Need tested or NOS CHT specifically for the 73 2.0. Part numbers 022 906 041 A or 0 280 130 017. Also want to give a CHT extension a try if anyone has one for sale.

Have the CHT new sorry no stand offs

https://900designs-container.zoeysite.com/c...rature-sensor-1

I think Brad at 914LTD has the extensions. That’s where I bought mine.

Unfortunately the 73 2.0 requires the specified part number to run correctly. Thank you for the suggestion.

Call Brad Mayeur's shop 914LTD On Monday 309-694-1797 he sells the standoff and just might have the head temp sensor also.

What is the downside of having the wrong type of CHT? I ask because our 73 2.0 runs exceptionally well but the temp gauge in the console only moves slightly when warmed up. Although this might be fine, the car is having warm start issues. If I cycle the fuel pump a few times the car will most likely start.

Actually it needs the additional resistor I'm currently running on mine (73).
Mark

It's a matter of resistance the 73 required the additional so the resistor is added inline.

What does the resistor look like? I recall these on a group buy some time back...

Never did a resistor GB, just the CHT sensor.

if I recall correctly it a 350 (or 300)ohm resistor that has the spade male and female in line so it can easily be added in line.

Thank you!

I'm currently running the correct CHT and the stock resistor. Runs good until I shut it off. Starts when hot but then sputters and just doesn't run smooth for about 10 minutes or until the heat has transferred evenly again. I wanted to try another correct CHT and a standoff to see if that might help the issue.

Thanks Mark, On the GB thread (http://www.914world.com/bbs2/index.php?showtopic=294539&st=60) you stated never to use resistor with your unit, has this changed? What is the specific setup for your 73. 2.0?

"The 1973 2.0L's came with the:
0280130017 head temperature sensor,
039971762A ballast resistor,
0280100037 manifold pressure sensor, and the
022906021E version of the ECU.

Does it smell rich when it's not running when warm? It almost sounds like the cht may be going out. When hot it should have almost 0 resistance. allowing a lean condition. When cold it should enriches (has more resistance). If this is the culprit the standoff would not help.

I'm wondering if the issue may be something else.

This post is worthy of the garage you may find more help there.

Thanks Mark, the car runs at 95% for three minutes and then perfectly — fuel mix smells good. The problem is that if I stop after 20 minutes, the car will not start unless I cycle the fuel pump several times and then it starts. The fuel pump is NOS, but tried a refurb from AA and no difference.

I’ll move this to the garage.

cheers

It does smell rich from the moment I start it but the plugs look great.

I happen to have one sitting next to the computer. Measures 275 ohms.

I think they are actually 250 Ohm specification IIRC but resistors often have a 10-20% tolerance. So I'm betting mine is 250 ohm +10%.

So, while this should probably be in The Garage, a bump for this.

Really, why does it matter what the resistance is, if we're effectively going to wreck its designed function with a spacer to slow down the drop in resistance?

There's two CHT sensors: per Paul's specs, 0 280 130 003 for the 1.7 and 0 280 130 012 for the 2.0.

Normal Value(s):
0 280 130 003 and 0 280 130 012: about 2.5 K ohms at 68 deg. F, less than 100 ohms with hot engine.
0 280 130 017: about 1.3 K ohms at 68 deg. F, less than 100 ohms with hot engine.

The function of the CHT is to "tell" the ECU that the engine is cold, please richen the fuel. This happens at higher resistance. Both are the same value when hot ("less than 100 ohms") so the wrong CHT doesn't matter after warmup.

By adding a spacer, we're slowing the conduction of heat to the CHT< keeping the resistance higher, longer.

Therefore...if we install the 2.5K ohm sensor on an engine that needs the 1.3K ohm sensor, then it keeps the car richer longer, but ends up in the same place once the engine is hot (and reducing the need for the spacer).

If we install the 1.3K ohm sensor on an engine that needs the 2.5K ohm sensor, then it leans the engine sooner, but ends up in the same place once the engine is hot. But that can be compensated by installing the spacer.

So where's my disconnect here?

Bottom line is idle quality and drive ability during the transient conditions.

ECU is an analog circuit that was designed around a specific sensor and inherent non-linear resistance curve. There is no closed loop control to adapt like a modern FI system has.

I’m with you on the spacer thing though. Adds another uncontrolled variable into the mix but historically some had success to their own liking (whatever that might be) with the spacer.