Nitrous is Pulsing from 2nd gear on. What are some causes?

I'm running a custom dual fogger nozzle NOS kit with Cheater solenoids. 40N and 30F ran great and is around a 100 shot on my car. I stepped up to 46N and 40F and it started surging on me. I am running a FPSS and a Walbro 255lph pump. The FPSS is set a 32 PSI, so I really dont think the FP is dropping that far, I could be wrong but what else could be causing it. I'm also running TR6 Plugs gapped at .035 and did pull 2 degrees of timing on the 150 shot. Full bottle at start of night and this pass was number 4 so the tank should have been plenty full as well.

Thanks guys for your help!

Mike

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1994 Z/28 M6, Green/Gray Metallic, Custom NOS System,JHC Hooker LT’s, 3.5 inch S&S Racing Y-Pipe, 3.5 inch S&S Racing Exhaust, Pro 5.0 Shifter, Accel 300+, LT4 KM, MSD 8.5 Wires, K&N FIPK, TB Airfoil, 160 Stat, ASP Underdrive Pulleys, Star Stage III Clutch, Weld Draglites w/BFG Drag Radials.

Sounds like bottle pressure. Do you have a bottle heater? if so what was your pressure? And also what size bottle are you using? I've heard complaints about 15lb bottles causing surging.

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Mario,
White 94 Z28 (http://www.z28roc.cz28.com/index.html)
Yeah I got a few mods
Video (http://www.z28roc.cz28.com/purge.mpg)

I do have a bottle warmer and my pressure was over 900. Any other suggestions.....

Thanks!

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1994 Z/28 M6, Green/Gray Metallic, Custom NOS System,JHC Hooker LT’s, 3.5 inch S&S Racing Y-Pipe, 3.5 inch S&S Racing Exhaust, Pro 5.0 Shifter, Accel 300+, LT4 KM, MSD 8.5 Wires, K&N FIPK, TB Airfoil, 160 Stat, ASP Underdrive Pulleys, Star Stage III Clutch, Weld Draglites w/BFG Drag Radials.

I had a similar problem, The cause of mine was the N20 Line routing. I had a couple of sharp bends using AN fittings, and that caused it to surge. It could be that, or perhaps you are not running big enough Lines???

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1994 Z/28, M6,T-Tops
TNT F1 Wet Kit, Centerforce clutch,
17" SS wheels, 275 Goodyear F1's, K&N CAI, HPP 3, 160 Thermostat, 3" custom Cat-Back exhaust with glasspack, Ported MAF, Hurst Billet plus shifter,Cold-air scoop, and an additonal mod or 2 for extra fun.

Check the fuel pressure. In my opion, 32 is way to low to set the fpss. Mine is set about 2 pounds below my fuel pressue (43 on a fuel system that runs at 45psi)

Your fuel pressure could be dropping to the mid to low 30's and causing a lean condition which will cause surging.

Might not be the problem, but it would be worth the time to check it out.

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If I'm playin, I'm sprayin

93 Z28 A3 - w/ Jet Hot coated Hooker LT's and true 3" duals
(hiflow cats, cutouts, and Car Chemistry insert mufflers)

[This message has been edited by speedmiser (edited June 25, 2002).]

Surging like the one described in always lack of nitrous.
Read the ideas all over and go from there.

Sounds like your nitrous filter is clogged. If your pressure is OK then that may be the problem. Also check your jets it definately sounds like a nitrous delivery problem.

Are you using a 46N/40F in EACH nozzle?

This seems mega rich to me. FYI this about a 150-175hp system (By Nitrous Jet Diameter), and you're using big time fuel (Probably enough for 200-225hp of Spray). Could be a large part of the problem.....

Also note that if your pump doesn't have enough VOLUME to support the jetting you're using, the PRESSURE could drop dramatically, causing the surging problem from the FPSS.....

Your 40/30 jet combo works out to ~125hp, with still an overly rich 175hp worth of fuel, but your pump, may be able to keep up with this load, and so the FPSS isn't pulsing.

Try leaning things out to a 40N/24F and 46N/28or31F.

Just some ideas for ya. http://web.camaross.com/bb/smile.gif

All standard disclaimers apply!!!!!!!

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Kurtis Tamez
LT4-396.com (http://www.lt4-396.com)
97 Z28 LT4-396
94 Firehawk LT1-396
Team NW F-Body (http://www.teamnwfbody.org)

[This message has been edited by KTamez (edited June 27, 2002).]

Yes, I'm running that jetting in each nozzle. I agree it is probably way to fat. I'm using the jetting recommended by NOS. But, when looking at jetting for a TNT dual nozzle kit it is around the size you suggest on the fuel side. I need to just put it on the dyno and see what A/F I'm getting, etc.

Thanks everybody for your help.

Mike

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1994 Z/28 M6, Green/Gray Metallic, Custom NOS System,JHC Hooker LT’s, 3.5 inch S&S Racing Y-Pipe, 3.5 inch S&S Racing Exhaust, Pro 5.0 Shifter, Accel 300+, LT4 KM, MSD 8.5 Wires, K&N FIPK, TB Airfoil, 160 Stat, ASP Underdrive Pulleys, Star Stage III Clutch, Weld Draglites w/BFG Drag Radials.