DIY_EFI Digest Monday, September 27 1999 Volume 04 : Number 548 In this issue: Re: DIY_EFI Digest V4 #547- throttle and timing Typical ignition timing response to throttle snap? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Sun, 26 Sep 1999 15:48:49 -0400 From: "Clare Snyder" Subject: Re: DIY_EFI Digest V4 #547- throttle and timing > > > >Date: Sun, 26 Sep 1999 00:49:35 EDT > >From: PHXSYS@xxx.com > >Subject: Typical ignition timing response to throttle snap? > > > >HI everyone > > > >I was wondering what effect rapid throttle movement has on ignition timing. > > > >I know that extra fuel is injected when the throttle is quickly depressed > to > >improve throttle response. Are there any ignition timing events that occur > at > >the same time to also improve throttle response? > > > >Do you get a little extra advance during TPS event or what? > > Not sure about Efi Systems but on a normal dizzys you just have centrifugal > (rev related) advance and vac advance (throttle positon/rev related). I > know that you don't need vac advance, all it does is improve part throttle > fuel ecconomy. On the Rover Mini Mpi system water temperature is also taken > into consideration... It also uses the MAP sensor (equiv of centrifugal) Pardon? The MAP sensor reads eqivalent to the Vacuum advance - measuring engine load. On a distributor with vac advance. high vacuum advances the timing under low load for economy. sticking your foot into it drops vacuum, effectively retarding spark to eliminate ping under load. A total engine management system would also have to take this into account. > and the CPS (crank positon sensor) to get the engine speed (centrifugal > advance). It also uses a cam postions sensor 'to run in sequential fueling > mode' Is this mode where it learns what fuel it should be putting in from > the Heated oxygen sensor? Why would it need to know where the cam is to run > in the mode? It also measures the actual cam period.... Why does it need to > know the actaul cam period? > > HTH, Thanx, > > Ade > ------------------------------ Date: Sun, 26 Sep 1999 00:24:35 +0200 From: "Espen Hilde" Subject: Typical ignition timing response to throttle snap? > Date: Sun, 26 Sep 1999 00:49:35 EDT > From: PHXSYS@xxx.com > Subject: Typical ignition timing response to throttle snap? > > HI everyone > > I was wondering what effect rapid throttle movement has on ignition timing. > I have heard that some systems uses timing retard under sudden accleration in turbo applications.The turbo needs time to speed up to deliver whats required, doing so, it makes a higher exhaust backpressure on the engine,than under steady state. The engine is more prone to detonations, because of more exhaust residuals /heat in the combustion chamber. One way to lover the detonation tendencies is to lover the timing. ------------------------------ End of DIY_EFI Digest V4 #548 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".