Engine Misfire after Hot Rod Cam Install

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

  1. 2010GlassGT

    2010GlassGT Junior Member

    33
    1
    Hi All,

    I installed Ford Racing Hot Rod Cams a couple months ago, along with new Motorcraft plugs, and new cam sprocket bolts. I've been through a couple tune revisions but every once in a while I'm getting a P0300 and/or P0316. They usually come up by checking with the X4, but a few times the Check Engine light comes on.

    Other times I'll have no codes whatsoever and no issues (after clearing). There has been no decrease in performance and all the datalogs I've taken look good per the tuner. I've always used 93 octane from reputable gas stations, so I don't think that's it.

    Any ideas on what could be causing this intermittent code? All connections good (VCT, COPs, plugs tight).

    Thanks.
     
  2. nfrizell

    nfrizell Junior Member

    43
    14
    That can happen when valve lash on valves are a little too tight. Same cylinder every time?

    Sent from my SM-G930V using Tapatalk
     
  3. 08MustangDude

    08MustangDude forum member

    226
    21
    PO300 is a random misfire, while the P0316 is misfire detected
    on start-up for the first 1000 RPMs. P0316 can be related to
    both the CAM and CRANK position sensors.

    This also happens with a different cam profile, it freaks out the timing
    advance system, but there really isn't an issue. If there is not an issue,
    the P0300 code should be tuned out. I saw a HP tuning video where
    that was done because of the code. If you're sure the hardware is all
    correct, fuel delivery is correct, then it's a tuning issue.

    Worst case scenarios:
    Check the exhaust camshaft sprocket bolt, if it's loose, cam should spin
    with the gear not freely or independent of the cam.

    You can also be just one tooth off timing.

    Worst case is a bent valve after the installation.
     
  4. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    There is no exhaust camshaft sprocket bolt, the 3v engine is SOHC

    You need to pull it down and retime the cams, you are a tooth off on one side
     
    jewc75 likes this.
  5. 2010GlassGT

    2010GlassGT Junior Member

    33
    1
    I used the Ford Timing Chain Wedge and marked the chain/sprocket with no movement during the install. I've also been running for 2,000 miles with no visible/audible issues, up to redline, and multiple datalogs. Is there any other way to check without pulling the front cover? Would the car even run normally if it was off by one tooth?

    Thanks.
     
  6. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    I feel like I answered this question for you on FB already...
     
  7. 2010GlassGT

    2010GlassGT Junior Member

    33
    1
    Sorry, but this is the only location that I've posted my issue. Appreciate your insights regardless, just trying to reach a resolution.
     
  8. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    There was a guy over the last couple of days in one of the S197 groups posting the same thing, lol.
    I would pull the front cover and look into the timing marks
     
  9. Eel Mit

    Eel Mit forum member

    118
    0
    Before you get carried away, do a compression test. If cam timing is off on one side, compression will usually be significantly lower on one bank than the other. A lot of tuners disable misfire monitors on cam cars anyway. That lope you hear results in the crank angle sensor speeding up and slowing down...which is exactly what the PCM looks at for misfires. Your tuner may just need to switch off those codes to keep the light off.

    I would only be worried if compression was off on one cylinder or if it threw a specific (P0301, P0302...) code.
     
  10. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    I've never seen a cam'd 3v need the misfire monitors disabled, especially with Hot Rod cams.
    It stands to reason the issue is related to what to OP messed with, which involved the possibility of the timing chain jumping a tooth. I wouldn't call it getting carried away to verify the timing marks are in place, this will also allow him to inspect the timing components for anything broken.
    The PCM doesn't care about the RPM oscillating, the cam angle sensor is used to compare data with the crank sensor and verify where the cam is in relation to the crank.
    When it comes to misfire detection it is mostly the crank sensor the PCM cares about, it is looking for the crank trigger wheel to be stuttering in it's rotation instead of a smooth linear rotation.
     
  11. 2010GlassGT

    2010GlassGT Junior Member

    33
    1
    Not sure if this is helpful in any way, but: I drove the car to work this morning about 45 minutes, 35 miles at about 70 degrees. I checked codes this morning when I got there with the X4 after clearing last night and there were none except P1000 (monitor testing not complete), normal. I stopped on my way home for gas after an hour of driving, but at about 90 degrees outside. In addition to the first code I had P0300 and P0316. I was only able to see this when reading with the X4, no check engine light. I was reading that the misfire codes are two step codes, where they need two or more key cycles for the light to come on. After several key cycles of starting and stopping, no light but the codes remained. This makes no sense to me right now.
     
  12. 08MustangDude

    08MustangDude forum member

    226
    21
    RocketcarX: I saw a video on the misfire code(s) being tuned out after installing
    these cams, specifically. They used the HP Tuner.
     
  13. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    I've installed much more aggressive cams using HP tuners in this platform and never had this issue.
    They probably didn't input the data correctly and used this as a bandaid.
     
  14. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    Are you using a 2 step?
     
