[gbassrace]

Big Jim - I have a 2018 with 10k miles w/ a Mountune Stage 1 tune. I just started feeling this a couple weeks ago, but as you say, the more you go the more it happens. Not cool at all!!! I don't think its the plugs bc after 20 seconds, it doesn't happen again. I think it's the ECU in some load protection mode and it absolutely needs to be tuned out. My Mazdaspeed3 never did this with a ProTune. I will def address this with my tuner when I get a Cobb AP and ProTune. Plz keep its up on your findings.

 

[SaxmanUSMC]

Well I finally installed my Mountune Recirc valve yesterday. Drove it around a bit on the stock tune and didn't notice any difference other than boost seemed much more consistent with no fluctuations.

Loaded my Stratified flash tune and have driven a bit on that yesterday evening and this morning, including a 70 mile trip. So far I am not noticing the hesitation as before, boost pressure is very consistent, and it feels like it is holding better at WOT.

The tune still feels a bit sluggish at part throttle. I don't think they re-mapped my sport/track throttle to aggressive like I asked. Regardless, so far no hesitation, but I need to drive it a bit more to make sure.

It does seem that the simple diaphragm design of the stock recirc could be a primary cause of this issue. I am going to try the Cobb Stage 1 OTS tune today and see if there is any of this hesitation.

 

[Big Jim]

Big Jim - I have a 2018 with 10k miles w/ a Mountune Stage 1 tune. I just started feeling this a couple weeks ago, but as you say, the more you go the more it happens. Not cool at all!!! I don't think its the plugs bc after 20 seconds, it doesn't happen again. I think it's the ECU in some load protection mode and it absolutely needs to be tuned out. My Mazdaspeed3 never did this with a ProTune. I will def address this with my tuner when I get a Cobb AP and ProTune. Plz keep its up on your findings.

Hey guys...UPDATE. got my iridium 6510 plugs yesterday. gapped them myself to .026. removed the old 6510 plugs with about 30k miles on them and fitted new ones torqued to 15 ft lbs.
1. engine vibrations are gone
2. throttle cuts are gone 100%...in all drive modes
3. return of what feels like 80 bhp
4. refitted UPR oil breather cap and no oil mist on my valve cover now
5. gas mileage going back up
6. smile on my face
The old plugs weren't in bad shape at all...just the gaps on all 4 were about .035...so way out of spec.
When i installed them 30k miles ago...they were gapped to .025
For the record: i was only getting throttle cut on WOT or 3/4 WOT pulls. It was not happening at half or part throttle. but im sure if i let the old plugs stay in there long enough...it would have starting happening in all situations. the past couple of weeks i noticed on 1 or 2 occasions it cut throttle 2 or 3 times very quickly on the same pull.
so it was consistently and progressively getting worse.
hope this helps.

 

[gbassrace]

Great! Doing my first plug change @ 10k mi from OE to 6510's. Yes, have felt power cutting lately and really hope this solves it. Will report back.

 

[SaxmanUSMC]

Update on mine.....

I put the stratified flash tune back on last week. I am back on the stock plugs gapped at .028-.029. all the hesitation and numerous part throttle negative corrections are gone.

Did a test yesterday; pulled the plugs and closed them down to .025-.026, which is what the tune was set for with NGK 6510 plugs. All the hesitation and neg corrections were back. Car drove like crap at part throttle. Idle and power delivery felt rough.

Pulled the plugs this morning and set them back to .028-.029. All is right with the world. No hesitation, power delivery is very smooth and strong, idle is butter.

It weird but apparently my car just does not like the close gap on plugs.

 

[gbassrace]

Interesting, I'd like to hear from some more peeps on their gap spec for 6510's. I am using 0.026 and it's fine but these are my first set after OE plugs.

 

[SaxmanUSMC]

Interesting, I'd like to hear from some more peeps on their gap spec for 6510's. I am using 0.026 and it's fine but these are my first set after OE plugs.

Everyone always states they are fine. I have a set of 6510 that are gapped to .026 but I had the same hesitation issues with them. I have not tested them at .028-.029 like I did the stock plugs though. Even so, as far as I know they are the same temp range anyway so it shouldn't be any difference.

