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Re: When asking ecm questions



> Brent Obermiller wrote:
> > P.S. Anyone know anything about the Turbo 2.8L Grandprix's ('88 I
> > think), like which ECM they use?

> Scott Sealander replied:
> Quite a bit, (I own one).  The turbo GP was available in '89 and '90,
> and uses a 3.1L engine.  The car uses a 1227727 ECM, just like (most)
> all the other 'W' bodies.  This is an underhood version of the 1227730.
>
> It is speed density, but the VE tables are VERY poorly calibrated in
> stock form, like higher VE's at 60 kPA MAP than at 100 KPA in some
> places!

I think you have to considered this to be more reflective of the engines VE
don't you?  Each engine has its peak VE areas at places other than at the
top of the load and/or rpm ranges ;-).  Consider the long runners and the
torque curve of this engine and I think this will make more sense.

> is also an error in the fuel algorithm in the stock chip.

Did you find the TPS  based table in the code yet to help you?

> With the stock cal, the car tends to stall often.

Check your deceleration enleanment tables and you will find the culprit.

>I am working on cals for bigger injectors,

That should be a couple single value changes to accomplish, if the code
helps you find the areas to change in the fuel calc.

>a 3-bar MAP,

I would suggest some caution here, the block/heads on the 3.1L only have a 4
bolt pattern per cylinder which do not provide a lot of even clamping
distribution.  And as well, the stock stretch-to-yield head bolts are weak
and will allow the head to lift if you get too much boost, (over 15 psi) not
to mention a few knocks when you are testing and tuning.  Best bet is to pop
the heads and install the FelPro version head gasket as well, order up from
ARP, some studs so you can clamp that head back down with some consistent
force.  Avoid going any bigger on the stud sizes as the extra clamping force
you will gain will distort the aluminum heads and you will be back with a
leaking head gasket again, unless you swap out to the Generation III heads,
these have more meat in the areas that count for claming force distribution,
they also flow (stock) 31% more air on the exhaust side (turbo cars might
like this ;-).

Good luck.

Jeff Middaugh
1990 TGP 13.89 (with only a chip and an air filter upgrade, 12's will be
this year)





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