msg1 Posted July 21, 2017 Share Posted July 21, 2017 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. Quote Link to post Share on other sites
Mk3 silver gt Posted July 21, 2017 Share Posted July 21, 2017 Id be interested in this because I have the exact same problem n I've swap the o2 sensor and tps aswell but cant get to the bottom of it but my last option is to get my mapped tweaked. Il be keeping a eye on this post Quote Link to post Share on other sites
msg1 Posted July 24, 2017 Author Share Posted July 24, 2017 yup Quote Link to post Share on other sites
Mk3 silver gt Posted July 25, 2017 Share Posted July 25, 2017 Does your engine her the most when it's 2000rpm or lower? because that's when mine does it Quote Link to post Share on other sites
msg1 Posted July 25, 2017 Author Share Posted July 25, 2017 Yeah about that is correct. It is usually when i am approaching a stop and my foot is off the gas pedal but the car is still in gear. Quote Link to post Share on other sites
msg1 Posted July 28, 2017 Author Share Posted July 28, 2017 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. Quote Link to post Share on other sites
msg1 Posted September 27, 2017 Author Share Posted September 27, 2017 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. Quote Link to post Share on other sites
GP82 Posted September 29, 2017 Share Posted September 29, 2017 Check that Your engine timing is correct. Check Your ignition timing. If this is all good, check the rotar arm, dizzy cap, leads, plugs and coil are healthy. Quote Link to post Share on other sites
gorganl2000 Posted September 29, 2017 Share Posted September 29, 2017 (edited) by any chance do both of you run standalone or piggyback,,,running any bigger injectors than stock? Edited September 29, 2017 by gorganl2000 Quote Link to post Share on other sites
Mk3 silver gt Posted September 29, 2017 Share Posted September 29, 2017 Saying that I'm running a apexi pfc and 430cc injectors Quote Link to post Share on other sites
gorganl2000 Posted September 29, 2017 Share Posted September 29, 2017 not saying with any certainty, but it may be something to do with the igition/fuel maps at those low rpm how aggressive is your timing around the low rpm (1000 - 2500rpm) while in vacuum? Quote Link to post Share on other sites
Mk3 silver gt Posted September 29, 2017 Share Posted September 29, 2017 Funny you say that I did wonder that but one thing I did notice is if I turn the fuel pressure down it helps but I'm just thinking now to get the map tweaked Quote Link to post Share on other sites
gorganl2000 Posted September 29, 2017 Share Posted September 29, 2017 (edited) i had this issue in the past with emu and larger injectorsso 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 September 29, 2017 by gorganl2000 Quote Link to post Share on other sites
msg1 Posted October 2, 2017 Author Share Posted October 2, 2017 In my case, i do not have any management apart from my stock ecu. Quote Link to post Share on other sites
msg1 Posted October 3, 2017 Author Share Posted October 3, 2017 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 Quote Link to post Share on other sites
msg1 Posted February 22, 2018 Author Share Posted February 22, 2018 problem solved, timing was way off Quote Link to post Share on other sites
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