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Author Topic: Random Misfire What Should I Check Next  (Read 7225 times)
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barmato
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« on: June 10, 2016, 12:08:16 AM »

My car has developed a random misfire that seems to be slowly getting worse.  Here is a little about the car, the symptoms, and what Ive tried so far.

Car Specifics
60,XXX miles
FM2 Conversion (GT2650)
Hydra
700 CC Deatschwerks Injectors
MBC set to 10 PSI
Ebay Intercooler
Forge Motorsports Recirculating Valve
NGK ZFR6F-11 plugs gapped to .028=.029 (new)
Magnecore Wires (about 7k miles)
Original fuel pump with original filter
Original coils

Symptoms
The car will occasionally miss while driving, anywhere from once every couple of minutes to a few times a minute.  It doesnt seem to be RPM specific as Ive had it happen at idle all the way up to redline.  It does it under light load while gently accelerating or at steady speed up a hill and also does it under heavy load during a full throttle pull to redline.  Even after a cold start I can hear it miss as the idle comes down from the initial flair.  It was doing it a little last year but only under light load around 2-3k rpm or so and I thought it was the known hiccup that the Hydra has when lugging it around.  Last summer I also remember it had a slightly rough idle accompanied by little pops from the exhaust during idle which I though was just the way the 700CC injectors idled.  The car was put away from around November until March this year and I installed the FM2 conversion during that time.  I didnt notice anything abnormal when I first got the car back on the road but lately its been happening more frequently.  When it misses at high RPMs its accompanied by a fairly loud pop from the exhaust which I assume is unburnt fuel from a misfire igniting inside the hot exhaust.  Along with the FM2 conversion, Jeremy tweaked my map but Im pretty sure all he did was adjust fuel.  The timing table and other settings all looked the same from what I can tell.

What Ive Tried
-Ive played with my tune.  I originally tried retarding the timing across the board but Jeremy though I might need more timing in the areas where it was happening so I tried that too.  Neither direction made any noticeable difference.  Jeremy also suggested playing with the ignition dwell so I increased the ignition dwell by .5ms and then 1ms with no noticeable change.  I installed new plugs even though my old ones only had about 8k on them. No noticeable change.  I checked the connections to the plug wires.  Checked the connectors for the IAT, TPS, Cam and Crank position sensors.  I checked/re-gapped my crank position sensor (it was well within spec). 
I also cleaned the main engine ground and throttle body ground.  About the main engine ground, it originally attached to the exhaust manifold through one of the bolts that attached the heat shield.  Now with the FM2 kit I wasnt sure where to put it so I asked FM and the tech on the phone was pretty sure they move them to the dipstick bolt underneath the nut that holds the dipstick in place so that's where I put it.  Does that sound right?  Is there anything between that bolt and the engine block that would prevent a good ground path?  Continuity measured fine but that doesn't necessarily mean it can handle the load.

What Next
Im not sure where to go next from here.   I was thinking about replacing either the cam position sensor, coils, or crank position sensor.  Jeremy offered to check out my Hydra as a last resort if I send it to him but I dont think Im there yet.  Any suggestions.  Does the failure mode of any of the 3 items Im considering replacing match the symptoms Im having. 

Thank you in advance.  This has been frustrating as I want to bring my car to Ken Hill for a proper tune but I feel I should sort out this issue first. 

Ben
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SilverMiataRacer
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« Reply #1 on: June 10, 2016, 12:19:45 AM »

It sounds like ignition to me.  Consider coils as a possibility.  It might be time to consider upgrading rather than spending money on new stock coils put that money toward a better system.

Just an aside.  You mention OEM fuel pump and filter at 60k.  The pump doesn't bother me but the filter is something I would have changed.
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Larry

4 Miatas but who's counting!!   Cool

White Knight    1991 Crystal White   #99 CSP
Silver Bullet     1992 Silverstone     #17 SM2  FM I+ Turbo  (Gone but not forgotten)
Honey B          1992 Sunburst Yellow #99 SM2 J.R. M45
Whooosh         2004 Titanium MazdaSpeed MX5  #403 of 4000
Subie              2006 Steel Gray WRX STi Cobb Stage 2 (Gone but not forgotten)
No name yet    2008 Velocity Yellow Tintcoat Z06 Corvette
No Name yet    2014 Ashen Grey Metallic Camaro 2SS 1LE

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Ernest Hemingway
Chrisbee
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« Reply #2 on: June 11, 2016, 05:15:03 AM »

I know there has been mention of a random "hiccup" while driving with the Hydra, but shouldn't be nearly as often as you're saying. I know I've noticed it with my MSM and the Hydra, but it's maybe once every 5-10 mins.
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2004 TI #3021. Purchased Oct. 2014 with 56k miles.

Engine: FM 2 kit with Hydra 2.7, 700cc injectors, and full 3" exhaust.
FM Crossflow radiator w/stage 2 airflow kit.
Suspension: Fox Racing with FM sway bars.
Wheels: 15x8 Enkei PF01s running 215/50 BFG G-force Sports.
Misc: Custom Speedhut boost gauge in place of stock oil pressure gauge. Temp gauge mod. ScanGaugeII. Blue instrument panel lights. Eclipse dash vents.

Definitely a work in progress!
Tickittyboo
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Posts: 454



Re:
« Reply #3 on: June 11, 2016, 10:35:10 AM »

I've been fighting a similar problem. Just for giggles, try zeroing your ltt values and turning your ltt and closed loop off. Does the car still misfire? I bet it's somewhere in your wbo2 system. When I do this that random hiccup goes away.
At the very least you would be helping me out by checking this out. :-)
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2004 Velocity Red MSM with Flyin' Miata's Big Enchilada tuned by Ken Hill, V-Maxx Extreme adjustable coilovers, FM front sway bar, 949 Racing End Links, Boss Frog Double Hoop Roll bar, Tr Motorsports c3m 15x9 wheels with 225 45 15 Hankook Rs3's and carbotech ax6 brake pads all around.
barmato
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Posts: 743


« Reply #4 on: June 11, 2016, 12:48:12 PM »

I've been fighting a similar problem. Just for giggles, try zeroing your ltt values and turning your ltt and closed loop off. Does the car still misfire? I bet it's somewhere in your wbo2 system. When I do this that random hiccup goes away.
At the very least you would be helping me out by checking this out. :-)
I will test the closed loop and get back to you. 

Are you running R87 firmware by any chance?  My issue does somewhat coincide with going from R85 to R87.  I may also try going back to R85 to see what happens. 
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barmato
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Posts: 743


Re:
« Reply #5 on: June 11, 2016, 03:32:59 PM »

I've been fighting a similar problem. Just for giggles, try zeroing your ltt values and turning your ltt and closed loop off. Does the car still misfire? I bet it's somewhere in your wbo2 system. When I do this that random hiccup goes away.
At the very least you would be helping me out by checking this out. :-)

Ok, I did what you said and turned off ltt and closed loop and then zero'd the ltt and sure enough the car ran without a "hiccup".  I drove it for about 45 minutes with zero "hiccup's".  I then turned just closed loop back on (left ltt off) and the problem immediately came back.  After about 10 minutes I turned off closed loop again and the problem was gone.  I think you're onto something here.  

Just a side note, my car ran leaner almost everywhere with closed loop and ltt off and seemed to be down on power a bit which isn't surprising considering some of the afr's I was seing.  

