Bosch 1000cc injectors on an Evo
Two things:
1) For everyone: I haven't had time to do a thorough followup test, buy my initial test of relieving the fuel pressure in the rail until just before starting seems to stop the issue. Can a few other people try disconnecting the FPR from the rail and leaving it disconnected until just before trying a warm start?
2) Can someone build and send me a voltage divider that converts 16 V to 5 V so I can log voltage at the injector?
1) For everyone: I haven't had time to do a thorough followup test, buy my initial test of relieving the fuel pressure in the rail until just before starting seems to stop the issue. Can a few other people try disconnecting the FPR from the rail and leaving it disconnected until just before trying a warm start?
2) Can someone build and send me a voltage divider that converts 16 V to 5 V so I can log voltage at the injector?
https://www.evolutionm.net/forums/7660874-post211.html
Debatable at this point still I think.
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From: Tri-Cities, WA // Portland, OR
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You will need high precision resistors for best results. If you do a 330 ohm in series with a 100 ohm and tap in the middle with the 100 ohm connected to ground and the 330 ohm connected to VCC, that knocks down the voltage by 0.3125 or 14 volts will look like (14*0.3125) = 4.375,
Two resistors running to ecu sensor ground, that way you don't have a floating ground skewing your readings. Still be aware that when cranking you might have a ground loop issue causing an "issue" and you are not actually getting a "result".
In 5-10 minutes the fuel pressure reduces in the rail 5-15psi.
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Not on everyone's car. I'm using the front O2 ADC to log a Kavlico pressure sensor attached to my fuel rail. The first plot in this post shows that fuel pressure in my car holds at 43.5 psi for a full 30 minutes after shutdown:
https://www.evolutionm.net/forums/ev...ml#post7667397
My warm start issues start picking up about 60 minutes after shutdown where the rail pressure has finally dropped to about 30 psi. I'm not dismissing the possibility that its a fuel pressure issue, but there needs to be another piece to the puzzle, such as warm injectors not having enough umph to overcome fuel pressure, for it to make sense.
The way to test this is to:
1) Relieve fuel pressure by pulling the FPR from the rail immediately after shutdown and leaving it disconnected until just before attempting a warm start.
2) Leave the FPR attached to the rail at shutdown. Pull the FPR just before attempting a restart (and then reconnect it) to relieve fuel pressure.
If its a leaky injector, #1 will help but #2 will not. If its a lack of ability of the injector to open (possibly due to fuel pressure, hot injectors, or something else), then possibly #1 and #2 will help.
https://www.evolutionm.net/forums/ev...ml#post7667397
My warm start issues start picking up about 60 minutes after shutdown where the rail pressure has finally dropped to about 30 psi. I'm not dismissing the possibility that its a fuel pressure issue, but there needs to be another piece to the puzzle, such as warm injectors not having enough umph to overcome fuel pressure, for it to make sense.
The way to test this is to:
1) Relieve fuel pressure by pulling the FPR from the rail immediately after shutdown and leaving it disconnected until just before attempting a warm start.
2) Leave the FPR attached to the rail at shutdown. Pull the FPR just before attempting a restart (and then reconnect it) to relieve fuel pressure.
If its a leaky injector, #1 will help but #2 will not. If its a lack of ability of the injector to open (possibly due to fuel pressure, hot injectors, or something else), then possibly #1 and #2 will help.
Last edited by mrfred; Nov 21, 2009 at 10:43 PM.
Not on everyone's car. I'm using the front O2 ADC to log a Kavlico pressure sensor attached to my fuel rail. The first plot in this post shows that fuel pressure in my car holds at 43.5 psi for a full 30 minutes after shutdown:
https://www.evolutionm.net/forums/ev...ml#post7667397
My warm start issues start picking up about 60 minutes after shutdown where the rail pressure has finally dropped to about 30 psi. I'm not dismissing the possibility that its a fuel pressure issue, but there needs to be another piece to the puzzle, such as warm injectors not having enough umph to overcome fuel pressure, for it to make sense.
