throttle body should make the system run leaner at idle, but the ECU adaptations do all kinds of funky things.