Po303 Assistance Requested
Hi, I'm a first time user/poster.
I have a 2007 lt 2.2, 5 speed.
It sat unused for about 3 years (no codes/running great) and just last week I decided to plate it and drive once again.
It now throws po303 however it did not when I last started it up a few months ago.
I've installed new oem plugs gapped at 45, swapped all coils around, compression is 150 on all cylinders, dumped a whack of seafoam in before and after oil change/filter and to gas tank and it runs considerably better but still throws po303. After reading posts here for several days, I became aware that the 07/08 had gm software issues that threw po303 erroneously and that it may be a mas or map sensor instead....so, changed both with new ones and it runs even better still....but throws the po303 eventually.
When initially started, the engine seems to be smoother (but that may be because of the higher revs - 1200 or so - until it drops to 800 and the slight miss can be felt. It also chugs/misses around 2000 rpm when under acceleration.
From what I read here, it seems that the two issues left that are suspect are either the ecm or plugged/fouled injectors.
A few questions;
I've found an ecm on kijiji from a 2006 lt, 2.2 5 spd., can it be installed directly to operate my 2007, or does it need a dealer "flash"? (any info on what ecm's are compatible? Will an automatic ecm operate a 5 spd model car?)
As this is not a pristine vehicle, I do not want to throw 400 in to it for injectors......can the injectors be "freed up" by an injector servicing while on the car? (seafoam made it run much better so far, but if there is solids lodged unlikely that is going to change with seafoam) And, I can pick up cheap injectors on amazon, that indicate they are compatible, (I realize that oem are designed for their specific application and are better, but I would rather spend 100 for 4 injectors then 400 on oems on a problem that I am not yet sure is responsible.)
Thanks for any input, it is appreciated.
Last edited by pioneer; 10-02-2016 at 08:33 PM.