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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-23-2014, 01:44 PM   #1 (permalink)
arz
EcoModding Lurker
 
Join Date: May 2011
Location: Elizabeth, CO
Posts: 31

Scoot - '01 Honda Civic EX
90 day: 40.77 mpg (US)

beater - '81 Isuzu Pup
90 day: 39.21 mpg (US)
Thanks: 2
Thanked 1 Time in 1 Post
Fiddling with Civic Idle

Been playing around with the new (to me) car, getting used to it and such, and noticed something that makes sense from an OEM point of view, but not from a squeezing the every mile out of a gallon of gas.

When I depress the clutch, brake and come to a stop, it will idle at 1500 or so for a few seconds, then drops down to 600ish. Or, coasting down a hill, taken out of gear, it will continue to idle at 1500. Not until I come to a stop for a few seconds will it drop to a normal idle speed.

Talking this over with a handful of car guys I know point that this is probably by design. Keep enough vacuum to have the PB and PS work. Ok, I get that.

Is there a way around this, to have it run at normal idle while coasting? Initial thought says yes, need to figure out the vacuum setup, and apply vacuum (electric pump plus canister) to where ever the sensor is that keeps it in high idle. Maybe even plumb that same vacuum source into the PS and PB system with the use of a one-way valve to draw vacuum as needed.

Or has this all been done and my searching has been lackluster?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-23-2014, 01:55 PM   #2 (permalink)
Corporate imperialist
 
oil pan 4's Avatar
 
Join Date: Jul 2011
Location: NewMexico (USA)
Posts: 11,265

Sub - '84 Chevy Diesel Suburban C10
SUV
90 day: 19.5 mpg (US)

camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

Snow flake - '11 Nissan Leaf SL
SUV
90 day: 141.63 mpg (US)
Thanks: 273
Thanked 3,569 Times in 2,833 Posts
Don't bother with the electric pump. A canister and check valve will be more than enough assuminig your civic did not leave the factory with them.

If you let off the gas for just a fraction of a second and allow the transmission to spin the engine with the throttle closed I would expect to see it develope at least 27in/Hg. If you could store that in a vacuum tank you will be all set to run vacuum assisted brakes.

The OEM may have found it cheaper to just fiddle with the ECU progeram to help run brakes insted of installing a tank and valve.
__________________
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
  Reply With Quote
The Following User Says Thank You to oil pan 4 For This Useful Post:
OG VX (09-23-2014)
Old 09-23-2014, 02:32 PM   #3 (permalink)
JDM hypeR mileR
 
OG VX's Avatar
 
Join Date: Aug 2014
Location: Mooresville, NC
Posts: 418

The OG VX - '92 Honda Civic VX
Team Honda
90 day: 68.64 mpg (US)
Thanks: 475
Thanked 418 Times in 198 Posts
I was running the exact same thing today while driving my VX.

Thanks for posting. Looking forward to any more replies/insight...
  Reply With Quote
Old 09-24-2014, 01:24 AM   #4 (permalink)
arz
EcoModding Lurker
 
Join Date: May 2011
Location: Elizabeth, CO
Posts: 31

Scoot - '01 Honda Civic EX
90 day: 40.77 mpg (US)

beater - '81 Isuzu Pup
90 day: 39.21 mpg (US)
Thanks: 2
Thanked 1 Time in 1 Post
A bit more reading today, and this seems to be a very common issue. One "expert" article even indicated that there really isn't a fuel loss from keeping the transmission engaged as the momentum will keep the engine running and not the fuel. Said they had oscilloscope readings across the injectors to show they basically weren't firing. (sounds like bunk to me though).
  Reply With Quote
Old 09-24-2014, 02:33 AM   #5 (permalink)
Liberty Lover
 
j12piprius's Avatar
 
Join Date: Feb 2011
Location: central california
Posts: 587

pris prius - '12 Toyota plug in prius
90 day: 71.09 mpg (US)
Thanks: 439
Thanked 83 Times in 60 Posts
Quote:
Originally Posted by arz View Post
A bit more reading today, and this seems to be a very common issue. One "expert" article even indicated that there really isn't a fuel loss from keeping the transmission engaged as the momentum will keep the engine running and not the fuel. Said they had oscilloscope readings across the injectors to show they basically weren't firing. (sounds like bunk to me though).
Do you have a link to the article?
  Reply With Quote
Old 09-24-2014, 08:50 AM   #6 (permalink)
Master EcoModder
 
oldtamiyaphile's Avatar
 
Join Date: May 2009
Location: Australia
Posts: 1,510

UFI - '12 Fiat 500 Twinair
Team Turbocharged!
90 day: 40.3 mpg (US)

Jeep - '05 Jeep Wrangler Renegade
90 day: 18.09 mpg (US)

R32 - '89 Nissan Skyline

STiG - '16 Renault Trafic 140dCi Energy
90 day: 30.12 mpg (US)

Prius - '05 Toyota Prius
Team Toyota
90 day: 50.25 mpg (US)

Premodded - '49 Ford Freighter
90 day: 13.48 mpg (US)

F-117 - '10 Proton Arena GLSi
Pickups
Mitsubishi
90 day: 37.82 mpg (US)

Ralica - '85 Toyota Celica ST
90 day: 25.23 mpg (US)

Sx4 - '07 Suzuki Sx4
90 day: 32.21 mpg (US)

F-117 (2) - '03 Citroen Xsara VTS
90 day: 30.06 mpg (US)
Thanks: 325
Thanked 452 Times in 319 Posts
Is it the clutch or brake that gives the high idle? or only when both are depressed?

