Results 1 to 12 of 12

Thread: 3.0 Leaning out...

  1. #1
    Mitsu booster
    Join Date
    Mar 2015
    Location
    ohio
    Posts
    14

    3.0 Leaning out...

    Long story... Only use - Road Course endurance racing - 7-14 hour races.
    3.0 - bored .040 over
    Large cam
    3" cold air intake setup.
    Speed pro pistons and rings
    Stock 19lb injectors.

    Ran a smoke test and no vac leaks.
    Ran exhaust leak check and no exhaust leaks (actually there was but replaced crossover gaskets and now there is none)
    Injectors are good.

    Timed to 15btdc
    New #4 rapid fire plugs gapped to .40
    MSD 6 ignition, msd coil, 8.5 magnacore wires

    New O2, Map and coolant sensor.
    New FPR. Pressure after turning off car holds at 40+ for a few hours. Was a 20 after a day.
    Fuel pump is walbro 190lph gsl391 external, inline pump (non high pressure - they make 2 models of the 190).
    Fuel cell - feeds and returns on 5/16 lines (had it returning on 1/4 line, but pressure jumps up to 50-52 at idle - spec is 48)
    14 volts to pump.

    Fuel Pressure at idle is 48.
    Pull vac hose, pressure jumps to 52-54
    Vac at idle - 15-16 (nomal for the cam in it) Drops to 0 when burping, jumps up to 25 then settles again.
    WOT, fuel pressure goes up to 50-52

    TPS sensor tests fine.
    O2 sensor - at car side of plug, 12 volts when checking heated + and - wires, 3.7 volts when checking bk/lb line that splices with TPS.
    Car running, at warm idle (180-190) voltage on o2 signal wire is jumping from .52 to .90. However most commonly hitting .68 to .82
    Burping throttle, drops to .25-35. Holding throttle at 3k, .25-.4
    Unplug vac line from FPR and plug vac line, o2 sensor reading jumps up in high .80's to .90's
    Unplug booster line and cause vac leak, reading drops to around .40

    There is a leak at the donut which I will fix. It is after the O2 sensor, so "shouldn't" have an impact, but... I will get it fixed. I would think if it was causing issues and the o2 sensor was seeing this leak, it would actually lean out the voltage and call for more fuel, not the opposite.

    Ever since the rebuild of the motor (done by reputable chrysler specific motor shop) - the plug tips are ash white. Prior to the rebuild and the engine bored at .030, they were nice and black.

    So, with all of this... why are the plugs ash white. Sure seams like it is running lean, yet, overall, the numbers seem to be ok.
    From the o2 sensor, it seems it might be sensing running rich and adjusting to lean out a bit, but as the numbers jump, I don't see it go under .45
    With swapping out the sensors, fpr, etc... I am at a loss at to what to try next??? I have a set of 22lb injectors I could throw in, which would dump slightly more fuel, or I have a 190lph high pressure that I could try and push more fuel through the rail, but not sure either of those would be much use. Thoughts???

  2. #2
    Super Moderator Turbo Mopar Staff contraption22's Avatar
    Join Date
    Dec 2005
    Location
    Havertown, PA
    Posts
    9,517

    Re: 3.0 Leaning out...

    What's your AFR read at WOT under load?

    The factory 02 sensor is ignored by the computer at WOT. It relies on tables to determine WOT fueling.
    That said, with your reduced vacuum at idle, the computer, not knowing that you've changed the engine's airflow demands, may be adjusting the LTFT somewhat to compensate by leaning out the fuel mixture across the board. This could affect WOT fueling.
    Mike Marra
    1986 Plymouth Horizon GLMF "The Contraption" < entertaining sponsorship offers
    Project Log:
    http://www.turbo-mopar.com/forums/showthread.php?69708-The-Contraption-2013-14&highlight=

  3. #3
    Mitsu booster
    Join Date
    Mar 2015
    Location
    ohio
    Posts
    14

    Re: 3.0 Leaning out...

    I will have to take it for a run today and see what AFR at WOT is reading. The one thing I did not have time to do this morning when getting the readings.
    I thought about getting a magnumtuning adjustable o2 sensor to adjust the signal to be a bit more lean and fool the ecu to make it run richer ? Not sure what my other options would be, other then megasquirt or a piggyback, which I prefer not to have to do at this time... if I don't have to...

  4. #4
    Moderator Turbo Mopar Staff Vigo's Avatar
    Join Date
    Feb 2006
    Location
    San Antonio,TX
    Posts
    10,798

    Re: 3.0 Leaning out...

    How are you monitoring AFR? Watching narrowband o2 voltage on, multimeter, scantool, dedicated gauge?

    If you have a non-stock set of cams that improve VE at high rpm, you would have higher fuel demands at high rpm. If you have a scan tool you could watch o2 voltage, injector duty cycle, and fuel trim at high rpm to see what the computer is doing.

    Also, have you ever watched fuel pressure when actually under full load and high rpm? Being able to hit full pressure at low engine load just by pulling the line off the regulator is not the same as hitting the pressure at full engine load, so there's a minor chance the fuel pressure is dropping below spec as load and rpm rise. But, a fuel supply issue would show up as a lean o2 voltage anyway so I would start just by monitoring o2 volts and high load and high rpm.

    Dont push the red button.You hear me?

  5. #5
    Mitsu booster
    Join Date
    Mar 2015
    Location
    ohio
    Posts
    14

    Re: 3.0 Leaning out...

    "How are you monitoring AFR? Watching narrowband o2 voltage on, multimeter, scantool, dedicated gauge?"

    Multimeter.

