I have a recent 76 2ltr transplant that I'm trying to get running. The engine won't start and smells flooded...so I need to start troubleshooting. The wiring harness by cylinder 3 has a single connection wire that is not connected and I can't seem to feel (find) the cylinder head sensor that should be located in the hole by Cylinder #3 (passenger rear). I can't feel the sensor or feel a hole? I'm thinking this could be part of my problem.

Do all 2ltrs have a head sensor in this location? Is there somewhere else it could be located?

Edit!
The PO had the heads switched...looking for options, advice...I really don't want to pull the heads

They could have swaped the heads around and you would find it on the driver's side. I

Hmmm...I hadn't thought about that one...I guess I could look in an adjacent spark plug tin hole on the other head and see if I can find it.

Omitting or disconnecting the TS2 will severely flood the engine. Sounds like you found the problem. If the head doesn't have the hole, you can drill and tap a new one. It's 10 x 1.5, IIRC. You'll have to remove the tin on that side though.

73 2.0 is the only one that uses a different head sensor and a resistor. 74-76 are all the same.

You can drill and tap the tin holdown screw next to the intake manifold for the CHT on #3. This is how is done on buses if the regular spot is switched.

Just checked the other head via spark plug hole...suprise the sensor is there with just a piece of the wire still attached---don't you just love previous owners!


If I have to pull the tin, to tap. What about the metal filings?? Would you make sure that both valves are closed and piston is at TDC...drill, tap then blow out the chamber? I'm a total novice in this area...any tips would be appreciated.


I am very interested in your suggestion...can it be done with the tin on? I'm not to sure about the location you are referring to..could someone supply (or use the pics included) to point to where Bleyseng is suggesting? Pictures included are from my spare motor in the garage...why didn't I notice this Before I dropped the new motor in..

For the time being, wire up the connector as it sits right now.

The number 3 head gets hotter (30 degrees) than any other head, but at least you will have it wired, and it will heat up and provide the correct feedback to the computer to lean out the mixture.

As far as getting it in the right spot, well its either you take out the motor and remove the tin to drill, or swap heads around, or drill and tap the head tin screw that is right below the plug, and bit towards the rear of the car, Geoff has a bus and can show you pics.
I have some head tin here, but IC no screw location near that plug.

If it was me, I would wire it up as it sits right now, get it running correct, and if needed, go to radio shack and place a resistor in the wiring system to make that work correctly.

DrewVw put in a variable setup using a volume knob (A POT) to get the car running perfect, then when he was done, he measured the resistance of the POT to determine the correct resistor to put in.

All that sounds complex, but its fairly easy to implement, and I am sure that Drew or one of the other EE types will chime in.

I personally think it will work fine if you just connect it as it.

Rich

I agree...connect it up first and then see what you got and go from there.

like rich said, due to some stuff done during the PO's rebuild process for my 1.7 it ran way too lean so I used an A/F Meter and a POT to determine how much added resistance I needed and then put in a static resistor in the line.

Car runs like a dream now...see what happens when you rig it up....

I appreciate everyone's input...Rich, I think I will try to get it running using the wrong cylinder with the existing head sensor. Tapping & metal filings scare me, unless I can do it safely with the motor in the car. Drew...what size (range) POT did you buy from Radio Shack? I don't have access to an A/F meter--options? Unfortunately, it feels like there is only an inch or so of wire on the orignal sensor..not enough to make it out the spark plug hole...and probably next to impossible to crimp extra wire to it...I'll probably have to cut a hole in the tin or remove the tin to get to it

Get a hole saw, 1 inch and cut a hole as if it were the correct location.
In order to keep your engine cool, plug the original hole on the passengers side, and get a new rubber gromet (Pelican) for the drivers side.

You are not creating any metal shavings inside the motor here, nor would you be on the other side...these bungs are there for the CHT to be drilled in.
Given that, just drill out the drivers side of the tin, and run the wire correctly, worst case is that you need to buy the two rubbers, and a new CHT to get the correct wire length and your good to go.

If you remove the old one, to install the new CHT correctly, you need two things.
First, take a long 3/8ths inch socket extension and on the male end use a dremel or a file to create a notch in the extension on the flat side.
this notch needs to be large enough to allow the wire to run through the socket, through the notch without getting pinched or cut...so make sure its smooth and big enough.

Second, once you are read to thread the new CHT in place, apply Milk Of Magnesia to the threads. It provided a better contact to the head for the CHT, and acts like a thread anti sieze.

The CHT hole does not penetrate the cylinder/head into the combustion chamber, so if the threads are messed up you can get a flat bottom tap, clean it up, and not worry about metal in the motor...its all outside (provided you dont drill any deeper)

So, you have a plan, now go shopping...

Rich

Rich

CHT doesn't go into the cylinder. Drill about 1/2" into the boss. There is enough material there that you won't go into the cylinder.

You will need a POT that can do from 0 to around 2000 OHMs in IMHO. Most of them go way higher than that but you most likely will need to add 200 - 800 OHMs if its running too lean. I actually used an old radio volume dial....

and remember....adding resistance makes it run RICHER. If its running too rich with the CHT then this will not work without really hacking it.

you don't need a A/F meter to get started. Just warm up the car really well and at idle turn the POT gently (which is INLINE with the CHT -> Brain ) and tune it by ear so that the car is running nice and even. Then adjust the idle and take it for a drive and see how it feels. Lather, Rinse, Repeat. making it run richer gives a bit more power but will drop your MPG. I run mine at 22MPG because I like the extra kick and don't mind the mileage.

Many people think this method is an abomination but its perfectly plausible scientifically (they did it from the factory for '73 2.0s) and it worked great for me when nothing else did, including changing out a bunch of the FI parts. Good luck.

Adding significant ballast resistance (200 or more ohms) to the TS2 sensor is a common D-Jet trick to richen the mixture. The problem is that the extra resistance causes the temperature compensation circuit in the ECU to function improperly. This circuit is designed so that once the head temperature is high enough so that the engine is fully warmed-up, the compensation circuit locks in at a set mixture level, regardless of if the head temperature varies. When you add a large amount of ballast resistance, you shift the characteristic so that the ECU thinks the engine is still warming up, no matter what the head temp is. This causes the mixture to vary as the heads get hotter and cooler (e.g. due to acceleration or other heavy loads). It may give you a richer mixture, but it's not an optimal way to do it.

Often, in cars with this type of lean mixture problem, there is another underlying issue - low fuel pressure, low fuel supply, maladjusted MPS, etc.

I must agree. I've had to do this myself, and I'm the idiot that switched the heads!!!!! Its the quick and easy way,

Thank you all for the advice and tips for my "switched head" CHT issue. I went ahead and did what Rich suggested and just cut another 1 inch hole on the other tin to access the already installed head sensor.

Right now I'm still troubleshooting to get the motor running, but at least the sensor is now connecteed. Once I get it running, I'll first try Drew's suggestion of the POT to hone in on the sweet spot and then buy a resistor with that resistance and replace the POT.

If that doesn't work, I'll pull the tin on the passenger's side and tap for a new CHT which I've already ordered from the BIRD place.

Since this is a desmogged 76 motor, who knows what tweaking I'll have to do.
Thanks again,
Mark