T.I. System Problem
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
The 71 TI system has a capacitor/condensor attached to the coil + terminal. This shown in the NCRS 1970-72 Corvette technical Information Manual and Judging Guide. J947452 DR 3MF is the number on the capacitor. What effect does it have on the TI system if it is bad???
Answer I found:Any external condenser should be connected to the coil (+) terminal only. As already pointed out, it is there for radio interference suppression only and plays no part in engine operation. For engine testing purposes it would be best to leave it disconnected.
Answer I found:Any external condenser should be connected to the coil (+) terminal only. As already pointed out, it is there for radio interference suppression only and plays no part in engine operation. For engine testing purposes it would be best to leave it disconnected.
Installing a capacitor on the + side of the TI coil slows down the shutoff (the high voltage rise time), causing a loss of energy in the coil, and promoting misfires.
I don't give a crap what NCRS says. Do you have any GM documents that suggest putting a capacitor there?
Thread Starter
Burning Brakes
Joined: Aug 2007
Posts: 1,084
Likes: 8
From: Illinois
It does NOT show a capacitor on the positive side of the coil in any of the diagrams or the 1971 Corvette Assembly or Service Manual----I agree. I will remove it from my ignition system and see if that eliminates the misfires. Thank you for that expert advice---it is greatly appreciated.
I will do the above and reclean/recheck the 3 negative grounds at the distributor, coil. and amplifier box.
If these don't help, my next step is to connect the system to an oscillosope and take a look at the voltage waves.
I will do the above and reclean/recheck the 3 negative grounds at the distributor, coil. and amplifier box.
If these don't help, my next step is to connect the system to an oscillosope and take a look at the voltage waves.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
If you get no improvement from removing the cap, I think I would go back to the basics- obviously, the TI system is working. Basic stuff like wires and cap. Even spray the wires with water while it's running in the dark and see if the wires are leaking. Even they may be fairly new they could still be leaking.
Thread Starter
Burning Brakes
Joined: Aug 2007
Posts: 1,084
Likes: 8
From: Illinois
YEA!YEA! As soon as the capacitor was removed from the positive coil contact the car ran perfectly. Thank you to 69427 (an engineer) for pointing this out--the NCRS manual is incorrect. Also thanks to Duke Williams and Jack Humphrey (both engineers) for also confirming 6927. You guys are what the different forums are all about--helping others.
