I recently put a NX wet kit on my 98 cobra, and went to get it dyno tuned and the tuner told me that when the spray turned on it would suck the fuel rails dry. I was wondering what you guys with nitrous on your 98 cobra had to do to run a 100 shot on your car. I have a 255walbro in tank. Thanks for any input
98 cobra nitrous question
- Thread starter BottleFed98
- Start date
He told you this as he was tuning the car or before he started tuning?Word to the wise work your way up to a 100 shot.Start with a 50 shot that you'll hardly notice,do a few hits check the plugs.Next a 75 shot repeat the process,then a 100 shot.
How are you activating the spray?WOT switch window switch or trigger?If you didn't delete the IMRC's please DO NOT SPRAY UNDER 3800 RPM's.
I'm using spray on a stock 98 no with issues.
How are you activating the spray?WOT switch window switch or trigger?If you didn't delete the IMRC's please DO NOT SPRAY UNDER 3800 RPM's.
I'm using spray on a stock 98 no with issues.
As we were tuning the car he said he can't get the afr's from spiking because my fuel rails are sucking dry but then it slowly goes down but only to about 12s. The jet in the fuel side is for a 125 shot and it still wouldn't go down. It's on a WOT SWITCH. IMRC has been deleted. How much are you spraying? And what fuel pump? Thanks for the reply!
Anyone?
I think the 98 cobra's still use the return style fuel system from the factory right? If so get a adjustable fuel pressure regulator and raise the fuel pressure, it might help.
Some of the later production ones have a returnless, op you might need a bigger pump or try and jet the kit down a little, also some wet kits will "spike" lean on the initial hit, you can get a "delay" for the nitrous solenoid that is adjustable to milliseconds
I think they had a return style system but return less fuel pump, that's what I've read. I've heard some kits will spike, but it spikes so much it's hiccups when the spray it's activated. I was hoping to get some feedback from some guys that run nitrous on their 98 Cobra. Because I figured it'd be fine running a 100 on stock basically everything. I thought the 255walbro would handle it. Is it possible that I got a faulty fuel pump?
No it's not, and if it is then there is something else wrong. Given everything is okay, it will not suck the rails dry. I ran 100 shot for years and years without anything besides colder plugs. (TR6) Stay with the 100 shot, it's completely fine for our cars.
No all 98's have the return style fuel system, the only thing different is the pump setup. 98's have a basket around the pump where the 96/97 are open
When I hit the 100 on the dyno it spiked really lean, so we went down to a 75 and it was still lean. so we jetted it up and the afrs still only come down to the 12s. If its not the fuel rails sucking dry, what could it be? what should I check? The car is stock beside exhaust and IMRC delete. I don't see why there isn't enough fuel. Could it be something with the Fuel pressure regulator? If so can I buy the Kirban Adjustable fuel regualtor from AmericanMuscle.com? Would it be a direct bolt in replacement?
How old is the fuel filter and what make,how much in the tank?A fuel pressure gauge would be helpful.For nitrous add a window switch or get a trigger on the shifter.Better to have more control of when the spray is deployed.I'm only spraying a 75 shot on a stock fuel pump.
The 98 Cobra is a transition year with the fuel system,some refer to it as the bastard year
This is quoted from a member here Cobra5289
The 98 Cobra uses a 2 speed fuel pump which is controlled by the EEC computer. It runs at low speed up to 3300 RPM when the EEC enables it to run in high speed, then when the air mass as measured by the MAF reaches a predetermined setpoint the pump runs in high speed. When the RPM's fall back down to 3250 it switches back to low speed. Unlike the 99 and up it doesn't use pulse width modulation (PWM) to control the speed instead it uses a resistor. In low speed 12 volts is supplied to the resister where it is reduced to something less. In high speed a relay closes bypassing the resister to supply the full 12 volts to the pump. The pump also runs in high speed for a few seconds when you first turn on the ignition to ensure the fuel system is primed and up to pressure when the car is started.
The 98 Cobra is a transition year with the fuel system,some refer to it as the bastard year
This is quoted from a member here Cobra5289
The 98 Cobra uses a 2 speed fuel pump which is controlled by the EEC computer. It runs at low speed up to 3300 RPM when the EEC enables it to run in high speed, then when the air mass as measured by the MAF reaches a predetermined setpoint the pump runs in high speed. When the RPM's fall back down to 3250 it switches back to low speed. Unlike the 99 and up it doesn't use pulse width modulation (PWM) to control the speed instead it uses a resistor. In low speed 12 volts is supplied to the resister where it is reduced to something less. In high speed a relay closes bypassing the resister to supply the full 12 volts to the pump. The pump also runs in high speed for a few seconds when you first turn on the ignition to ensure the fuel system is primed and up to pressure when the car is started.
I'm not sure how old the filter is, but it's just a factory type filter.
Replace the filter with an OEM one,perhaps it's slightly clogged.
I'll try that and let you know how it goes! I'm taking it to another tuning shop on Mondays and their gonna take a look at it. Thank for the input guys!
It still hiccups a little on the initial hit, I'm gonna try to get a new fuel pressure regulator and try to turn up the pressure and maybe that'll help
Do you think the walbro 255lph could be sucking the basket dry when the system activates?
You have got me wondering about mine now .but mine is a 96
To solve the return style or not just look on the fuel rail and see if u have one or two lines. If two its return style which most that year should be returnless style. Hope this helps.
Wvragtop. Yours is a return style for sure.
What fuel pressure are you guys running with the nitrous?
I remember reading somewhere that people running power adders were putting extra holes in the pump basket because the basket was getting sucked dry. No personal experience with it, but might be worth looking into.
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