When i went to dyno my car the other
day the tech tuning it couldn't get it
to stop running lean under boost.
We are talking 8-9psi
He had it set to 6in 6 out could this cause the problem?
I have the 04 ecotec with the 1 bar . Could this be the Map
Resistor trick?
If so should i just have them add a 330 ohm resistor or is the
diode a better idea?
I'm going back again today so if anyone has any suggestions
i would love to hear it thanx.
5in 5out... But here's the problem...
The SAFC works by adding voltage to the MAP sensor when it wants to adjust the fuel. Well at 0PSI your MAP sensor is already maxed out, so adding voltage isn't going to do anything. The SAFC cannot adjust the fuel in boost.
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Yes i know the rise in rate fmu is handling that
i was just trying to fine tune the fuel
with the safc.
Ahh my fault got what your saying now.
So the safc only lowers the cycle time of the
injector. It can't lengthen it?
See this is why i was trying to have it tuned
by a tech but i think he f'd it up
Is the resistor trick necessary on my car then?
Is it something i should suggest to the tech.
I appreciate you walking me through this
No, point is, the SAFC is not going to solve your lean problem in boost, the only way to fix it is to get more fuel into your engine, which the SAFC is incapable of doing after you hit 0 PSI. Adjust your FMU higher, change your fuel pump, or change your injectors. You could also add an EIC.
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Injectors a possibility.
Hahn informs me the injectors and fmu
should be perfectly sufficient for 250hp at 10-11psi
I checked with them first.
My goal was to Tune the fmu to running rich in that area
and use the safc to get better control of my a/f ratio
My only thought now is the fmu is messed up
If he is boosting 8-9 Psi, then couldnt the safc be tuned so that it tells the computer there is 11-12 Psi flowing. After all the max on the Map sensor is Roughly 15 Psi, so at 8-9 Psi its not sending the full 5 volts to the ecu.
safc's are used to do one thing, "kinda" lean out fuel. me and my friend did all the figuring hands on.. what he "had" 03 eco, 12-1 fmu, msd pump, safc2.. after all the playing around we did, not on a dyno so i may be wrong, but taking hundreds of pulls adjusting boost from 5-8 psi, and playing with the enrichment skales on the safc, what we found out was that with tthe fmu shooting the fuel presure into the 100's the car was just running pig rich no matter what we did with the safc. and see this is the opposit of your problem.. so @!#$? um. you have a fmu and safc? is there any added fuel? or just the fmu? and you may have the fmu backwards.
r.i.p rotary
DCStang67 wrote:If he is boosting 8-9 Psi, then couldnt the safc be tuned so that it tells the computer there is 11-12 Psi flowing. After all the max on the Map sensor is Roughly 15 Psi, so at 8-9 Psi its not sending the full 5 volts to the ecu.
Map sensor is 1 bar, 14.7 PSI, this is also the pressure at sea level, so yes, at 0 PSI (turbos boost OVER the atmospheric pressure), you are having roughly 14.7 PSI in your engine of air. Boost at 5 PSI and you're at 20. The map sensor does not read anything over atmospheric, which is 0 PSI relatively speaking.
And the SAFC does not work by telling the map sensor what PSI its reading, it simply changes the voltage that gets sent to the ECU.
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