[Diy_efi] Making a fake O2

[jeff matthews]

I'm extremely surprised, especially with
the Miata, that you can open the throttle and
accelerate long enough to make boost, but not to
switch the ECU out of closed-loop.  A lot of engines
would go bang if you tried to run them that way, with
narrow-band closed-loop.

Yes, these engines will go bang if you boost w/ the ECU in  closed loop, esp 
the protege 2.0L's.  That is why, using a map sensor and simple comparator 
circuit, I send the ECU a signal of .39v under boost.  Otherwise it will try 
and lean out too much and BOOM!
W/ the miata I see boost around 2K rpm partial throttle,  5psi by 2200rpm 
WOT and full boost  by 2600-2800rpm's
(have run as much as 12psi all the way to 7200rpm's.)  I keep it set @ 
~=8psi though,  That helps keep it civil :)  over 10K miles this way--and 
stock clutch

On the Porsche set up, what does your A/F's look like?
Stock ecu?  No fuel control? or can you 'chip' that ecu?

FWIW  I went threw many stages with the miata, earlier ones did not use any 
o2 modding either ,including using an AFPR, worked well never had any 
problems and I know of a few people that don't use any O2 mods on their 
OBDII's-- But it is a mandatory on the protege , so it wasn't anything to 
throw an extra one on the miata.  I know of others (mostly supercharged 
miata's) that complained of a slight hesitation in partial throttle 
response,  which after they 'clamped' their O2 voltage, the problem went 
away.

Best regards,
JEFF

<br><br><br>From: "Marc Reviel" 
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19:14:12.0157 (UTC) FILETIME=[97408ED0:01C56939]<br><br><br>----- Original 
Message ----- From: "Adam Wade" 
<espresso_doppio at yahoo.com><br>To: 
<diy_efi at diy-efi.org><br>Sent: Friday, June 03, 2005 7:08 
PM<br>Subject: RE: [Diy_efi] Making a fake O2<br><br><br>>--- jeff 
matthews <maple69vt at hotmail.com> wrote:<br>><br>>>I have a 
1996 Miata and 2003 Prot?g?.  They both<br>>>have the stock ECU's.  
But because I get board<br>>>around the garage they both are 
turbocharged.  They<br>>>both need to run richer under 
boost.<br>>>They both have piggy back fuel and timing 
controls,<br>><br>>Ahh.  THAT answered my question.  It's not the 
stock<br>>ECU dealing with the boost, it's an outboard<br>>controller. 
  I'm extremely surprised, especially with<br>>the Miata, that you can 
open the throttle and<br>>accelerate long enough to make boost, but not 
to<br>>switch the ECU out of closed-loop.  A lot of engines<br>>would 
go bang if you tried to run them that way, with<br>>narrow-band 
closed-loop.<br><br>FYI, I am just finishing a prototype of a twin turbo 
upgrade for the Porsche Boxster.  The test mule is a 1999 model, 2.5L, 11:1, 
no variable cam timing, and last year before they went to e-throttle.  I 
designed it for low-boost/earliest spool up - 2000rpm = 2.5psi, 2400 = 5psi. 
During part-throttle/mild acceleration, it is almost always running positive 
boost, and does remain in closed-loop. I have about 1200 miles heavy testing 
on it. So far, no issues at all (not even a CEL). No piggyback stuff, stock 
ECU 
programming.<br><br>-Marc<br><br><br><snip><br><br>_______________________________________________<br>Diy_efi 
mailing 
list<br>Diy_efi at diy-efi.org<br>http://lists.diy-efi.org/mailman/listinfo/diy_efi<br>