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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 07-30-2010, 03:28 PM   #1 (permalink)
insane in the propane
 
Join Date: Jul 2010
Location: palm beach
Posts: 58

Cloud Car - '96 Dodge Stratus ES
90 day: 39.15 mpg (US)
Thanks: 3
Thanked 8 Times in 4 Posts
How to: reduce the rich condition of a cold start.

most cars today upon a cold start will run the engine rich to aid in starting and perhaps warming up the cat. if you can lean out the overly rich condition to make it more along the lines of 14.7:1 you will reduce fuel consumption during the warmup phase.

for this post i will be using degrees Fahrenheit.

i have found that if you change the resistance of the coolant temp sensor you can fool the computer into running the engine at any rich or lean ratio you want while (and only while) it is in open loop mode. on my car it runs quite rich when cold starting. this rich condition stays that way until the computer switches to closed loop. using a stopwatch and a obd2 scanner that monitors open-closed loop status, i have determined this takes about 3 minutes.

what i did was add a 2000 ohm 1/4 watt resistor in PARALLEL with the coolant temp sensor. this had the effect of increasing the cold water temp read by the computer by 30 degrees. now when i start the engine, it no longer gives a 1 second puff of black smoke upon startup. the engine runs just a touch rougher during the 3 minute warmup but it isnt a big deal to me.

you are probably thinking to yourself, yeah if i increase the temp by 30 degrees when its cold, then it must increase 30 degrees when hot!. this is not true and i will explain why.
coolant temp sensors change their resistance on a non linear scale. the resistance increases or decreases exponentially depending on wither its cooling down or warming up. my 2000 ohm resistor increases the temp read by the computer by 30 degrees when the engine is cold, but it only increases the temp read by the computer by 5 degrees when the engine is fully up to operating temperature. this means i can leave the resistor connected all the time and never need to disable it. i also have not had a check engine light caused by the resistor. i have driven about 5000 miles now with the resistor hooked up and have not had any problems.

the way you find out exactly what resistor value to use is by wiring up a potentiometer in PARALLEL with the coolant temp sensor. try to use a with a value of 10Kohms full and 0 ohms when turned the other way. this way you have a lot of wiggle room. the pot is available at rat shack for a few bucks. the second half involves a obd2 scanner which is capable of showing the computers instant open loop-closed loop status as well as showing an instant readout of the coolant temp sensor in degrees.

i dont know how to measure fuel economy gains from this mod but its got to count for something.

__________________
96 stratus "es" v6 auto-stick
supplementary propane injection
injector kill switch, alternator kill switch
Charging system voltage increased to 15.5V
secondary and tertiary 12v batteries in the trunk
on-board battery charger
lights converted to led's
potentiometer controlled tps for ign timing
welded straight pipe in place of cat-cons
removed egr
3 inch body drop
90psi fuel rail & -50% low volume injectors
run 15% diesel 85% gas
  Reply With Quote
The Following 2 Users Say Thank You to C3H8 For This Useful Post:
RobertSmalls (07-30-2010), saand (07-31-2010)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-30-2010, 05:29 PM   #2 (permalink)
Master EcoModder
 
Phantom's Avatar
 
Join Date: Jan 2010
Location: Independence, KY
Posts: 602

Blue Meanie - '02 Volkswagon Golf TDI
TEAM VW AUDI Group
90 day: 48.52 mpg (US)

Wife's car - '05 WV Passat TDI

Rudy - '94 Chevy C2500
Thanks: 89
Thanked 46 Times in 43 Posts
I just have a quick question the 3min warm up for the car is that from a cold start and idling?

Why I bring this up is my Grand Prix also takes about 3min to change over to Closed Loop, but I have noticed that if I start driving right away it changes over much quicker.
__________________
I move at the speed of awesome.


"It's not rocket surgery!" -MetroMPG
  Reply With Quote
Old 07-30-2010, 05:44 PM   #3 (permalink)
insane in the propane
 
Join Date: Jul 2010
Location: palm beach
Posts: 58

Cloud Car - '96 Dodge Stratus ES
90 day: 39.15 mpg (US)
Thanks: 3
Thanked 8 Times in 4 Posts
yeah, 3 minutes is what it takes from cold start and idling.

and yes if you start driving right away it will change over quicker. but a lot of people like my self tend to let the engine idle for 20-30 seconds after a cold start to give things a chance to start working, and the oil a chance to circulate before putting load on the engine.
__________________
96 stratus "es" v6 auto-stick
supplementary propane injection
injector kill switch, alternator kill switch
Charging system voltage increased to 15.5V
secondary and tertiary 12v batteries in the trunk
on-board battery charger
lights converted to led's
potentiometer controlled tps for ign timing
welded straight pipe in place of cat-cons
removed egr
3 inch body drop
90psi fuel rail & -50% low volume injectors
run 15% diesel 85% gas
  Reply With Quote
Old 07-30-2010, 06:12 PM   #4 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,177

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: 2,476
Thanked 2,542 Times in 1,534 Posts
You have oil pressure almost immediately after starting an engine. I see no reason to idle. I just start and go almost immediately.
__________________
Current project: A better alternator delete
  Reply With Quote
The Following 2 Users Say Thank You to Daox For This Useful Post:
Frank Lee (08-01-2010), NachtRitter (08-05-2010)
Old 07-30-2010, 07:03 PM   #5 (permalink)
Left Lane Ecodriver
 
RobertSmalls's Avatar
 
Join Date: Aug 2008
Location: Buffalo, NY, USA
Posts: 2,257

Prius C - '12 Toyota Prius C
Thanks: 79
Thanked 286 Times in 199 Posts
Simple, clever, probably effective. I may have to try something similar.

