Hello Nick88,
I know what it's like to not have a lot of disposable income, which would help to explain
why I like to gather as much diagnostic confirmation info as possible prior to replacing parts.
You are in luck, for if you take advantage of a little hidden gem that the TBI computers have
onboard where you can use the SES light to tell you in real time if:
* You are in Open Loop or Closed Loop mode.
* If you are in Closed Loop mode, is the O2 sensor reporting lean, stoich, or rich?
The name of the function is "Field Service mode", and it's accessed by shorting
pins A & B together on the ALDL (Assembly Line Data Link) connector under
the dash, followed by starting the engine. (See 1st attachment for FSM specifics.)
Thanks to a fellow forum member, you can actually watch the SES light in
Field Service mode. (Note: This was done accidentally, for he was shorting
the pins in order to retrieve the computer codes while the key was on, engine off,
and then started his truck.)
Here's a link to his video: (
SES light indicating Open Loop, Closed Loop, Rich, etc)
And while you are watching it, you can refer to what I was able to interpret from
the flash patterns. (See 2nd attachment.)
****
To summarize, for zero cost you can find out how long it takes your engine to
go from Open Loop right after startup to Closed Loop. You will also be able to
see how well your O2 sensor is staying in Closed Loop mode while sitting at a
long red light, etc. And with a little practice you should be able to see via the
duty cycle (on time vs off time) just how close your engine bay is running to
stoich vs too rich or too lean.
Let us know if you decide to try the Field Service mode that's embedded in your
TBI computer. And given the mpg you are seeing, I'm going to assume that your
SES light is going to be sharing good news, especially on the parkway.
In other words, you will be able to infer if everything is running normally (in Closed Loop mode)
or if you happen to be in 'Limp Home' mode. (Open Loop on a up to temp engine.)
Best of luck with your hunt for the Code 32 fix.
Cheers --