Engine Misfire after Hot Rod Cam Install

Discussion in '2005+ Mustang GT 4.6L Tech' started by 2010GlassGT, Jul 30, 2019.

  1. Laga

    Laga Junior Member

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    Well, it’s like this. I bought a supercharger from them and it came with a tune and ran fine. Then I bought long tube headers from them that came with a tune and it ran fine. Then I bought the cams that came with a tune and it ran like crap. Not only that, but the wiring harness for the Edelbrock SC had a short. I was promised a new one and never got it. I had to trace the short down and solder it myself. As far as the tune, it was super rich which caused the car to idle super bad. Even for a cam. I had to let it idle for OVER 10 minutes before I could back it out of the garage without dying. Once warmed up on the road it got 9 MPG. Shut it off after going to the store and it’s another 5 minutes of idling before the car will move without dying. Unless you rev it up and drop into drive. Despite repeated calls to Brenspeed, they offered no help. I was told” That’s just how it is with a supercharger and cam. Once Lito tuned the car, all it needs is 30 seconds of warm up and I can back out the garage now. The car also gets 18 MPG, and runs like a beast.
     
  2. 07 Boss

    07 Boss forum member

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    Just out of curiosity, Why did you buy Rockers to run with your supercharger? That just seems like such a poor choice especially for a twin screw set up. You have a nice broad power curve with a twin screw with pretty instant torque. The tighter LSA will give you a peakier torque curve with the power falling off earlier as you enter higher RPM's and bleed off more power. I would have thought that a larger valve overlap with a longer exhaust duration would be more conducive with a twin screw.
     
  3. Midlife Crises

    Midlife Crises Junior Member

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    Edelbrock supercharger is a roots not a twin screw.
     
  4. Laga

    Laga Junior Member

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    FB99B1E1-E32F-4146-A699-EE0713C961DF.jpeg
    Because squeezing every HP out of the car was not my primary concern. The car is more of a show car than a race car, although I am taking it to a 1/2 mile speed trap race next week. I wanted the sound of the cam. I was looking at three possible cams. The Rockers, Mutha Thumpers, and Ford Racing. My research showed all around better performance and drivability with the Rockers. Plus, at that point, Brenspeed, promised a tune that would provide what I was looking for. A choppy sound, drivability, and some added power. They had a video of a Mustang with a E-Force SC and the Rockers on their site. I thought it was just what I was looking for. And it is. That is once Lito tuned it because the car wasn’t drivable with the Brenspeed tune and their attitude of “ that’s just how it is”.
     
  5. 07 Boss

    07 Boss forum member

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    Yes it is, but the power output produces the same kind of torque curve and benefit from the same type of cam profile. It was more that I was referring to as opposed to the actual inner workings, but I stand corrected. I should have used the term PD blower instead.
     
  6. 07 Boss

    07 Boss forum member

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    Fair enough.

    I have also heard about Brenspeed's inability or unwillingness to data log and adjust tunes. They are no better than buying a canned tuned, not sure why they call it custom tuning when it's not.
     
  7. Laga

    Laga Junior Member

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    It makes no sense. The datalog with Lito was incredibly easy. I don’t know why they would not help. This was the third tune from them after spending more than $10K with them and never asked for help before. Very disappointing.
     
  8. 2010GlassGT

    2010GlassGT Junior Member

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    Wanted to post an update for everyone. I've been working with my tuner and am now on a new version for about a week. So far, I have no codes and it runs great in all conditions. I'll keep everyone posted as time goes on, but hopefully it was just a slight adjustment in the tune.
     
    RocketcarX likes this.
  9. Laga

    Laga Junior Member

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    Congratulations.
     
  10. GlassTop09

    GlassTop09 Junior Member

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    Good deal!
    Hope it all works out for you.
    :waytogo:
     
  11. MilehighGS

    MilehighGS Junior Member

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    Lito tuned my DOB setup with HR cams, and the car runs great, very good road manners.


    Sent from my SM-G975U using Tapatalk
     
  12. GlassTop09

    GlassTop09 Junior Member

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    This is a funny post I'm making due to me checking my car w\ my Foxwell N301 scan tool (was bored) sometime after this thread's conclusion & I noticed that the IM readiness light was yellow instead of green (indicates that there was a monitor that hasn't set or a pending DTC code has set, red light shows a permanent DTC code set) so I went in to check & saw that the spark monitor had a pending DTC code set & guess what it was.....P0300 random misfire! I had never seen this since owning the car (2 yrs to date).

