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Track times a bit slower lately....things to check, replace?

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JA$ON

JA$ON

ching chong potato
Sep 7, 2004
17,332
2
  • #1
    My car had recently developed a slight hesitation when I hit (blip) the throttle, and has started to hiccup slightly once I pull 4th at the track. I have been using leaded 110 gas at the track for the past two seasons and I realized I have never replaced the O2 sensors.

    I dont have any codes related to the sensors , but do have a few unresolved codes when my EGR was deleted, but not completely eliminated in the tune. Still getting an EVAP canister code or someting along those lines.

    I pulled the plugs and they all looked fine, (similar color, not crazy sooty or lean-white) and its probably time to flush the radiator just to be safe. Fuel filter is very new when I had a -8 line installed, and PPRV is deleted.

    I guess my question really is can the O2 sensors, EGR affect ET & MPH at the track??? I was under the impression that O2's are only related to part throttle drivability and have no affect at the track when the car is @ WOT. I have one tune with the EGR deleted correctly but the 2 step doesnt work, and one tune with 3 EGR codes, but the 2 step works......I havent been able to do any decent comparison between the 2.

    ETs and MPH has been slightly down, but nothing major, I've just noticed it not pulling as cleanly as before.

    Other possibilities:
    1.Replace the FRPS to be safe.....Can the FRPS start to have gone bad? I've never replaced it and my car has seen the limiter and fuel cutoff a few times?

    2. Replace the plugs anyway, with new BR7EFS

    3. Replace BOTH O2 sensors, still original, has seen two seasons of 110 leaded gas.

    4. Change oil

    5. Flush/replace engine coolant, IC system is all water/water wetter.

    6. Clean MAF

    I have a few big races coming and want this thing running like a top

    Thanks for the help
    Click to read more...
     
    JA$ON

    JA$ON

    ching chong potato
    Sep 7, 2004
    17,332
    2
  • #2
    SCT guys plz check out my datalog....

    I'm trying to post a log of a recent run. I did notice that my manual IC pump switch was not functioning properly last time. If the IC pump (meziere) wasnt working, how would the ice in the trunk melt?

    On this past coolant temps were 198-200 the entire time, is that high?

    I'm trying to post the Livelink LOG.....
    launch was at 172 seconds and you can go from there, does anyone see anything??

    I'll host the condensed .csv (excel) file, just open it thru Livelink.....

    http://www.mediafire.com/?3tywzlsjvzo

    please help, maybe were on to something....

    i dont know everything to look for :(
     
    Flatliner

    Flatliner

    I'm kind of a big deal...
    Mar 3, 2004
    35,000
    0
  • #3
    Is this the log I sent you from Byron?

    -Without the a/f we can't tell what your o2s are doing and that would tell us if your o2's are bad by monitoring the stft's

    -
    Open Loop and Closed Loop are two terms used to describe the fueling mode the computer is in.

    In closed loop fueling, the computer takes readings from the oxygen sensors which read +/- of 14.64 AFR (Stoich) and makes corrections for it. If your car is idling @ 13.5 AFR, the 02s can see this, and will know to pull out enough fuel to get back to stoich.

    In open loop, the fueling is purely based off the MAF transfer function and the open loop fuel table. This table has to be calibrated any time you make MAF changes, and changes that affect the airflow of the MAF.

    When a car is started, the computer is in open loop until certain criteria is met. The o2 sensors need to be heated to work properly, so this is the main reason there is a delay.

    After the sensors are heated up, the car goes into closed loop and the O2 sensors make their corrections.

    The computer will go back into open loop under a variety of conditions. Throttle Position (TP) is one way.

    There are parameters in the computer that determine what the TP is for Open Loop, and other things.

    When that TP is reached, and the car goes open loop, and richens up.
    Click to expand...

    - if this is the log from Byron that day, your temps were hella cold compared to mine and Slash's, hence his trunk looks familiar... :lmao:

    - that day Carla and I were down about 5mph if I remember correctly
     
    JA$ON

    JA$ON

    ching chong potato
    Sep 7, 2004
    17,332
    2
  • #5
    IATs in check (134 early-staging, dropping to 84 at top of 4th), downstream IATs in check (102-130 at 4th gear), coolant 198-200, MAF counts high but OK (under 1000 w/SCT2400), load 2.0, 23* spark uptop in every gear......what am i missing?
     
    Flatliner

    Flatliner

    I'm kind of a big deal...
    Mar 3, 2004
    35,000
    0
  • #9
    - voltage no, not logged, however your car would drive like crap under normal driving conditions

    - I corrected the o2 statement... the o2s are off and the car runs off of the MAF function... but the only way to truley tell what the car is doing is to throw the LM1 in there. Then you can see what the car is commanding and if need be, then an adjustment may be needed for your tune.

    - I haven't looked at my logs, but the car leans out between shifts, so I am not sure if the computer is still in WOT mode or not...


    - Call me tomorrow night, maybe we can throw my LM1 in and go datalog the bitch!
     