How much did it increase your temperature reading when hot?

My radiator fan kicks on and off based on the coolant temperature reading. I only have a 5-10F window between the radiator fan and the thermostat.
  Reply With Quote
Old 07-30-2010, 07:16 PM   #6 (permalink)
Basjoos Wannabe
 
ShadeTreeMech's Avatar
 
Join Date: Apr 2009
Location: Arkansas
Posts: 870

The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
Thanks: 174
Thanked 49 Times in 32 Posts
I'd just start driving. A modern engine wil be ready for a load in the time it takes to put it in gear after starting. If you're worried about it much, just be easy on it for the first bit.

My car reads closed loop in a matter of about 30 seconds. Is your o2 sensor a wideband or narrowband? IIRC the wideband is a bit quicker to start reading.
__________________
RIP Maxima 1997-2012


Quote:
Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
  Reply With Quote
Old 07-30-2010, 07:36 PM   #7 (permalink)
Master EcoModder
 
Phantom's Avatar
 
Join Date: Jan 2010
Location: Independence, KY
Posts: 602

Blue Meanie - '02 Volkswagon Golf TDI
TEAM VW AUDI Group
90 day: 48.52 mpg (US)

Wife's car - '05 WV Passat TDI

Rudy - '94 Chevy C2500
Thanks: 89
Thanked 46 Times in 43 Posts
Ok I just checked my car on the way home after sitting for 6hrs the car was reading the ECT (Engine coolant temp) at 100F the air temp was ~93F. I started driving as soon as I started the car it took 46.4sec to enter Closed Loop.

I'm not saying that this will be the same for every car but I do know that the fastest way to warm a car up it to drive it. In the winter the car can idle for ~13 min to get warmish or I can get heat out by driving 3mi.

Thanks for the info and remember the OL/CL stuff I'm going by is for OBDII it could be completely different on OBD1 or OBD1.5
__________________
I move at the speed of awesome.


"It's not rocket surgery!" -MetroMPG
  Reply With Quote
Old 07-30-2010, 09:34 PM   #8 (permalink)
Hypermiling rookie
 
Laurentiu's Avatar
 
Join Date: Jan 2010
Location: Limassol , CY
Posts: 288

Opel Corsa B - '96 Opel Corsa 1.2 8V
90 day: 47.27 mpg (US)

VW Bora 1.6 16V - '02 Volkswagen Bora/Jetta
90 day: 35.84 mpg (US)
Thanks: 17
Thanked 36 Times in 21 Posts
Quote:
Originally Posted by RobertSmalls View Post
Simple, clever, probably effective. I may have to try something similar.

How much did it increase your temperature reading when hot?

My radiator fan kicks on and off based on the coolant temperature reading. I only have a 5-10F window between the radiator fan and the thermostat.
Well, the device could be rigged to a button ON/OFF, it would be possible , no ? Also , even better I would think you could put a timer in the circuit, one that could be set to let's say 3 minutes. You start the car, the timer starts as well (like staircase-lights) and then it stays on for that initial minutes you need a leaner burn, then turns itself off to avoid starting the radiator-fan at lower than needed temps.
I don't know, I'm not mechanically inclined so my idea might not work..
__________________






"It has been my observation that most people get ahead during the time that others waste" Henry Ford
  Reply With Quote
Old 07-30-2010, 10:41 PM   #9 (permalink)
Left Lane Ecodriver
 
RobertSmalls's Avatar
 
Join Date: Aug 2008
Location: Buffalo, NY, USA
Posts: 2,257

Prius C - '12 Toyota Prius C
Thanks: 79
Thanked 286 Times in 199 Posts
The Insight loves the heat, and I'd like to know why. You can get into lean burn much sooner in 90F weather than 70F, and I see an improvement in FE that air density alone can't explain.

I've been thinking about replacing my ambient air temperature sensor (an IMA system input) with a resistor corresponding to ~150F. I'd like to find out if a coolant temperature sensor lie-box would also be helpful.

Now, Propane, if your 3kOhms adds 30F during the summer, what's it going to do in the winter?

I'm also very curious about how rough my precious, sensitive Insight will run when it misjudges the coolant temperature. I guess we're going to find out.

P.S. 0 Ohm pot in parallel = instant CEL, yes? Coolant temperature sensor reporting absolute zero.
  Reply With Quote
Old 07-31-2010, 12:47 AM   #10 (permalink)
Hyperlurker
 
daring4's Avatar
 
Join Date: Mar 2010
Location: Glendale, AZ
Posts: 87

D-max - '04 Chevy Silverado Ls

Notch - '65 Volkswagen 1500 S

MTCHBX - '05 Scion XB
90 day: 40.41 mpg (US)
Thanks: 12
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by RobertSmalls View Post

P.S. 0 Ohm pot in parallel = instant CEL, yes? Coolant temperature sensor reporting absolute zero.

I'm gonna guess you didnt mean "absolute zero"! Mine dont go negative, but it is late and had nothing better to do than respond...

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Disconnected Idle Air Control - for lower RPM after a cold start Lazarus EcoModding Central 19 04-15-2011 04:50 PM
Winter cold start & idling warm-up experiment MetroMPG Hypermiling / EcoDriver's Ed 17 12-17-2010 04:39 PM
Reverse Lights Not Working On Cold Start FastPlastic Off-Topic Tech 5 11-06-2009 01:58 PM
Starting to get cold... jamessw Hypermiling / EcoDriver's Ed 40 11-17-2008 09:43 AM
Why won't my truck roll start cold? extragoode Hypermiling / EcoDriver's Ed 8 05-25-2008 09:22 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com