    FP goes up to 52-54 at WOT under load.

    I'll take it for a run at lunch and see what voltage I get at load and high rpm and report back.
    (I have a set of 22lb injectors I could throw in as well to test... I know the ecu will not see them as being larger and pulse will still be the same, but they would dump a bit more fuel per pulse - right? - Is it worth trying or just a waste of time?)

  6. #6
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
    Join Date
    Dec 2005
    Location
    Greenville/Spartanburg SC area
    Posts
    7,557

    Re: 3.0 Leaning out...

    Go to 24 lb injectors. I have Rick Loziers old 3.0 V6 Daytona, it has cams and some other work and headers, and it ran shitty on the stock injectors. Put Ford blue top 24# injectors in it (Mustang Cobra and 460 big block used them) and it runs much better.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  7. #7
    Super Moderator Turbo Mopar Staff contraption22's Avatar
    Join Date
    Dec 2005
    Location
    Havertown, PA
    Posts
    9,517

    Re: 3.0 Leaning out...

    In this day and age, I cannot imagine attempting any kind of tuning without a wideband A/F gauge. They aren't expensive anymore.
    Mike Marra
    1986 Plymouth Horizon GLMF "The Contraption" < entertaining sponsorship offers
    Project Log:
    http://www.turbo-mopar.com/forums/showthread.php?69708-The-Contraption-2013-14&highlight=

  8. #8
    Moderator Turbo Mopar Staff Vigo's Avatar
    Join Date
    Feb 2006
    Location
    San Antonio,TX
    Posts
    10,798

    Re: 3.0 Leaning out...

    Well, a low compression non turbo engine with conservative timing is not very sensitive to WOT AFRs as long as they are on the rich side of what a narrowband will read. A wideband would help get the last bit of power out of it and can be helpful for diagnosis, but you could definitely avoid blowing it up with 'just' a narrowband.

    Dont push the red button.You hear me?

  9. #9
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
    Join Date
    Dec 2005
    Location
    Greenville/Spartanburg SC area
    Posts
    7,557

    Re: 3.0 Leaning out...

    Quote Originally Posted by notbob View Post
    (I have a set of 22lb injectors I could throw in as well to test... I know the ecu will not see them as being larger and pulse will still be the same, but they would dump a bit more fuel per pulse - right? - Is it worth trying or just a waste of time?)
    Correct. I would try them, that's all I did on mine was just drop them in. No fuel pressure change.

    FWIW I did exactly that on my stock '93 D150 5.2, original 19# injectors were clogged up so I put in a set of 22# injectors from an '02 Mustang GT. Works just fine, little rich on cold startup but after that runs great. My dad drives it everyday.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  10. #10
    turbo addict
    Join Date
    Jan 2006
    Location
    Hazelwood, MO
    Posts
    6,566

    Re: 3.0 Leaning out...

    This may sound dumb/trivial, but try running NGK spark plugs and re-reading them. I know it doesn't sound like it should ever mater, but I've witnessed it in person...where an engine will run like garbage on one brand of plug, but run perfect on another.

  11. #11
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
    Join Date
    Dec 2005
    Location
    Greenville/Spartanburg SC area
    Posts
    7,557

    Re: 3.0 Leaning out...

    I have too, although usually it doesn't matter. A long time ago I saw this on my '72 D100, ran like garbage on AC Delco plugs, perfect on Champions.

    FWIW I generally only run NGK's in my TM's, either GR4 or GR5. I tried the Autolite AR51 plugs but saw no difference. Have also run Autolite 64's and factory Champion R12YC's and saw no real difference either.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  12. #12
    turbo addict Turbo Mopar Contributor
    Join Date
    Dec 2005
    Location
    Seattle
    Posts
    7,063

    Re: 3.0 Leaning out...

    Really not clear what the changes were before and after. Same cam or you changed to the large cam? Are your lifters able to take up all the lash?

    I can't imagine trying to tune fuel with no real sense of actual fueling. That large cam will mess up the VE curve so much that you have to perfectly tune the leanest and richest points of WOT to just fit into the decent AFR range. Reading plugs when the fuel goes from rich to lean or vice versa is going to be deceptive. Wideband will make getting fueling as close as possible a non question.
    Brent GREAT DEPRESSION RACING 1992 Duster 3.0T The Junkyard - MS II, OEM 10:1 -[I] Old - 11.5@125 22psi $90 [U]Stock[/U] 3.0 Junk Motor - 1 bar MAP [/I] 1994 Spirit 3.0T - 11.5@120 20 psi - Daily :eyebrows: Holset He351 -FT600 - 393whp 457ft/lb @18psi 1994 Spirit 3.0T a670 - He341, stock fuel, BEGI. Wife's into kid's project. 1990 Lebaron Coupe 2.2 TI/II non IC, a413 1990 Spirit 3.0 E.S. 41TE -- 1993 Spirit 3.0 E.S. 41TE -- 1994 Duster 3.0 A543 1981 Starlet KP61 Potential driver -- 1981 Starlet KP61 Parts -- 1983 Starlet KP61 Drag 2005 Durango Hemi Limited -- 1998 Dodge 12v 47re. AFC mods, No plate, Mack plug, Boost elbow -- 2011 Dodge 6.7 G56

Similar Threads

  1. Leaning out the bottom end to build boost
    By badandy in forum EFI Tuning
    Replies: 11
    Last Post: 01-11-2009, 11:07 PM
  2. leaning tire
    By 90turbo in forum Suspension, Brakes, Wheels, Traction
    Replies: 9
    Last Post: 10-27-2006, 07:07 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •