Hello,
I've just upgraded my 1985 GL 5-speed with a Stage 1 turbocharger from PureTurbos and am experiencing a slight but noticeable hesitation occurring when I rev up hard (WOT) from about 2K through to over 5K --- it always occurs at around 4K, but doesn't happen each and every time. It happens in 2nd or 3rd gear and maybe others, but I haven't taken the car that high in speed with this issue. Otherwise, the car dives fine. I'm listing all the engine mods I've had done so that perhaps someone might know what to look for ..
JWT Engine ECU with Mustang MAF sensor
Euro Cams
1mm oversized intake and exhaust Ferrea valves
Ported heads
Bosch 440cc Green Top injectors
Adjustable NISMO fuel pressure regulator set to 3 BAR (fuel pressure gauge installed in line)
Denso/Kyosan Fuel pump (no dampener)
Gutted intake plenum
1 BAR bypass actuator preloaded to 0.4 BAR
Larger 240SX throttle body
Recirculation surge valve installed
This issue only started to occur when I replaced the Turbocharger and fuel pump (done at the same time). There are no issues above 4K as the car continues to run strong and hard up to redline. And if I don't go to WOT but still accelerate hard, there's no hesitation at 4K. This makes me suspect that the fuel pump is not the issue, and I might benefit from a fuel damper. Perhaps some sort of pressure resonance is occurring and the demands at WOT aren't being met by one or more injectors due to a low pressure zone forming in the fuel rail. Can such an issue occur? I'm also wondering if it might not be a bad idea to remove the fuel pump's voltage from ECU control and have it go at full voltage all the time --- the amperage difference is not all that much. I can replace the pump with a relay to fool the ECU into thinking it's controlling the pump's voltage (when in fact it's varying voltage to the relay) and run a steady 12V through the relay to the pump. (A Bosch relay will work within the voltage swing the ECU allows.)
I'll be more than happy to answer any other questions you might have regarding the car and what I've done. Thank you.
I've just upgraded my 1985 GL 5-speed with a Stage 1 turbocharger from PureTurbos and am experiencing a slight but noticeable hesitation occurring when I rev up hard (WOT) from about 2K through to over 5K --- it always occurs at around 4K, but doesn't happen each and every time. It happens in 2nd or 3rd gear and maybe others, but I haven't taken the car that high in speed with this issue. Otherwise, the car dives fine. I'm listing all the engine mods I've had done so that perhaps someone might know what to look for ..
JWT Engine ECU with Mustang MAF sensor
Euro Cams
1mm oversized intake and exhaust Ferrea valves
Ported heads
Bosch 440cc Green Top injectors
Adjustable NISMO fuel pressure regulator set to 3 BAR (fuel pressure gauge installed in line)
Denso/Kyosan Fuel pump (no dampener)
Gutted intake plenum
1 BAR bypass actuator preloaded to 0.4 BAR
Larger 240SX throttle body
Recirculation surge valve installed
This issue only started to occur when I replaced the Turbocharger and fuel pump (done at the same time). There are no issues above 4K as the car continues to run strong and hard up to redline. And if I don't go to WOT but still accelerate hard, there's no hesitation at 4K. This makes me suspect that the fuel pump is not the issue, and I might benefit from a fuel damper. Perhaps some sort of pressure resonance is occurring and the demands at WOT aren't being met by one or more injectors due to a low pressure zone forming in the fuel rail. Can such an issue occur? I'm also wondering if it might not be a bad idea to remove the fuel pump's voltage from ECU control and have it go at full voltage all the time --- the amperage difference is not all that much. I can replace the pump with a relay to fool the ECU into thinking it's controlling the pump's voltage (when in fact it's varying voltage to the relay) and run a steady 12V through the relay to the pump. (A Bosch relay will work within the voltage swing the ECU allows.)
I'll be more than happy to answer any other questions you might have regarding the car and what I've done. Thank you.
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