[Diy_efi] Donegan ECU

[Tom Visel]

Those OEMs that moved the regulator to the fuel tank did it for 
evaporative emissions control reasons - less heat in the tank means 
fewer vapors to deal with.  This is the same batch of deep thinkers that 
brought us oxygen sensors after the catalytic converter(s) for measuring 
catalyst efficiency.  If the "Donegan ECU" isn't going to be OBD-II 
compliant (or did I miss something) why bother to have the extra two 
oxygen sensor inputs?  The poor OEMs only have them so they can 
guarantee to the EPA that they have a way of measuring catalyst 
degradation since all emissions systems have to be monitored.
TomV

Steven P. Donegan wrote:

>Well - for track days I simply put dry ice in my fuel cold-can thing -
>that solves most vapor-lock style problems and lasts for a couple of
>hours. Simple low-tech solution to that problem. Given the lack of
>response to my original posting I believe providing PWM fuel pump
>control and support for a fuel pressure sensor is useful. 
>
>Given that I normally run at Willow Springs or Buttonwillow during the
>winter months temps are not normally a factor anyway.
>
>On Thu, 2007-01-04 at 12:23 -0600, cobraman at insightbb.com wrote:
>  
>
>>My "Edelbrick" ProFlow has fuel pressure controlled with engine vacuum. On track sessions on very hot days, the fuel in the rails will boil under hard braking - accelerator closed (low fuel pressure). When you finally step on it (52 psi), nothing happens until the vapor "recirculates" or is expelled.  Usually takes a second or so.  I don't think dead heading would do any better - probably just need to keep a constant fuel pressure. 
>>IMHO, hot fuel should give better economy - easier to vaporize - for those green members.  TomS
>>
>>
>>
>>
>>
>>
>>
>>ld
>>    
>>
>>>consume the gas in the rails well before it got warm :-) However this
>>>does raise a point - perhaps my ECM/PCM/EFI computer needs a way 
>>>to open
>>>a fuel return line and to sense fuel temp in the rails? Any 
>>>ideas on how
>>>useful that would be in the 'real world' anyone?
>>>
>>>On Thu, 2007-01-04 at 14:56 +0800, Mike wrote:
>>>      
>>>
>>>>Isnt one of the main needs for fuel return the fact the fuel 
>>>>        
>>>>
>>>is heated quite a
>>>      
>>>
>>>>bit in the fuel rail whilst its waiting for injection ?
>>>>
>>>>Of course there is a commercial factor as fuel returns used to 
>>>>        
>>>>
>>>be so
>>>      
>>>
>>>>much cheaper than any electronics but getting around the fuel 
>>>>        
>>>>
>>>heating etc
>>>      
>>>
>>>>Also the issue of control feedback is an issue to avoid 
>>>>        
>>>>
>>>vapourisation> during hot start, the good thing about return is 
>>>this can be flushed out,
>>>      
>>>
>>>>and esp for a turbo as a pressure hold tank can "remember" the last
>>>>max pressure and temporarily raise the fuel rail pressure to 
>>>>        
>>>>
>>>this during
>>>      
>>>
>>>>start to avoid vapour issues... etc
>>>>
>>>>Regards
>>>>
>>>>Mike
>>>>
>>>>
>>>>
>>>>At 07:23 AM 1/4/07, you wrote:
>>>>
>>>>        
>>>>
>>>>>This sounds cool...is closed loop control of fuel pressure an 
>>>>>          
>>>>>
>>>oem feature for any new vehicles? Or just something you are 
>>>trying out? Are you going to use a PI controller? I am guessing 
>>>when you snap the throttle open the PI controller should know 
>>>about this quite quickly...not wait to see a drop in fuel 
>>>pressure? 
>>>      
>>>
>>>>>>To add something somewhat useful to the list in this reply 
>>>>>>            
>>>>>>
>>>I'll say the
>>>      
>>>
>>>>>>Donegan ECM is coming along nicely :-) The input board is 
>>>>>>            
>>>>>>
>>>going to fab
>>>      
>>>
>>>>>>out at about 3.0 inches by 2.2 inches (exactly matching the 
>>>>>>            
>>>>>>
>>>CPU board -
>>>      
>>>
>>>>>>ARM based Steve). Inputs designed in are MAP, MAT, 
>>>>>>            
>>>>>>
>>>Barometric, Coolant,
>>>      
>>>
>>>>>>Throttle, Oil pressure/temp, 4 ea O2 sensors, Crank and Cam 
>>>>>>            
>>>>>>
>>>position, 2
>>>      
>>>
>>>>>>ea EGT sensors - well pretty much everything everyone told 
>>>>>>            
>>>>>>
>>>me should be
>>>      
>>>
>>>>>>sensor inputs. Fuel pressure input I'll put on the 'relay' 
>>>>>>            
>>>>>>
>>>control board
>>>      
>>>
>>>>>>- that will do PWM control of the fuel pump eliminating the 
>>>>>>            
>>>>>>
>>>need for a
>>>      
>>>
>>>>>>regulator or return line.
>>>>>>
>>>>>>Happy New Year :-)
>>>>>>            
>>>>>>
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>>>>>          
>>>>>
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