89blackbird

I am rebuilding my 5.7 liter in my 89 GTA. I want to replace all the sensors. Some of them are easy to tell the guys at the parts counter. Others they don't get it. How do I tell them?? Would I be better off taaking all the old ones with me?

Mkos1980

iTrader: (8)

I just replaced all the sensors on my 89 TPI
-Coolent temp sensor CTS
-Knock Sensor
-Manifold Air Temp sensor MAT "or" Inlet air temp sensor IAT
-Mass Air Flow Sensor MAF
-EGR Valve with (temp probe dealer item 10 bucks)
-Throttle position sensor TPS
-Oxygen Sensor 02
Theres prob more but this is what I did.

Vader

89,

For the cost of only a few of the sensors you can purchase a good DMM and test the sensors, replacing only those that don't check out. I'll be you save some real cash, adn you'll have a good instrument when you're done. If you were talking about ALL the sensors (MAF included) you could nearly buy an oscilloscope for that alone.

Ions91Z28

DMM = Digital Multi Meter?

You can use that to test the sensors?


Please give more detail of the oscilloscope as well. I checked e-bay cause I didn't have a clue what they were, about all I figured out were they look confusing.

Blackened

He was kidding about the 'scope. You don't need to buy an expensive peice of equipment like a scope to test the resistance of various sensors. Most of the sensors can be tested using a cheap VMM and save a lot of cash doing so.

89blackbird

OK sounds good. How is testing done and what are the normal readings (ohms ?)

Vader

BB,

There are some sensors that can be tested with an ohmmeter, and others that should be tested with a voltmeter. In any case, a DMM will cover most of the needs. Temperature sensors produce a given resistance at a given temperature. A TPS can be tested for resistance as well as voltage. An oxygen sensor should be tested with a voltmeter, either in or out of the circuit. A MAP or BARO sensor can be tested in circuit for the correct voltage output an a known vacuum or pressure. Even an analog MAF sensor can be tested with a voltmeter for correct output. The IAC is NOT a sensor, but a stepper motor. It is an output load, not an input load, but you can still test it with an ohmmeter. The only things you may need an oscilloscope for might be a digital MAF, the distributor reference pulses, and the detonation sensor. If you get a really good DMM, it will have a frequency counter and duty-cycle scale, so a scope may be totally unnecessary. In addition to sensors, the better quality DMM can be used to check ignition components like in-circuit HEI modules, coils, wires, injector coils, solenoids, injector duty cycle, IAC steps, any relay, general wiring, etc.

Of course, anything that can be tested with a voltmeter can be tested with a scope, but why bother when the DVM is smaller and generally faster (and certainly less expensive)?

Any good automotive reference will list the correct parameters for testing sensors and components, so instead of an oscilloscope, you may want to spend that extra cash on a good service manual ("Helms"). Between that and a good DMM, you should have tools that you can use for a long time and save some cash in the future, too.

Bill Kirsch

I agree with not replacing every single sensor on your motor, but also, I think it's a good idea to replace some of them! While you have the whole motor apart, it's a good idea to replace some things. While they might test out fine, do you really want to risk not replacing a $10 sensor while you have very easy access to it?

Replacing expensive things like the MAF is a no brainer, don't do that until it breaks! plus that is easy to get at without tearing into the motor. Things like EGR/sensor, or course you would want to replace while your in there!

If your putting it back together and a sensor looks like it would be a beeach to replace later, be on the safe side and do it now!

Bill