How to: reduce the rich condition of a cold start.

[mwebb]

my 1995 VW jetta 3 with ABA engine did have EGR - thank me very much .
-----------------------
Using Pico 6 software and scope with a Fluke PV350 pressure transducer in #1 spark plug threads , zeroed to ambient barometric pressure prior to the capture ....

here is a running compression waveform , captured with pressure transducer in the spark plug thread , engine at idle running
Honda D16Y7 1.6 sfi engine , no EGR No variable cam timing
but it has EGR now .

the upper horizontal cursor is 0 psi or ambient barometric pressure
above the line is pressure
below it is vacuum

note the two vertical cursors around 325 and 357 degrees
showing a 5psi pressure spike in the combustion chamber as , the exhaust valve has already closed and the piston has not yet reached 360 degrees TDC and now

when the intake valve opens , that residual 5 psi of exhaust gases will be added to the intake air as EGR

on this capture it is a problem related to incorrect camshaft timing
but
it shows how engines with no EGR valve and variable cam timing can have EGR function
without an EGR Valve


to learn more about EGR
[QUOTE]http://autospeed.com/cms/title_EGR-C...7/article.html
look also at the refrences listed at the end of the article
study and learn

[C3H8]

first of all, you need to learn how to read what people write instead of just trying to interpert what i say and putting words in my mouth.

first thing that comes to mind is you trying to compare using a diesel fuel additive to diesel fuel. i dont use diesel additives! i dont know how to make that any more clear.

by the way, notice how when i called you out on that you dropped the subject as if it did not exist. go test diesel fuel if you like. i never messed with an additive.

second thing would be you calling me out on the 15% diesel thing. i never said adding diesel helps my mpg's!! (which you claim i said because you are being a straw man) i only said that my mpg's remained the same with or without the diesel., and the only reason i add a bit of diesel is because its about 60 cents cheaper per gallon then gasoline is. i dont know how to make it more clear then that.

but you keep mis quoting me. i never said adding diesel improves fuel economy. if you would bother to actually read what i type then you might understand. i did say that i get the same mpg's when adding diesel. not better, but the same.

as far as egr goes, i don't have a data logger. i have no way to extract data from my car and add it to the website other then writing down what i see on a piece of paper. i have already blocked and thrown away the egr so i am not putting it back on to test it more for you. it just isnt going to happen.

all of the vehicles that i said did not have egr, also did not have any sort of variable valve timing. i know this because i personally replaced the timing belts on most of them. so why don't they have egr? its because egr is bogus. its there for emissions only.
if there are some engines that see increased mpg's from the use of egr then fine. but i don't own one and i haven't seen one. my car and my engine gets better mpg's without egr. and no it doesn't have variable valve timing,
this is fact. i did back to back testing, multiple times, along the same road, using cruise control, trying to eliminate any variables as possible. egr killed my mileage. did you ever stop to think that maybe MY engine really does benefit from an egr block off?

i'm going to say a few things again, so you can hopefully understand it exactly in the way i meant it. ready?

"my engine gets better mileage with egr disabled"
"my engine has higher ignition timing with egr disabled"
"15% diesel does not increase my mpg's"
"adding the diesel only because its cheaper"


do you know what straw man is? it is when one person is arguing position X and another person will not argue X, they only come back with skewed arguments for position Y.
this is what you are doing. look up straw man here.
Straw man - Wikipedia, the free encyclopedia

quit being a straw man.

[Arragonis]

I don't know if you have noticed but nobody is watching this fight any more ?

[Olympiadis]

C3H8,
You are correct in that fooling the CTS (coolant temp sensor) can result in improved fuel mileage by several means, and have other advantages you may not have thought of.
I started making and using CTS trickers (I call "Tricker Boxes") in the early 1990's as a tuning and troubleshooting aid. I have been tuning cars for performance or gas mileage since 1990. Back then, there was almost no reliable means of datalogging besides DIACOM, which is what I had, and very little support calibrating (tuning) automotive ECMs. Even after more tuning suites and support became available, I found that the old tricker box was still an invaluable aid for tuning, and extremely handy to have around for day-to-day driving. I would not do, or own a project that didn't use some form of the tricker box function.
Here's a link to some diagrams I drew up for different CTS/gauge schemes and a shot of my spares that have collected over the years from past projects, or taken out of service due to upgraded or enhanced design.
Tricker boxes pictures by olympiadis3 - Photobucket


The project boxes you see are easy to make from Radio Shack parts, and serve well as a temporary plug-n-play type of device for testing or tuning.
I prefer the switchable kind which my diagrams represent.
In the diagrams, there is a DPDT switch in the middle which has 6 electrical connection terminals. The slider type switches from Radio Shack (seen on a couple of my old boxes there) are unreliable, so I prefer a heavier duty all-metal switch.
MCM Electronics has some very nice quality 10-turn potentiometers (extra precision) in various resistance ranges. Part # 502-0105 is a common one I use, but the range needed depends on the particular CTS. Different auto makers use different sensors. For example, most Fords need a much higher range of resistance.
With some sensor/gauge set-ups, it is possible to use a bi-level potentiometer as you can see in one of my diagrams. This allows you to switch your temp gauge display back and forth to check between your tricked temp setting, and the actual coolant temp. This allows quicker adjustments without need of a DMM and a resistance conversion chart. This isn't needed in all vehicles, depending on how the gauge data is displayed.

