Go Back   EcoModder Forum > EcoModding > Instrumentation
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-16-2009, 11:19 PM   #1 (permalink)
EcoModding Lurker
 
Join Date: Aug 2009
Location: Ontario, Canada
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Open/Closed Loop and Scan Gauge

A quick question - I had an erratic FE reading on my scangauge in my Saturn yesterday (I usually see 5.8ish litres per 100km's, but I suddenly had 9.9 litres per 100km's - today was back to normal, not sure why it showed so bad yesterday, the car ran exactly the same as always). Maybe the SG lost its marbles for a day. But I digress.

So I had changed the parameters I was monitoring on the SG to see if something was amiss that may have caused my FE reading change. I monitored Intake Air Temp, Cooloant Temp, Litres per 100 km's and Open/Closed Loop operation. I noticed whenever the injectors shut off, that the car slipped into open loop for the duration the injectors were off. It went Closed loop as soon as I pressed the throttle again.

Does this make sense? I guess the ECU goes open loop because since there is no fuel flow, checking for a rich/lean condition is a moot point. Maybe it would throw a code if it didn't go open loop. Please forgive my ignorance on the subject, just trying to make sense of it all.

Thanks

Rick

__________________
2000 Saturn SC1 5 speed - 53 MPG (Cdn)
1996 Mazda Miata - 39 MPG (Cdn)
2002 Ford Ranger Ext Cab 4x4 4 litre - 25 MPG (Cdn)

"I smelled like bologna, so the ladies weren't digging me that night"
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-17-2009, 01:18 AM   #2 (permalink)
EcoModding Lurker
 
Join Date: Nov 2008
Location: boise id
Posts: 64

The XT - '92 Yamaha XT225 Serow
Last 3: 80.67 mpg (US)

White Civic - '08 Honda Civic Hybrid
90 day: 38.23 mpg (US)

Blue and White Beast - '78 Ford F150
90 day: 11.33 mpg (US)

Red T100 - '93 Toyota T100
90 day: 14.7 mpg (US)
Thanks: 1
Thanked 4 Times in 3 Posts
I see the same thing with my Jeep. I think it must be the way most ECUs are programmed. I suspect it's the only way the logic in the computer will allow it to shut off the injector pulses, since it is doing the shut off based on RPM and throttle position alone. I don't worry about it, since the injectors are off I'm getting infinite mileage anyway
  Reply With Quote
Old 09-17-2009, 12:42 PM   #3 (permalink)
EcoModding Lurker
 
Join Date: Aug 2009
Location: Ontario, Canada
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
Good to hear its more commonplace. The more I think about it, it does make sense that this happens.

Cool.

My FE readings today were bang on again...wish I could figure out why they were so high that one day.

Rick
__________________
2000 Saturn SC1 5 speed - 53 MPG (Cdn)
1996 Mazda Miata - 39 MPG (Cdn)
2002 Ford Ranger Ext Cab 4x4 4 litre - 25 MPG (Cdn)

"I smelled like bologna, so the ladies weren't digging me that night"
  Reply With Quote
Old 09-17-2009, 01:04 PM   #4 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,176

CM400E - '81 Honda CM400E
90 day: 51.49 mpg (US)

Daox's Grey Prius - '04 Toyota Prius
Team Toyota
90 day: 49.53 mpg (US)

Daox's Insight - '00 Honda Insight
90 day: 64.33 mpg (US)

Swarthy - '14 Mitsubishi Mirage DE
Mitsubishi
90 day: 56.69 mpg (US)
Thanks: 2,475
Thanked 2,539 Times in 1,531 Posts
That is how it works. No fuel = open loop.

__________________
Current project: A better alternator delete
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com