still burning too much gas...

[mikeinaus]

replaced it a couple months back and confirmed its in spec by testing it with the water/thermometer and voltmeter...

[crazycanadian]

tried 2 different sets of injectors both ze/de ones... bluetops i think they were???

wheels are spinning freely. front bearings are new and the rears are fine. ebrake is not dragging it needs to be tightened if anything. alignment was done last august.

ill see if i can get it hooked up to a labscope Adam. doubt i can get a driving reading with it but i can probably get idle and rev readings, im also not sure if id be able to get screenshots of the data. anything else you suggest i hook into and monitor readings?

You can try Mike... Since you are in school and learning this stuff its not a bad idea to play with it... At idle with the O2 warmed up you should see it switching slowly... After it idles for a little bit you'll probably notice the switching slow right down till it doesn't switch anymore... That will be normal, its just the O2 sensor cooling off... With having headers and the 02's only looking at 1 cylinder it'll probably happen faster then it would if the car had stock manafolds...

At 2500 you really want to see it switching consistantly between .2 - .8V... If its biasing rich that might be an indication that something is causing it over fuel... But I wouldn't focus in on this...

You really need to see whats going on while you are driving...

[mikeinaus]

ill talk to my teacher about going for a test drive. were in electrical atm and its driving me nuts. i havnt done math in like 10 years lol and i cant wrap my head around the different laws and rules for figuring out loads and everything...

[wytbishop]

If you need a hadn with the math or understanding Ohm's law and Kirchoff's rules feel free to drop me a line. I might be able to help you out.

[mikeinaus]

i got a chance to play with the labscope today. from the readings im thinking the rear o2 is dead.
front O2 = Green
Rear O2 = yellow

rpm held at 2000rpm
http://s878.photobucket.com/albums/ab34 ... EO0005.mp4
different scale
http://s878.photobucket.com/albums/ab34 ... EO0001.mp4

idle 650rpm
http://s878.photobucket.com/albums/ab34 ... EO0002.mp4

throttle blurp
http://s878.photobucket.com/albums/ab34 ... EO0003.mp4

[crazycanadian]

Classic mistake mike... Always double check your voltage scales.... The picture you have is distorted most likely because you had channel 1 set to 10 or 20V scale.. and Channel 2 was set to a 5V scale.. When I watch the video and look at the digital numbers your rear O2 is switching just fine... It seems to get up over .8V and down below .2 of a volt.. At idle its normal for your O2 sensors to flat line, especially because you are only looking at 1 cylinder on each bank due to the aftermarket header design..

[Daninski]

I hope you realize that running a 2.5" exhaust improves performance but also causes your car to run richer. I'm constantly washing the soot off my rear bumper. I bet if you dropped down to a 2.25" cat that may help, I was going to try it myself. Since I switched to full synthetic oil (AMSOIL) I gained over 50klms per tank of fuel.

[crazycanadian]

I hope you realize that running a 2.5" exhaust improves performance but also causes your car to run richer. I'm constantly washing the soot off my rear bumper. I bet if you dropped down to a 2.25" cat that may help, I was going to try it myself. Since I switched to full synthetic oil (AMSOIL) I gained over 50klms per tank of fuel.

Its not that he's going to run richer... If it caused the car to run richer it would show up in the O2 sensor readings... Its because with an free flowing intake and exhaust the motor moves air threw it more efficiently.. Since we run a MAF style system there is more measured air flowing threw the motor... More air = more fuel...

At this point Mike I think to get better fuel economy you'll need to step up and go with a stand alone system...

[Daninski]

I hope you realize that running a 2.5" exhaust improves performance but also causes your car to run richer. I'm constantly washing the soot off my rear bumper. I bet if you dropped down to a 2.25" cat that may help, I was going to try it myself. Since I switched to full synthetic oil (AMSOIL) I gained over 50klms per tank of fuel.

Its not that he's going to run richer...

Since we run a MAF style system

Yes he will run richer and we run a VAF not a MAF. I've owned both 2.25" exhaust and 2.5" and as you should know O2 sensors can only correct so much. If they could completely correct rich situations we wouldn't need to chip or use KL31/36 ECUs would we.

[Ryan]

Indeed, this is a VAF setup. ECU does a calc to determine airflow mass. narrowband sensor, it can still run rich due to breathing mods. Not catastrophically so, but it can.

