The Australian 300zx Owners Association  

Go Back   The Australian 300zx Owners Association > Technical > Z32 Technical

Z32 Technical Discuss all 300ZX (Z32) related Technical topics here - how do I diagnose, modify, repair etc

Reply
 
Thread Tools Display Modes
Old 18-04-2017, 03:12 PM   #1
antman
Member
 
Join Date: Nov 2009
Location: International
Thanks: 2
Thanked 10 Times in 7 Posts
Strange CAS Behaviour

Hi guys, I got a CAS related issue when cranking with fully charged battery...no spark at all.
I removed the CAS and turned the CAS shaft by hand and spark and injectors work. Fuel pressure also primes.
Checked loom for breaks/intermittent faults and also checked all earths are ok...fitted new CAS loom connector and tried 2 other known working CAS units..same issue.
I also checked cam turns when cranking...took the plastic cover off the CAS to see it turns while cranking.
Why does CAS not work when on the motor???

What am I doing wrong?
antman is offline   Reply With Quote
Old 18-04-2017, 03:33 PM   #2
WazTTed
Grease Monkey
 
WazTTed's Avatar
 
Join Date: Jun 2005
Location: Western Australia
Thanks: 76
Thanked 82 Times in 71 Posts
have you checked the Cas pin on the end of the cam isnt damaged?
__________________
WazTTed is offline   Reply With Quote
Old 18-04-2017, 04:30 PM   #3
antman
Member
 
Join Date: Nov 2009
Location: International
Thanks: 2
Thanked 10 Times in 7 Posts
Yes I have checked that as well. Also checked that the cas turns when cranking.
Pretty stumped here.
antman is offline   Reply With Quote
Old 18-04-2017, 04:55 PM   #4
Chrispy
Pretentious Upstart
 
Chrispy's Avatar
 
Join Date: Jan 2006
Location: Queensland
Thanks: 411
Thanked 1,029 Times in 684 Posts
Tried a different PTU?

Any error codes?

I'm clutching a straws though.
__________________
Whiner.
Chrispy is offline   Reply With Quote
Old 18-04-2017, 06:16 PM   #5
Fists
Senior Member
 
Join Date: Aug 2011
Location: ACT
Thanks: 32
Thanked 164 Times in 151 Posts
Install the CAS, clear ECU codes then try crank it, then check codes again and see if it throws a CAS code. If no codes and you have the ability to try a hill start without getting your car stuck down the street then that could be a useful test, the ECU may not be getting the 'cranking engine' signal for the starting injection pulses (different to normal running injector pulses).

Also probably check battery voltage, ECU could be starving for power while cranking.
__________________
--Tom

Blue '91 Fairlady Z: TT, targa, 2 seater
Fists is offline   Reply With Quote
Old 18-04-2017, 08:12 PM   #6
ProckyZ89
Senior Member
 
ProckyZ89's Avatar
 
Join Date: Jun 2008
Location: New South Wales
Thanks: 26
Thanked 58 Times in 40 Posts
How are you checking for spark?
So you have spark when the CAS is removed and your turning by hand?..
__________________
222.4rwkw~stock turbos 14.5psi (98)
438.4rwkw~GTX2863R 25.5(98wmi)
497.4rwkw~GTX2863R 30>25 (e85)
ProckyZ89 is offline   Reply With Quote
Old 18-04-2017, 11:20 PM   #7
antman
Member
 
Join Date: Nov 2009
Location: International
Thanks: 2
Thanked 10 Times in 7 Posts
Quote:
Originally Posted by ProckyZ89 View Post
How are you checking for spark?
So you have spark when the CAS is removed and your turning by hand?..
Have another coil pack with plug earthed on top plenum.Yes correct, sparks by turning by hand.
antman is offline   Reply With Quote
Old 18-04-2017, 11:23 PM   #8
antman
Member
 
Join Date: Nov 2009
Location: International
Thanks: 2
Thanked 10 Times in 7 Posts
Quote:
Originally Posted by Fists View Post
Install the CAS, clear ECU codes then try crank it, then check codes again and see if it throws a CAS code. If no codes and you have the ability to try a hill start without getting your car stuck down the street then that could be a useful test, the ECU may not be getting the 'cranking engine' signal for the starting injection pulses (different to normal running injector pulses).

Also probably check battery voltage, ECU could be starving for power while cranking.
A tow start is a good check....no hills in my ares.. Thanks
antman is offline   Reply With Quote
Old 20-04-2017, 04:33 PM   #9
Martin Williams
Senior Member
 
Join Date: Aug 2008
Location: Queensland
Thanks: 26
Thanked 54 Times in 46 Posts
What voltage have you got across battery terminals when you are cranking engine? What is the CCA or cold cranking amps of your battery?
Martin Williams is offline   Reply With Quote
Old 28-04-2017, 03:11 PM   #10
antman
Member
 
Join Date: Nov 2009
Location: International
Thanks: 2
Thanked 10 Times in 7 Posts
Thanks for all the advice. Good news is it is sorted.
This is a first for me...the PS pump pulley had jammed due to the fact that the bolt that it pivots on was not tightened and prevented the pulley from turning. So when cranking there was enough friction on the PS belt to slip without squealing but enough drag to really labour the starter. What I assume the problem to be was that the starter was drawing so much current the ecu was being starved of power. After I sorted the jammed PS pulley the motor started. Funny thing is the motor still cranked at the same speed with and without belt drag. There may still be an issue of poor earth or power feeds that maybe need sorting.
Thanks again for the advice.
antman is offline   Reply With Quote
Old 21-05-2017, 08:28 PM   #11
tassuperkart
Its a lie I tell you!
 
tassuperkart's Avatar
 
Join Date: Feb 2008
Location: Tasmania
Thanks: 209
Thanked 345 Times in 243 Posts
The CAS is powered from ignition via the ECCS relay and a fuseable link on the drivers side near the firewall.

Id say what you have is a "lazy" relay that is releasing when the starter is engaged and not pulling in.
Or the fuses are corroded and showing high resistance.

A simple testlight on the CAS +ive power wire (B/W) and ground B() will confirm this when cranking under load, as you had or try with all the headlights and accessories on flat out to give the battery a bit of a hiding.

E
__________________
Im not a complete idiot.....some parts are missing!
tassuperkart is offline   Reply With Quote
Reply

Lower Navigation
Go Back   The Australian 300zx Owners Association > Technical > Z32 Technical

Thread Tools
Display Modes

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

Forum Jump


All times are GMT +10. The time now is 02:29 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.