TI Ignition Trouble Shooting?
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Pro
Joined: Feb 2013
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TI Ignition Trouble Shooting?
I've rebuilt everything on my 68 L71 with TI Ignition. I've used the trouble shooting guides, but still can't seem to get spark out of the original system. All components check out ok. On crank the Volts drop to 9.6 ish is that enough or do I need to trouble shoot this? The Engine turns, but there is no indication of combustion at all. I've swapped the TI Amp Board, and Coil, the wiring is all new from Lectric, the battery is new, all cables are new. The Starter is newly rebuilt.
Any suggestions?
thanks!
Any suggestions?
thanks!
Advanced
Joined: Sep 2012
Posts: 94
Likes: 2
From: Seattle Wa
I have a similar problem with my 69 and I am still in line to get it into my corvette mechanic to get it resolved. I have a replacement board in my TI box and I get no spark to the coil durring cranking. However, it will fire just as the key is released from the start position. It won't run, but it fires as I release the key. I also have the original OEM factory board and it works just fine in the box but it's old and I don't trust it. My mechanic told me that the manufacturer of the new replacement board says it takes a minimum of 10 volts for the replacement unit to work properly. The OEM unit doesn't need that many volts to function. So in my case my mechanic says I have a voltage drop somewhere and he needs to get it into the shop to find out where it is. All my wireing is new from Lectric Ltd and correctly installed so I can't imagine what the problem is. As soon as I can get it fixed I will post the results of what we found.
Thread Starter
Pro
Joined: Feb 2013
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sounds Exactly like what I'm experiencing! definately let me know what you find in terms of voltage drop and what it is causing it? How is your starter grounded? I'm wondering if the new cables could be causing part of the Voltage drop?
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Joined: Sep 2012
Posts: 94
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From: Seattle Wa
Honestly, I don't remember how the starter is grounded. I don't recall a seperate ground cable for it. I'll check it tonight if I get a chance. I've got my baby all covered up under a cover, and blankets and comforters in the garage until it stops raining here in Seattle. Might not be able to respond until the weekend.
Race Director
Joined: May 2006
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If you look at this diagram the positive side of the coil is a resistance wire which explains the voltage drop. You may want to contact this company with your issues.
http://tispecialty.com/articles/66-71diagram.htm
http://tispecialty.com/articles/66-71diagram.htm
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Joined: Sep 2012
Posts: 94
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From: Seattle Wa
Understood. I have no experiance with this and am going from memory right now so I may be a little off on this but as I recall, with the seperate TI wireing harness the non TI wire in the main harness is not used. It is removed from the coil, dead ended and the seperate TI wireing harness is connected as shown in that diagram by the white 12 gage wire to the positive terminal on the coil. This diagram indicates that there is another resistance wire feeding power to the unit and I believe that this may be our issue. I am not equipped to verify this and will defer to my vette mechanic who has a lot of experiance with this. I just cant get to him as he has a bunch of guys lined up ahead of me. But, I'm thinking that a 12 volt jumper wire to + on the coil might tell the story. I just don't want to fry something.
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Understood. I have no experiance with this and am going from memory right now so I may be a little off on this but as I recall, with the seperate TI wireing harness the non TI wire in the main harness is not used. It is removed from the coil, dead ended and the seperate TI wireing harness is connected as shown in that diagram by the white 12 gage wire to the positive terminal on the coil. This diagram indicates that there is another resistance wire feeding power to the unit and I believe that this may be our issue. I am not equipped to verify this and will defer to my vette mechanic who has a lot of experiance with this. I just cant get to him as he has a bunch of guys lined up ahead of me. But, I'm thinking that a 12 volt jumper wire to + on the coil might tell the story. I just don't want to fry something.
Safety Car
Joined: Nov 2007
Posts: 4,500
Likes: 810
From: East Central Florida
I had identical issues with a '67 L71 TI system. Cranking, no spark. As soon as I would release the key to run, it would try to fire. This was a first time engine run after rebuild with a new TI module/harness but with a used distributor, which appeared NOS.
The result was a bad pickup coil in the TI distributor.
Dave Fielder's guide below. You need to measure 500-700 ohms at the dist pickup terminals as it rotates. In my case I was getting intermittent readings.
Use the chart below to step through where the fault may show up.
http://tispecialty.com/articles/66-71.pdf
I opened up the pickup coil carefully, and discovered a cold solder joint on one of the lead wires to the micro-wire inside the coil. I was able to resolder it. Problem solved.
Also check the terminals in your pickup coil to TI harness. Make sure you have a good solid connection. Also verify your ground at the TI module with a ohm meter to the engine ground.
The result was a bad pickup coil in the TI distributor.
Dave Fielder's guide below. You need to measure 500-700 ohms at the dist pickup terminals as it rotates. In my case I was getting intermittent readings.
Use the chart below to step through where the fault may show up.
http://tispecialty.com/articles/66-71.pdf
I opened up the pickup coil carefully, and discovered a cold solder joint on one of the lead wires to the micro-wire inside the coil. I was able to resolder it. Problem solved.
Also check the terminals in your pickup coil to TI harness. Make sure you have a good solid connection. Also verify your ground at the TI module with a ohm meter to the engine ground.
Safety Car
Joined: Nov 2007
Posts: 4,500
Likes: 810
From: East Central Florida
One more thing to mention......
You won't get direct battery voltage on the coil when cranking in a TI system.
