Lean spike when spray hits
Thread Starter
Staging Lane
Joined: Jan 2010
Posts: 58
Likes: 0
Lean spike when spray hits Working on an 02 z28 cam only car with the Racetronics pump and wiring kit and an NOS plate jetted at only 100hp. Spray is delayed 1 sec ater launch. When spray hits afr spikes to 20:1. Obviously car nose dives then runs out great with afr of 11.8to 12.0 for the rest of the pass. This happens every time I try to spray it. I dont have FP guage in car but at idle I have 63psi.
I do my own pcm tuning and on launch on motor alone I have a small lean spike around 3000rpm, exactly where the spray goes lean. I have added 20% more fuel to the fuel tables with no response so I suspect a fuel delivery problem. Could it be the in tank regulator causing this? Do I just need to go with a stand alone fuel system? I have tuned carbed BBC's for years so I am not new to nitrous at all. Any help is appreciated. This thing hasnt been dynoed but runs 11.60 in quater on motor at 118mph.
I do my own pcm tuning and on launch on motor alone I have a small lean spike around 3000rpm, exactly where the spray goes lean. I have added 20% more fuel to the fuel tables with no response so I suspect a fuel delivery problem. Could it be the in tank regulator causing this? Do I just need to go with a stand alone fuel system? I have tuned carbed BBC's for years so I am not new to nitrous at all. Any help is appreciated. This thing hasnt been dynoed but runs 11.60 in quater on motor at 118mph.
Last edited by nitrousjunky; Jul 11, 2010 at 08:57 AM.
Thread Starter
Staging Lane
Joined: Jan 2010
Posts: 58
Likes: 0
There is a12" line from the rail to the fuel solinoid then a 18" line from the fuel solinoid to the plate. There is also a 18" line from the nitrous solinoid to the plate. I can see where a longer line from the nitrous line would help a little but would it fix a 20:1 lean spike? The car falls flat on its *** like you let all the way off the throttle then runs like it should.
Im still thinkin fuel delivery problem since I have this problem to a much smaller extent on motor alone. Thanks for the reply.
Im still thinkin fuel delivery problem since I have this problem to a much smaller extent on motor alone. Thanks for the reply.
Put a fuel pressure gage on it and you will probably see pressure is dropping... how old is the fuel filter? Maybe the install of the racetronix pump isn't correct? If you have a lean spike on motor, something is wrong...
What kind of power is the car making?
The racetronix kit properly installed is good for about 650HP rear wheel. Like stated above you need to put a fuel pressure gauge on the car to problem solve correctly.. If the filter is old change it. I have seen a dirty filter cause alot of problems.
Dave
The racetronix kit properly installed is good for about 650HP rear wheel. Like stated above you need to put a fuel pressure gauge on the car to problem solve correctly.. If the filter is old change it. I have seen a dirty filter cause alot of problems.
Dave
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Working on an 02 z28 cam only car with the Racetronics pump and wiring kit and an NOS plate jetted at only 100hp. Spray is delayed 1 sec ater launch. When spray hits afr spikes to 20:1. Obviously car nose dives then runs out great with afr of 11.8to 12.0 for the rest of the pass. This happens every time I try to spray it. I dont have FP guage in car but at idle I have 63psi.
I do my own pcm tuning and on launch on motor alone I have a small lean spike around 3000rpm, exactly where the spray goes lean. I have added 20% more fuel to the fuel tables with no response so I suspect a fuel delivery problem. Could it be the in tank regulator causing this? Do I just need to go with a stand alone fuel system? I have tuned carbed BBC's for years so I am not new to nitrous at all. Any help is appreciated. This thing hasnt been dynoed but runs 11.60 in quater on motor at 118mph.
I do my own pcm tuning and on launch on motor alone I have a small lean spike around 3000rpm, exactly where the spray goes lean. I have added 20% more fuel to the fuel tables with no response so I suspect a fuel delivery problem. Could it be the in tank regulator causing this? Do I just need to go with a stand alone fuel system? I have tuned carbed BBC's for years so I am not new to nitrous at all. Any help is appreciated. This thing hasnt been dynoed but runs 11.60 in quater on motor at 118mph.
Convert it to a return system.
FP gauge
FP Safety switch
Dual pumps
JMO, Good luck
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I had the same problem as you and my tuner told me to shorten up my fuel line, but leave my nitrous line longer...I did this, and it fixed the problem...I also am a cam only car with a racetronix fuel kit.
to give you a idea, my N20 line coming out of the solonoid is 12". My fuel line going into the plate it 5". Also what seemed to help with the lean spike alot was having a small n20 solonoid, and a larger fuel solonoid.
that gives you a general idea what im talking about. My lines are routed cleaner now, but they are all this mounted the same.
to give you a idea, my N20 line coming out of the solonoid is 12". My fuel line going into the plate it 5". Also what seemed to help with the lean spike alot was having a small n20 solonoid, and a larger fuel solonoid.
that gives you a general idea what im talking about. My lines are routed cleaner now, but they are all this mounted the same.
Thread Starter
Staging Lane
Joined: Jan 2010
Posts: 58
Likes: 0
Thanks for the replies everyone. Here goes: Fuel filter is new. I installed a #120 jet on the fuel side and sprayed this into a jug. While activating the solinoid and reving tha car at the same time the fuel pressure only blipped 5psi. I am not thinking fuel supply problem anymore. I have a theory that when I launch my car on the motor it bogs because it only flashes to 2400rpm. I am thinking that bog causes the lean spike. When I am spraying I use a time delay spraying about 1 sec out of the gate because I still have the 10 bolt rear. All along I have been thowing more fuel at it to cure some thing that couldnt be cured. I thiink I have too much fuel making it misfire showing a false lean condition on the wideband. I have retuned the fuel tables at low rpm and now the car is definitely more responsive.
Am I on to something here or do you think I am way off track? BTW I have a 3600 stall I plan on installing soon.
Am I on to something here or do you think I am way off track? BTW I have a 3600 stall I plan on installing soon.
There is a12" line from the rail to the fuel solinoid then a 18" line from the fuel solinoid to the plate. There is also a 18" line from the nitrous solinoid to the plate. I can see where a longer line from the nitrous line would help a little but would it fix a 20:1 lean spike? The car falls flat on its *** like you let all the way off the throttle then runs like it should.
Im still thinkin fuel delivery problem since I have this problem to a much smaller extent on motor alone. Thanks for the reply.
Im still thinkin fuel delivery problem since I have this problem to a much smaller extent on motor alone. Thanks for the reply.
