2002 TB Onboard MPG Calculation

Printable Version

Blazer Forums >> Mechanical & Maintenance >> General Tech Help >> GMT 360/370 Tech >> 2002 TB Onboard MPG Calculation

Page: [1]

Login Message << Older Topic   Newer Topic >>

2002 TB Onboard MPG Calculation - 6/3/2008 6:23:22 AM    mohawks76   Posts: 5 Status: offline How does the onboard instant MPG feature calculate the instant MPG?  What data does it capture and what is the calculation? I'm making some modifications that may cause this feature to report an incorrect MPG and I would like to know how the changes will effect the calculation. Post #: 1

RE: 2002 TB Onboard MPG Calculation - 6/3/2008 9:50:00 AM    swartlkk Posts: 12807 Joined: 5/1/2005 From: Waterloo, NY Status: offline Calculation is based off of IPW (injector pulse width) which the computer translates into fuel consumption and uses in conjunction with the RPM of the motor and the speed you are travelling at.  If you are not changing the fuel pressure, then you are not changing these basic calculations.  If you are changing the fuel pressure...  Well, I do not believe that there is an easy way to correct for that, but the difference can be determined through back calculation of instantaneous MPG, RPM, MPH, and IPW to figure your fuel consumed during one injector pulse.  Then modify that through some further calculations (not easy) to figure your change in fuel consumed and its factor on the MPG calculations.  But since you are driving an '02 TB, I will start off by saying that it is VERY difficult to do anything to these motors that would require the increase of fuel pressure so I do not think that is where you are going with your modifications. *Moving to GMT360/370 Tech* _____________________________ Kyle- The new - '04 Buick Rainier CXL The old - '00 Olds Bravada - Traded 5/30/07 The restoration - 1970 Chevelle (in reply to mohawks76) Post #: 2

RE: 2002 TB Onboard MPG Calculation - 6/3/2008 10:22:05 AM    mohawks76   Posts: 5 Status: offline I have installed an HHO bubbler that injects hho gas into the intake manifold through the PCV vent line.  When running, it sends the O2 sensor signal down to 120mV.  I am modifying the signal back up to about 420 mV and sending it to the ECU.  Runs smooth with no change in power. I will be making a 650 mile run this week so I will be checking actual MPG, but I was trying to figure out if the instant MPG displayed was going to be accurate or if skewed, what kind of a skewing it will take. Your thoughts? (in reply to swartlkk) Post #: 3

RE: 2002 TB Onboard MPG Calculation - 6/3/2008 12:43:21 PM    swartlkk Posts: 12807 Joined: 5/1/2005 From: Waterloo, NY Status: offline What causes the O2 sensor to drop to 120mV and stay there...?  This should not happen regardless of the fuel source.  You are, after all, burning hydrogen.  An O2 sensor senses free oxygen in the exhaust and compares it with the free oxygen level of the outside atmosphere.  By skewing the signal back to the PCM, you are defeating the gasoline fuel system...  It'll run, but it won't be dynamic. In the long run, I think you are just wasting money.  This process of electrolysis requires electricity.  Electricity generated by the electrical system of your vehicle.  If this system was truely lossless (what it would have to be to make any appreciable net affect), you would see a benefit, but it isn't.  You will always have more energy put into the process than you extract. < Message edited by swartlkk -- 6/3/2008 12:55:05 PM > _____________________________ Kyle- The new - '04 Buick Rainier CXL The old - '00 Olds Bravada - Traded 5/30/07 The restoration - 1970 Chevelle (in reply to mohawks76) Post #: 4

RE: 2002 TB Onboard MPG Calculation - 6/3/2008 1:34:22 PM    mohawks76   Posts: 5 Status: offline Research HHO and EFIE Defeating the gasoline fuel system is the objective. Thanks for your assistance. (in reply to swartlkk) Post #: 5

RE: 2002 TB Onboard MPG Calculation - 6/3/2008 1:40:27 PM    swartlkk Posts: 12807 Joined: 5/1/2005 From: Waterloo, NY Status: offline I know what they are and I do not believe that you will defeat the gasoline fuel system...  But whatever.  I get a kick out of the explanation of these gimics on most of the websites that pop up with a google search on those two keywords.  Everybody is looking for the miracle cure! Best of luck and let us know the out come of your trip.  I wouldn't worry about the little things until you have a working setup that is capable of actually making a difference. _____________________________ Kyle- The new - '04 Buick Rainier CXL The old - '00 Olds Bravada - Traded 5/30/07 The restoration - 1970 Chevelle (in reply to mohawks76) Post #: 6

Today's Posts
Most Active Topics
Make A Donation
Forum Rules & FAQ
RSS Feeds

Chevy Blazer Prices

Chevy Blazer
Trailblazer SS

Top 10 Posters
swartlkk 12807 drperry 3850 chevy lover 3409 hanr3 3376 m00nwater 3269 eurogoldls 3063 paddle_grl 2929 hillbillyino 2880 xblazer01 2659 thegr81 2621

New Vendors
AMSOIL - Performance Oil Technology
K&N Engineering, Inc.