Need Tuning Help

Discussion in 'Gen II' started by SYNFULL, Oct 6, 2008.

  1. SYNFULL

    SYNFULL Viper Owner

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    I have been trying to lean out my GTs with the vec 2 but my changes don't seem to have made much difference. My AFR still is hitting around 10 (I don't think it till record anything lower than 10). I have lowered the ms in the fuel load table, and I have lowered the % in the rpm table but it is still running rich at wot. Do I need to get more drastic in the cuts or is there another way I should be leaning it out like lowering individual injecor pulse?
    Here are some pics of my settings.
    Thanks for any suggestions
    [​IMG]
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  2. 99 R/T 10

    99 R/T 10 Enthusiast

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    Get ahold of JD, but is there a possiblilty that it could be a bad O2 or air intake temp sensor?
     
  3. KenH

    KenH Enthusiast

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    SYNFUL,
    Rather than running too rich, you are actually running dangerously lean.

    If you look at your A/F, it is running between 12:1 and 15:1 under WOT (purple line) and is very erratic. You should be running more in the 11.5 to 12.2 range. The line above the 10:1 line is 12:1.

    For best results (if you have a good long straight stretch to test), doing your WOT logging pulls in 4th gear gives better results than 1-3. 3rd gear works OK if you are space constrained.

    I have copied one of my logs for comparison against your log. The green A/F line is running between about 12.2 and 11.8 during the WOT portion of the run and is more what I would expect to see.

    For adjusting A/F, I prefer to keep the Fuel Load alone for the most part and adjust the Fuel RPM %. Your Fuel Load table provides almost the full load by 1.1PSI. I ramp the load up starting at about -10PSI and ramp it fairly smoothly through the full boost range. That may be part of why your A/F is looking erratic as you are not adjusting fuel load based on boost for the most part.

    You should not use your injector offset for WOT A/F tuning. They should be adjusted to get proper LT fuel trims only in closed loop operation and to balance the cylinders based on sparkplug readings for the various cylinders.

    Other things that can affect A/F is the amount of timing advance you are running. Increasing timing advance (within reason) causes the car to run leaner. Also if your water/methanol is tuned for Octane boosting rather than just cylinder cooling, its adjustment can have an affect on A/F as well.

    BTW, are you sure you are going WOT on those runs? What is the yellow line graphing? O2 sensors are not used during WOT and won't affect the tune, but if you are not actually going WOT (such as the TPS sensor is bad and you stay in closed-loop operation), the O2 sensors can stay in play and they will fight with the VEC2 to try to pull the tune lean and it would not seem to adjust to tuning inputs correctly. I had that problem on my car.

    [​IMG]
     
    Last edited: Oct 7, 2008
  4. EllowViper

    EllowViper Viper Owner

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    Nice graph Ken. Not to detract from the original post, but it looks like when your W/M comes on, you are able to add about 3 degrees timing in over stock. Pretty agressive! I'm basically taking all retard out when my W/M comes on basically returning to stock timing at WOT/full boost. Really roars and I love my new 6.5 pulley! I agree with your comments on the fuel load table. Synfull has too much MS of fuel coming in at low boost. I think I'm somewhere around .6 to 6.0 max graduated from -10 PSI to 7.9 PSI. I never introduce more than 6.0 MS of fuel load. His % table doesn't look too bad..maybe a bit lean since my minimum is around 70% from 4000-6000 RPM. Right now, my AFR is 12.X +/- but I haven't retuned for the 6.5 Lb pulley...just swapped it, added some load table fuel , and went for a drive. Seemed close enough on my WB so what the heck!! I'm indicating 10 PSI on my boost gauge.
     
  5. KenH

    KenH Enthusiast

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    SYNFULL,
    I remembered that my TPS issue was related to the fact that even though my throttle bodies looked like they were fully opening, they were not, so my TPS never got to a high enough voltage to cause the PCM to go into open loop mode during WOT. I fixed that by redrilling the throttle cable mounting bracket and moving it back towards the firewall a small amount. If you have a voltage meter, you can measure the output of the TPS sensor and tell if that may be a factor or not.

    EllowViper,
    The 3 degrees advance is the most aggressive tune I have run. The car just seems to run better when I add a little additional advance in the upper RPM range over about 4000. When I throw a 'safe' tune in such as in the middle of winter where I am more likely to encounter lean conditions, I will frequently do as you do and just run the stock advance.

    I also run Torco Accelerator to raise the octane since 92 is the best I can get around here at normal gas stations. I kick it up to around 94-95 as a further safeguard against detonation with my cast pistons. I also see some boost creep up in the 10PSI range as you can see on the graph. I have probably put 15,000 miles or so on the Roe with no problems once I got the initial gremlins sorted out (which was very difficult)
     
  6. EllowViper

    EllowViper Viper Owner

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    How much W/M are you running? I have 2 x 315 ml nozzles at 150 PSI. Activated at 4.5 PSI and 2500 RPM. Gas here in Tampa is 93 octane...but I see it can contain up to 10% ethanol which I think is where they are getting the octane boost.
     