The way to test this is to:
1) Relieve fuel pressure by pulling the FPR from the rail immediately after shutdown and leaving it disconnected until just before attempting a warm start.
2) Leave the FPR attached to the rail at shutdown. Pull the FPR just before attempting a restart (and then reconnect it) to relieve fuel pressure.
If its a leaky injector, #1 will help but #2 will not. If its a lack of ability of the injector to open (possibly due to lack of fuel pressure, hot injectors, or something else), then possibly #1 and #2 will help.
https://www.evolutionm.net/forums/ev...ml#post7667397
My warm start issues start picking up about 60 minutes after shutdown where the rail pressure has finally dropped to about 30 psi. I'm not dismissing the possibility that its a fuel pressure issue, but there needs to be another piece to the puzzle, such as warm injectors not having enough umph to overcome fuel pressure, for it to make sense.
The way to test this is to:
1) Relieve fuel pressure by pulling the FPR from the rail immediately after shutdown and leaving it disconnected until just before attempting a warm start.
2) Leave the FPR attached to the rail at shutdown. Pull the FPR just before attempting a restart (and then reconnect it) to relieve fuel pressure.
If its a leaky injector, #1 will help but #2 will not. If its a lack of ability of the injector to open (possibly due to lack of fuel pressure, hot injectors, or something else), then possibly #1 and #2 will help.
Yes I have been doing this for the last couple months on both the FIC2150 and the ID2000. On a fuel system with base pressure set at 43.5psi it will even run on the O2 feedback if you insist on having it on.
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From: Tri-Cities, WA // Portland, OR
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From: Charlotte, NC
Thank you for your help.
Last edited by Shawnmsr; Nov 23, 2009 at 12:48 PM.
Not on everyone's car. I'm using the front O2 ADC to log a Kavlico pressure sensor attached to my fuel rail. The first plot in this post shows that fuel pressure in my car holds at 43.5 psi for a full 30 minutes after shutdown:
https://www.evolutionm.net/forums/ev...ml#post7667397
My warm start issues start picking up about 60 minutes after shutdown where the rail pressure has finally dropped to about 30 psi. I'm not dismissing the possibility that its a fuel pressure issue, but there needs to be another piece to the puzzle, such as warm injectors not having enough umph to overcome fuel pressure, for it to make sense.
The way to test this is to:
1) Relieve fuel pressure by pulling the FPR from the rail immediately after shutdown and leaving it disconnected until just before attempting a warm start.
2) Leave the FPR attached to the rail at shutdown. Pull the FPR just before attempting a restart (and then reconnect it) to relieve fuel pressure.
If its a leaky injector, #1 will help but #2 will not. If its a lack of ability of the injector to open (possibly due to fuel pressure, hot injectors, or something else), then possibly #1 and #2 will help.
https://www.evolutionm.net/forums/ev...ml#post7667397
My warm start issues start picking up about 60 minutes after shutdown where the rail pressure has finally dropped to about 30 psi. I'm not dismissing the possibility that its a fuel pressure issue, but there needs to be another piece to the puzzle, such as warm injectors not having enough umph to overcome fuel pressure, for it to make sense.
The way to test this is to:
1) Relieve fuel pressure by pulling the FPR from the rail immediately after shutdown and leaving it disconnected until just before attempting a warm start.
2) Leave the FPR attached to the rail at shutdown. Pull the FPR just before attempting a restart (and then reconnect it) to relieve fuel pressure.
If its a leaky injector, #1 will help but #2 will not. If its a lack of ability of the injector to open (possibly due to fuel pressure, hot injectors, or something else), then possibly #1 and #2 will help.
I will try and get this taken care of over the holiday weekend - time / weather depending.
I have done this before and it always seemed to start much better but I didn't leave the FPR off until time to restart....I just unbolted it, relieved the pressure and then re-installed it and let the car sit for like 30-45 min but it did always seem to start much better.