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Heavy Jerking at Low Acceleration


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Hi Guys,



I have recently changed my HG. Since then though, I have been having a problem everytime I am coming to a stop. Let's say if I am approaching a red light and leave the car in whatever gear be it a very low or high gear, the car begins to jerk really heavily/violently. At full revs it works fine, the problem is only when slowing down. If I go into neutral while coming to a stop, there is absolutely no jerking. I think my O2 sensor is on its way out as well so....don't know if that is contributing too.


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Forgot to mention that I also changed the fuel pump when the HG was changed. Took it out last night and noticed that when it jerks, both the O2 and voltage readings dip alot.


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  • 1 month later...

I still have not got around to changing my O2 sensor. I am however getting normal readings on the air/fuel gauge. What i find strange is that my battery voltage reading fluctuates by 1 volt less when it jerks/idles erratic. It idles almost as if there is a misfire.


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i had this issue in the past with emu and larger injectors


so i had the ignition map and fuel map adjusted in the low rpm/vacuum range and that helped a lot...i suspect there was some "fighting" between the stock ecu and emu in my case at low rpms



with a full standalone you should be able to tweak it a bit with total precision



i'm not a tuner, so i cant speak with any conviction, but maybe at low rpm excessive ignition is not so good when the engine is naturally trying to cruise/slow-down---hence the jerking effect, as you are slowing down the car, while the ignition setting is trying to keep the engine going forward


Edited by gorganl2000
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will a mismatched fuel pump cause this jerking?...keeping in mind that i do not have any engine management. i am not sure what pump the mech used, i know that it was a new pump but not the oem starlet pump


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  • 4 months later...

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