 

[hydrostream]

In my Mustang something used to happen around 15mph after a cold start. IIRC it was the ABS self test, but I never would have guessed it until I researched it. Can’t remember if it was just a noise or a hesitation, but I do remember at first impressions it didn’t seem like anything related to the brakes.

I’ll pay more attention next time I’m in my RS.

 

[Big Jim]

Update on mine.....

I put the stratified flash tune back on last week. I am back on the stock plugs gapped at .028-.029. all the hesitation and numerous part throttle negative corrections are gone.

Did a test yesterday; pulled the plugs and closed them down to .025-.026, which is what the tune was set for with NGK 6510 plugs. All the hesitation and neg corrections were back. Car drove like crap at part throttle. Idle and power delivery felt rough.

Pulled the plugs this morning and set them back to .028-.029. All is right with the world. No hesitation, power delivery is very smooth and strong, idle is butter.

It weird but apparently my car just does not like the close gap on plugs.

lots of folks are running diff gaps here...some at .020 or .018. depends on the build...the plug...the tune.
kinda frustrating hearing that you had that much neg affect from .025 and .028
i had my 1st hesitation last week...after 5k miles since last gap at .026.
im gonna try the ngk ruthenium hx (95605) plugs in a month. i'll try .024 next

 

[gbassrace]

I'm seeing that larger may be a solution not smaller.

 

[SaxmanUSMC]

I'm seeing that larger may be a solution not smaller.

In my car at least it seems to be. I have not seen any issues from it on wide open pull datalogs either. Planning on getting the logs together for my refinement this weekend.

 

[mexrs]

Bringing this back to life incase anyone has more to add to the issue

 

[Big Jim]

i have no more throttle cuts under heavy acceleration. ive mastered the plug gap...lol.
but i still have rough cold start idle. im sure this is due to the gasket needing proper "amended" work.

 

[hydrostream]

After paying attention more, I definitely get a hesitation when my car is cold on the first acceleration out of my neighborhood. I’m going to assume it has something to do with the warm up fuel scheduling or whatever, hah!

 

[SaxmanUSMC]

Mine has been good on the stock motorcraft plugs at .028-.029. I pulled the tune though and have been running the car stock since my last post though.

Now car is getting prepped to sell unfortunately. Just to uncomfortable for me as a daily driver.

 

[CarloVeRS]

Hi All past posting legendsim picking up this issue. It started without reason.
Changed plugs, checked gaps, cleaned throttle body, cleaned and checked ALL air flow sensors, replaced fuel filter and charged up the battery. New recirculation valve.

Anyone find a fix or reason for the issue.

Thanks.

 

[axelr]

There are two very different issues discussed in this thread:

• Misfires/cuts at WOT and slightly rough running at idle and elsewhere.
• Occasional misfire-like/torque control effect around 3000rpm at light throttle/acceleration.

The two are unrelated.

The first one is easy: worn spark plugs (around 1mm (0.039”) gap) get you cuts at WOT and high load. Too little gap and you get less combustion stability because the flame start less regularly from cycle to cycle and cylinder to cylinder. Too cold plugs and you get fouling and rough idle, especially cold. Colder + tigther gap is a recipe that gives you that rough feeling cold and beyond. Stock plugs with stock gap of 0.8mm (0.031-0.032”) cures all those issues. Tuners can increase the coil energy a few percents at high load where it counts. My $0.02ct: Use whatever NGK or Denso if you like but don’t mess with the gap of 0.8mm (0.031-0.032”), and stick to the stock heat range unless you run the car constantly at high load like on a track day, which is never on the street. Have a track day set that is colder and that you only use on those days if you are an advanced amateur with a heavy foot, otherwise don’t bother. I tried the ITV20TT, ITV22, ITV24, and ITV27 (multiple sets) and my choice is the ITV20TT with 0.8mm gap. The engine runs like a Rolex.

The second problem eluded all tuners. It is mildly apparent in the stock calibration and somewhat exacerbated depending on what was changed in the tune. It can be cured. I’d advise to look around the HDFX transient performance settings.