RE:Re: toasting an O2 sensor, hesitation at boost, and more

[QSHIPQ@aol.com]

Phil writes:
> It was found by an independent researcher that the code in the 200q20v
> Hoppen, (earlier) Intended Acceleration, and TAP chips were functionally
> identical, with no significant variance in the code.  However, the code is
> designed to operate with a 2.5 bar pressure transducer (PT), as the code is
> set up to allow 2.2 bar. A 2.0 can't do 2.2.

>>Actually, they usually can.  What happens is that they deliver a
>>(correct) voltage out of the range expected by the ECU, so the ECU
'>>sees' overboost and shuts down the fuel pump. 

Not my understanding Phil.  Pressure transducers can only "control" the chip 
tables to their rated capacity.  Most 2.0bar computer (chip) mods will shut 
down the Fuel pump at 1.95bar>, the car will never see 2.2bar with a 2.0PT 
(in fact, most won't see 2.0bar with a 2.0 bar PT).  Look at it this way:  
Everything above 1.95 bar in a 2.0 PT is the same voltage.  So, in order for 
a chip mod to get the ECU to actually 'see' and/or react to 1.2bar pressure 
differently than 1.96bar, you need a 2.5 or 3.0bar PT.  OR more specifically, 
a 2.0PT with 1.2 bar boost, means the voltage output is exactly the same from 
.95-1.2bar (and above) boost pressures.  My brother is a Motorola tech 
engineer familiar with test PT, and his warning is well taken:  PT are not 
meant to whack maximum output reliably.  Eventually the PT will fail (or 
worse, just get more innacurate) if it's whacked at or above it's max 
designed output too many times.  Luckily for all of us, the Bosch PT seem to 
be most durable in this respect.    

> The _real_ 'el cheapos'
>just put a simple voltage divider circuit between the PT and the ECU to
>fool the ECU into thinking boost is lower than it is, and shove in a big
>spring or Schrapnelknobbeln. 

Luckily for all listers , because of this very list (the artistes formerly 
known as the qlcc nerds), the above are waaaay passe.  I know of no current 
voltage divider circuits being sold by the major players anymore.  Some of 
you with early stage 1 and II mods (3years or more old) may have the above. 

 >Chief symptom? The dashboard boost gauge
>is either disconnected or the owner is told to mentally remap its
>output: "Yeah, it's only saying 1.3 bar but it means 1.8".  

My thinking of dashboard guages is well known here.  They average (which 
means they might never read peak), are usually inaccurate, and are only a 
guideline.  My first question when I hear a boost claim, "where did you see 
that?"  "On the dash guage."  My advice, you run modded boxes, get a good 
analog boost guage.   Beware too, Phil, the guage circuit can be modified on 
the boxes to be accurate.

>A second
>kludge of some sort is then required to increase fuel flow - cheapest is
>a different profile in the metering head cone or a tweak to control or
>system pressure.  

The metering head cone or attachments to the flap (ala Golf mods) really 
allows more airflow around the flap, not really more fuel.  Once a metering 
head is at it's maximum, a profile change won't allow more fuel, only more 
air.  Few tweek system pressure, because that really doesn't do much, other 
than put a higher strain on a set of old system pressure lines.  The control 
pressure, is a good area to look at, since most control pressure systems can 
be tweeked to allow more fuel.  

>The cost of doing something like this is about $60 -
>I've seen people pay over $1000 for it.  The ECU _isn't_ remapped.  Easy
>to check - pull the ECU apart and look for the chip.  If there are any
>extra wires soldered around the pressure sensor area, beware.

Agreed.  Remapped chips are the answer, but really have been for some time 
now.  In the case of OBD systems, they have to be.  It's really the older 
(4yrs+) Mac 01/02>11C mods that should heed the above carefully.

HTH

Scott Justusson