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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 01-20-2012, 08:44 AM   #1 (permalink)
Master EcoModder
 
Kodak's Avatar
 
Join Date: Feb 2011
Location: USA
Posts: 346

Canyon - '07 GMC Canyon 2wd regular cab
90 day: 24.95 mpg (US)
Thanks: 41
Thanked 39 Times in 24 Posts
No DFCO?

I've been operating under the assumption that my pickup probably has the fuel cutoff feature. I was never sure of the exact rpm at which it kicked in, but I assumed it was a little under 2k somewhere, and I thought I felt a little bump at 1800.

Now that I have the SG-e I can find out for sure. Well, I took 2nd gear out to a little over 3k rpm, started engine braking, and expected the gauge to read 9999 to indicate cutoff. The gauge read pretty high, like in the low 100's, but it did not appear to cut fuel. In fact, coasting in neutral versus coasting in gear appears to net better FE.

Did I not rev high enough to reach DFCO, or am I reading the gauge incorrectly? I used the instant mpg feature. For the record, I certainly did have my foot entirely off the throttle, and the engine speed in the low 3,000s.

Thanks for any insight.

__________________
EcoDriving: Turning more fuel into usable forward motion.
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 01-20-2012, 09:20 AM   #2 (permalink)
Pishtaco
 
SentraSE-R's Avatar
 
Join Date: Jun 2009
Location: Bay Area, California
Posts: 1,485

Mean Green Toaster Machine - '06 Scion xB
Team Toyota
90 day: 48.92 mpg (US)
Thanks: 56
Thanked 284 Times in 181 Posts
1. Your truck may not have DFCO. Our '06 Hyundai Elantra didn't have it.
2. I don't know if SG-e handles DFCO. If it does, it should have a way to set TPS cutoff values, and a way to display when you go into open loop.
3. Check if your truck goes into open loop when decelerating in gear, throttle off. That will tell you if it's going into DFCO.
__________________
Darrell

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.5 mpg avg over 53,000 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg
  Reply With Quote
The Following User Says Thank You to SentraSE-R For This Useful Post:
Kodak (01-20-2012)
Old 01-20-2012, 09:21 AM   #3 (permalink)
Master EcoModder
 
Kodak's Avatar
 
Join Date: Feb 2011
Location: USA
Posts: 346

Canyon - '07 GMC Canyon 2wd regular cab
90 day: 24.95 mpg (US)
Thanks: 41
Thanked 39 Times in 24 Posts
Ah, that's right! I can check if the O2 sensors are being used. Thanks for that. I'll try it today.
__________________
EcoDriving: Turning more fuel into usable forward motion.
  Reply With Quote
Old 03-30-2012, 09:02 AM   #4 (permalink)
Master EcoModder
 
Kodak's Avatar
 
Join Date: Feb 2011
Location: USA
Posts: 346

Canyon - '07 GMC Canyon 2wd regular cab
90 day: 24.95 mpg (US)
Thanks: 41
Thanked 39 Times in 24 Posts
I forgot about this for a while, but made an interesting observation yesterday that I can't interpret.

Fuel cutoff is supposed to engage above a certain rpm, right?

Well, yesterday I was engine braking in 2nd gear. The engine speed was in the low to mid 2k's, and the SG-e was reading some reasonable number that I can't recall.

Then, I felt a very minor 'bump' after the engine fell below X rpm, after which the gauge read 9999. Odd. I suspected the exact opposite. I though the injectors would cut off at high rpm, and reengage after falling below a certain value.

Do you suspect a gauge setting issue, or is this how the Canyon's Vortec 2900 works?
__________________
EcoDriving: Turning more fuel into usable forward motion.
  Reply With Quote
Old 03-30-2012, 11:06 AM   #5 (permalink)
Master EcoModder
 
AndrzejM's Avatar
 
Join Date: Oct 2011
Location: Poland
Posts: 840

Berta - '97 BMW 318 tds Compact
90 day: 62.03 mpg (US)

Charlie - '07 Citroen C4 Grand Picasso Exclusive
90 day: 37.58 mpg (US)
Thanks: 184
Thanked 166 Times in 116 Posts
Sometimes there is a switch on the throttle that signals closed throttle to ECU. Maybe yours is just malfunctioning? Check this, maybe that is causing the trouble.
__________________


Quote:
Gerhard Plattner: "The best attitude is to consider fuel saving a kind of sport. Everybody who has enough money for a strong car, can drive fast and hit the pedal. But saving fuel requires concentration, self-control and cleverness. It's a challenge with the nice effect of saving you money that you can use for other more important things."
  Reply With Quote
Old 03-30-2012, 11:14 AM   #6 (permalink)
Eco-ventor
 
jakobnev's Avatar
 
Join Date: Oct 2010
Location: sweden
Posts: 1,213

Princess - '92 Mazda MX-3 GS
House of Tudor
Team Mazda
90 day: 53.54 mpg (US)
Thanks: 49
Thanked 415 Times in 262 Posts
Send a message via MSN to jakobnev
I assume your engine was fully warmed up when you tested this?
__________________




