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After driving for awhile the engine is completly warmed up and upon decelerating and accelerating the engine would hesitate for lack of power.Prior to this I bypassed the TCS solonoid and ran full vacuum because I had this problem before.I wanted to recconnect and try again.The solonoid wiring is hooked up along with the transmission switch at the tranny,head temp sender and firewall relay all hooked up.Is the problem only the solonoid?If not how do I test the components.Temp sender is new.
1. The solenoid should not operate unless the engine is warmed up AND the trans is in top gear (4th for Muncie, 3rd for THM400).
2. It can take 20-30 seconds in gear for the solenoid to operate. So, with a 4 speed it's easy to test because you can put it in 4th with the clutch in, wait 30 sec and hear your idle speed increase. As I don't own an automatic I can't definitively tell you the answer on how to test that one.
3. The solenoid can be removed from the car and tested with a power source. Actually, I suppose it could be done in-car as well. I've used a battery charger and it works fine. The solenoid should click when power is applied. More specifics are in the Archives.
Patrick
Vice-Chairman (West), Michigan Chapter NCRS
71 "deer modified" coupe
72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
2008 coupe
Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.
I hooked up a battery charger to the solonoid and it does click.Then the problem I am having is another component.Any thoughts as to what it might be?
I have a 4 speed Muncie M20.
I run 14 degrees ATC per the owners manual.It is an LT1.Setting the timing at 8 degrees per the emissions label the car lags.The owners manual is the correct setting other LT1 owners agree.I had set the timing with the solonoid vacuum lines bypassed and ran the line from the advance to the bottom port of the carburator at the "T".
If the solenoid's not energizing, (retarding timing),
(1)you won't be able to test or rule out the trans switch, (3rd or 4th gear in a 4 speed).
(2)you can't rule out a bad temp sender, since that doesn't retard the timing until warn (1-2 minutes),then retards to the initial 8 degrees.
I would follow Patricks advise, but try to energize the solenoid on the engine. If it energizes you might assume you found the problem. Just to be sure you will then be able to test the other components as patrick described.
If the soleniod IS energized,(timing is retarding), then any of the other components can be tested or eliminated by there own operation.
The system may be checked for proper functions by connecting a vacuum gage in the hose between the solenoid and the distributor. Full vacuum should be obtained when the transmission is in the gear as indicated on the chart when the engine is warm and running. If full vacuum is not found the cause may be:
1 fuse blown
2 wire disconnected at solenoid
3 wire disconnected at trans
4 trans switch failed
5 temp overide switch energized-check by disconnecting lead
6 solenoid failed
If no vacuum is found in high gear, the cause may be:
1 clean air line and distributor vacuum line reversed at solenoid
2 plunger return spring broke
3 foreign material in solenoid
4 dist. or manifold vacuum line broke or disconnected
5 Trans switch or wire shorted to ground
I'd then warm it up, and with clutch pedal pressed in, put it in 4th gear. Wait 20-30 secs, and have a bystander listen for the click (or feel for it by touching the solenoid). If it clicks, then the SYSTEM works, but the execution might not. In other words, the vacuum hoses may be connected improperly or be blocked.
If it doesn't work, then think the relay on the firewall, and often less likely the switch on the trans. The trans switch can be checked for continuity in 4th gear, and as it's a simple mechanical switch its odds of failing are less than the electrical relay on the firewall.
Patrick
Vice-Chairman (West), Michigan Chapter NCRS
71 "deer modified" coupe
72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
2008 coupe
Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.
Terry Mc. walked me through this a few years ago. Lets see how much I remember. You have several components and some can be tested: 1. the switch on the transmission (which is widely available) 2. the thermostat on the right head 3. the solenoid and 4. the TCS timer.
1. ensure that you have a good contact between the trans linkage and the switch (sorry - don't remember how to test it)
2. pull the double connector off of the TCS temp unit and ground it to the block. If the rpm increases, you have a bad temp unit. They are still available.
3. you already proved that the solenoid moves when activated with DC power
4. if all of the other units pass inspection and it is the TCS timer, you may be SOL. I was fortunate to find a pristine unit on a parts car at Carlisle. That may be your best bet.
Btw, the 1972 Chassis Service Manual has a fairly good diagnostic section on the TCS system. Do you own a manual for your car and have you run the tests?
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