DIYPNP cold start strange problem - 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 03-26-2013, 06:26 PM   #1
Newb
Thread Starter
 
Join Date: Mar 2011
Location: Sussex, England
Posts: 25
Total Cats: 0
Default DIYPNP cold start strange problem

Hi,
I'm trying to iron out my last few megasquirt issues on my '95 1.6.

When starting from cold with coolant temp less than about 10 degrees c (50 farenheight) the car instantly stalls due to too much fuel. At that temp I need around 8ms cranking, and then once running just over 2ms. What happens is that once started the injectors are running 4ms which instantly stalls the engine. The only way I can prevent the stall is with throttle opening. I have ase zeroed out so i'm pretty sure thats not the problem.

I think this started either when I fitted a trigger wheel to the crank pully or uprgaded the firmware to grant slenders latest firmware.

So I'm using a DIYPNP with pre3.3alpha5 gslender v2.8, with sequential injection. A crank posistion sensor, and the oem cam position sensor.

I have attached a log and my tune. Thanks for any help.
Attached Files
File Type: msl 2013-02-21_12.29.35.coldstart2msl.msl (327.0 KB, 64 views)
File Type: msq mxnige_tune.msq (91.9 KB, 59 views)
mxnige is offline   Reply With Quote
Old 03-28-2013, 01:40 AM   #2
Junior Member
iTrader: (5)
 
Join Date: Mar 2012
Location: Gilbert, Az
Posts: 337
Total Cats: 26
Default

Just a few observations, I might be off but:

1. You have 0.0 priming pulse everywhere. Maybe set it to 5.0 for all temps or something.
2. Your ASE Enrichment Percentage is 0.0 across the board, this could be why it dies immediately after starting. Try something like 40 at -39, down to 30 at 91
3. Your ASE taper is 0.0 again, set it to a flat 500 across the board for now


Try making those changes & let us know what happens.
SJP0tato is offline   Reply With Quote
Old 03-28-2013, 08:04 AM   #3
Newb
Thread Starter
 
Join Date: Mar 2011
Location: Sussex, England
Posts: 25
Total Cats: 0
Default

Thanks for the reply

ASE makes the problem worse as it adds fuel just after starting. The problem is that the pulsewidths are almost double what they should be after starting, its like i need negative ASE at cold temps.
mxnige is offline   Reply With Quote
Old 03-28-2013, 09:15 AM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

your dead times are too fast at 13.2v, if you have stock 95 injectors, you need to use like 1.1 or 1.2.

You have Additional Banks 2-3-4 active, I dont believe you need to do that. Just use additional drivers for the seq. fuel, no need to have banks active.

You have VE Fuel trims on and two of the 4 tables are apparently adding a little extra fuel. This is the first I've seen these tables on the MS2 firmware, kinda neat.

Your req fuel is set to 3.0, so I'm assuming you have 1000cc injectors...I dont even think ID1000cc have a deadtime of 0.5ms at 13.2v, and if you were idling at 3ms of pw, I'd assume that to be like 12.0:1 AFR, not 15.0:1.

And that probably explains why your VE Fuel table has such high values...

and agian, explains your lack of need for the ASE and warmup tables.
Braineack is offline   Reply With Quote
Old 03-28-2013, 09:30 AM   #5
Newb
Thread Starter
 
Join Date: Mar 2011
Location: Sussex, England
Posts: 25
Total Cats: 0
Default

Braineack

I have bosch ev14 550cc injectors, the dead times in my tune are the ones that were given to me on the injector specification sheet.

I've added extra fuel in cylinders 3 and 4 in an attempt to compensate for the fact that i'm still using the stock coolant routing and no dual feed fuel rail. The amount added is complete guesswork to be honest.

The required fuel is set low with VE numbers high so that I can get more resolution, so each increment on the VE table makes a finer change.

Is the transition from craking fuel to running fuel normally tapered or does it just jump from one to the other? Is there a way change this transition time?

I've played lots with cranking rpm but the best I can get it is with cranking rpm at 400.
mxnige is offline   Reply With Quote
Old 03-28-2013, 09:32 AM   #6
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,833
Total Cats: 1,786
Default

good luck.
Braineack is offline   Reply With Quote
Old 03-28-2013, 09:42 AM   #7
Junior Member
iTrader: (5)
 
Join Date: Mar 2012
Location: Gilbert, Az
Posts: 337
Total Cats: 26
Default

Quote:
Originally Posted by mxnige View Post
Is the transition from craking fuel to running fuel normally tapered or does it just jump from one to the other? Is there a way change this transition time?
It goes:
crankingPW -> ASE/ASE-taper -> Warmup Enrichment -> Normal Operation


Quote:
Originally Posted by mxnige View Post
I've played lots with cranking rpm but the best I can get it is with cranking rpm at 400.
That's the RPM threshold that the ecu uses to determine if it's cranking:
if (rpm < 400) { cranking = true }
SJP0tato is offline   Reply With Quote
Old 03-28-2013, 03:27 PM   #8
Newb
Thread Starter
 
Join Date: Mar 2011
Location: Sussex, England
Posts: 25
Total Cats: 0
Default

Quote:
Originally Posted by Braineack View Post
good luck.
why thankyou
mxnige is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 01:45 AM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM


Tags
diypnp, megasquirt, stall

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 11:02 PM.