2016: 128.75L for 1875.00km => 6.87L/100km (34.3MPG US)
2017: 209.14L for 4244.00km => 4.93L/100km (47.7MPG US)
  Reply With Quote
Old 03-30-2012, 12:16 PM   #7 (permalink)
Master EcoModder
 
Kodak's Avatar
 
Join Date: Feb 2011
Location: USA
Posts: 346

Canyon - '07 GMC Canyon 2wd regular cab
90 day: 24.95 mpg (US)
Thanks: 41
Thanked 39 Times in 24 Posts
Quote:
Originally Posted by AndrzejM View Post
Sometimes there is a switch on the throttle that signals closed throttle to ECU. Maybe yours is just malfunctioning? Check this, maybe that is causing the trouble.
Hmm. For what it's worth, zero throttle input usually reads a throttle position of ~18. It varies a bit from 17 to 18. I've read that this is normal, and it's been that way since I've had the gauge.

Quote:
Originally Posted by jakobnev View Post
I assume your engine was fully warmed up when you tested this?
Yes. Normal operating temperature, so I'm sure it was in closed loop.
__________________
EcoDriving: Turning more fuel into usable forward motion.
  Reply With Quote
Old 04-02-2012, 01:10 PM   #8 (permalink)
EcoModding Lurker
 
Join Date: Feb 2012
Location: United States
Posts: 25

F.O.R.D - '87 Dodge Dakota LE

Failure - '01 Toyota Corolla CE

Aveo - '07 Chevrolet Aveo LS
90 day: 36.87 mpg (US)
Thanks: 1
Thanked 1 Time in 1 Post
In my car, when i first got the scanguage, it was reading 9999 when i let off the accelerator. I could feel the engine braking effect. I was getting insane values on my average though, as high as 75MPG/AVG. As it says in the manual for the gauge, the accuracy will improve over time. This refers to when you fill up, and input data in the scangauge. My theory is that it is calibrated at the factory for 'x'Gas x 'y'RPM = 'z'GPH. When you fill up, you tell it that your car actually used X* amount, and it will adjust its computing accordingly. Once mine had a 5 fill-ups, and about 3000 miles, it started reading something like 142MPG with no throttle. The average economy dropped, and is now displaying accurately. I think the scanguage is designed not to show 9999 unless you haven't calibrated. Who is to say that this is the exact number? You could, in theory, go an infinite amount, but this would throw off the average faster than you can blink.
I can feel the engine braking, and now, since my brakes are bad, regularly employ it. It is rare that i ever touch the brake pedal(exception to hold steady at a red light, or to decelerate those last 5MPH that first gear cant do.
If there is even a tiny amount of fuel being injected it would greatly decrease the resistance of the engine, and would not allow compression braking. (can be calculated mathematically, but i am running out of time to continue writing this...)
The gauge now reads a couple thousand MPG, but not 9999 if i turn off the engine, put it in neutral, and coast. This is because it defaults to 0.05GPH, even if i am sitting, parked, engine off, but key in, it will say this...
You have DFCO, trust me. The gauge will get more accurate as time goes.

I reset mine because it glitched and thinks i pay $72/gallon, and when i try to adjust, it wont go lower than 71.8... EVEN THAT DIDNT SOLVE THAT!!! but i regret that i lost the calibration...
  Reply With Quote
Old 04-02-2012, 01:40 PM   #9 (permalink)
EcoModding Lurker
 
Join Date: Feb 2012
Location: East Tennessee, USA
Posts: 74

CRX HF - '91 Honda CRX HF
Team Honda
90 day: 68.45 mpg (US)
Thanks: 1
Thanked 9 Times in 4 Posts
My S-10 with 4.3L VORTEC glides so bad that engine braking for more than 5 seconds is rare Haha. In my friend's 2010 VW Jetta Sportwagen, you can downshift (auto with manual shifter) and engine brake. When you do, you have to engine brake for about 10 seconds THEN it will cut off and the factory gauge will show "----". When you first start engine braking, it goes down usually to around 30MPG or so before it shows "----".
__________________
  Reply With Quote
Old 04-03-2012, 04:50 AM   #10 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Russellville, KY
Posts: 540
Thanks: 8
Thanked 33 Times in 27 Posts
If I'm in 5th gear in my '97 Escort wagon it goes into DFCO within 1-2 seconds after releasing the throttle. If I recall correctly it stays in DFCO until the RPM's reach about 1100-1200 RPM. When I first got my Scan Gauge II it didn't show that it was going into DFCO. I calibrated something, without looking at the owners manual I don't remember what it was, but afterward it showed it was going into DFCO mode. I'd be very surprised if your truck doesn't have DFCO, I'm pretty sure even my '88 Escort has it.

__________________



  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com