Iowa4Runner
New member
rando said:
I'd love to get more pins and connectors of the same type, do you know where to get them?
Does the MPG computer error change as the miles pile up?
- Thread starter Iowa4Runner
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I'd love to get more pins and connectors of the same type, do you know where to get them?
Good Times
New member
Sounds like ALOT of work just to get that darn computer to read the correct values!
Iowa4Runner said:
I still don't quite understand why the car has to be moving, at this stage. "min fuel flow situation" will be when the RPMs are lowest. "max fuel flow situation" will be when the RPMs are highest. It really doesn't matter what the rest of the car is doing. The engine will use the same amount of fuel at X RPMs no matter what speed you are traveling. When you coast down a hill with the engine idling at 1500 RPMs, it will consume the same amount of fuel as when you're lightly accelerating at 1500 RPMs.
The difference will be the Miles Per Gallon calculation. That calculation requires you to know how far you've gone. Since you are only measuring the duty cycle of the injectors, mileage/time has no bearing, yet. Please don't needlessly endanger other people by driving around staring at a scope!
If I have my choice between reving the engine too hard in the driveway or driving around where I might hit someone, the choice is pretty clear.
Iowa4Runner
New member
CMiYC said:
To put it simply- RPM does not control the pulse duration of the fuel injectors, the throttle does. You have to fully open the throttle to get max pulse duration. For a variety of reasons, sitting in the driveway flooring the engine isn't practical and may not give useable results. As for min pulse duration, I'll simply say that it doesn't happen at idle.
CMiYC said:
Not only is that untrue, it just doesn't make sense. Take a ride with my scope and you'll change your mind. It'll be a double bonus, you'll learn about 4Runner fuel injection and I won't endanger people's lives by "staring" at my scope. :rolleye2:
rando
Senior Member
Iowa4Runner said:
At first I wondered about this too, but once you mentioned the duty cycle variations it all made sense. I'm pretty sure the engine ECU tweaks the fuel volume based on a hole host of sensor data (engine speed, gear, speed, acceleration, throttle position, etc.)
As for the safety aspect of this, you could consider a digital scope in single shot trigger mode. I found this to be the safest way to do the speed sensor monitoring. I'd get the truck on a nice strait clear piece of raod and drive a constant speed. Then I'd just reach over and push the trigger button and save the trace.
BTW, does the min duration actually happen during engine braking? It would seem to me at that moment that you don't need much (if any fuel) to keep the engine turning.
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Iowa4Runner
New member
rando said:
The safety aspect of the scope is really a non-issue. I was able to get the difficult setup stuff (like the trigger) done while sitting in my driveway. When driving it only takes a quick glance to get an idea how wide the trace is. I just need rough values so I can be sure the PIC counter won't overflow during a long pulse. It's about as taxing as checking your rearview mirror or speedometer. Besides, I was on a county road with no cars, or people around. I can assure you nobody was in any danger.
rando said:
Yeah, in fact if you let off the gas when the RPM is sufficiently higher than idle, it stops injecting fuel completely. After the RPM drops, the injectors start pulsing again and the duration gets a little wider as the engine settles into an idle. It's pretty cool.
nathannookie
New member
HuntRunner said:
I called Corporate, and then my Dealer...Carson Toyota...months ago. I even refered them to the pertinent links on this site. They wrote up a report, but have NEVER gotten back to me about it.
See the thread;
http://toyota-4runner.org/showthread.php?s=&threadid=2034
