[DeTomaso] EFI

Wed Oct 5 14:50:27 EDT 2011

5 okt 2011 kl. 20:09 skrev "Jerry R Knotts" <knottsj at galstar.com>:

> Ford Mass Air ECUs from early on, know how far away the O2 sensors are from 
> the exhaust port and the pulse timing by rpm,and supposedly can adjust 
> specific cylinder injection pulses by knowing the fireing order.

Not really. It adjusts the banks separately, but not per cylinder.

There is a table with HEGO delays, but it is used to tune the feedback delay to improve learning speed and stability.

The Ford efi is really advanced.

I adjusted the injector timing today, delaying the opening events at low rpm to avoid having unburnt fuel going through the exhaust due to cam overlap, and it appears to have improved idle mixture.

The internal Ford manual, which describes everything, is available on the net, and I am frequently amazed at how clever the system is.

Thomas

> 
> jerry
> ----- Original Message ----- 
> From: "Ken Green" <kenn_green at yahoo.com>
> To: "Kirby Schrader" <kirby.schrader at gmail.com>; "Mikael" 
> <mikael_hass at mail.tele.dk>
> Cc: <detomaso at realbig.com>
> Sent: Wednesday, October 05, 2011 12:53 PM
> Subject: Re: [DeTomaso] EFI
> 
> 
>> I'm putting together a system using a FAST XFI ECU, and they use feedback 
>> from the O2 sensor to make corrections to a VE table. I'm sure you have to 
>> be close to get started, but it seems like it makes sense. Hopefully I'll 
>> know more in a few months.
>> 
>> But it's really a two dimensional problem, fuel and timing. I don't think 
>> the O2 sensor tells you anything about timing (not totally sure about 
>> that), and you'd have to get on a dyno to optimize advance. I was talking 
>> to Jim Bell (owns Kenne Bell Superchargers) yesterday and he said that 
>> there are things you can do with timing to improve mileage under low load 
>> conditions, like cruising on the freeway. Not something I'd want to play 
>> around with.
>> 
>> I asked Jim about an idea I had and he said some of the new cars actually 
>> have a cruising mode where they open the throttle and control the engine 
>> by the amount of fuel injected to reduce or eliminate parasitic losses 
>> from having to suck air in past a mostly closed throttle body. Lots of 
>> neat things can be done when you get away from carbs.
>> 
>> Ken
>> 
>> 
>> ________________________________
>> From: Kirby Schrader <kirby.schrader at gmail.com>
>> To: Mikael <mikael_hass at mail.tele.dk>
>> Cc: detomaso at realbig.com
>> Sent: Wednesday, October 5, 2011 7:38 AM
>> Subject: Re: [DeTomaso] EFI
>> 
>> Good suggestions. Sometimes there are really strange things. I am trying 
>> to
>> tune my Pantera and was having difficulties. Turns out my 13 year old MAP
>> sensor is reading 45kpa when it should be saying 101. And it seems to be
>> intermittent at that. Makes for difficult tuning.
>> 
>> As a comment though... most systems I know about and have read about are
>> only closed loop during cruise.
>> I could be wrong, but they all switch off closed loop during full throttle
>> and fall back to a map.
>> 
>> These so called 'self learning' systems are all BS as far as I'm 
>> concerned.
>> You have to get close manually before you can go closed loop. There's no 
>> way
>> the system will compensate for something that's completely out in left
>> field. No way. I don't care what you read in the marketing blah blah blah.
>> 
>> This is the same as a carburetor. You have to pick the right type of carb,
>> CFM and jetting to get close and then you start tuning for YOUR engine. I
>> bought a carburetor once that was supposed to work as is. My car would
>> hardly run.
>> 
>> And remember... when a new EFI system is put on a production car, the car
>> companies literally have a full team of engineers and technicians who run
>> the engine on a dyno and then take the cars out to all parts of the 
>> country
>> and run them through tests in all conditions. Altitude, cold, hot, humid,
>> etc..
>> Why? To set up the maps and feedback loops so the system works as you 
>> would
>> expect it to when you buy it off the showroom floor.
>> 
>> Ever seen the documentary on the development of the Ford GT? They couldn't
>> even get the engine to START the first time around!
>> The 'EFI expert' of Ford ended up using what I think I remember hearing as 
>> a
>> program from a Crown Vic! Just to get it running! Then they started 
>> tuning.
>> 
>> So even the experts have to work hard to get a EFI system set up the first
>> time around.
>> 
>> And we're talking about each an every one of us having a completely
>> different engine. Different heads, cams, compression, bore, stroke, blah,
>> blah, blah.... so each and every map and setup will be different.
>> 
>> OK, I'm off my soapbox now... I like my EFI setups and will continue to 
>> use
>> them.
>> 
>> FWIW,
>> Kirby
>> 
>> 
>> 
>> On Wed, Oct 5, 2011 at 09:06, Mikael <mikael_hass at mail.tele.dk> wrote:
>> 
>>> Suggestions: I was sitting here thinking, can I suggest some remedy for 
>>> the
>>> lean and severe bogging. Justin, I'm sure you've done all the sensible
>>> things, so I'll give you a few totally weird suggestions, forgive me.
>>> -Some EFI systems work strange if they don't get enough juice
>>> (electricity).
>>> Is your alternator fine? Grounding? Are there grounding wires from engine
>>> and gearbox to chassis?
>>> -I once had a car that did the same, but with a carb. It turned out to be 
>>> a
>>> wire that was neither isolated nor fastened properly, so the g-force made
>>> it
>>> short against the engine
>>> I know, weird suggestions.
>>> 
>>> Some comments, from many angles, from a carb fan:
>>> -Not many people can feel the difference between a properly tuned EFI and 
>>> a
>>> properly tuned carb
>>> -On non-fuel-economy cars, I'd never do EFI. Why add complexity? Why 
>>> spend
>>> money?
>>> -All carbs I've had have on an O2 meter shown a little lean when
>>> accelerating, and still have excellent throttle response
>>> -Buying things partly because the company claims to have experts sitting
>>> waiting to take your call is very optimistic. These are slightly trained
>>> call center employees, with targets on number of calls per day. My
>>> experience is that you quite soon know more about their product than they
>>> do
>>> 
>>> Question: Are any of those EFIs closed loop? That's how OEM works, and if
>>> it
>>> is, then tuning should be unnecessary
>>> 
>>> Mikael
>>> 
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