Engine start problems- a mystery....
Engine start problems- a mystery....
Ever since the blower was installed, I have occasionally had the following problem:
When starting with a key, the engine sometimes fails to start up. It will crank, turn over, and the rpms will drop pretty quickly to zero after moving jerkily between 0-800 rpm as if the car is starved for air or fuel. (the behavior is similar to that exhibited when the car loses fuel pressure due to removing the fuel pump fuse) Opening the throttle on start, if I do it in time, fires the car right up in this circumstance.
I also have a Viper 790XV with remote start. When I use this to start the car, it invariably starts right up (unless I attempt a remote start right after a failed key start). The Viper does the following when it starts the car: it cranks the car, and revs the engine. I can see this whenever I sit in the car and use the remote start to start the car.
I saw this as a fuel flooding problem (I have a walbro and 370cc injectors, so I assume the engine is getting too much fuel and not enough air on start SOMETIMES- the car doesn't ALWAYS fail to crank, turn over and run with a key).
The mystery deepens a little more, though, when you consider this:
1. I just had an AEM AFPR installed to lower base fp to 34 psi. Nothing changed.
2. The Viper cannot possibly control a completely mechanical throttle mechanism, and as far as I know it has no linkge to the IACV- so HOW is it revving the car on start?
I also have an SAFC-2 installed. Is there any way to adjust fuel trim on start-up so that this doesn't happen?
When starting with a key, the engine sometimes fails to start up. It will crank, turn over, and the rpms will drop pretty quickly to zero after moving jerkily between 0-800 rpm as if the car is starved for air or fuel. (the behavior is similar to that exhibited when the car loses fuel pressure due to removing the fuel pump fuse) Opening the throttle on start, if I do it in time, fires the car right up in this circumstance.
I also have a Viper 790XV with remote start. When I use this to start the car, it invariably starts right up (unless I attempt a remote start right after a failed key start). The Viper does the following when it starts the car: it cranks the car, and revs the engine. I can see this whenever I sit in the car and use the remote start to start the car.
I saw this as a fuel flooding problem (I have a walbro and 370cc injectors, so I assume the engine is getting too much fuel and not enough air on start SOMETIMES- the car doesn't ALWAYS fail to crank, turn over and run with a key).
The mystery deepens a little more, though, when you consider this:
1. I just had an AEM AFPR installed to lower base fp to 34 psi. Nothing changed.
2. The Viper cannot possibly control a completely mechanical throttle mechanism, and as far as I know it has no linkge to the IACV- so HOW is it revving the car on start?
I also have an SAFC-2 installed. Is there any way to adjust fuel trim on start-up so that this doesn't happen?
Your running just the 370's (actually they are about 410cc) and the stock MAF? No emanage or a piggy back fuel controlling system (besides the SAFC)?
The SAFC cannot controll fuel at idle. If you are just running the 370's and stock MAF your probably flooding the engine from time to time.
The SAFC cannot controll fuel at idle. If you are just running the 370's and stock MAF your probably flooding the engine from time to time.
Originally Posted by I30tMikeD
Your running just the 370's (actually they are about 410cc) and the stock MAF? No emanage or a piggy back fuel controlling system (besides the SAFC)?
The SAFC cannot controll fuel at idle. If you are just running the 370's and stock MAF your probably flooding the engine from time to time.
The SAFC cannot controll fuel at idle. If you are just running the 370's and stock MAF your probably flooding the engine from time to time.
That is correct.
Any steps I can take to alleviate the flooding? I have a Z32 MAF waiting to go in (but untuned I am purdy scared of running lean in the mid and top-end). Dyno is sometime this upcoming week.
Originally Posted by RichMax
Ever since the blower was installed, I have occasionally had the following problem:
When starting with a key, the engine sometimes fails to start up. It will crank, turn over, and the rpms will drop pretty quickly to zero after moving jerkily between 0-800 rpm as if the car is starved for air or fuel. (the behavior is similar to that exhibited when the car loses fuel pressure due to removing the fuel pump fuse) Opening the throttle on start, if I do it in time, fires the car right up in this circumstance.
I also have a Viper 790XV with remote start. When I use this to start the car, it invariably starts right up (unless I attempt a remote start right after a failed key start). The Viper does the following when it starts the car: it cranks the car, and revs the engine. I can see this whenever I sit in the car and use the remote start to start the car.
I saw this as a fuel flooding problem (I have a walbro and 370cc injectors, so I assume the engine is getting too much fuel and not enough air on start SOMETIMES- the car doesn't ALWAYS fail to crank, turn over and run with a key).
The mystery deepens a little more, though, when you consider this:
1. I just had an AEM AFPR installed to lower base fp to 34 psi. Nothing changed.
2. The Viper cannot possibly control a completely mechanical throttle mechanism, and as far as I know it has no linkge to the IACV- so HOW is it revving the car on start?
I also have an SAFC-2 installed. Is there any way to adjust fuel trim on start-up so that this doesn't happen?
When starting with a key, the engine sometimes fails to start up. It will crank, turn over, and the rpms will drop pretty quickly to zero after moving jerkily between 0-800 rpm as if the car is starved for air or fuel. (the behavior is similar to that exhibited when the car loses fuel pressure due to removing the fuel pump fuse) Opening the throttle on start, if I do it in time, fires the car right up in this circumstance.
I also have a Viper 790XV with remote start. When I use this to start the car, it invariably starts right up (unless I attempt a remote start right after a failed key start). The Viper does the following when it starts the car: it cranks the car, and revs the engine. I can see this whenever I sit in the car and use the remote start to start the car.
I saw this as a fuel flooding problem (I have a walbro and 370cc injectors, so I assume the engine is getting too much fuel and not enough air on start SOMETIMES- the car doesn't ALWAYS fail to crank, turn over and run with a key).
The mystery deepens a little more, though, when you consider this:
1. I just had an AEM AFPR installed to lower base fp to 34 psi. Nothing changed.
2. The Viper cannot possibly control a completely mechanical throttle mechanism, and as far as I know it has no linkge to the IACV- so HOW is it revving the car on start?
I also have an SAFC-2 installed. Is there any way to adjust fuel trim on start-up so that this doesn't happen?
The first part of this mystery, I think, is solved. This problem occurs somewhat less frequently once the car has been run a long time. It appears the cold-start map is the culprit:
http://forums.maxima.org/showthread.php?t=421678
See StephenMax's thread partway down. Getting a remote-start installed may actually be good if you run larger injectors and fuel pump and have no other way to lower fuel output during a cold start...
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