Microtech Area is for discussing Microtech systems

No spark LT8

Old 06-09-14, 02:11 PM
  #1  
Rotary Freak
Thread Starter
iTrader: (3)
 
funkjaw's Avatar
 
Join Date: Jul 2008
Location: San Jose, CA (NorCal/S.F. Bay Area)
Posts: 2,504
Likes: 0
Received 0 Likes on 0 Posts
No spark LT8

1987 TII
LT8
Stock ignition and CAS
Taurus Alternator

Car had LT8 installed and wired up about 3-4 years ago and has been running ever since. Yesterday I put in a new fuel pressure regulator, but found the car had a dead battery (sat for a week, not sure why the battery died in a week as it is a fairly new battery).

So we jump the car, and fire it up with the purpose of tuning the car. Car immediately acts like it has a spark issue.

After much inspection, we find that nothing seems out of the ordinary in terms of ignition components. We go to fire it up again, but this time it won't even start. Throwing a timing light on reveals we are not getting spark out of any of the coils, and the microtech confirmed this by showing 0 RPM (as well as my tachometer).

Threw in another CAS I had kicking around, same issue. Checking the connector at the microtech shows continuity from the CAS to the ECU. Microtech was also flashing orange when cranking as well with solid green light and no red light.

So we put the microtech in test mode by changing cylinder value to 0. We try cranking and we DO get a spark signal from the microtech (my understanding is it takes the CAS out of the equation and generates it's own signal). The plugs were firing at while in test mode as well as an RPM signal on my tachometer.

We then take it out of test mode and again I have no spark signal coming from the microtech but this time, the red light flashes and returns a "no rpm" error.

I am starting to think my Microtech is dead... possibly whatever part of the ECU that receives the crank input.

One thing of note is I drove around with a 1.0V voltage drop from the alternator to the battery (for a few weeks). I discovered that the microtech was wired to the alternator which was pumping out "15.95" volts at times to compensate for the voltage drop... I fixed the voltage drop issue last week with some fresh wiring. Is it possible the microtech did not like that 16volts and burned something up?

Any thoughts. suggestions???

Thanks!!
funkjaw is offline  
Old 06-14-14, 10:16 AM
  #2  
Engine, Not Motor
iTrader: (1)
 
Aaron Cake's Avatar
 
Join Date: Feb 2001
Location: London, Ontario, Canada
Posts: 29,671
Likes: 0
Received 23 Likes on 22 Posts
I guess the only way to confirm this would be to connect a CAS directly to the Microtech (connectors are the same as those used on ATX computer power supplies) through a short harness and then spin it by hand. If it picks up RPM, the Microtech is good.
Aaron Cake is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Prediict
2nd Generation Specific (1986-1992)
32
11-18-15 08:41 AM
Aramir
New Member RX-7 Technical
24
10-18-15 02:39 AM
tctwaites
1st Generation Specific (1979-1985)
5
09-22-15 08:48 PM


Thread Tools
Search this Thread
Quick Reply: No spark LT8


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: