Super VXer
Are you using a ScanGauge or something to see what the system is doing? I'd be interested in the Fuel Injector Trim #'s, as this may be an indicator of what's happening in there. (I've played a bit with them to help figure out my problems, you have to program them into the Scangauge - Xgauge)Originally Posted by MoonRaker
If you don't first THINK THINK, you could end up in deep DO DO!
Super VXer
Ive figured out whats happining with the trims, it seems that the foward wideband 02s want to see around 700 and even if you try to show less flow across the maf (2 volts less) it trims to compansate. I have a trouble code thats been there for a while showing the EGR isnt working correctly, I pulled it apart and it seems it was somewhat sticky but has nuthing to do with the setup since its been there for a while prior to the generator. I havent coughed up the money for a new valve because it dosnt make a difference in the way the truck runs. I just switched to a higher output generator so im gona need to trim fuel to get the most out of it. Gotta rember that the ECU is programed to give the proper emmisions value. You could run it fine a little leaner but it runs it richer to get the cat to work properly. Hmm, maybe punching the cat out will tell the foward 2 02 sensors to pull fuel out?? Gona try other stuff first but its an idea. Im trying to avoid throwing any other codes because that might cause the ECU to get thrown into open loop, or that might be somthing to try also, open loop is the ECUs pre programed tune, it usauly goes into openloop under haevy load or certain codes being thrown. Might try disconecting the rear o2 sensors.
Super VXer
to get more reliable results you should be standardizing your measuring and monitoring process.
the most reliable way to measure fuel economy is this:
1. fill up your tank
2. reset your trip meter before you leave the pump
3. drive for a while
4. fill up your tank again
5. [trip mileage]/[fuel to fill tank] = MPG
if you want to make sure that it's perfectly accurate make sure your speedo is reading correctly, the speedo gets it's signal from the same place as the odo and trip meter so typically those are only as accurate as the speedo.
I'm not sure how it works on the VX but digital speed sensors often have an adjustment screw on the back of the gauge cluster, failing that Dakota Digital makes a unit for $80 that will let you adjust your speedo exactly. use a GPS to tune it, or if you know a LEO with radar equipment you can have them help.
On top of that you can get an OBDII scanner for ~$100 that will provide you with real time A/F ratios and Injector cycle times to let you know what you're engine is doing at all times.... if you've got a laptop you can probably get an even cheaper OBDII cable and record the results from a trip. Some more expensive OBDII units (~$200) can record the trip data to be dumped to a desktop computer later on.
This would make it VERY easy to test the results of your system. fill up, turn it on, set the laptop to record and do a 5 mile loop. Mark your mileage turn the system off, fill up again and do the same 5 mile loop. Did you see a difference? Do this while keeping with the speed limit and use land marks to start your braking distances... trying to keep as consistent as possible. Best bet is a highway loop where you're staying at a constant speed for extended periods of time.
Saying "I got X miles on my last tank" is rather ridiculous IMO... the fuel gauge unholy in-accurate and can fluctuate quite a bit depending on just the pitch of your car never mind temperature, pressure, humidity, etc. Similarly if you drove different places on one tank to the next, did you use your AC more this week or last week?... even the mixture from one gas station to the next or from one week to the next from the same station can effect your mileage by a couple MPG. Measuring your A/F and Injectors among other things will also show you if your engine is ACTUALLY running more rough or smoother (as opposed to your butt dyno), as well as show you how well it's running in any given RPM range. Depending on the data you get you might also be able to derive average HP and torque as well.
"test results" are only as reliable as the quality of the test
Last edited by twistedsymphony : 07/14/2008 at 10:21 AM
Super VXer
Well, that sounds like a good way to make some adjustments but you have to worrie about long term fuel trims wich I monitor on my OBD2 scanner wich is real time, I can monitor the voltage comming from each of the 4 O2 sensors, the maf sensor. I havent loaded the programs that monitor each injector yet but id say that its not needed for what im trying to acomplish. My plan wich im going to do tommorow is disconnect the front 2 O2 sensors and maybe all 4. I want to force the truck into open loop wich will base the fuel maps on the maf.
Super VXer
Ok, just went and pulled the plugs on the front O2 sensors. The OBD2 showes them at a voltage of .450 and the other .455 locked so no adjustment, before they showed in the .650 to .850 range verying. The rear sensors were still reading but ALOT leiner, in the .050 at idle and .3 under excel so thats working. Ow, forgot to mention im still bleeding air in through the Vac side of the throttlebody along with the hydro gismo. I stopped the leak and the rear 02s went to .350 at idle. It seemed I was bleeding to much air for open loop so the truck started stumbling, I adjusted the bleed till the idle was stable with the gismo running, forgot to turn it off to see what happens. When I got back from a ride the rear 02s were .010 to .005, and it was still running pretty good??? holly crap. I have a freshly filled tank, lets see if were gona see even more milage, might break 300 this time.
Super VXer
Ok, twisted , tryed it your way. I mounted the trusty shop wideband. Filled the tank and clocked 50 miles, average speed 65 70, returned to the sceen of the same pump, filled 2.2 gallons. The wideband was between 16 and 19 to 1 air/fuel. So, thats around 23 to 24 MPG. that sure beats 16 to 20 that I was getting before. Ok, new idea that I talked to a very smart guy I now that worked at Pratt & Whitney as and engineer. He said to heat the gasoline to the point of vapor using the exaust manifold as a pre heater. He said when they tryed it they got almost 80 MPG on a V-8. Ok, it sounds dangerous to me but ill give it a try. Im thinking of a throttlbody settup. Put in a switch to shut off the port injection when the vapor system gets up to temp.
Super VXer
My Cobra used to do that. We called it vapor lock. Tended to kill the engine. Not a good thing. Fuel pumps don't work well pushing vapor.
Gregg
2001 Proton Yellow #1379
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