Hey guys, about a week ago I picked up a used 99 Z28, 6spd, with 65,000mi on it. Driving the car home (hour away) The SES light came on. I took the car to autozone and had the codes pulled P0172 and P0175. both banks running rich. I've weeded through posts on here and LS1.com and haven't found anything like my sistuation. Here's what I"m working with.

Reset PCM, code goes away then will come back. (did that twice then gave up) Just the other day I got in to go to work, and the light didn't come on. (temperature was cool to cold outside) a day later and maybe 60mi later it pops back on. (Mid-day to mid-afternoon) Now today the light popped on about 3 o clock. I ran a few errands then leaving the grocery store about 6ish when it cooled down the light went off.

I"d appreciate any suggestions you have, I've ruled out fuel injectors and plugs because i would think that would be constant, I"m having the same thought with 02 sensors but i'm not too sure. I have a set of 02 Simms on my T/A I could try but I would like you's imput first. Thanks

 

well first off...o2 sims are for the rear sensors..which have nothing to do with rich or lean.

so that means it could be your front sensors...i would change them and see what happens.

maybe find someone with scanning software and see if they can help ya out

 

My first suspect is the MAF. Has it been swapped, modified, damaged? One of our club members bought a WS6 and when the original owner put the stock MAF back on, he put it on rotated 90 degrees (vane went left-right instead of up-down) and it threw codes. We rotated it back to the normal up-down orientation, reset the code, and it never came back.

This C5 site always has good info. Check This Page for some detailed info on your codes and soome suggestions for fixing the problem.


If your MAF is not stock, swap it out and reset the code and see if it solves the problem.

 

Thanks rncotton I lightly looked over it and the one thing I did notice is that the maf is descreened, I've heard mixed things about that mod so I dunno. Thanks again for throwin me a suggestion I"m gonna go look at it right now.