Tach bounces when warm - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 12-12-2010, 06:34 PM   #1
Junior Member
Thread Starter
 
Join Date: Jun 2008
Location: New Forest, U.K.
Posts: 336
Total Cats: 4
Default Tach bounces when warm

Gents, I have been asked to help a guy with his MS and thought I would ask here to see if any of you have run into this before and have any idea's. Car is a 1995-6 1.8 with a mini cooper charger on it. M/S1 3.0 pcb, built by a 3rd party as per brainiacks write up.

It runs fine but the tach is playing games. When cold everything is ok, but after 2-3 min of running the dash tach starts to hop all over the place. The M/S gets a clean signal all the time and the datalogs come back fine with no spikes or odd readings. But the tach is hopping all over the place. Now this is a 1.8 so I know the coils work a bit different than mine (I am 1.6) so just plugging my MS in with his map in not an option right? Any idea's?
Blaize is offline   Reply With Quote
Old 12-13-2010, 05:03 AM   #2
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,658
Total Cats: 39
Default

Bad earths, even stock cars do it, clean up the ground near to the throttle body.

From the year it's likely still a 4 pin coilpack, so the tacho is fed from them, you could build a tacho output circuit and feed it from the ECU, that may help, but I'd do the above 1st.
richyvrlimited is offline   Reply With Quote
Old 12-13-2010, 09:41 AM   #3
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,824
Total Cats: 1,781
Default

Your dash tach gets its signal directly from the coils...

Sorry, read your sig and not the post

Last edited by Braineack; 12-13-2010 at 10:19 AM.
Braineack is online now   Reply With Quote
Old 12-13-2010, 10:05 AM   #4
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,658
Total Cats: 39
Default

it's a 95-96, so it may be a 96 with a 3 pin coilpack and fed from the ECU, then again it may be a 95 and fed from the coilpack
richyvrlimited is offline   Reply With Quote
Old 12-13-2010, 03:20 PM   #5
Junior Member
Thread Starter
 
Join Date: Jun 2008
Location: New Forest, U.K.
Posts: 336
Total Cats: 4
Default

Yeah, sorry I don't know the exact year. I "think" its a 95 but not sure. I'll have a look at the grounds then and see if there is anything there to be corrected
Blaize is offline   Reply With Quote
Old 12-13-2010, 03:23 PM   #6
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago (Over two miles from Wrigley Field. Fuck the Cubs. Fuck them in their smarmy goat-hole.)
Posts: 26,315
Total Cats: 1,913
Default

Look at the coilpacks. Specifically the low-side electrical connectors going to them. Does each connector have three or four wires going to it?
Joe Perez is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM
Now shipping NC MX-5 (2006-15) Precision Sliding Seat Mounts FAB Fab9 Tuning - Miata Performance Parts 0 09-11-2015 01:02 PM
how to Make 94-95 tach work with MSPNP2 JacksonRacingEngines Engine Performance 10 09-10-2015 10:52 AM
Sold fail wagon Miata parts for sale/trade 2 09-07-2015 09:51 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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 03:30 PM.