  7. SYNFULL

    SYNFULL Viper Owner

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    Thanks for the input everyone. I am going to check my TPS voltage and try to get some better logs. I was in second gear and I'm not sure if I got the pedal all the way to the floor. I am going to try 3rd & 4th gear and try a smooth transition to wot instead of mashing the pedal. I will post tonight or tomorrow.
    Thanks again
     
  8. SYNFULL

    SYNFULL Viper Owner

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    Would a check engine code prevent the pcm from going into open loop? I keep setting codes 0138 and 0137 which are rear 02 sensor, even though I have 02 simms.
    I also noticed I have to really mash my gas pedal down to get full open. I move the throttle cable mounting bracket back to see if that helps also.
     
  9. EllowViper

    EllowViper Viper Owner

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    Yes. It will default into a preset tuning mode that dumps gas into the engine to protect if from an over lean condition while you limp home. I saw this on a simple 02 heater code CEL when I put my ODB-II reader on and it indicated falut-open loop during idle...where it is in normal closed loop. Kinda surprised me but once I saw it, it made sense.
     
  10. SYNFULL

    SYNFULL Viper Owner

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    I cleared the engine code and di a new log in 3rd gear. It is definetely lean. I think it is was dumping in fuel like ellowviper said. The timing is retarded for detonation. What do you guys think?

    [​IMG]
     
  11. RedSrt007

    RedSrt007 Viper Owner

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    With 8lbs of boost, 13/14:1 a/f's, and 3 degrees of timing pulled out @4k, your playing with fire..bad.

    Get those a/f's in the low 11's, pull 5 degrees out across the board (to start out with) and go from there. I would hate to see you go through a motor not knowing exactly how to tune your car....

    Are you using a vec2 or 3?

    PM me and Ill give you my email, shoot me over your tune.

    -Red
     
  12. Burntrubber

    Burntrubber Viper Owner

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    listen to this man, he tuned mine, and has tuned many VEC2 & VEC3 cars...he tuned his own 12# Roe!!!!
     
  13. KenH

    KenH Enthusiast

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    That's a much more stable looking run.

    Now you need to bring your a/f down to a safe range. I would select all the cells in the FUEL RPM window and scale them to 120% or so. That should shift the whole a/f line down a point or so. Do another run and adjust again as necessary to get the main portion of the a/f safely down to the 11.5-12.0 range.

    That will get you into a safe range from which you can then start optimizing from such as raising or lowering points on the a/f to get a fairly smooth line.

    Since you are running water/meth I would then be tempted to ease up a bit on the timing retard while feeding a little more fuel in to maintain the a/f ratio while watching for detonation. I think running 12# is a much different deal than 8#, but Red has tried just about every option known to mankind when it comes to a Roe, so I'm sure he has some good insights and would trust his judgment.
     
    Last edited: Oct 8, 2008
  14. KenH

    KenH Enthusiast

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    I use mine strictly for cooling rather than as an octane boost. I ramp the load starting from -2.5PSI and full on at 4.5 PSI. Starts at 1500RPM and ramps to 5000RPM. I run standard 2 x 325ml nozzles at what ever the Roe pump puts out for pressure..
     
  15. SYNFULL

    SYNFULL Viper Owner

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    RedSrt007 has been kind enough to review my tune and make some changes for me. He increased the fuel, powered the meth on sooner, and took out a little more timing. This is the newest log and I think looks much better. I can't thank him enough!!
    [​IMG]
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  16. RedSrt007

    RedSrt007 Viper Owner

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    Still needs more fuel...updated tune sent.
     
  17. KenH

    KenH Enthusiast

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    The tune is looking MUCH better. A little more fuel across the board and you'll be in good shape.

    If drivability feels good through the RPM range during WOT once your a/f is in line I'd leave it alone.

    If you have some mid range point where it doesn't feel like it is pulling as strongly, you might log TQ on your VEC. Even if the graph isn't showing the right numbers, it can show a point in the RPM range where the TQ drops off (dips) and that can sometimes be improved with a little more timing advance (or less retard) in that area. If you do change this, you will likely need to add a little more fuel back in at that same point to keep a/f the same.

    I'd be interested to see what your W/M tune looks like now (graph or settings). That can be one of the trickiest areas to tune and I am always interested in seeing how others are tuning in this area.

    --- Ken
     
  18. ViperBing

    ViperBing Enthusiast

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    Looks a LOT better!
     
  19. SYNFULL

    SYNFULL Viper Owner

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    Here is a shot of the w/m tune that RedSrt007 adjusted for me.

    [​IMG]


     

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