WOT Problems on Stage 2 Turbo Nytro Powderlites w RB3

[jhillam]

I have an '08 Nytro with Powderlites Stage 2 kit on it, purchased this last fall from a prior owner that maybe didn't disclose his true reason for selling. The install is very clean, the kit is well thought out and the whole sled is immaculate, but I have had constant problems trying to get it to run WOT without sputter (feels like lean-down). It is most peculiar--it will run crisp on throttle response and between 11-12.5 on A/F ratio up to about 65% throttle, beyond that it falls on its face and sputters and the A/F gauge goes to 13-15 or sometimes blanks out "--" and I hurry and get off the throttle. It will run up to 65% throttle at 15 psi boost and run 100 mph on flat and 75+ up a big hill, but I can't go WOT or it sputters. It does this at min 10psi boost and at max 15 psi boost regardless. I ride at 6-10K feet elevation and it does it regardless of elevation. I have suspected the following and tested accordingly (results show no problem):

1) Wrong Map (I have tried Powderlites maps posted Last Feb, 2010, April 2010, and the more recent Nov 26, 2010 map that Dave posted. I have even created my own map loading up to 150% duty cycle top to bottom in the final three columns of the map and it still seems to lean out and sputter on top. I have confirmed that the changes take, because I can sit and run it on the laptop and add enough/take away enough fuel in first column to get the motor to die)

2) RB3 Connection (I pulled it and confirmed that it was loaded with dielectic grease; i put more in, but don't see this as a problem)

3) RB3 Firmware (Dave emailed me the latest firmware RB3_Nytro_3Bar-V47)

4) RB3 Configuration (I have become confident in the purpose of every parameter in RB3 Configuration: Correction Pump Settings (I like it best at 2%/35%/200ms for throttle response), Voltage Max/Min settings (currently at 1.75/4.71), RPM limiter settings (+500 rpm), Switch Map settings, Hold RPM settings, etc... I have even hand-pump tested the 2-bar MAP sensor AND the load % readout in Rapid Master and now have a precise conversion table showing manifold gauge boost to MAP voltage to RB3 load% comparison to assist with fine tuning of voltage parameters to identify fuel map column per gauge boost read out. I have confirmed that all of these parameters work as they are supposed to, with the exception of Correction Pump adjustment off idle since it is was designed to be driven off of throttle position and in the Powderlites configuration it is driven off of MAP sensor voltage which actually drops temporarily when you open the throttle due to manifold vacuum)

5) Fuel filter (I pulled the tank and had some particles lodged in the fuel filter. After cleaning I noticed no differences)

6) Fuel hoses ( I have hand traced fuel hose from tank to pump, to fuel rail and to fuel regulator. Slightly steep bend in one place, but looks good)

7) Fuel (I started out running pump gas but feared for the life of my engine with A/F spikes way above 13 at WOT. I went to Avgas (ran best) and now VP 110. Will go back to pump gas once lean-down is solved)

8) Onboard Diagnostics (I have no fault codes and I have went through every diagnostic check available on the multifunction display. Everything checks out okay)

9) Fuel Pump (I questioned output so I adjusted regulator up to max pressure and fuel pump can hold over 100psi. I ran bypass into a handheld gas can and output was phenomenal)

10) Fuel Regulator (My regulator is a large, flat red anodized unit with a 13mm hex nut and an allen head set screw for regulation adjustment. It bypasses to the fuel tank and has an airline tied into it from the top of the airbox. There is no name on it so I don't know the brand. I bench tested it and presume that it is a 2:1 rising rate regulator. Setting it at 50 psi at atmosphere results in about 75 with 10 psi above atmosphere plumbed in. My sled has vent cut-outs above and below the fuel pressure regulator so it stays cool so I don't expect vapor lock)

11) Spark Plugs (Steve Packer ("TurboDoc") rode my sled while I rode his Aerocharged Pro RMK and he suggested I change the plugs. I pulled the originals and replaced with NGK iridiums of same heat range. I noticed very little/no difference)