    Now this was a surprise as I hadn't noticed any misfires occurring, so I went into the Onboard Monitor Check & pulled up the Misfire Monitors (Mode 6) & sure enough there were recorded last count misfires on all cylinders except #5 but the EWMA counts were all at 0% which says that these misfire counts are very random & are definitely not sequential. Some background: I had also installed a set of cams (Lunati VooDoo #21270700 cams) roughly 2 months back & had the car retuned shortly afterwards. So I cleared the DTC (which clears all the data so all starts over) & started monitoring my car over several days w\ my scan tool checking the Misfire Monitors across cold starts & just before shutdown after parking as well as checking FT's & picked up some interesting info. First thing on initial starts I noted that the car would momentarily stumble sometimes as if a cylinder didn't have good combustion while spinning up...especially on a cool early morning 1st start but would straighten out quickly & go on as normal, whereas on startups later on in the day I detected no issues & the misfire total counts hadn't changed once engine had reached hot idle. LTFT's at idle showed B1 @ -7.8%, B2 @ -1.3%...large spread between banks is odd. The spark monitors showed that the misfire counts weren't consistent across all cylinders & were varying across all cylinders but no counts ever exceeded past 31 on any cylinder but the cylinders that consistently showed the most misfire counts regardless were #3, #7, #8. Now the plugs in my engine were changed out in 11-17 shortly after I bought the car (car had 139,487 mi at purchase @ 10-17) w\ MC HJFS24FP OEM plugs & the coil boots were also changed out (had this done at Ford dealership while having other work done due to owner's manual calling for changeout after 100,000 mi & had no maintenance records on car) so these plugs have a little over 10,000 mi on them....which is nothing. I remembered that during the Lunati cam install I didn't number match the coils to the cylinders that they came off of when removing them. In general this shouldn't matter but in reality this CAN matter as coil's secondary windings can get electrically conditioned to the plug\cylinder that it was installed on & can be thrown off if swapped to another plug\cylinder that has higher cylinder compression\resistance thru plug (fire weak or not at all) as well as primary windings due to connector contact\current flow resistance thru wiring so generated magnetic field during dwell time can be weaker.....the older these coils get the more they are prone to this. Ran olm checks across primary coil windings to see but not expecting to find much difference since having no dead misses....all checked out at .8 to .9 ohms so I knew that the issues had to be secondary winding related & since these coils were the OEM coils w\ a lot of miles on them I bought a new set of OEM coils (FP coil package) to replace them.
    After installing these the amount of recorded misfires went down drastically but didn't completely clear out but the idle LTFT's didn't change either (engine power output clearly did improve due to better combustion from the hotter spark from fresh coils) so after giving it a few days to see if the spark misfire counter results would improve (then I clearly heard a coil misfire inside a plug well on B1 changing the engine speed during a warmup after a startup) I went & bought a new set of Champion Iridium #9406 plugs (went w\ Champions this time due to having good success w\ them back in my younger days) to replace the OEM plugs to see if I got any improvement (wasn't expecting to find any obvious issues w\ the MC OEM plugs). Gapped them to .040" per OEM spec & installed them making sure to keep the same coil on the same cylinder this time. As expected I saw no visual clues w\ the OEM plugs to point towards misfires....all gaps were at .040"-.042" so within spec, saw no broken\cracked\tracked porcelains or boots & all tips looked good, no burned electrodes w\ a light brown hue on the insulators (indicating slightly rich fuel mixture). But on initial startup after plug changeout the spark monitors went almost to 0 counts (had only 1 count on #1, #3, #7 w\ 2 counts on #8, rest were 0) & the LTFT on B2 went from -1.3% to -6.3% w\ B1 going from -7.8% to -7.0%. The change in LTFT on B2 definitely proves the cylinder misfires on B2 #7 & #8 were plug related (not necessarily no spark but a weak spark causing insufficient fuel burn thus throwing the cylinder accel velocities off & B2 O2 sensor picking up the extra unburned oxygen once in CL driving the LTFT to go much leaner on B2 vs B1..). Engine showed even more power improvement after plug changeout. Ran a vacuum test on engine at idle.....gauge needle was dead still pulling 21"Hg of vacuum indicating no mechanical issues & no vacuum leaks.
    This got me to thinking about what could cause these misfires after a cam swap & the obvious thing that came to mind is the ground in advanced cam timing difference of aftermarket cams vs OEM cams when the cam phasers are locked at base timing (phaser full advance on 3V's) during startup. I know that these Lunati's have 14* advance cam timing ground in vs the OEM's 5.25* advance so the initial cylinder pressure would be higher at startup w\ these cams vs the OEM cams which can put a higher load on the ignition system to fire the cylinders when cold which could cause misfires (or uneven cylinder accel velocities) from weaker spark\no spark then ease up once the cylinders warm up, EOP builds up to allow the cam phasers to unlock so the PCM can now control the cams & retard the cam timing for EGR purposes which will reduce the cylinder pressure which could stop the misfires (or smooth out the cylinder accel velocities) at idle, but also the amount of fuel injected may be too heavy (rich) at cold startup (judging by the idle LTFT's once the PCM goes into CL along w\ the physical OEM plug inspection) causing plug fouling thus misfires but stops being an issue once the engine warmed up. This along w\ me swapping the coils across cylinders during the Lunati cam install most likely exposed the weaker ignition parts breaking down that were conditioned to the cylinders while the OEM cams (tune w\ OEM cams as well) were being used so coils & plugs were involved w\ my P0300 issue but fueling may be the main culprit that started it all.

