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Old 12-18-2021, 06:34 AM   #15
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cplvan is on a distinguished road
Join Date: Dec 2021
Posts: 18

2001 SL
Default Re: P0131 code with hesitation when accelerating and poor gas mileage

Originally Posted by trottida View Post
How many miles on your SL SOHC? How long have you had it and what was the mileage when acquired?

Check for vacuum leaks as I mentioned this morning and Waiex mentioned this afternoon. Check both the vacuum lines and the intake manifold gasket.

Something is off with the coolant temperature situation reading too high and now too low after you replaced the thermostat. You've already replaced the ECTS so look at the ECTS connector again and answer these questions...
  • Has it been replaced before (shows evidence of wires from the harness being cut and spliced)?
  • If replaced have the wires been soldered and shrink tubed correctly?
  • Do they have crimp connectors which are a known point of failure on this circuit?
  • Looking at the connector pins does it look like there is coolant residue or dirt present?

Loss of power will also happen with a clogged pre-cat attached to your exhaust manifold or a clogged catalytic converter. If you run the car too rich for an extended period these components get clogged with carbon deposits.

How does the exhaust smell? Any unburnt fuel smells?

I had it for about 6 months so far and but over 10k miles on it. Thereís about 75k miles on it right now. Iím not totally sure how to check for vacuum leaks.

No it doesnít look like the connector has been replaced before and there no coolant residue or dirt on the connector pins.

It does feel like there is a bit of a loss of power. The exhaust smells fine. No unburnt fuel smells.
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