Quote:
Originally Posted by monroe74
duff: "you just have to ask the right questions"
Then maybe I should start with this question: what's the right question that you think I need to ask that I haven't already asked?
"you car should have one?"
Yes, my car has a TPS.
"you can map out the A/F ratio which may help find efficient vs inefficient operating regions."
I don't know what you mean.
The trick is to create a BSFC map, or the equivalent, without the use of a dyno. I don't know how to do that, but maybe you do.
To assess "inefficient operating regions," I have to do more than just know the throttle position, and the AFR. I also have to have the engine under a known load, so I can maintain a steady state and monitor how much work is being done per unit of fuel consumed. Dynos were invented to solve this sort of problem.
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What I meant by the “right questions” wasn’t that I had all the answers but just to ask questions. Having never met you I don’t know your knowledge base or your technical abilities. “How do I do that” is a great question if you really don’t know. I frequent a few different boards and this board by far has the most knowledgeable people, I am not sure how many actual mechanics there are here but there is at least one that I that I have been able to discern. There are many engineers though for sure.
With a voltmeter tied into your TPS go out and drive your car. If you can get a friend with a clipboard to come along and record data great, if you cant talk into a tape recorder as you drive. Record TPS voltage, RPM and A/F ratio and build a map like a BSFC map. The RPM that peak torque occurs at is a published value. That will be the sweet spot for fuel economy for your engine. More data around this region would be more valuable. Maybe just do that RPM alone, as the A/F ratio might stay constant against TPS for all RPMs. You will need an open area that you can vary speed and accelerate free of traffic as some TPS reading will accelerate the car.