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Timing advance setting with Engine Management System
Not me. I got a woody! </boi-oi-oi-oing!> hahaha :D
> good info dan.
> now does anybody else have a headache after reading that much techinical
> info
>
> On 5/3/05, Dan Bubb <jdbubb@ix.netcom.com> wrote:
>>
>> For full throttle I think what you have is pretty close.
>> Full advance by 2500 seems a little fast to me, so I'd lower the value at
>> 2440 somewhat.
>>
>> Couple general comments about spark timing and setting up load points on
>> an aftermarket engine
>> management just cause I can't help myself.
>> 1. I don't think these engines need a huge amount of total advance at WOT
>> based on input from both
>> TT and NGP. I would think 32-34 max would be good. Plus you have a higher
>> than normal compression
>> ratio and that speeds up the burn rate meaning you need even less advance.
>> 2. The burn rate in the combustion chamber varies with throttle opening.
>> More throttle=higher
>> density in the chamber=faster burn rate. So, at partial throttle (cruise
>> conditions) you need to
>> have more advance. So, you might try adding more advance in the lower load
>> positions. As an example,
>> if your engine cruises at .5 bar/15"vac then you probably want to have
>> 12-15 deg more advance at
>> that RPM point then you do at WOT for that RPM. In other words you want to
>> emulate the vacuum
>> advance of mechanical distributors.
>> 3. Engines are generally linear in their requirement for fuel or ignition,
>> but with some exceptions.
>> One is around idle where some monkey business , mostly with the ignition
>> timing, can improve idle
>> quality especially if you have wild cams. The second is engines with wild
>> cams tend to have weak low
>> speed performance and at a certain RPM "come on the cam".
>> The TEC II (and also Megasquirt) has 8 load and 8 RPM points. I would
>> adjust the RPM points so you
>> have a couple close to the idle speed, and several around the RPM where
>> the cams kick in to handle
>> the drastic change in fuel required there, of course one at your max RPM,
>> and last one or two in
>> between those points.
>> For idle, one at the desired idle speed, then one RPM point a few hundred
>> below that. This lets you
>> put in the actual idle advance at the idle RPM and really bump up the
>> advance if the idle should
>> falter some. So, say 6 deg across all load points at 1000 RPM and 20 deg
>> at all load points at 700
>> RPM. Idle drops down, advance kicks in and helps to bump the idle back up.
>> Let's say your cams kick in around 4000. If it's a big change in power
>> then you may want an RPM
>> point at 3700, one at 4000 and one at 4300. The ignition requirements
>> don't change drastically when
>> the cams come in (or maybe it just doesn't matter that much) but for good
>> drivability the fuel will
>> change quite a bit and that's why you need a bunch of RPM points around
>> non-linear behaviour.
>> Also, since you're running ITB,s I'd also bunch the load points towards
>> the higher end of the range
>> especially if your using MAP (manifold absolute pressure) for load. Maybe
>> if you're running throttle
>> position for load this would be less important.
>>
>> I'd put in an ignition map here but the formatting will be all hosed. So,
>> if you'd like my idea of
>> an ignition map LMK and I'll send you one in Excel.
>>
>> And one last comment. You are going to run more than 7000 RPM?? I bet your
>> power peak will be that
>> high and you need a few hundred RPM beyond that for maximum performance
>> through the gears.
>>
>> Anyway, that's what I think. Most of this is based on experience with a
>> 2.0L 8V with ITB's and a 306
>> cam using Megasquirt running to 8000 RPM.
>> Hope this is clear for all that read this far.
>> Dan
>>
>> ----- Original Message -----
>> >From: "Don Walter" <dswalterwi@gmail.com>
>> >To: "Scirocco List" <scirocco-l@scirocco.org>
>> >Sent: Monday, May 02, 2005 9:56 PM
>> >Subject: Timing advance setting with Engine Management System
>> >
>>
>> >Okay with the TEC 2 I can set an 8x8 grid for the Advance based on RPM
>> and
>> >MAP (manifold air pressure). I have a 16V 2.0L with Autotech Sport Cams
>> and
>> >have looked heavily throught the Bently on an idea how I should be
>> setting
>> >the advance table. As near as I can find the idle advance should be
>> around 4
>> >to 8 degrees with the full advance by 2500 rpm as 13 degrees mor than
>> base.
>> > Quote from Bently:
>> >CIS-E rpm-dependent timing advance:
>> >total timing @ 2500 rpm = measured base timing value (4 to 8 degrees
>> BTDC)
>> >plus approixmately 13 degrees
>> > In the TEC 3 grid I have it set on average as:
>> >12 degrees at 816 rpm
>> >17 degrees at 1628 rpm
>> >34 degrees at 2440 rpm
>> >36 degrees at 3252 rpm
>> >36 degrees at 4064 rpm
>> >36 degrees at 4876 rpm
>> >36 degrees at 5668 rpm
>> >36 degrees at 7000 rpm
>> > 36 degrees total I am thinking about turning down to 28 degrees total.
>> > Does anyone have any input as to how they have theirs set?
>>
>> --
>> Don Walter - Waukesha, WI
>> 1986 2.0L 16V TEC 2 Black Scirocco (see progress at
>> http://www.cardomain.com/memberpage/708939)
>> 1986 2L 16V Toronado Red Scirocco (under repair)
>> 1988 1.8 16V Toronado Red Scirocco (sold on 3/29/04)
>> 1984 1.8 8V Pewter Scirocco (sold years ago)
>> 1971 Karman Ghia (sold)
>> 1969 Karman Ghia (sold)
>> 1969 Beetle (sold)
>>
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