    Flatliner

    Flatliner

    I'm kind of a big deal...
    Mar 3, 2004
    35,000
    0
  • #12
    Factory O2 Sensors
    Matt Hill
    Matt Hill Motorsports, LLC
    www.matthillmotorsports.com

    There are often questions and misinformation posted on the internet about factory O2 sensors. Here is some information to help out in this area.

    To understand how factory O2 sensors function, it is important to first understand some principles of combustion. Stoichiometric, or “stoich,” combustion is a term referring to an ideal process in which fuel is burned completely. This would be a complete combustion process chemically transforming and burning all carbon (C) to carbon dioxide (CO2), all hydrogen (H) to water (H2O), and all sulfur (S) to sulfur dioxide (SO2). Stoich is the ideal condition under which a vehicle should run while in closed loop, or part throttle conditions. It is safe for the engine, clean burning, and efficient. Differing fuels will each have their own differing stoich points of air/fuel ratio (AFR). Gasoline, for example, is stoich at 14.64:1. Methanol is stoich at roughly 8.0:1. E-10 (10% Ethanol) fuel is stoich at roughly 14.13:1. Similar other oxygenated fuels can be stoich in the 14.2-14.4:1 range. Race fuels also have differing stoich points, depending on their chemical makeup.

    Factory O2 sensors sense the stoich point of fuel in the exhaust pipes, post-combustion. The most common manner in which this is done in modern sensors is for the sensor to have a bulb made of zirconium ceramic inside the sensor, behind the vented cover. Behind the bulb lie two electrodes in the form of two strips of platinum. Air inside the exhaust pipe is compared to air outside the exhaust pipe. The different amounts of oxygen in the air cause differing amounts of voltage to flow through the ceramic bulb. Greater differences create greater voltage.

    The O2 sensor will generate around .9 volts when the AFR is rich and there are low levels of unburned oxygen in the exhaust. Lean mixtures result in lower voltages, down to around .1 volts. The sensor will generate voltage of around .45 volts reflecting stoich when it is achieved.

    The PCM in fuel injected vehicles uses this data collected from the sensors to assist in maintaining the stoich ratio in closed loop. Fuel is added or subtracted based on the voltage data coming back from the sensors.

    During normal operation, the sensors, when properly heated, will switch back and forth from rich to lean of stoich. If one were to watch their voltage switch on a properly tuned vehicle, he would notice that they switch around an average point of .45 volts or so. If the sensors switch around a point higher or lower than stoich, the sensors may have failed or the vehicle may no longer be running at a stoich AFR and may be genuinely rich or lean. Small scale oscillations will generally show failed sensors.

    Running leaded fuel over time will permanently coat and damage the sensor. This coating will then cause the voltage to hang somewhere in the .4-.5 volt range. This gives the false reading and may even appear as if proper function is occurring when, in fact, it is not.

    Factory narrow-band O2 sensors also have no way of providing actual AFR. Anything stating otherwise is incorrect. The only data which can accurately be determined is that the vehicle is running stoich, rich of stoich, or lean of stoich.

    OBD-II equipped Ford (and most other) vehicles will only use the first sensor in each bank for actual fuel trim data. There is a second sensor downstream of the catalytic converter. This sensor is used to determine the active state of the catalytic converter and its efficiency.
    Click to expand...


    So you need to shift faster... or let me drive your car :lmao:

    We should still datalog it...
     
    JA$ON

    JA$ON

    ching chong potato
    Sep 7, 2004
    17,332
    2
  • #14
    RD SNAKE said:
    I'm thinking possibly a coil pack is going out on you.
    It would be a good idea to replace both the front o2 sensors w/ all of that leaded gas.

    How many miles on the car?
    Click to expand...

    what leads you to think of a faulty coil pack?

    i will replace the o2's even though my synapsis is that they have nothing to do with WOT performance:dunno:

    maybe i clocked my MAF wrong when we pulled it off to check the plugs? i dont have a pic or remember where it was before but i think it was like 10 oclock or so.....

    29K miles...5K with leaded gas TOPS
     
    JA$ON

    JA$ON

    ching chong potato
    Sep 7, 2004
    17,332
    2
  • #18
    Well, lets revisit this, I posted on the RWTD tuning forum and Ed chimed in with

    "Jason,
    You've got a fuel delivery issue. If you look at your datalog you will see the RTLS_FPUMP_DTYC going well above the recommended 90% maximum. It gets up to as high as 98% at the top of the RPM range. At that point the PRES_DROP_F_INJ parameter struggles to maintain the commanded 39psi.

    Then after the shift the RTLS_FPUMP_DTYC actually pegs at 99.99% at tip-in.

    The sequence repeats at the top of every gear and tip-in to the next higher gear throughout the run.

    Have you made any recent changes to your fuel delivery system?
    The first thing that I would do is change your fuel filter and see if that helps. If it doesn't you will need to look for fuel line kinks or other restrictions causing your pumps to overwork to keep up with the fuel demand.

    Let me know if you have any questions.

    Regards,
    Ed"

    So what else besides changing the fuel filter?? Maybe its the cheapo 110 octane Sunoco I get??

    check for kinks, etc.....
     
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