Ok so first off I have a mail order tune for speed density on my car and have the rear o2's deleted.
I've noticed my car runs really rich and gets bad gas mileage. I had my neighbor across the street hook up his snap-on scanner and said I had a couple codes. One was MAF sensor (sense I don't have one on?), then the right front o2 sensor was throwing a code, as well as the injectors having a code for high voltage?

I'm assuming with the o2 sensor throwing a code, it's triggering the fuel injectors to max out which is why it's rich and dumping fuel??

If I'm going speed density, do I even need the o2 sensors? Should I replace them? I'm going to have my car dyno-tuned the end of this month so I want to work the bugs out first. Thanks for any input!!

If your mail order tune was indeed speed density..it shouldnt have a maf code,and yes you should use atleast the front 2 o2 sensors for a healthy running speed density tune.having a bad o2 can cause that bank of injectors to run rich for compensation of keeping the motor running smoothly based on other parameters.

Change the o2 first..then clear the codes and see what comes back and work down the bugs.then get a true tune you can trust.

Thanks for the response. Yeah I got a set of stock o2 sensors from a buddy of mine who parts out cars. I'm going to put them on and clear the code and see how it does.

I'm getting the car tuned this Friday so I also put in a new set of plugs, and the old plugs were pretty fouled out. I hope it all works out.

Well I've replaced the o2 sensor with a stock one that I got from my buddy. The old o2 sensor that I took out had a red sleeve on it and believe was a Bosch sensor.

Anyways, put the stock AC delco one in, and seems to do a little better. Doesn't smell like fuel as much but has that slight hesitation when taking off when its cold. When its warmed up, it fine. Im sure once its tuned he will get that a/f dialed in.

this is why I refuse to give people mail order tunes for speed density or cam changes.

its one thing to setup a PCM for a swap (delete vats, rear O2s , egr ect) but once you do custom VE changes its any ones guess.



best you can do is make sure all sensors are providing correct info, no vacuum leaks just go over every last aspect with a fine tooth comb then go back to the tuner and let them know what going on.

^^^ Agree 100%