12) Boost Leakage (My motor shuts down if I hold my hand over muffler outlet so I don't suspect any exhaust problems. I have hand traced the whole intake plumbing and I don't have problems making boost so I don't suspect anything here)

13) Clutching (I have a shockwave adjustable helix so it is easy to keep off the rev limiter so I don't suspect this is a problem)

As you can see, all of the more obvious stuff checks out fine. I went up tonight to do some very detailed tests, even holding the laptop while riding across a field and viewing Rapid Master read-outs. I ran through every map and voltage configuration that Dave has published on this site and I ran the full scale of available boost (per bleed off valve controller) and got great results from idle to 65-70% throttle. Opening it up that last little crack just cuts it off immediately every time and it cleans up when I cut back throttle. Tonight I observed the most interesting thing yet--I could hold 70% throttle and run 85 mph across field at 8800 rpm shift out and when I gave it more throttle, the rpms would drop off to 8500-8600 and motor would cut out like out of fuel.

My final thought tonight was that the stock TPS sensor might be screwed up. I have not done a voltage readout, but under Diagnostics mode, it ranges from 16% to 96%, which is within factory tolerance.

Any help on what to check next would be greatly appreciated.

2008 Nytro MTX
Powderlites Stage 2 Turbo
KMOD Skid

 

[gunnerthesnowman]

Have you talked to powderlites , since its his kit he should know what to look at or do.

 

[srx74]

I would suspect if you dont already have them you need bigger injectors. From what I've read stock injectors will not flow enough. I have opted for the bigger injectors on my new project I'll let you know how it works next week!!!!

 

[kinger]

I'm not a expert on the nytros but I do beleive your out of fuel injector to. Dave would be best to ask.

 

[FLYBYU]

I'm not a expert on the nytros but I do beleive your out of fuel injector to. Dave would be best to ask.

x2

 

[gsxr]

You can, t run more than 9lbs thru stock injectors at 1000 ft above sea level , even with fuel upgrade.

Need larger injectors or turn down boost.

 

[Choids454]

Injectors

Running the same kit. 9lbs of boost with factory injectors is the max. I was getting lean conditions. Just purchased bigger injectors from Hurricane and will be able to run 15lbs of boost.

 

[mbarryracing]

I'd be hesitant to say the kit combination wasn't proven by PL and won't work with stock injectors yet. I have taken my stock injectors with a good rising rate regulator over 21 lbs boost before running out of turbo. The fact you almost immediately go lean at 65% throttle doesn't seem like injectors maxed out, that would be gradual with boost...
An instant lean condition can be caused by cylinder misfire, unburned air passing into the exhaust and getting read by the AFR sensor. There has been some discussions here about spark plugs and boost, spark getting blown out, etc.
You had mentioned you replaced the spark plugs with non-stock irridium plugs, but also didn't mention what gap you used...
Try new STOCK plugs at 0.018" gap and see if that solves a potential misfire gremlin first, at least it's an easy and rather inexpensive trial. Then start looking at fuel supply.

 

[powderlites]

No fuel

What's the voltage on sensor one idling? and maybe it has 3 bar and not a 2 bar Map sensor.
Simple test is to set voltage max down or put some regulated air to Map and boost gauge while idling and watch map to make sure it goes over to right colum on map.
3bar is lower then 2 bar or maybe 1 bar map sensor?
at the altitude you should be able to run about 12 psi easy.

 

[fast n furious]

My stage 2 would never go past 8 lbs or it would fall on its face. I have spent a fortune and alot of trouble shooting hours to make it work like it was supposed to ( as advertized ). Now it is capable of 18-20 lbs YES YOU NEED BIGGER INJECTORS

 

[thamax]

they don't make a iridium in a CR9EB, but you might want to set your fuel system up right with the regulator tied directly to the fuel rail so its a flow thru system where it goes pump, fuel rail, and regulator. also i don't think a single rb3 map posted on this site actually works well they didn't for me at elevation so its a find out on your own but check your fuel pickup line in the tank it might be getting kinked when u hammer on the throttle i saw that once to and it would go crazy lean and kill the rpms in that range u are talking. its fuel related for sure

 

[jhillam]

Re: No fuel

What's the voltage on sensor one idling? and maybe it has 3 bar and not a 2 bar Map sensor.
Simple test is to set voltage max down or put some regulated air to Map and boost gauge while idling and watch map to make sure it goes over to right colum on map.
3bar is lower then 2 bar or maybe 1 bar map sensor?
at the altitude you should be able to run about 12 psi easy.

