I was running at 18 psi a few days back for about 2 weeks. I only put it down back to 10.5 psi because :

(a) john banks got me paranoid and am now waiting for an AFR
(b) Fuel consumption went up dramatically

edit ~ I'm not worried of the engine block as its a closed deck (MY 93 early model ain't it) but the pistons are another story all together.

[Edited by Katana - 6/3/2002 12:11:05 PM]

 

The Max I can run on an MY94, which uses a different MAP to the Post MY97, is just under 17psi.

That's If I want the fuel cut to still work.

The FCD is set to 'step-in' at 4.05V (11psi approx) and 'step-out' at 4.75V (16.5psi approx), car runs approx 14psi with PPP.

If I set slightly above 4.75V for some reason it won't 'Step-out' even if 4.96V is applied. Which is a bit strange, but will do for now.

This is only experienced when fully connected to the car and pressure applied to the MAP sensor.
If it is bench tested using a power supply to provide the varying MAP voltage it works fine. My thoughts are that maybe something in the ECU is loading the signal ?

I might try bringing up the lower level by 100mV to see if I can gain another 100mV at the top end.

[Edited by Scott.T - 6/3/2002 12:23:25 PM]

 

Scott,

As always you're one step ahead of me I was intending to run 15.5PSI.

My FCD works fine on bench but not tested in car yet.

I assumed the ECU would have a very high impedence & thus would work as expected so I'm surprised to hear you get different results when on the car

I assume you're using something to supply pressure to the MAP (big syringe?) - Did you manage to simulate above 18 PSI & does your MAP sensor give the readings we expect at the top end?

Just a bit concerned that maybe the MAP is not capable of producing above approx 4.8V & so it never steps out?

Hopefully will get a chance test this on the car one night this week & will post my results.

Any thoughts on the above?

Cheers,

Chris

[Edited - to say just re-read your post so dis-regard questions over MAP working above 4.8v]

It appears that you have already tested the MAP Senor up to 4.96V so that is probably not the problem.

Just a suggestion - It might be worth checking/changing the impedance around the circuit?

Will still do all these checks & post my results.


[Edited by Chris.Palmer - 6/5/2002 8:50:01 AM]

 

Just fitted (at last) the DIY FCD to my MY94 PPP'd Scoob, and intend to run about 16psi.

What are u running at ?????

 

Hehe, I got an FCD from a friend. Its not the DIY one. Once my AFR has arrived, I'll see how it runs at 18 psi again. My engine should be able to take it if I take a few precautions.

 

Anymore Entries ???

 

Chris,

The MAP can produce upto 4.96V when the engine is running or 5V when 'just' the ignition is on.

So I am a bit miffed why I can't set the 'Step-out' Value any higher than 4.75V. Perhaps the Potentiometers are pulling down the signal being read. But then if they are I would of expected to see this when bench tested.

I used a foot pump, with gauge attached to the MAP sensor input. Not very accurate, but I could see the 'Step-In' working at 4.05V and then 'Step-Out' at some point, although due to the crude method of applying pressure, could not really determine exactly where, but it looked to be around 4.7-4.8V.

Anyway, this morning was the 1st chance I got to try this (on the way to work) and managed to get a bit more boost with the Actuator shortened by 2 turns. I'll see what it settles at over the next couple of days, once the ECU had re-configured.

 

Just read your reply - makes my email question over then number of actuator turns seem pretty stupid.

Anyway - excuse to BTT