If you look at the diagram below, you'll notice the yellow wire to the R terminal on the starter solenoid. That supplies direct battery voltage to the TI amp via the 18G Pink wire, not to the coil +.
This differs from a points system which supplies direct battery voltage to the "+" of the coil while cranking.
http://tispecialty.com/articles/66-71diagram.htm
You won't get direct battery voltage on the coil when cranking in a TI system.
If you look at the diagram below, you'll notice the yellow wire to the R terminal on the starter solenoid. That supplies direct battery voltage to the TI amp via the 18G Pink wire, not to the coil +.
This differs from a points system which supplies direct battery voltage to the "+" of the coil while cranking.
http://tispecialty.com/articles/66-71diagram.htm
Last edited by rich5962; Feb 12, 2013 at 07:03 PM. Reason: link
Advanced
Joined: Sep 2012
Posts: 94
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From: Seattle Wa
Great information Rich. I wouldn't be surprised if it is the pick up coil. It is supposed to be new but it has been sitting on my mechanics shelf for 10 years. I will pass along all your comments to him when I take her over to get this fixed. It's so reassuring being able to count on the experts on this forum. I've been hanging around here for the last 6 months and am always amazed at the wealth of knowledge available here. Thanks to everyone. Oh, and I didn't mean to hijack your thread 68RPOL71. I'm just sharing your frustrations. 
Safety Car
Joined: Nov 2007
Posts: 4,500
Likes: 810
From: East Central Florida
Great information Rich. I wouldn't be surprised if it is the pick up coil. It is supposed to be new but it has been sitting on my mechanics shelf for 10 years. I will pass along all your comments to him when I take her over to get this fixed. It's so reassuring being able to count on the experts on this forum. I've been hanging around here for the last 6 months and am always amazed at the wealth of knowledge available here. Thanks to everyone. Oh, and I didn't mean to hijack your thread 68RPOL71. I'm just sharing your frustrations.
The TI distributor I bought for that '67 was like new, bought from a man that had it maybe 20+ years. We were amazed how good it looked. Fact is, it was likely removed at a dealership for warranty in '68 and sat on a shelf all those years because it was bad. We got it many years later, and of course, was still bad.
I hope you both solve your problems. It may be the pickup coil, or just a bad connection somewhere.
BTW.........don't apply direct battery to the coil +.
Extra thought.....Your fault could also be a bad ignition switch. Make sure you have voltages as shown on the guide with key "On" and "Crank". When cranking, ignition feed must still have voltage.
Rich
Advanced
Joined: Sep 2012
Posts: 94
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From: Seattle Wa
One final question Rich. Could I expect the pick up coil to still be defective if the engine starts and runs great when I install the original OEM circuit board in the TI module? Like I said above, this problem only exists for me after installing a new design circuit board that I got from M & H Electric. I actually tried two different new ones from them with no difference. But with the OEM board installed she runs and drives strong with no missing or any hesitation. It was M&H that told us we needed a minimum of 10 volts for their unit to operate properly. I also called Lectric Ltd and they told me that if the original factory wireing had a resistor wire in it, then theirs did too. Puzzling for sure. Thanks again!
Safety Car
Joined: Nov 2007
Posts: 4,500
Likes: 810
From: East Central Florida
One final question Rich. Could I expect the pick up coil to still be defective if the engine starts and runs great when I install the original OEM circuit board in the TI module? Like I said above, this problem only exists for me after installing a new design circuit board that I got from M & H Electric. I actually tried two different new ones from them with no difference. But with the OEM board installed she runs and drives strong with no missing or any hesitation. It was M&H that told us we needed a minimum of 10 volts for their unit to operate properly. I also called Lectric Ltd and they told me that if the original factory wireing had a resistor wire in it, then theirs did too. Puzzling for sure. Thanks again!
If low voltage is a concern, make sure your battery is fully charged, or replace it if in question.
When using the replacement board, you have to make sure that the 3 terminals are not shorting to the case when the cover is replaced. I have found you have to carefully bend the terminals downward after the pigtail wires are installed. You can see they stick up a bit. Also make sure that the circuit board is properly grounded to the case with the hold down screws. The replacement board is not the exact same profile as OEM, so you need to ensure it doesn't short out anywhere.
Edit.....
I'm not familiar with the M&H board but it may have clearance issues like shown. The ones I've used are made by K & B Products.
http://kandbcorvetteproducts.com/
Last edited by rich5962; Feb 13, 2013 at 08:54 AM.
Advanced
Joined: Sep 2012
Posts: 94
Likes: 2
From: Seattle Wa
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Here is the M & H board. They say they have sold thousands of them with no isues. We even sanded all the mounting holes to remove the cad plating and used star warshers to get a good ground. Nothing! It's got to be something in my wireing. My battery is brand new.
[/IMG]Here is the M & H board. They say they have sold thousands of them with no isues. We even sanded all the mounting holes to remove the cad plating and used star warshers to get a good ground. Nothing! It's got to be something in my wireing. My battery is brand new.
Advanced
Joined: Sep 2012
Posts: 94
Likes: 2
From: Seattle Wa
Rich, Just in case anybody is still interested, we finally got to the bottom of my low voltage issue. It turned out to be the pick-up coil inside the distributer. Although it was brand new NOS there was a broken wire down deep in the coil. My talented mechanic diagnosed the problem and was able to repair the unit. Now she runs like never before. 
Thanks again for all your helpfull information
Thanks again for all your helpfull information