The old tricker box in the lower right corner has a pot for both CTS and IAT.
The IAT function is primarily for troubleshooting and setting up ECM/PCM calibrations. It's NOT of significant benefit for daily driving. Some racing applications can use them as a spark advance adjustment - more advance for increased octane, or less for N2O use. It can make a needed difference, especially when the Spark vs IAT table (in the calibration) is set up in advance. Factory calibration has only minimal spark adjustment based on IAT, and some calibrations have none.

These boxes you see in my pic are old test-n-tune boxes made for quick in&outs. For permanent installs, a rotary switch with some fixed resistors mounted on a board is all that is needed in a lot of cases. You use a DPDT on/off switch between your rotary, sensor, and ECM, and a few fixed-value choices via the rotary. For instance, if your ECM turns on your electric cooling fan at 230*F, then you use a fixed resistor for 225*F as one of your rotary choices to prevent fan operation. If you want a fan over-ride (to turn on the fan) choice on your rotary, then have a 235*F choice on your rotary switch. If you want 100% stock configuration, then just flip your DPDT switch to off.

[Olympiadis]

Aside from all the valuable uses I have for this sort of function, I'll stay on topic for now and post results of a CTS tricker on my 2003 Ford Focus project. I'll make a separate post about this car as a project when I have more time.

Before:
First morning cold-start & commute -first leg only.
Average ambient temp over 8 data points = 77.1*F (beginning of leg)
Average coolant temp over 8 data points = 150.8*F (end of leg)
Average MPG at end of first leg = 34.7 (8 data points)

After:
Activated CTS tricker 10 seconds after start-up. Set to 225*F.
Average ambient temp over 1 data point = 65*F (beginning of leg)
Average coolant temp over 1 data point = 146*F (end of leg)
Average MPG at end of first leg = 37.5 (1 data points)

*Notes: I had wired this car for a CTS tricker, but not using one - was planning to run other tests first. I have kept complete mileage logs of this car since August 2007, and recently collected a great amount of baseline data in preparation for testing several new modifications. After seeing this thread, I decided to throw in one of my old CTS trickers for some testing, so I could contribute recent data. I have piles of test data from years past, but every vehicle type responds a little differently due to differences in the control algorithms and calibrations. A switchable CTS tricker combined with a Scangauge2 make this testing relatively easy.

*This 2003 Ford Focus has always been able to go into closed-loop operation very quickly, even with low coolant temperature, due to having a heated O2 sensor located very near the exhaust port, and having thermo-tech insulating wrap around the exhaust header/manifold. By quick, I mean less than 30 seconds, and sometimes as quick as 15 seconds after a cold start from 70*F. Most cars out there (especially older ones) aren't that quick at reaching threshold for closed-loop, and so tend to remain in warm-up enrichment longer. Clearly a quicker closed-loop was not a significant factor in this particular test.

*What I have noticed and logged about this Focus is that even in closed-loop, the coolant correction factors add considerably to fuel usage after a cold start due to the increased idle speed and throttle-follower settings for the IAC. This is a big factor with me and this car because I do engine-on coasting. I have not as yet taken the time to go into the PCM calibration and adjust the idle speed and throttle-follower settings on this vehicle.

Any AE - Acceleration Enrichment (or pseudo AE) used is also increased due to coolant temp factor. TCC (torque converter clutch) operation also has a coolant temp threshold, and this is just one more factor where a low coolant temp can cost you mileage.

This morning (02-Aug-2010) was my one "After" data point. I thought this would be good because it was unusually cool here for august at 12* cooler than the previous 8 data points average. 75*F was the coolest morning out of those previous 8 points.

My MPG consistently follows the ambient temperature, and especially so on the first leg of my commute, which includes the cold start. Higher starting temps have shown higher MPG, and vice-versa. This, I think was a very good reason to start the CTS-tricker testing today. It's starting out at a disadvantage compared to the previous 8 data points, but has potential to make a bigger difference. The first leg of my commute is only a 10 minute drive which drops about 100 feet elevation, and so has a lot of coasting right after the cold-start. This is why my actual engine coolant temp stays pretty low during the first leg of my commute. It's a perfect opportunity to show what a simple CTS-tricker can do in a situation like this.

Here are the before & after engine-on coasting numbers.

