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LT8s & spark plug wires

Old 11-23-15, 11:59 AM
Old Rotary Dude
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LT8s & spark plug wires

Just wanted to toss this out there for ppl using the LT8s. This may be the same for other Microtechs or even other ECUs. I found out about this after weeks of tracking things down (only to find them good), replacing parts that didn't need replacing, etc...

I have a LT8s on my FC and my tuner was having issues with the timing moving, literally jumping 30 degrees or more. We stuck the CAS several times only to literally watch, with a timing light, the timing jump from 15 BTDC at idle up to around 4000 rpms to 15 degrees ATDC. Tuner wouldn't even has his laptop hooked up, so we knew it wasn't something on the tuning side.

Turns out that he had a radio interference/wire noise tester (really neat device) and we tested the main input from the CAS to the LT8s and had an insane amount of interference until roughly 4000 rpms and then it would settle down. The only thing that we had not given a thought to were the plug wires because they were new Racing Beat wires.

Everyone knows these wires are super nice and I have ran these wires since the 80s with no issues on many other rotaries. The one thing I didn't consider was that I did not order OE replacement RB wires, I ordered full race RB wires. These wires have little to no shielding and seemed to be the culprit for my issue. So, after weeks of replacing things and rewiring stuff, I picked up a set of $30 NGK OE wires and the issue was immediately resolved . The tuner was able to do his thing and get the tune straight.

All that to say, there is nothing wrong with RB plug wires, they are great as they have always been. Just don't use their race wires if you are running an LT8s Microtech, or possibly other standalones.

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Old 11-28-15, 10:14 AM
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With any EFI system, non-shielded ("non resistor") wires are never an option due to interference. Regardless of the EMS. Some are better than others at noise rejection (Microtech is one of the best in my opinion...you probably wouldn't have been able to start the car if it was a Haltech) but few are going to reliably trigger with 4 antennas broadcasting directly beside the sensor.
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