Can use some help - LS1 => Porsche 928
07-11-2010, 01:27 AM
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Can use some help - LS1 => Porsche 928 Greetings,
I am attempting to complete my 2001 vette LS1 to Porsche 928 conversion. Engine starts and idles perfectly. When I accelerate under load, it bogs down terribly. If I accelerate slowly, it works fine, power and all. I have included a display of key engine parameters, which show problems.
I installed a fuel pressure regulator on the rail, it shows 58 psi (which is correct) when under pressure, and pressure stays at 58 when pump is turned off. When I go Wide Open Throttle (WOT), the pressure drops to about 45 psi. Would that drop cause the really bad bogging down that I am experiencing? Would low fuel pressure cause the incorrect spark advance shown in the display below?
PLEASE SEE SCAN DISPLAY BELOW FOR THIS DESCRIPTION:
In the scan below, I accelerated to WOT twice, which resulted in terrible no-power bogs. I then accelerated slowly, which worked perfectly, as shown in the graph.
Knowing very little about what it is supposed to look like, I would think that the advance dropping to -9 during WOT is wrong. I plotted WOT in my Chevy avalanche and advance goes from +11 to +26. In this plot, when I accelerate slowly (good power), the advance goes from +12 to +29, thus telling me that a positive advance is what it should be doing.
So, my question is, does anyone know of any sensors that feed the computer that have the ability to cause such an incorrect advance. Can a bad IAT do that? This includes inputs from the transmission (this computer, in a porsche, has no transmission inputs) and anything else anyone might know about, that I might not have connected.
Thanks to any and all,
928vette
I am attempting to complete my 2001 vette LS1 to Porsche 928 conversion. Engine starts and idles perfectly. When I accelerate under load, it bogs down terribly. If I accelerate slowly, it works fine, power and all. I have included a display of key engine parameters, which show problems.
I installed a fuel pressure regulator on the rail, it shows 58 psi (which is correct) when under pressure, and pressure stays at 58 when pump is turned off. When I go Wide Open Throttle (WOT), the pressure drops to about 45 psi. Would that drop cause the really bad bogging down that I am experiencing? Would low fuel pressure cause the incorrect spark advance shown in the display below?
PLEASE SEE SCAN DISPLAY BELOW FOR THIS DESCRIPTION:
In the scan below, I accelerated to WOT twice, which resulted in terrible no-power bogs. I then accelerated slowly, which worked perfectly, as shown in the graph.
Knowing very little about what it is supposed to look like, I would think that the advance dropping to -9 during WOT is wrong. I plotted WOT in my Chevy avalanche and advance goes from +11 to +26. In this plot, when I accelerate slowly (good power), the advance goes from +12 to +29, thus telling me that a positive advance is what it should be doing.
So, my question is, does anyone know of any sensors that feed the computer that have the ability to cause such an incorrect advance. Can a bad IAT do that? This includes inputs from the transmission (this computer, in a porsche, has no transmission inputs) and anything else anyone might know about, that I might not have connected.
Thanks to any and all,
928vette
07-11-2010, 01:07 PM
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Might it be related to open loop fueling? Are you using an oem ecu and tune?
I am a little familiar with Subaru tuning, but am very new to the LS1 world, so take my questions with a grain of salt.
I am a little familiar with Subaru tuning, but am very new to the LS1 world, so take my questions with a grain of salt.
928, accelerating, bogs, chevy, converion, conversion, conversions, guide, handle, hybrid, ls, ls1, ls1tech, ls3, porsche, tranmission, tranmition
