MS1 drivability issues/questions
04-21-2011, 06:29 PM
#1
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MS1 drivability issues/questions
I have had the MS1 installed on my 91 for over a year now. First on my old 200k mile 1.6 and now on the fresh 1.8 I installed over the winter, no turbo yet. Everything is tuned pretty well. It runs very well with no major issues.
At low rpm and low load (driving in parking lot in 1st) it is very toutchy on the gas. Its kinda hard to describe and has made it even harder to search for. It is like a little self induced oscillation that is very hard to control unless you give it a little more gas or speed up. It really sucks in stop/go traffic. I checked to see if maybe it was related to the fuel pressure regulator since it was happening at low maps and ran it for a while with the vacuum line diconnected and plugged. Still same behaviour. I built a MS1 years ago for my brothers FFR cobra and we had the same issue with it, I attributed it to alot of low end torque in a very light car and the nut behind the wheel. I definitely do not have that much torque in the 1.8 so I doubt that is the issue in the MS'ed Miata.
I have also noticed a very slight oscilation when cruising at 70mph some times. It is very subtle. I gave tried to correlate the oscillations with fluctuations in MAP or any other readings but MAP does not change at the rate that I feel the oscilations at cruise.
On my brother's cobra it improved greatly when he switched to MS2 a whie back, don't really know why, I think it might be due to MAP averaging or something.
At low rpm and low load (driving in parking lot in 1st) it is very toutchy on the gas. Its kinda hard to describe and has made it even harder to search for. It is like a little self induced oscillation that is very hard to control unless you give it a little more gas or speed up. It really sucks in stop/go traffic. I checked to see if maybe it was related to the fuel pressure regulator since it was happening at low maps and ran it for a while with the vacuum line diconnected and plugged. Still same behaviour. I built a MS1 years ago for my brothers FFR cobra and we had the same issue with it, I attributed it to alot of low end torque in a very light car and the nut behind the wheel. I definitely do not have that much torque in the 1.8 so I doubt that is the issue in the MS'ed Miata.
I have also noticed a very slight oscilation when cruising at 70mph some times. It is very subtle. I gave tried to correlate the oscillations with fluctuations in MAP or any other readings but MAP does not change at the rate that I feel the oscilations at cruise.
On my brother's cobra it improved greatly when he switched to MS2 a whie back, don't really know why, I think it might be due to MAP averaging or something.
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04-21-2011, 11:55 PM
#4
My old MS1 drove better than my current Haltech in it's current state. Not much time has been done tuning it though for drivability. The Haltech surges a lot (no tps right now) and the MS1 never erally did (also no TPS).
I imagine though when I go back for the Rotrex tune with my BMW tps things will be completly diff.
It's all in the tune, not the hardware... for the most part.
I imagine though when I go back for the Rotrex tune with my BMW tps things will be completly diff.
It's all in the tune, not the hardware... for the most part.
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04-22-2011, 08:24 AM
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I will when I get home. I would not quite define it as surging, especially since I am running NA. It is just a slight oscilation in the power delivery. Its one of those weird things that is hard to describe unless you are sitting in the car. I was hoping that this might be a more common phenomena like the 65mph shimmy.
I went ahead and tuned with a target AFR that was constant accross the whole <2500rpm and <40kpa as well as a constant advance in the same area to ensure that I am not moving accross a timing change or fueling change which could cause any upsets or transients. The resulting VE table is smooth in the area as well.
I have tried two different MS1 boxes and both give the same results, not that that really proves anything.
I went ahead and tuned with a target AFR that was constant accross the whole <2500rpm and <40kpa as well as a constant advance in the same area to ensure that I am not moving accross a timing change or fueling change which could cause any upsets or transients. The resulting VE table is smooth in the area as well.
I have tried two different MS1 boxes and both give the same results, not that that really proves anything.
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