For starters....
We're talking about a 91 RS with a 305 TBI.

I've been doing some reading both here on the boards and in some manuals. It seems alot of problems are attributed to the sensors failing and needing replaced.

I'd like to add that this is our only means of transportation and it has 125,000 miles on the ticker.
I've read that some sensors should be replaced after 30,000 miles while other can go a bit further.

Basically I'd like to do a sensor tune-up / replacement before they decide to fail and leave us stranded on the side of the road.
All of the sensors on the car are original.

My question is a simple one.

Which sensors should I replace?

 

SB,

Personally, with few exceptions, I'd test the sensors before replacing them. The only sensor that actually degrades as part of its function is the exhaust gas oxygen sensor. That should be replaced at around 30,000 miles for peak efficiency. The signal tends to degrade over time, and "fools" the ECM into providing an incorrect mixture.

The other key sensors for reliable operation are the coolant temperature sensor, MAP sensor, and throttle position sensor. The TPS can be tested for linear resistance. The MAP sensor should provide an analof voltage output that is fairly linear with vacuum applied.


You can probably test the resistance of the CTS sensor at various temperatures and verify its accuracy. It may be more important to flush the cooling system instead of changing the sensor as a preventive measure.

Since you have a non-adjustable TPS, just test the resistance through the full operating range. And if you have a handheld vacuum pump, you can test the voltage output of the MAP sensor with the engine off/ignition on.

Other than those, most sensors are incidental or not that critical, and really can last a lifetime. It's probably far more important to maintain fluids and filters than replace sensors as a maintenance item. If you haven't changed the transmission oil and differential oil in the last 30,000 miles, it's time. Unless you've repacked the front wheel bearings within 15,000 miles, plan on it soon. Of course, engine oil and filter, air filter, and PCV valve are very important. Test the spark plug wires, clean or replace the distributor cap and rotor, and clean or replace the spark plugs every 25,000 miles and you should have little to worry about.

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Later,
Vader
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"Click - Click - BOOM!"
Adobe Acrobat Reader

 

Vader once again I have to express many thanks to you.

I'm going to make a list from your reply and keep it on file incase anything in the future happens.

I don't think the o2 sensor has ever been replaced on the car. So I think it's time for a new one.

The rest I'll check like you said and see what I come up with to see if they need to be replaced.

And I agree with all the fluid changes and tune-up suggestions you mentioned.

But I do have one question regarding the tranny fluids.
Frankly I don't think the tranny fluid has ever been replaced. And I've have not performed a fluid change in the 3 years I've been involved with the car.
But I've read some discussion on these boards saying not to change the fluid if the fluid has never been changed. I read this may cause problems rather than avoiding them.
Something about shavings or similar to that lines.

How do you feel about this issue?
Is it hog wash?

I was going to do a fluid and filter change in the tranny but had seconds thoughts after reading that post.
The fluid is still very red and the tranny works great, no slipping or anything like that and we do a lot of mountain driving with up to 9% grades in this car.

I wanna think it's BS but I have a doubt.

Thanks Again!!