Sensors and alike - what affects driveability

[Clemens]

It seems like my 96 has a bit less gas mileage than it used to and it seems a bit rough when cold.
I replacef most of the vacum lines, plugs, wires, distributor, rotor, front O2 sensor (all oem bosch, bougicord or bluebox volvo), new air filter, cleaned the IAC and PCV. I still need to get a new maf. An IPD TCV and a turbo bypass valve membrane are on the way. What else is there to do? Crank and cam position sensor? What about the coolant temp sensor? Does it affect driveability or is this one just for the temp gauge? Which sensors and alike am I missing?

[abscate]

most ALL of the vacuum lines !!

[Clemens]

It's so many. Hidden down where no man's hand can reach...

[scot850]

Temp sensor does affect consumption, starting and drive-ability as it tell the engine how much fuel to add based on engine temperature. If it is reading in the normal position on the gauge then chances are it is ok. If it is slow to respond or reading low there may be an issue and need replacing. You will have read that the connector by the power steering pump is prone to corrosion and bad connections so worth checking. You can also check the resistance values to compare to ambient temperature when the engine is cold. There are values on here somewhere for that.

MAF will also reduce fuel consumption if dirty or beginning to fail.

Finally if the turbo bypass membrane is weak it will affect the performance and make the car work harder to get the boost, but if it was bad you would probably feel it. You can remove the pipe to the TCV from the valve and suck on it and see if it holds a vacuum. If it does it is ok for now but can get tired with age.

TCV also becomes lazy with age. If you are replacing with an IPD upgraded version with the 3 plastic legs, be careful how you fit them. The 2 on the side of the unit are ok, but the middle one should only be wound in no more than 3-4 turns. If you wind it in more than that it will push the small filter mesh into the valve and prevent it giving boost. I learned the hard way as IPD have never update the install instructions to warn of that. It may feel loose but don't follow the urge to wind it in further!!!

Neil.

[misha]

Ect is the same for both...ecu & gauge.
What about rear o2?
It's used for fine tuning the air/fuel mixture and CAN affect gas mileage on M4.4 cars and M4.3 if fitted(depends on market).
R should have M4.4.

[Clemens]

Nope, it's an automatic, so it should have m4.3 like the t5r.
Who''s OE for the temp sensor?

[misha]

But you should have two o2 sensors.
Volvo Ect is SWF(Valeo)....only aftermarket i would use is Vernet.