blac94Z

ok so long story short i used some 100 octane about 4 1/2G about a week ago
and after that night ive used 91 ever since but now when i turn my key on
my tach starts to jump and i can hear my fuel pump in sync with the abs under the hood
(sounds like coin registering in a video game) now when i drive it, the car does like little sudden jerks
but if i clean it out(rev the engine) it will idle perfect until it sits for about 30 sec then it will rev up high to about
2500 rpm on its own or it will act as if the engine wants to shut off. I hooked it to the 9495 scan and i got a left O2 sensor was reading lean
i cleared it and it never came back, so basically i need some of your knowlegde on what maybe the case.

Injuneer

Was it leaded fuel? .... destroys O2 sensors.

blac94Z

im not sure I will call the station on my break and find out, will this make my car run this way ? and could it be my fuel pump going out ? or maybe a filter I have never changed it personally.

Injuneer

If it's unleaded, it won't hurt anything, and would not cause your problems. It also isn't needed for your car, nothing to be gained except weight reduction from a lighter wallet. At 2,000-ft elevation of Las Vegas, octane requirement is reduced below what is stated in the Owner's Manual.

What is the comment about hearing the fuel pump in synch with the ABS? I don't understand.

blac94Z

well its not synched in but I can hear it will key in on position the fuel pump priming and then I can hear it getting a little weak in priming and then you hear this noise coming from the abs junction under the hood a little weird with what's going on here
would you think it could be my fuel pump ? ps. when I start the car cold it will idle perfect until it starts to get heat in it and it will shut off if it idles long enough with out mashing on the gas .

blac94Z

It was leaded 100 octane i put in so what would be my next step ?

Injuneer

How long it takes to ruin the stock O2 sensors with leaded fuel is a variable. Some will fail immediately, others will take longer to fail. I still have my stock O2 sensors in the collectors of my headers, mainly used as plugs for the bungs. Don't run in closed loop, since I use heavily leaded fuel for the 300-shot of nitrous. But I can still see the O2 sensor readings on my Scanmaster, and one is reading very low all the time, and the other one seems to be functioning normally.

Denso claims to have an O2 sensor that is "two times more resistant to silicone and lead poisoning". When they first came out about 10 years ago, a magazine did a test to see how long they lasted, and one of them failed as soon as it got hit by the exhaust from leaded fuel.

Not sure how a defective O2 sensor would cause sudden RPM surges. That's more commonly caused by problems with the cam position sensor module in the Opti.

Since you have Scan9495, I would start with a data log showing the surge and other events, if possible.

blac94Z

Ok will do when i get home tonight, also going to test fuel pressure to make sure its correct bc like i said i have never changed the inline fuel filter nor the o2 sensors

blac94Z

And would the o2 sensors letting to much fuel get into the motor and make it shut off ?

Injuneer

If it's running extremely rich, it could foul the plugs, cause misfires and stumbling. But you should have codes for running that rich. But it won't cause surging to 2,500 RPM, or sudden cut outs.

blac94Z

Noted thanks I will post my results tonight

blac94Z

could it be that the plugs are being washed out bc when I rev it to about 5500 rpm
once or twice it clears up and wont do it for another 3 min or so

blac94Z

Quick up date qith my key on engine off i can hear my fuel pump prime then it will stop and then i will hear it again and cut in and out is my fp going bad and my tach will jump with the fuel pump with key on engine off

blac94Z

ok I hooked it to my scanner I have no codes whats so ever beside my air pump and that has been on since I bought the vehicle, I start to notice when I get low on fuel
is when it will start to hiccup or if im coming to a right turn with low fuel or if im leaning on a hill to the left going in reverse it also started to hiccup im going to go buy a fuel pressure gauge today bc AutoZone told me 170$ to rent there's and harbor freight has them for 15$ to own

Injuneer

You need a data log, not a code scan.

You do realize that the code for the AIR pump is causing your radiator fans to run all the time? All you need to do is put a good fuse in the circuit. If the fuse continues to blow, unplug the pump, then replace the fuse, leaving pump unplugged = no code.

$170 to rent.... must be a kit with adapters for all various makes and models. Are you sure that isn't just a "deposit" until you return it? I have a 20 year old decent quality gauge with good hose length and bleeder valve that I paid $30 for.