key on, pressure spike - Miata Turbo Forum - Boost cars, acquire cats.

MEGAsquirt A place to collectively sort out this megasquirt gizmo
Sponsored by:
Sponsored by:

key on, pressure spike

Old 09-06-2011, 05:32 PM
  #1  
I'm Miserable!
Thread Starter
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,866
Total Cats: 3
Default key on, pressure spike

Sometimes when I key on my car I get a pressure spike on my boost gauge, seen it go up to 1.5 bars, its quick.

My guess is the coils firing though I did the the Joe spark output mod and figured that it shouldn't be doing this

MS2 pcb v3

I will grab a pic of it soon
Techsalvager is offline  
Old 09-06-2011, 11:19 PM
  #2  
I'm Miserable!
Thread Starter
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,866
Total Cats: 3
Default

bump, no one knows what to look at?
Techsalvager is offline  
Old 09-07-2011, 08:41 AM
  #3  
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 75,288
Total Cats: 2,154
Default

sounds like the issue people would have back in the day...but never remember seeing any boost spikes...especially not that significant. Do you have a mechanical or electric boost gauge?
Braineack is offline  
Old 09-07-2011, 09:09 AM
  #4  
I'm Miserable!
Thread Starter
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,866
Total Cats: 3
Default

mechanical boost gauge, you can hear a sound at the same time, a puff\pop or something like that.
Techsalvager is offline  
Old 09-07-2011, 09:46 AM
  #5  
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,641
Total Cats: 41
Default

I used to have it even with the improved spark mod.

Replaced the injectors, issue went away. They were RX7 550's. Can only assume they were leaking slightly.
richyvrlimited is offline  
Old 09-07-2011, 10:05 AM
  #6  
I'm Miserable!
Thread Starter
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,866
Total Cats: 3
Default

I know injectors are suppose to fire but I wouldn't think that would cause this issue without spark happening to ignite the fuel and cause the pressure spike.
Techsalvager is offline  
Old 09-07-2011, 10:18 AM
  #7  
Elite Member
iTrader: (1)
 
Join Date: Jun 2006
Location: Warrington/Birmingham
Posts: 2,641
Total Cats: 41
Default

I can only tell you what I experienced.

1) I have the improved mod.
2) It still 'backfired' into the intake.
3) Changing injectors fixed it.
richyvrlimited is offline  
Old 09-08-2011, 05:46 PM
  #8  
I'm Miserable!
Thread Starter
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,866
Total Cats: 3
Default

Finally I got a log of it when it happened
Notice in there the wideband is effected, not sure if its noise, I doubt it, but if so I think the igintion is sparking off and any fuel left unburnt is being burnt.

thoughts?




Uploaded with ImageShack.us
Attached Thumbnails key on, pressure spike-issuei.jpg  
Techsalvager is offline  
Old 09-08-2011, 07:55 PM
  #9  
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 75,288
Total Cats: 2,154
Default

(Posting from my phone.)

What's odd is spark advance stays at zero and doesn't read off map.

This is with joes mod and spark output set to inverted?
Braineack is offline  
Old 09-08-2011, 08:04 PM
  #10  
I'm Miserable!
Thread Starter
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,866
Total Cats: 3
Default

Yes Joes mod and spark output set to inverted
Techsalvager is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
nick470
MEGAsquirt
7
06-16-2017 02:53 PM
Quinn
Cars for sale/trade
6
10-23-2016 08:58 AM
stoves
Suspension, Brakes, Drivetrain
5
04-21-2016 04:00 PM
JesseTheNoob
DIY Turbo Discussion
15
09-30-2015 03:44 PM


Thread Tools
Search this Thread
Quick Reply: key on, pressure spike


Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.