ecu mods--elec. boost controllers

[Ameer Antar]

thing is though, a mod would be a lot easier and cheaper than an ecu 
replacement.  ECU's are at least $200 guaranteed, plus you need to have 
that one modified too, which actually doesn't sound that much better for 
the engine than just playing w/ the boost sensor voltages. In fact there 
are quite a few MAC 11 mods that just use resistors and reprogrammed boost 
fuel cutoff. If my ECU, is doing fine, I'd rather just work w/ what I have. 
I don't really feel like dealing w/ whether a new ECU would have extra 
sensors, plus that ECU is designed for an engine w/ a comp. ratio of 7.8 
vs. 8.3 for KH, and prolly 8.5:1 on my KH.

You say you used the MAC 7, which is what I have for my KH. I was told this 
box can't be re-programmed. How did you modify this? Thanks again.

-ameer

At 08:06 PM 10/18/00, you wrote:
>Ameer
>
>   I have modified the Mac-7 to use in my 89 200 TQ and it worked fine.
>  I would think you could modify the Mac-11 to use with the KH engine.
>Therefore you would have a chipped KH engine.
>
>Pat Korach
>Kirkland, WA
>
>Ameer Antar wrote:
>
> > there's a lot of ecu mod talk. Mostly about cheap and dirty ways, not
> > replacing the chip. Well, I've been thinking about it, b/c the ECU for the
> > KH engine does not have a programmable chip, so a hack is the only option
> > other than ECU/harness transplant. If the ecu is designed for 1.4 bar, I
> > was thinking of regulating the boost pressure to the ecu. I want to be able
> > to get .8 bar or so, but I don't want to change the way the engine operates
> > below 1.4 bar. The other resistor or aquarium valve mods change the
> > apparent pressure throughout the range. However, if you could
> > electronically control a ecu leak valve, you could tell it to seal shut
> > until 1.4 bar, then gradually divert excess boost beyond that point, until
> > it reaches some set limit. The circuit would probably be just need a couple
> > pressure sensors and an op-amp or 2. The only thing is finding a cheap air
> > valve that can be controlled by an electric signal.
> >
> > To limit the boost pressure sent to the ecu, you could make the valve open
> > slightly and adjust its position just as an aquarium valve, but by sending
> > it a voltage. Or you could do it by opening and closing the valve at
> > different duty cycles to achieve the right amount. The problem w/ this is
> > the valve would prolly have to move very fast. The problem w/ the first
> > method, is that I've never seen a solenoid valve which had variable
> > opening...ie. it's either open or closed. I was thinking of using an old
> > wastegate freq. valve, but I'm not sure how if it'd work, and my car
> > doesn't even have one. How so those boost controllers like GRreddy or Apex
> > products work? Do they use a variable valve or do they use a duty cycle on
> > the valve? Wonder if the valve can be bought separately...I guess I could
> > just buy a boost controller and replace the wg spring, but I'd rather come
> > up w/ something myself if they're like $200. I've asked lot's of questions
> > so I really appreciate any info you can send me.
> >
> > -ameer
> > '84 5kT