Need help, new to cars. Engine smoking.
 

Hello, I just bought an FRS weeks ago and the previous owner got it tuned with Ecutek and tuned it to JDL headers. So before he sold me the car he took out the headers and entire exhaust. So I went and bought used Tomei UEL headers and rest exhaust is stock.
So I put in both 02 sensors and whenever the upstream sensor is plugged in, My car engine bay smokes white, then shuts off after like 10 seconds. Whenever I unplug the upstream sensor the car runs fine, no smoke and it stays on. So I bought a new upstream sensor and I replaced the old one. And the problem is still happening with the new one. I have CEL P0031 and it’s the upstream sensor: HO2S HEATER CONTROL CIRCUIT LOW BANK 1 SENSOR 1.
Another thing I have E85 in the car right now don’t know how old, the previous owner took off the flex fuel kit. It’s just been sitting in the driveway and need help. Please and thank you.

Google says there is something wrong with the O2 sensor wiring. Perhaps it is shorting out and burning something. Start at the sensor and track the wiring back to verify it is undamaged. Not sure what else would cause these symptoms.

If you aren't running flex fuel, fill up with premium ASAP to dilute the e85.

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Okay I’ll do this tomorrow asap thank you so much

Is the car still tuned at all?

I would suspect that the previous owner removed all of his modifications and did NOT reflash back to stock like he should have, which is an asshole move on his part, so your current ECU program is looking for a flex fuel sensor where you now have connected your O2 sensor back up to. If this is indeed the case, it's not going to run properly even if you fill back up with 93 octane, if it even runs at all.

Where the smoke is coming from, now that's an interesting problem.

You should contact him and start asking some questions about what all was done and who tuned the car when it was done.

He also should have known that selling you the car in this condition would cause major problems. He sounds like a real prick. I wonder if he was a member here.

Whatever you do, DON'T run it until you get a reflash back to stock or install a new flex fuel kit.

Anyone know what the output looks like on an ethanol content analyzer? If zero volts means 0% then it should run fine on 91. If zero volts means 85% alcohol then you'll have issues

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Yeah it’s still tuned

The O2 sensor output voltage will fluctuate. The ECU will see that and try to make fuel and timing compensations for those fluctuations. It will not run properly.

But the O2 sensor is already accounted for in the tuning. People run e85 with no flex fuel already. So long as your mix is consistent it would be ok. A fluctuating mix would be problematic. In this case, I assume he doesn't intend to use e85 any longer. So if zero volts from ECA means no ethanol, his tune won't be adjusted for ethanol and will therefore run properly. If it's 5v for no ethanol though, then that's bad

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Flex fuel and E85 aside the fact that the car has white smoke with the sensor plugged in does not sound good. There should not be any smoke in the engine bay no matter which fuel is burning.

Did you check the oil for anything dilution? Maybe drain the fuel tank, depending on how full it is.

Can't believe he sold you a tuned car for flex fuel and then removed the kit. Did you start it before buying it?

You're wrong in this case.

His ECU is still tuned for flex fuel. His ECU is looking at whatever is plugged into the ECU's input of the rear O2 sensor, be that the output of an Ethanol content analyzer or an O2 sensor. It's expecting to see the output of an Ethanol content analyzer, but now it's seeing the output of an O2 sensor, which fluctuates with the actual exhaust gases in the pipe after the rear catalytic converter.

The people that are running straight E-85 have a specific tune for that mix and don't require an input on the O2 sensor wire to the ECU to tell the ECU what the Ethanol content of the fuel is. It's predetermined by the tune. That's the main difference between a flex fuel tune and an E-85 tune.

And remember, most pump gas these days already have up to 10% Ethanol in it already.

The ECU needs to be reflashed to stock or he needs to install a new flex fuel kit.

EDIT: And then figure out where that smoke is coming from.

The big issue sounds like you have a tune for parts and systems that are not installed on the car anymore. You need a new tune or to get it flashed back to stock. 2nd issue is white smoke from engine bay. Is there something electrical burning or coolant?

What flex fuel kit did it have? These will communicate to the ECU to control it tuning. This would have plunged into a O2 sensor or the evap solenoid.

Where are you in Dallas? PM me if close I could swing by.

Kudos! No substitute for hands on help from an experienced enthusiast.