ravencr

I have since removed the stock MAF and replaced it with a Supra MAF for increased airflow, but I soon found out the voltage is less for the same amount of airflow. Does anyone know what the normal voltage output is from the stock MAF? Do you have this across the full RPM range. I would love to have a copy of if possible, because that's the first thing I'm going to do with the SMT-6 that I should have this week. Any help would be greatly appreciated!

Chris

Dr. Zhivago

I currently don't know what the voltage curve is for the stock MAF. I will be measuring it at some point soon. I will send you the data then.

Good luck in your search!
Dr. Z

Gadget

Dr. Z

I have something for you to test while you are tesing things.

Hook up your scan tool and while driving crank your ECT control down and see if that will trip the ECU into OPEN LOOP while you are driving. If it does leave it there. I think you have a switch that turns the mod on or off. Flip that switch under moderate acceleration and see if it trips the ECU back and forth from open to closed loop and see if the truck and trans behaves oddly when you do it.

If it seems to control open and closed loop at will without any odd side affects, measure the resistance your mod is set at and let me know.

Gadget

www.GadgetOnline.com

Dr. Zhivago

Hey Gadget,

Can Do! I'll let you know. I don't think it will trip it onto Open Loop, but I haven't paid close attention to it either. If I had a bigger Pot on it, it might, but I think that once the O2 Sensor heats up, it goes to Closed Loop and stays there until WOT. We'll see.

I noticed on a cold engine that Closed Loop occurs after about 45 seconds to a minute. I can take a look at that today for ya. I'll post the results here later.

In the meantime, here is an interesting article along the lines of the kinda stuff that you're thinking about. I think you'll enjoy it.

Peace!
Dr. Z

ravencr

So Gadget, do you know the stock MAF sensor voltage? I figure you don't since you didn't say so. I would love to hear the results on the ECT thing. Sounds interesting with lots of potential.

Chris

Gadget

0-5 volts ascending.

Gadget

www.GadgetOnline.com

Gadget

Z:

So you see how screwy those FMUs are. To much in some spots and not enough in others. What a hassle to make that other thing just to compensate.

If you install the proper size injectors, then it is just a matter of changing the numbers on the table in the injector controller to get everything just right.

Gadget

www.GadgetOnline.com

ravencr

Thanks Gadget! I knew that part, but I was wondering what the voltage is throughout the RPM range, so I can easily boost the voltage to that same range on my Supra MAF. Any ideas?

Chris

Gadget

There is no way to know that because it is always going to be different depending on engine load and ambient conditions.

The MAF measures the volume of air passing through and takes its temp to determine its mass, hence Mass Air Flow. The ECU uses this calculation to determine how much air by weight is being injested and injects the proper amount of fuel by weight to go with it. Many people are mistaken it is so many parts air to so many parts fuel by volume, like say 14.7:1, but it is not volume, it is weight.

I think I know what you are tying to do and it is not going to work. You can not get that Supra MAF to work with stock injectors. It will never happen. The signal ratio is way different. The Supra MAF is also a 0-5 volt system, but I don't know of any piggy backs that can boost the signal far enough to bring it into range of the ECU.

Remember that the Supra MAF will not reach 100% or 5 volts unit like 650 HP or so where the 100% of the stock MAF is probably around 300 or so. You just can not make up that difference with a piggy back. With 305cc injectors you are going to be increasing the voltage in the neighborhood of 40%. With stock injectors you are going to need to boost it a hell of a lot more then that and the piggy backs just don't have enough control authority for that.

Remember, that guy that said that 360cc injector with the Supra MAF is just about perfect??

Gadget

www.GadgetOnline.com

ravencr

I was under the understanding that I could easily adjust the MAF sensor voltage using the SMT-6. I could be wrong, but that's what they've told me. I was hoping this would be a simple adjustment, but it may not. I'll let you know how it works out!

Chris

Gadget

If you install 360cc injectors is should be a snap to dial in.

Gadget

www.GadgetOnline.com

ravencr

I thought the 360cc injector in combination with the Supra MAF would require no piggy-back possibly. I don't have a clue how installing the larger injectors would make a bit of difference, unless he is basing this strictly off the increased amount of fuel keeping the same duty cycles. Is this what he is claiming to your knowledge?

See, the SMT-6, runs the current MAF sensor output through the piggy-back, which, in turn, I can make the voltage anything that I want it to be within 0-5V's. Is this different than the FTC1-E? I figure that if I can increase the voltage then it would be the same thing as installing the larger injectors, right? That almost sounds right to me, but this would still mean I have more air flow, which is where I might run into the trouble, right?

Chris

Dr. Zhivago

Okay,

Here's what I found testing the ECT mod as Gadget asked me to:

With a 1K Ohm Pot, the max drop I can achieve on the "Apparent" Coolant Temperature is around 77* F. My "Normal" ECT is 171-174 with the TRD Low Temp Thermo installed. Cranking the ECT Mod to full swing drops it to 95*. Here's a pic:



As you can see in the pic, it stays in Closed Loop. Sorry Gadget. I doubt if I used a bigger Pot that it would go to Open Loop. This is a shot of me idling, but it did not make a difference whether I was driving or standing still. However, I did find one more scenario where the ECU goes to Open Loop - Decellerating in Gear at any speed in any gear. Here's a pic of me in 3rd gear during a Decel:



You can of course see that it says Open Loop. I am pretty sure that the ECU cuts all Fuel during this time so as to reduce emissions and improve engine braking.

And Chris, Gadget is right about the MAF, just use the big injectors (360-370) and you won't have to tweak the the MAF signal so hard to get the truck to run right. And, you're probably SOL on getting your truck to run with the stock injectors and that Supra MAF. I was gonna get you a MAF Voltage Curve based on different loads on my stock engine, and if you still want that, I can get it for you, but it won't be until later in the week.

As for that article, it was a good read though, huh Gadget? But you're right, what a hassle... If there's anything else you want me to look at, just ask. I hope the news today wasn't too disappointing. Talk to you later.

Dr. Z

ravencr

Dr. Z,

I would love to see the MAF sensor information that you could do by later this next week. That would be a huge help for sure. I can't get the larger injectors right now, so I've got to make it work if it's at all possible. I'll let you guys know.

Also, why would the computer go into open loop while decelerating with the gas off the pedal? I thought the only time the computer went into open loop was when the throttle was over 80% depressed.

Chris