Before: Starting temp = 75*Fwt
.RPM...--GPH-- (gallons per hour - fuel usage per Scangauge2)
.1400.... 0.73
.1350.... 0.67
.1325.... 0.64
.1300.... 0.61
.1250.... 0.61
.1200.... 0.57
.1200.... 0.55
.1150.... 0.52
.1100.... 0.50
.1100.... 0.48
.1050.... 0.47 (stopped in neutral)
.1050.... 0.41 (stopped in neutral)
.950...... 0.38 (stopped in neutral)

After: Starting temp = 65*Fwt
.RPM...--GPH-- (gallons per hour - fuel usage per Scangauge2)
.980..... 0.44
.900..... 0.40
.850..... 0.40
.825..... 0.33 (stopped in neutral)
.800..... 0.29 (stopped in neutral)

I will of course collect a few more data points with the CTS in operation before I move on to testing something else. I will update my original post with the new data averages for a few days.

[C3H8]

Olympiadis, great post!

I had never realized the resistor on the coolant temp sensor could make that much of an impact, but I had always suspected something else was going on besides making the computer go into closed loop quicker. It just seemed to me that I was getting too good of a fuel economy number from going into closed loop alone. and now I know why!

I had never thought of things like acceleration enrichment being even richer when the engine is cold vs fully warmed up. I do know all too well what AE is, It's fuel injection's version of an accelerator pump. i have 6 red LED's on my dash that are hooked up to each of my 6 gas injectors. when the engine is cold and I touch the throttle, I can SEE acceleration enrichment via all 6 injector LED's lighting up at the exact same time, for I'm guessing 1/4 of a second. I guess this is how fuel injection simulates an accelerator pump valve.

[EdKiefer]

Olympiadis How come your water temps are so cold (150F ) fully warmed up ?

Is that actual temp or just what gauge reads ?

[suspectnumber961]

I've done the CHT sensor and TPS (throttle position sensor) on an '86 Nissan 720 4x4.

I have 2 rheostats in the dash and a switch also on the CHT sensor.

I notice that in warmer weather I can leave the CHT switch "on" and get a good start...in colder weather...it's more difficult to start.

The TPS mod will allow leaning the engine out to the point of reduced power.

I also run an EFIE at 200 mvs....seems to allow the O2 to cycle more easily than with no added mvs.

I don't believe I've documented an mpg gain though. I was having several other tuning/electrical issues with this truck and eventually I put things back to stock...thinking my messing around was the problem...when I noticed an increase in power.

Since I have the rheostats in the dash I can adjust things at will....now running at about 1/2 the LEAN setting I once ran.

What I am messing around with on my wagon is a a fuel vaporizer that has indications of both improving power and mpg....but I really haven't been able to finish testing it....having issues with the gas valve closing up and not allowing gas to vaporize.

Since I can lean the truck down real well...I eventually want to test a fuel vaporizer on it.

Here is some info on the subject:

http://www.nonags.org/members/nijqk/Sensor_mods.doc

[Olympiadis]

Originally Posted by EdKiefer

Olympiadis How come your water temps are so cold (150F ) fully warmed up ?
Is that actual temp or just what gauge reads ?

The first leg of my commute is only a 10 minute drive which drops about 100 feet elevation, and so has a lot of coasting right after the cold-start. This is why my actual engine coolant temp stays pretty low during the first leg of my commute.

If not for all the coasting, normal operating temp is 190*F. It gets up to temp fairly quick with a steady highway cruise, but that's not what I'm testing here.

[Olympiadis]

Originally Posted by suspectnumber961

I notice that in warmer weather I can leave the CHT switch "on" and get a good start...in colder weather...it's more difficult to start.

I've not used actual rheostats for this function, but you should use a switch so you can use the actual coolant temp sensor for cranking/starting.
Once running with a little heat in the spark-plugs you should be able to switch back to your resistance setting with no problem.

As of yet I have not used a TPS tricker, though in theory the concept should have at least some functionality in some applications. Holding a steady TPS% reading while using cruise-control on the highway comes to mind. When the CC-unit applies more throttle there would be a lack of AE from the AE vs delta TPS table. You could get less "pump shot" that modulations of the throttle would've normally caused.
Some systems that also calculate the AE based on load sensed from a MAP or MAF sensor may not benefit from a TPS tricker.

Another scenario where a TPS tricker could be useful is on large/heavy vehicles that require a lot of throttle during normal driving. Limiting TPS range and modulation could prevent PE mode from being activated too often or by accident. Of course this would be in cases where you don't have access to adjust the PCM/ECM calibrations.

I may give the TPS tricker a try though. I'd like to see just how well it mates with cruise-control on the highway. I wouldn't expect very good results on this Focus though. It has a MAF and very quick adaptive fueling. It's something I'll have to try to know for sure.