MAP sensor rise time (response time), and noise on MAP signal
Could you guys datalog this test:
While idling, jab the throttle very quickly and briefly around 3x, about a second apart. Then from the datalogs, examine the rise time - the time it takes between - when the log shows the throttle hitting about 15-25%, to the time that the MAP sensor reads about 85-90 kPa. I have an AEM, and in my case with just one restrictor, it's about 80-100 mS. My problem is that my MAP signal is noisy. If I make the restrictor smaller, the rise time goes to > 150 ms, and it causes a tip-in hesitation. I'm interested especially with data with the MAP sensor connected to the FPR. I have a 2000 so I don't have an FPR. |
Well that's interesting.
Do you think a large fuel filter damping the noise on the MAP would also cause a delay in the rise time? I'm wondering if the fuel filter approach would dampen things without slowing the response as much as a restrictor. |
Yes and possibly yes. Thus my post. :)
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I don't have the specific data you're looking for, but here and here is some data I collected on the MAP noise issue. I think it can probably be solved by sampling the MAP sensor in a different way (either at a different crank angle or by oversampling and filtering) but I haven't had a chance to experiment.
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Thanks. I don't expect there to be a difference between the snubbers you linked (porous disc), and a simple restrictor (I used a 5 mm long piece of 3/16" brass rod stock with a .035 hole drilled through).
Has anyone experimented with different pickup points on the VICS manifold? |
Jason, what map sensor are you using on your AEM?
I have a GM 3 bar and i am experiencing some strange issues that im sure i could get tuned out with something like this. (main problem is free revving holding say 10% throttle (delta tps=0) the RPM will swing as much as 1000rpm) |
MAP sensor. I was using a GM 2 bar, but now I switched to a Motorola 2.5 bar.
I'm uncertain if I had the same problem with the 2 bar, but I expect I did, but it's just that I am tuning my fuel map now much more finely and thus only noticed the problem now, in prep for running moar boost. |
I built a circuit which works great:
https://www.miataturbo.net/ecus-tuning-54/my-electronic-map-filter-circuit-48665/ |
Interesting. When I have time I am going to try implementing a discrete time equivalent in the MS2. An exponential smoothing algorithm would be easy to implement and present low CPU overhead.
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kday if you do it digitally you may want to combine a 2 pole bessel (my filter) with a little bit of hysteresis and median filtering.
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