RojoDojo

I think I may have figured it out...

I got under the car today after work and got to looking around. Last time I had a smaller but similar issue, I had just gotten my new Bassani X-haust installed that same day, I just attributed it to bad gas due to filling up at a station I'd never been to and the problem going away with a new fuel filter. I may have actually moved the wiring of the O2 sensor...

So, I got to looking around, and sure enough one of the O2 sensor wires looks like it's stretched and crimped near the base from not being long enough. I decided to hook the laptop up to my predator and car tonight, did a couple runs and wouldn't you know it, the voltage to the O2 sensor is WAAAAAAAAAAY off and it's coming up between -30% and -90% enrichment on the bank 2. Voltage was at 0.0000 at one time, hovered around 0.002+/- and on the other sensor it was usually around 0.8200+/-. Explains why I was getting lean codes too

;-)

Give me your theories...

I'll be replacing both of these sensors, as well as getting the BBK O2 Extensions since I'm sure I'll be upgrading the headers as well. Should be the fix to the problem though.

Fuel system is fine after further investigation.

157dB

All US GOVERNMENT approved underground fuel tanks have a double liner
with sensors inside the second liner to detect the slightest leak of fuel.
There should NOT be any older gas stations using the old unapproved
leaker tanks since the year 2000 or so. So the groundwater leakage into
old tanks theory is not applicable unless you buy your gas from the
deliverance gas station in rural bumsville thats under the governments radar.

And now the truth comes out.
Cant diagnose when we dont know the story 100%. []

1morepart

OCTANE BOOSTER'S KILLED MY PLUGS and did the same "thing" as you describe!!!!!!! my money is one a shot set of plugs!!!!! IMO, go ahead and order them....also, try the advise of cleaning the TB and reloading the tune, but stay the hell away from Octane Death......i have never used sea foam, but i heard it is a good product.....the only thing i will EVER put in my tank is good ol' 93 because it is tuned for that...good luck

RojoDojo

Was more than a month ago, figured it was a non-issue considering the problem went away when I changed the fuel filter and I thought the guys putting my exhaust in knew wtf they were doing. Read the whole statement.

RojoDojo

Believe it or not, I haven't had any DTC's in a couple days, driveability has sucked obviously, but I have been taking it easy on the car while driving it to work anyway. The codes were the two ST banks showing lean. Which is weird 'cause at idle the fuel trims are showing up more negative after calculations, as opposed to more positive at cruising speeds. This in turn would be indicitive of a dirty MAF in my experience and NOT the O2 sensor as I thought. Meh, I'll just go ahead and replace the sensors anyway, let me know what you think about my fuel trim theory... Gonna hit up the parts store Thursday for some cleaner and I'll update.

I ended up going through the whole tank down to about a gallon and a half left and put in about a 1/2 tank of some good 93 from a Shell I found just in case I have to get the fuel pump out on Thursday after cleaning the MAF... So far after driving from the station and around for about 30 miles no change in driveability so it's not the gas I don't think...

Never saw crimps in my fuel lines, would you rule out a fuel rail obstruction? ****, I may end up changing the plugs, rail, pump and injectors after this just to be sure...

RojoDojo

Cleaned the MAF, no change. Gonna put it on the lift tomorrow morning and get the hicks that changed the exhaust to do some O2 sensor checking.

:-)

At the very least they'll be able to tell me their ideas, and no charge...