Electronic failure I am....... - Miata Turbo Forum -Boost cars, acquire cats.

Welcome to Miataturbo.net   Members

General Miata Chat A place to talk about anything Miata

LinkBack Thread Tools
Old 08-09-2008, 10:17 PM   #1
Thread Starter
iTrader: (17)
Vashthestampede's Avatar
Join Date: Feb 2007
Location: Danbury, CT
Posts: 4,630
Total Cats: 45
Default Electronic failure I am.......

Summery of the issue.

Car started and idles ok. Quick look at the Kenwood screen and it reads to me "PROTECTED". I feel that grounds might be the cause and do a search on google for proper grounding recommendations. I learn that having multiple items grounded to the same point, is not good. I had the ECU, LC1 wideband and gauge, and the Kenwood unit all grounded at the ECU ground location on the block. I changed the ground for the Kenwood and it works fine now, as well as the car idles smooth.

Now, when I hit the throttle I can hear a "click....lick hick click" sound from under the dash. Like a fuse, relay, something that clicks? The idle dive bombs and the car stalls. Or I can blip the gas a couple times, hear some more clicks (not every time) and then take my foot off the gas and let it stall. Since I had the car started last the only thing I really have fucked with is the electronics.

After reading more on grounding, I am almost certain this is my problem. However .01% of my brain is capable of working with electronics. Sometimes I'm lucky and I zone out while working with wires and when I'm done things work, but not always 100% all the time.

Any ideas?

Vashthestampede is offline   Reply With Quote
Old 08-09-2008, 10:49 PM   #2
Junior Member
Join Date: May 2007
Location: NC
Posts: 246
Total Cats: 0

Multi ground theortically should not be a problem - although i had the same prob with my AEM UGEO - it did not like sharing a ground with my boost gauge.... Although I just added 3 new gauges and they are fine sharing grounds ?? Strange...
mtncrvr is offline   Reply With Quote
Old 08-10-2008, 10:13 AM   #3
Elite Member
iTrader: (5)
m2cupcar's Avatar
Join Date: Jan 2005
Location: Atlanta
Posts: 6,936
Total Cats: 133

My EGT refused to work properly sharing grounds with other gauges. And the LC1 had issues until all grounds were separate. IMO it won't hurt to try it.
m2cupcar is offline   Reply With Quote
Old 08-10-2008, 12:44 PM   #4
Boost Pope
iTrader: (8)
Joe Perez's Avatar
Join Date: Sep 2005
Location: Chicago
Posts: 24,444
Total Cats: 1,531


In theory, it is best for all devices which are part of a system (such as the ECU, WBO2, sensors, and displays) to use the same ground, so long as it is a very good ground.

When multiple devices which interact use different grounds, there is a real potential for the various grounds to have slightly different resistances, thus causing an imbalance in the voltage potential across these devices. This can cause sensors to be misread and such.

If you had a problem with everything connected to one ground, then that ground was insufficient. Either dirty or bad connections, inadequate wire, etc.

Now I'm not saying they all need to go down the exact same wire. The MS, the WBO2, and the sensors can all have their own ground wires. In fact, it's preferable for big noisy high current stuff like coils and injectors to have their own separate ground connections. This is one shortcoming of the MS- even in the current 3.0 PCA, the injectors use the same ground as all the sensors and logic circuits. OEM ECUs provide separate ground paths for the high-current stuff, to prevent them from putting noise on the analog circuits.

Regardless, they all should ideally terminate at exactly the same place. In my case, I have two big ring terminals at the back of the head where all the ECU-related ground wires end up.
Joe Perez is offline   Reply With Quote
Old 08-10-2008, 01:16 PM   #5
Elite Member
iTrader: (5)
m2cupcar's Avatar
Join Date: Jan 2005
Location: Atlanta
Posts: 6,936
Total Cats: 133

On the EGT is was a power ground that shared the same anchor point as the AF and Oil temp gauges. On the LC1 it was the signal sharing the same ground with power grounds. Once those were moved, everything worked ok so I classified it as fixed.
m2cupcar is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 12:25 PM
MS PNP requires reading and following directions??? satisfied MEGAsquirt 141 10-06-2015 10:44 AM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 10:28 PM
Squiblez 1996 Montego blue Squiblez Build Threads 2 09-22-2015 10:17 AM
Maruha 10mm lift cams + Supertech SUB; lifter edge wear? Der_Idiot Engine Performance 12 09-03-2015 03:31 PM

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 04:55 AM.