[Diy_efi] Motronic fuel cut on excess boost??

[Kenny W]

Quoting Chris Wilson <chris at formula3.freeserve.co.uk>:

> Friday, August 30, 2002, 5:06:56 AM, you wrote:
> 
> 
> > Chris, you could try putting a potentiometer
> in line with the MAP
> > sensor to scale the output from the MAP.  I've
> thought about doing
> > this, but it does it all the time, even in
> vacuum, which isn't good.
> 
> > --Perry
> 
> AFAIK it doesn't have a MAP sensor, works of AFM
> (swinging gate type)
> throttle pot and RPM, with normal temp trimming.
> If it HAS a MAP sensor
> I haven't found it! UK spec 1988 Volvo 740 turbo
> intercooler, on
> Motronic, the one with 2 flywheel sensors, one
> counting ring gear
> teeth, the other about 90 degrees BTDC ( a metal
> tab on the flex plate,
> it's an automatic). Cheers.


Yeah, you just have a flapper door. North American 
Equivalents were running LH at this point, the euro 
Motronic cars use air doors. 
Perry, on the scaling thing, what if it were scaled 
with a slightly more sophisticated circuit- ie the MAp 
signal is first fed to a comparator, which will then 
route the signal to one of 2 possible op amps to scale 
the voltage differently for low load/vaccuum and higher 
loads? I had high hopes for being able to scale my MAF 
based volvo setup to run bigger injectors, but do to 
the non-linear way in which pretty much all of our 
sensors report air mass (or manifold pressure) I think 
it'll only really work with a fairly minor increase, 
I'm going to replace the 30# injectors with 35#, I'm 
hoping an AMM tweak will suffice. I'm starting to think 
the best bet is to either re-map, buy a fuel controller 
like an HKS or Apex-i, or find some other way to add 
more fuel (all of these thngs short of a stand-alone).  
Any htoughts on whether or not I'll get away with the 
30lb-to-35lb swap with a little AMM output tweak? Seems 
like a pretty small change.

-Kenny
AKA Captain Bondo

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