  15. RocketcarX

    RocketcarX 95% of my weight is fuel

    2,648
    163
    Check and double check your work, go over the ignition coil and injector connectors. Rule out the basics and then consider pulling the timing cover
     
  16. 2010GlassGT

    2010GlassGT Junior Member

    33
    1
    I'll start checking basic stuff this weekend and see if I can find anything. Cleared the codes this afternoon and nothing popped up after a 20 minute drive and the car was fully warmed up by that point. It seems to only trip when running for a while at hotter temperatures. I am not running a two step, it was just my lingo to describe the system logic for the check engine light to come on.
     
  17. GlassTop09

    GlassTop09 Junior Member

    42
    13
    I went & checked on the origin of the Ford P0316 DTC code & found that this DTC came about sometime in '06-'07 due to Fed gov demand to start monitoring for OL cold start emissions (was only monitoring for emissions once PCM was in CL operation prior). Since the PCM is in OL operation due to O2 sensors being inoperable (no signal output) due to low O2 sensor operating temps at initial startup the PCM is looking at the crankshaft sensor for crankshaft acceleration velocity of individual cylinders to then compare against the other cylinder's acceleration velocities to determine if a cylinder is "out of phase" (most interpret as a misfire, thus emissions due to spewing unburnt fuel into exhaust) during the initial startup up to the 1000 rpm mark (usually when the O2 sensors reach the operating temp they need to start generating a signal to the PCM then the PCM goes into CL operation). As long as the accelerations during this time period are within a certain threshold all is well but if at least 1 cylinder's acceleration falls below a certain threshold in comparison to the other cylinders accelerations then the PCM will set this DTC. This could also cause the P0300 random misfire DTC to set as well since the PCM has to be in CL (needs the O2 sensor output along w\ the crankshaft sensor output) in order to isolate a misfire to a single cylinder (the P0301, P0302, P0303, etc). Ford vehicles earlier than '06-'07 won't have this P0316 DTC capability unless the PCM firmware has been updated....most likely thru a TSB issue.

    The actual cause can be a LOT of things, but 1 known thing in particular in this instance is the distinct cylinder acceleration velocity variations caused by large overlap camshafts which really are more prone to setting off a P0316 code if the original OEM cold start crankshaft acceleration thresholds (calibrated to the engine cylinder accelerations using the OEM camshafts) in the tune are being used as these camshafts will cause excessive variations in crankshaft accelerations, especially at low engine RPM's (thus the sound most admire) & are very sensitive to outside influences (temp at cold start, fuel quality at cold start, quality of the tuning associated w\ them, etc). This can be fixed in the tune in 3 ways..... 1.) reset the start up crankshaft acceleration offset threshold to more favorably match the acceleration patterns from the cams or, 2.) retune the engine to smooth out the accelerations to bring them back within the OEM thresholds or, 3.) disable this particular P0316 DTC code in the tune so the PCM won't be checking for this during start up as this is strictly due to an emissions requirement during cold startups while the PCM is in OL operation....that is, as long as it is not required to be active in the PCM to pass emissions testing. Once the PCM is in CL & these conditions still exist they'll show up as P0300, P0301, P0302, P0303, etc so you have a decision to make as to which path you want to go down.

    When you're checking the codes, check to see if the code is set as a pending code or permanent code (pending codes will not initially set the MIL as more instances are needed for the PCM to determine if issue is a permanent issue....only when the PCM has determined the issue to be a permanent one will the MIL come on). Don't remember if a SCT X4 tuner will read a pending code (I use a hand held scan tool for this as I'm also looking at other items that you can't see using a SCT X4 tuner) so can't reply to that.

    I find that it helps to understand the meaning\intention behind a particular DTC code to then compare to known conditions to help w\ diagnosis.

    PS--This issue could be as easy to fix by just increasing the engine's idle speed enough to smooth out the engine crankshaft velocity variations caused by these Hot Rod cams...…………..just a thought...………..
     
    Last edited: Aug 3, 2019
  18. 2010GlassGT

    2010GlassGT Junior Member

    33
    1
    Thanks for the input GlassTop09, it's really appreciated. I had the check engine light come on Friday and had since cleared it. I've also sent some additional logs to my tuner to see if he can see anything. This weekend I checked all my connections and all the plugs. The plugs look perfect and no issues with any connections.

    Today I ran the same commute in near identical conditions and there are no codes. I'll keep everyone posted.
     
  19. Laga

    Laga Junior Member

    6
    0
    New member here. FWIW, I installed a Detroit Rocker cam around last Christmas and had a few misfire codes. Part of it was probably the terrible tune that came from Brenspeed. But then, I got a faulty crankshaft position sensor code. Sensor was cheap and easy to replace and codes went away. And once Lito tuned the car, it drives like a dream now. Good luck. 2005 Mustang Gt 52K miles.
     
  20. Badd GT

    Badd GT forum member

    296
    12
    so, you think brenspeed cant write a tune for their signature cam?