    Am curious as to what your tuner found\did w\ your tune as I know the HR cams have 19* of advance cam timing ground into them. I am planning a second session w\ my tuner for other reasons (had a false knock issue detected during dyno runs & afterwards had found an exhaust clamp hitting the gas tank shield on B1 side so wanting to verify the false knock was resolved after repairs) but will now add this to his list as well to revisit the fueling especially at startup\idle. I am also contemplating to change out the crank position sensor as well w\ a new 1 just to freshen all this up even though I can't detect any issues w\ it at this time w\ the equipment I have to use (am contemplating getting a better scan tool that can perform bi-directional testing & these sensors are pretty cheap in general) so will get w\ my tuner to see if he can see anything here (most likely not) as well while on the rollers this time.

    If all does check out I may move to a hotter plug to compensate for the richer fueling......
     
    Last edited: Aug 21, 2019 at 2:42 PM
  13. MrAwesome987

    MrAwesome987 forum member

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    I can echo this... just had Lito tune my car with a DOB setup and DR SC cams, and it runs much, much better than the tune I got from a local dyno tuner. Car drives great.
     
  14. Laga

    Laga Junior Member

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    I would definitely look into datalog tuning with Lito before trying hotter plugs to dealer with rich conditions. The tune that came with my cams was super rich at startup and idle to the point where my eyes would burn waiting for the car to warmup enough to back out of garage. Installing new crank sensor also worked for me. Cheap and easy.
     
  15. GlassTop09

    GlassTop09 Junior Member

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    Did a little more investigation since my last post. Car is running very good at this time on the Champion #9406 (RET8ZWMPB4) Iridium Spark plugs (these plugs were a cross match to the MotorCraft HJSC24FP Double Platinum OEM spark plugs, the OEM Champion equivalent is #7406-RET9ZPMPB Double Platinum which also cross matched as well) w\ scan tool spark monitors showing all 0's on all cylinders now from startup thruout to shutdown. I then took my trusty Klein DVOM & ran an olm check on the MC plugs to check the condition of the center electrodes since these plugs are a resistor design & here provided is the results of this checkup:
    IMG_0091.JPG
    As you can see, I identified some of my misfire issue as 2 of these plug's center electrode resistor tested to had broken down giving very high & inconsistent olm readings above spec (resistor specs for these MC plugs is between 2K-9K olms). Had 1 plug jumping between 4.20K-OL, the other never gave a reading other than OL so at least these 2 plugs are known to fire weak or not at all when cold but would start firing better once they got some heat into them from the center electrodes expanding & reducing the resistance in the resistor to allow the spark to go thru to the tip.....these plugs have a copper center core firing thru a platinum tip to a platinum ground strap (thus the "double platinum" designation). So from this finding the original coils are "technically" still good, only issue is how much damage has some of them incurred from having to fire across bad plugs (just because the others show to pass a resistor olm test isn't a guarantee that they're good AND a coil's secondary windings breakdown failure may be the cause for the spark plug resistor failures...….scan tool showed intermittent misfires across all cylinders except 1 initially). Note the tip condition of each plug.....unless I had ran the olm test on them you'd never thought they were bad...…always follow up w\ testing to confirm\deny. DVOM meter was set to 20K olm range to fully cover the resistor specs.

    So from all this I'm gonna chunk both the old coil set (except the coil boots\center wires as these were new replacements) & these spark plugs...………. I'm also gonna get a professional level scan tool w\ bi-directional capability & all the necessary attachments to enable me to perform all these tests & maybe make a little money doing diagnostic work on the side.

    I chose to go w\ the Champion #9406 Iridium version due to the stronger copper-nickel alloy center electrode core w\ iridium tip (resistor spec is somewhere around 5K-10K) vs the copper center electrode core w\ platinum tip so hopefully they don't break down on me going forward. As posted before I've always had good service running Champion spark plugs in the past so decided to give them a shot w\ this Ford. The MC OEM plugs have a listed manuf heat range of 6, the Champion #9406 plugs have a listed manuf heat range of 8 but they show to cross match. I have looked far & wide to find a heat range scale for these MC plugs to determine which way the actual heat range comparison between the 2 is swinging w\o success (can find this for all other spark plugs) but since they do cross match the heat range differences should be very small.

    But you know what can happen from assuming...…...

    I know I'll find out for sure once I get her back on the dyno so until then I'm gonna keep my right foot under close supervision…..

    Always amazed at the sequence of events that can occur when a specific part is changed on an engine that can set off a chain of subsequent part failures.....welcome to the world of modding!

    :biggrin:
     
    Last edited: Aug 23, 2019 at 8:44 PM
  16. GlassTop09

    GlassTop09 Junior Member

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    This might just happen once I get me a small laptop to use......I'm also looking at getting an AutoEnginuity scan tool setup which would Segway perfectly w\ getting a Lito tune as I already own a SCT X4 tuner...…..

    ;)