TCS operations check

[Kurt G.]

What is the best way to check the operation of the TCS system on an early '72 with 4 speed manual transmission? Does it have to be done while driving or can it be done while shifting into 4th gear and idling?

[Monte M.]

Re: TCS operations check

Kurt,

The TCS also has the temperature sensor in the head as well. When you first start the engine the heat sensor is closed which open the vacuum advance. As soon as the engine wars up, the heat sensor in the head opens and breaks the complete circuit closing the vacuum advance.

The vacuum advance is closed until you put it in 4th gear. The relay closes with it in 4th gear opening the vacuum advance.

You can do all this with the car sitting in the driveway. Just be careful while it is in 4th gear sitting there.

My suggestion is the disable the TCS after you make sure it works right. What I have done in my 72 is I have a small jumper vacuum hose that keeps the TCS open all the time allowing the car to run much better with a normally functioning vacuum advance. It makes quite a difference.

Monte

[Joel A.]

Re: TCS operations check

With it idling, clutch down, put the shifter in 4th, and the idle should speed up. If it has the timer, it may take 20 seconds or so before it kicks in.

[Monte M.]

Re: TCS operations check

Joel has it right, but that is the second part of the whole system.

1972 did not have the timer delay. It has a jumper in place instead, so do not worry about a delay.

It is a really basic system. The system is all set up and ready to go. They have put one relay and one sensor in the way of the grounds. When it heats up, it opens the ground making the system shut off. the other is in the trans. When you put it in 4th gear, it closes the ground completing the circuit.

It is as simple as when it has a ground completing the circuit, you have vacuum advance. If something open the circuit, it shuts off the vacuum advance.

The shame is, if the system is working the way it was designed, it shuts off the vacuum advance when the engine needs it the most. By keeping the vacuum advance from working when the engine really needs it, it reduces the emissions by starving the engine.

[Paul O.]

Re: TCS operations check

Kurt

The system works in this way for a 1972.

1. With the manual transmission in 4th gear a ground is given to a time-delay relay anywhere from 25-45 sec the relay fires ground is applied to the solenoid (rt side intake manifold) it energizes and vacuum is applied to distributor vacuum advance also the throttle solenoid at carburetor. Engine RPM increases.

2. Temp sensor in the right cylinder head is for if the engine temperature goes to or above 200? some degrees it then also gives a ground for also given to increases engine RPM for additional cooling. Due to fan speed increase.

3. Do not remember off the top of my head how system operates upon initial start but it would have a system break down in the shop manual for a 1972.

That is a basic break down.

[Monte M.]

Re: TCS operations check

Kurt,

I want to correct something I said. I get so used to dealing with the big block side of things, I forget that there are sometimes differences.

Paul is correct in saying there is a delay if you have a small block. In the big block cars the timer relay was deleted and a jumper was installed. So, in the big block cars there is no delay.

The system is there to prevent the timimg from advancing as it normally would while driving in 1st through 3rd gear except when the engine is cold.

[Kurt G.]

Re: TCS operations check

Thanks guys. I was pretty sure I had it right, but I'm sitting in a hotel room bored to tears, started thinking and boom, got dangerous.

[Monte M.]

Re: TCS operations check

Kurt, I drew this for another member who was having trouble figuring his TCS system out. This drawing is for a big block so there would be a timer where this drawing has the jumper.I hope it helps a little. Sometimes seeing the actual sensor or relays can help.Best of luck

[Terry M.]

Re: TCS operations check

What is the best way to check the operation of the TCS system on an early '72 with 4 speed manual transmission? Does it have to be done while driving or can it be done while shifting into 4th gear and idling?

Kurt,
Since you are sitting in a hotel room, my telling you to consult the NCRS Performance Verification Manual (Hey guys, I bet that's a new one for most of you) isn't going to do much good. There used to be a good description of the TCS operation in the Operations portion of the 1970-72 TIM&JG, but I think we removed that to the PV manual when the Operations ****s (n a z i s) got carried away.

The above people (Joel & Monte) finally got it right = depends on which size engine you have. Time delay (and don't panic if it takes somewhat more than 30 seconds) for small block and no time delay for BB. Joel has the temperature part right, and between Joel and Monte they got the rest of it right, finally. Good job guys without consulting the books. Or did you cheat and use the open book?

[Terry M.]

Re: TCS operations check

Terry,
My first post was pretty clear. After that things may have gotten a little confusing. I think poor Kurt got more than he asked for.

Just in case anyone cares, I updated the drawing I posted earlier. I hope the additional note makes it a little more clear.

Monte

[ATTACH=CONFIG]46848[/ATTACH]

If this board would let me I would offer only four letters: WTMI

[Patrick H.]

Re: TCS operations check

If this board would let me I would offer only four letters: WTMI

Now imagine if Jack H had joined in - I think we'd be down to the minute details of the TCS systems.

[Don L.]

Re: TCS operations check

Kurt,

My suggestion is the disable the TCS after you make sure it works right. What I have done in my 72 is I have a small jumper vacuum hose that keeps the TCS open all the time allowing the car to run much better with a normally functioning vacuum advance. It makes quite a difference.

Monte

Monte,

Please expand on "allowing the car to run much better". My '72 is a SB 4 spd.

Thanks

[Patrick H.]

Re: TCS operations check

Monte,

Please expand on "allowing the car to run much better". My '72 is a SB 4 spd.

Thanks

Don,

I can tell you that on the orange 72, changing from a TCS system to a full time vacuum - even with a stock curve - has it running smoother with far better throttle response. When the owner drove it this past weekend he couldn't believe the change. Neither could I.

I'd highly recommend bypassing your TCS except for on judging days.

Patrick

[Don L.]

Re: TCS operations check

Because of some past readings on how TCS affects (as yet undefined) performance, I put a short piece of hose, for use as a bypass, in the glove box. I've never used it but may try it now.

I am keenly interested in what folks are seeing for performance when the TCS is bypassed, because lately, I may be noticing a lack of power when accelerating in 4th gear. I could be imagining this - need to drive the car more to see. Hopefully, I'll give the bypass a try this weekend. Will report back if I notice anything.

[Patrick H.]

Re: TCS operations check

I could be imagining this - need to drive the car more to see. Hopefully, I'll give the bypass a try this weekend. Will report back if I notice anything.

Give us an update in a couple of years.