97 turbo ms1ns issues - Page 2 - 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 05-28-2008, 04:18 PM   #21
Junior Member
Thread Starter
 
Join Date: Feb 2008
Posts: 62
Total Cats: 0
Default

ok, does the MS put out ground or 12V on pin 37?

i can be a little thick headed sometimes, thanks for the help.
jamiemiller is offline   Reply With Quote
Old 05-28-2008, 04:42 PM   #22
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: 26,317
Total Cats: 1,914
Default

Quote:
Originally Posted by jamiemiller View Post
How i tested them, i checked the 12v inj on the relay board to chassis ground and saw 12vdc. when i checked the inj1 and inj2 wiring i showed no change when cranking or at rest.
Well, it sounds like you're probing the right spots (INJ1 and 2 between the injector and the MS) however if you are probing with a simple voltmeter then it's likely you will see no change at that point. The MS should indeed be pulling those points to ground in order to fire the injectors, but the pulses are very brief- typically 4 to 6 milliseconds while cranking- and a normal voltmeter cannot respond that quickly. In order to accurately measure these points, you need an oscilloscope.

Quote:
Originally Posted by jamiemiller View Post
ok, does the MS put out ground or 12V on pin 37?
Assuming you've built that part of the circuit to spec, it provides a closure to ground. Note the following:



Pin 37 of the DB-37 is connected to the point called FP1, and the CPU output pin 33 to the point called FP-1. Careful of the difference here.

When the CPU wishes to turn on the pump, it drives its own pin 33 high to +5v. This goes through R16 and biases the base of Q2 positively, which since it is an NPN transistor causes it to turn on. This allows current to flow in from FP1 (DB37 pin 37) and pass through Q2, then through R40, to ground.

R40 and Q19 form an overcurrent protection circuit. As the current passes through R40, it creates a slight voltage differential across it. If the current becomes too great, then the voltage at the top of R40 rises to a level sufficient to turn on Q19, which pulls the base of Q2 to ground, shutting off the circuit.


Quote:
i can be a little thick headed sometimes, thanks for the help.
No, you're asking all the right questions and it seems like you've got a good handle on troubleshooting. We've all been through this phase.
Joe Perez is offline   Reply With Quote
Old 05-30-2008, 06:15 PM   #23
Junior Member
Thread Starter
 
Join Date: Feb 2008
Posts: 62
Total Cats: 0
Default

what would happen if Q19 is not installed? hypothetically..............would the fuel pump output not function?
jamiemiller is offline   Reply With Quote
Old 06-03-2008, 10:17 AM   #24
Junior Member
Thread Starter
 
Join Date: Feb 2008
Posts: 62
Total Cats: 0
Default

its alive, just need to figure out timing.

thank you for all the assistance.

i was missing q19, r40 and d4.

works much better. Does anyone have a slick way of setting base timing? My CAS has been moved.
jamiemiller is offline   Reply With Quote
Old 07-21-2008, 02:40 PM   #25
Junior Member
Thread Starter
 
Join Date: Feb 2008
Posts: 62
Total Cats: 0
Default

New thread created.................

Last edited by jamiemiller; 07-22-2008 at 11:14 AM.
jamiemiller is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Another Cast Manifold Corky Bell Prefabbed Turbo Kits 18 11-22-2016 10:01 PM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
Odd Steering issue interestedofold Suspension, Brakes, Drivetrain 5 09-29-2015 02:42 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 03:56 PM.