[crazycanadian]

I hope you realize that running a 2.5" exhaust improves performance but also causes your car to run richer. I'm constantly washing the soot off my rear bumper. I bet if you dropped down to a 2.25" cat that may help, I was going to try it myself. Since I switched to full synthetic oil (AMSOIL) I gained over 50klms per tank of fuel.

Its not that he's going to run richer...

Since we run a MAF style system

Yes he will run richer and we run a VAF not a MAF. I've owned both 2.25" exhaust and 2.5" and as you should know O2 sensors can only correct so much. If they could completely correct rich situations we wouldn't need to chip or use KL31/36 ECUs would we.

You have part of the concept right, but a lot of miss understood information there....

When I say MAF style system, I am not talking about the sensor that does the physical air measurement, I am talking about how the computer calculates air flow... In our case the computer physically measures air flow with the use of a VAF sensor.

O2 sensors don't make the corrections, they are only a sensor that reports to the ECU. They report how well combustion is taking place and how much fuel is left over. Don't get confused by the name, an O2 sensor does NOT measure air.

The ECU makes fuel trim corrections based on what the O2 sensor is reporting as well as other sensors. It does this in order to maintain fuel control for emissions purposes.

You are right at some point the ECU runs out of fuel trim corrections that it can make, this is when it starts to loose fuel control. This loss of fuel control shows up in the O2 sensor readings. Mikes lab scope video at 2500rpms is a perfect example of good fuel control. If he had a problem with running rich, you would have seen the O2 sensor still switching, but only between .4 or .5 and .8 or .9V... This is called biased rich...

If the problem is bad enough the O2 sensor might just stop switching all together.. If thats the case the ECU has no fuel control at all... If running like this long enough our cars will eventually set an O2 sensor code.. This will only happen under a constant light/mid throttle cruise condition though... Our computer systems are pretty primitive when it comes to fuel control and how well they can control it..Also code setting parameters are pretty lack luster...



Since this thread is all about fuel millage the BIGGEST thing we need to know is how well the computer is doing its job with fuel control... We have extremely limited ways to do this since we can't go in with a scan tool and look at what the ECU is doing... We can only do it 2 ways... 4 or 5 gas analyzer readings before the cat, or graphing O2 sensors.. If the computer is keeping perfect fuel control all the time when its supposed to be then you are stuck... You have to buck up and find away to program the ecu better, or go to a stand alone.... If the computer isn't keeping fuel control, then you have to chase down why and fix that first...

[Ryan]

The engine has a map for all running conditions.

cold idle, hot idle, cold cruise, hot cruise, wide open throttle, overrun, all throttle transience, etc.

It makes corrections based on other factors, too

VAF reading, ECT reading, O2 reading, AIT reading, perhaps others.


Any of these things could be at fault.

Extra fuel will be used to meet your driving demands. Also, if your compression is low, or the motor is otherwise not in tip top shape, it will take more effort(throttle, air, and fuel) to cruise at the same speed.

Drive around at 90 KPH for a bit, see what happens.

[Daninski]

O2 sensors don't make the corrections, they are only a sensor that reports to the ECU. They report how well combustion is taking place and how much fuel is left over. Don't get confused by the name, an O2 sensor does NOT measure air.

The ECU makes fuel trim corrections based on what the O2 sensor is reporting as well as other sensors. It does this in order to maintain fuel control for emissions purposes.

Bla bla bla,,,,,,(next paragraph)

You are right at some point

Without wanting to sound argumentative do you think we just fell off the turnip truck here? Clarifying my explanation about O2 sensor operation is fine, we know the ECU does the corrections according to the voltage received from the sensors but then to give a lecture on O2 sensor theory of operation.
If your going to start correcting us,,,or me then use correct terminology yourself. You said MAF, we don't use MAFs we use VAFs so stop trying to cover your azz after the fact. I knew what you originally meant but I never went off on a tangent trying to impress everyone.
Finally after trying to impress us all with your vast knowledge you finally got around to actually contributing some useful information in your last paragraph.

Thanks.

[Juans_93_MX3]

Have you tried using K8 fuel injectors on your KLZE?
If I am correct, K8 fuel injectors dont spray out as much fuel as ZE. Maybe that might help?

Also, a K8 ECU is programmed for a smaller throttle body and different fuel injectors. Does the Probinator chip account for that?

[mikeinaus]

Yes it does. But I'm using a de ecu/vaf. And I'm thinking k8 objectors would be a good way to ruin the engine. The idea is to get an ideal fuel trim, not go super lean.