RWD - 1990 240 ECT replacement - OEM and Teflon tape

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1990 240 ECT replacement - OEM and Teflon tape 200

Hi Mark,

I remember working with you on a 1990 before and I thought you found out it to be a basic spark issue. Is this the same car? You said here that you let the other 1990 car go.

The last time you were dealing with the ECT and whether Teflon tape would fool with its operation.
We concluded that it would affect the resistance signal. You said you got it in there so that good.

I too believe that the ECT will not kill the engine randomly at idle either.
The ECT is only an input perimeter factor of the ECT and ICU programs that would adjust mixture and spark timing. In extreme cases of an overheating, that signal from the ECU would enrichen the mixture to cool the combustion flame and the timing would shift to retard to reduce detonations.
For safety reasons there should not be away to shut off the engine without lots of warning lights or actual falling into a limp mode.

From this stand point of the codes given they are saying its a mixture problem mostly caused by a bad reading from the O2 sensor input. Of course this cannot shut the engine down.
You can have the engine running and have verified voltage reading to know if it's is working.

A voltmeter set on the lowest range for sensitivity to read a range of less than one volt is the ticket. You clip one lead of the meter onto the exposed and connected part of the wiring spade, out there by the firewall.
Clip the other lead of the meter to a ground point on the engine, body of the car or even the negative post of the battery. The voltage will constantly vary in the middle of the one-volt range.
I have a meter made with 10 led lights that run up and down like race track Christmas tree. It's very visual to show up if the sensor is lazy or hanging at one end of the scale.

This also tells me that the cars electronics are shifting the mixtures from that output. I can rev the engine and the O2 sensor will respond quickily to rich and lean but once the rpm stabilizes the O2 rolls more back to bouncing in the middle. This is a normal temperature running engine.
If there is a misfire the sensor will show it went rich and then dive lean when the engines electronics try to correct it.
The AMM just keeps putting out a steady signal as this does not effect incoming air metering as that cylinder just keeps sucking even with a burnt intake valve. The AMM affects overall performance and starting. Just shutting off to kill the engine is a stretch for me to believe at this point.

So going to basics that like a hundred years old I'm talking ignition. It use to be points, then hall sensors and now proximity sensors.
We are at the other end of a century but we cannot get away from the plagues of creating sparks.

Here is where we got a doubling down going on with a trigger mechanism not just doing a spark but telling the other electronics to get their act together!
We know the CPS can go bananas in many strange ways that it can throw erroneous types of signal waves!
Of what I know how computers, they can be absolutely finicky on what you tell it and how it reacts.
I want to say start there and know it's a good one if you haven already.
Especially, if you said it bogged down at high speed and now just turns off.

The next thing would be the electronic relay out behind the battery. Service its conductor paste and mostly it's connector.

If you have to go farther the ICU's becomes suspect. I have read that in areas like Maylasia they get overheated. This was found out by mounting a computer fan to blow on it and the problem of shutting down went away.

So if you are going to junkyard mechanics try these ideas.

Ok good luck, keep us posted.


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New 1990 240 ECT replacement - OEM and Teflon tape [200]
posted by  martnplyr  on Sun May 13 11:56 CST 2018 >

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