Regardless, all you have to do is remove the relevant switch(es). The clutch switch isn't needed (bypass the starter interlock if so equipped), and you can also wire in a separate switch to run the brake lights. Simple.
__________________






  Reply With Quote
Old 09-24-2014, 08:52 AM   #7 (permalink)
Master EcoModder
 
oldtamiyaphile's Avatar
 
Join Date: May 2009
Location: Australia
Posts: 1,510

UFI - '12 Fiat 500 Twinair
Team Turbocharged!
90 day: 40.3 mpg (US)

Jeep - '05 Jeep Wrangler Renegade
90 day: 18.09 mpg (US)

R32 - '89 Nissan Skyline

STiG - '16 Renault Trafic 140dCi Energy
90 day: 30.12 mpg (US)

Prius - '05 Toyota Prius
Team Toyota
90 day: 50.25 mpg (US)

Premodded - '49 Ford Freighter
90 day: 13.48 mpg (US)

F-117 - '10 Proton Arena GLSi
Pickups
Mitsubishi
90 day: 37.82 mpg (US)

Ralica - '85 Toyota Celica ST
90 day: 25.23 mpg (US)

Sx4 - '07 Suzuki Sx4
90 day: 32.21 mpg (US)

F-117 (2) - '03 Citroen Xsara VTS
90 day: 30.06 mpg (US)
Thanks: 325
Thanked 452 Times in 319 Posts
Quote:
Originally Posted by oil pan 4 View Post
Don't bother with the electric pump. A canister and check valve will be more than enough
Where would one find such a beast?
__________________






  Reply With Quote
Old 09-24-2014, 11:32 AM   #8 (permalink)
arz
EcoModding Lurker
 
Join Date: May 2011
Location: Elizabeth, CO
Posts: 31

Scoot - '01 Honda Civic EX
90 day: 40.77 mpg (US)

beater - '81 Isuzu Pup
90 day: 39.21 mpg (US)
Thanks: 2
Thanked 1 Time in 1 Post
Quote:
Originally Posted by oldtamiyaphile View Post
Is it the clutch or brake that gives the high idle? or only when both are depressed?

Regardless, all you have to do is remove the relevant switch(es). The clutch switch isn't needed (bypass the starter interlock if so equipped), and you can also wire in a separate switch to run the brake lights. Simple.
High idle when coasting. Out of gear, clutch in or out. Then I brake to come to a stop, and it continues to at 1500rpm until I've been at a complete stop for about 3-4 seconds. Then it drops to approx 600.

When idling at 600, unless I start moving, it stays there regardless of brake or clutch pedal action. Have not tried idling at 600, then rolling to speed - I'll give that a try later today.

Quote:
Originally Posted by oldtamiyaphile View Post
Where would one find such a beast?
NAPA or your favorite friendly neighborhood auto parts store.
  Reply With Quote
Old 09-24-2014, 11:35 AM   #9 (permalink)
arz
EcoModding Lurker
 
Join Date: May 2011
Location: Elizabeth, CO
Posts: 31

Scoot - '01 Honda Civic EX
90 day: 40.77 mpg (US)

beater - '81 Isuzu Pup
90 day: 39.21 mpg (US)
Thanks: 2
Thanked 1 Time in 1 Post
Quote:
Originally Posted by johnlvs2run View Post
Do you have a link to the article?
Coasting in Neutral or Gear to Save Gas - Coasting and Fuel Economy - Popular Mechanics
  Reply With Quote
Old 09-24-2014, 12:41 PM   #10 (permalink)
Rat Racer
 
Fat Charlie's Avatar
 
Join Date: May 2011
Location: Route 16
Posts: 4,150

Al the Third, year four - '13 Honda Fit Base
Team Honda
90 day: 42.9 mpg (US)
Thanks: 1,784
Thanked 1,922 Times in 1,246 Posts
Quote:
Originally Posted by arz View Post
...there really isn't a fuel loss from keeping the transmission engaged as the momentum will keep the engine running and not the fuel. Said they had oscilloscope readings across the injectors to show they basically weren't firing. (sounds like bunk to me though).
It's bunk. The injectors aren't firing, true, but I'd rather use my momentum for moving forward instead of spinning things that don't need spinning. Engine braking is engine braking: burning momentum is the same thing as burning gas.

__________________

Quote:
Originally Posted by sheepdog44 View Post
Transmission type Efficiency
Manual neutral engine off.100% @MPG <----- Fun Fact.
Manual 1:1 gear ratio .......98%
CVT belt ............................88%
Automatic .........................86%

  Reply With Quote
The Following User Says Thank You to Fat Charlie For This Useful Post:
Daox (09-24-2014)
Reply  Post New Thread






Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com