1) Sensor 1 = 1.4 v @ idle

2) Voltage per gauge boost is as follows (4100' elevation)
Gauge Boost Voltage on Rapid Master
0 psi 1.75 v
2 2.1
4 2.3
6 2.9
8 3.3
10 3.6
12 4.0
14 4.2
15 4.5
15.7 4.6
17.5 psi 4.8 v (Max achievable*)
*everyone reading this should take note that your unique map sensor might not precisely match manufacturer spec and if you are set too high on max you will not be able to put out voltage as high as that required for final columns of your map, especially at altitude.

This is appears to be a 2-bar sensor.

I confirmed with trace tool in Rapid Master that the load % jumps columns precisely in accordance with my conversion table above. (I love how easy rapid bike is to use once you understand boost to volt conversion)

3) If the stock injector system can run 12 psi at sea level, appropriately set up, I should be able to run 15+ at my altitude

Can butterfly valve in throttle body be in such a position that it blocks off or creates a vortex around the vacuum line output causing the problem only past 70% throttle opening?

Does the diagnostics function on multifunction display show correct TPS output or do I need to use the multimeter to read volts?

Is the rev limiter sensitive to throttle position? In other words, could the rev limiter for some reason be knocking it down below 8500 rpm at WOT but not at 70% throttle?

Do you think there is any merit to the other post on this site saying my fuel pump should be plumbed direct to fuel rail then off to pressure regulator?

Have you ever seen inconsistencies in fuel pressure regulation with this type of pressure regulation unit?

Could I be completely wrong and could this be rich condition (I don't think so)?

 

[jhillam]

they don't make a iridium in a CR9EB, but you might want to set your fuel system up right with the regulator tied directly to the fuel rail so its a flow thru system where it goes pump, fuel rail, and regulator. also i don't think a single rb3 map posted on this site actually works well they didn't for me at elevation so its a find out on your own but check your fuel pickup line in the tank it might be getting kinked when u hammer on the throttle i saw that once to and it would go crazy lean and kill the rpms in that range u are talking. its fuel related for sure

1) Plugs in it when I bought it were NGK CR9E. I had installed NGK CR9EIX with gap closed slightly to 24 thousandths.

2) I have hand traced the fuel lines from filter to injector. In-tank line is stiff and holds the filter down near tank bottom. Not flexing with acceleration/deceleration from what I can see

Can you PM me a picture or a more depth explanation of your flow through fuel pressure set-up?

At altitude have you had to go richer with RB3 or leaner?



Thanks

 

[jhillam]

I'd be hesitant to say the kit combination wasn't proven by PL and won't work with stock injectors yet. I have taken my stock injectors with a good rising rate regulator over 21 lbs boost before running out of turbo. The fact you almost immediately go lean at 65% throttle doesn't seem like injectors maxed out, that would be gradual with boost...
An instant lean condition can be caused by cylinder misfire, unburned air passing into the exhaust and getting read by the AFR sensor. There has been some discussions here about spark plugs and boost, spark getting blown out, etc.
You had mentioned you replaced the spark plugs with non-stock irridium plugs, but also didn't mention what gap you used...
Try new STOCK plugs at 0.018" gap and see if that solves a potential misfire gremlin first, at least it's an easy and rather inexpensive trial. Then start looking at fuel supply.

Your recommendation is easy enough. I will try new stock plugs and tighten the gap in to see if I'm not arcing a spark at current 24 thousandths gap width. The fact that I'm running VP 110 while testing lends to the problem since the lead ruins plugs faster.