Note: forwarding this from someone that wrote this to me
MK
wanted to share some important technical info with all of you so that you would not have to go through the nightmare I have been through with my car for most of this year.
About 10 months ago, my mechanic did a computer test and told me my coolant sensor was bad. This is the one that screws into the side of the “water box” on the cylinder head. The “water box” is where the thermostat is located. The sensor is brass, with two threaded “posts” coming out of the “bakelight” (black plastic) end of the sensor.
One of the posts was broken off. I found the new sensor at NAPA, which according to their catalog was the correct sensor. I ordered one and installed it, Part # ECH TS5005. The sensor looked like this:
I presumed it was the updated design, noting that the sensor was designated for all cars from 84 going forward. I also had to order a new connector.
I put this in my car and that’s when troubles got worse, but not right away. The broken post had already been tripping off the “Power Loss” light. When I ran “fault codes” I got all kinds of readouts, which may or may not have been accurate. To summarize, I replaced both engine and fuel computer modules, oxygen sensor (twice), replaced all of the vacuum lines (which was good, I found a couple of broken ones).
The car would not start all the time, and when it did, it would sputter and belch out dark gray smoke. On occasions when it didn’t start, I pulled the spark plugs and they were wet with gasoline. I had the injectors re-built, nothing got better. And I was getting 10 MPG.
I had a conversation with a friend in Great Autos of Yesteryear and he asked me about sensors. After some research, I found information on ALLPAR.com which explained that the 84 sensor (first photo) had an ohm value in the mid 5’s. The 85 sensor (bottom photo) is designed for a different computer and has an ohm value of 9. The net effect was that the new sensor was the wrong one and was dumping twice the gasoline into the cylinders.
I also realized that the air charge sensors are the same as the coolant sensors, so I just ordered the air charge sensor from NAPA (part # ECH TS5009 which is the upper photo) and installed it.
This has fixed the problem. The car starts instantly, is getting over 20 MPG and the “Power Loss” light has not come on since.
The 84 was the FIRST year of the turbo, and has many many parts for the engine management system that are unique to the 84. In most cases, any part designed for the 85 and up will not work. Since auto parts companies don’t really know much about a 32 year old car that had limited numbers, this kind of mistake can occur often.
For me, it was expensive, and made my car barely drivable for almost ten months. I’m sharing this so you won’t go through a similar nightmare.
This information applies to ALL 84’s with turbo, but may also apply to non-turbo 84’s as well. Check the sensor type, and make sure you replace it with the same type of sensor.
Happy New Year to all of you.
Ed Garren
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