Ben
« Last Edit: June 11, 2016, 03:47:15 PM by barmato » Logged
Tickittyboo
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« Reply #6 on: June 11, 2016, 08:50:28 PM »

I've been fighting a similar problem. Just for giggles, try zeroing your ltt values and turning your ltt and closed loop off. Does the car still misfire? I bet it's somewhere in your wbo2 system. When I do this that random hiccup goes away.
At the very least you would be helping me out by checking this out. :-)

Ok, I did what you said and turned off ltt and closed loop and then zero'd the ltt and sure enough the car ran without a "hiccup".  I drove it for about 45 minutes with zero "hiccup's".  I then turned just closed loop back on (left ltt off) and the problem immediately came back.  After about 10 minutes I turned off closed loop again and the problem was gone.  I think you're onto something here.  

Just a side note, my car ran leaner almost everywhere with closed loop and ltt off and seemed to be down on power a bit which isn't surprising considering some of the afr's I was seing.  

Ben
Glad to hear is not just me. Anyone else out there experience this? I've gone back and forth with Jeremy on this numerous times and he just says it probably the known hydra hiccup that they can't seem to fix. But it still strikes me odd that my car running on its base map (a Ken Hill tune) works perfectly smoothly. But starts acting up when ltt and closed loop are on. I have had a hard time capturing it on a data log. I need to go for a ride as a passenger and just keep working on that. I'm hoping you will mention your findings to Jeremy. The little hiccup isn't the end of the world but it sure would be nice to get it dealt with. I've had it since day one of my Hydra install. The gains of the tuned hydra are still well worth putting up with this issue though.
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2004 Velocity Red MSM with Flyin' Miata's Big Enchilada tuned by Ken Hill, V-Maxx Extreme adjustable coilovers, FM front sway bar, 949 Racing End Links, Boss Frog Double Hoop Roll bar, Tr Motorsports c3m 15x9 wheels with 225 45 15 Hankook Rs3's and carbotech ax6 brake pads all around.
barmato
Fifth Gear
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Posts: 743


« Reply #7 on: June 11, 2016, 09:00:50 PM »

I have captured it on a log that I sent to Jeremy. He suggested my coils may be getting weak, i need more timing in those areas, or i need to increase dwell.  I havent replaced the coils but the other two suggestions didnt make a difference.  He did say it was definitely not the known Hydra hiccup since the log I sent him had it ocuring twice and both times under full boost at 4-5k rpms.  I guess its not my coils if turning off closed loop and ltt makes it go away. 

Does yours ever happen in bost at high rpm or just putting around.  Happens both for me.

What firmware are you using?  Do you happen to know if I can load a previous firmware but use my same map or do I need to go back to an old map?
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'95MSM
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Turbo clocked downward, new i/c plumbing


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« Reply #8 on: June 11, 2016, 09:41:23 PM »

If a coil is getting marginal, any change (boost, afr, etc) that makes it harder for the spark to jump the plug gap can cause a misfire. I don't think you can confidently rule out your coils.
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'05 running gear + '95 body
3.63 ring & pinion FM content: Blouch compressor mod, FM-Link, i/c & no-MAF intake.   BEGi: Stainless SGDP w/ metal core performance cat.   Custom stuff: Compressor clocked downward w/ new i/c pipe, big radius throttle elbow, 2.5" mid-pipe w/ Hushpower II, dual 2" axle-back w/ open Supertrapps, Toyota 4 pc cop ignition

245.2 whp on default FM-Link maps (with OEM midpipe)
barmato
Fifth Gear
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Posts: 743


« Reply #9 on: June 11, 2016, 11:12:50 PM »

So to answer my own question there was no issue with flashing the firmware back to R85 and running the same map.  Interestingly on the R85 firmware with "closed loop" and "ltt" enabled the car ran perfectly with no hiccups during about a 45 minute drive.  I want to do some more testing still but my initial reaction is there's a bug with the R87 firmware. 

Mark,
As for your comment about the spark, a lean mixture (which I got with closed loop and ltt turned off) would be harder to ignite so that doesn't seem to explain why the car was running better but leaner.  I wonder if the ignition timing changes with closed loop and ltt turned off or just fuel. 
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StackSilverson
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Posts: 395


I'm loving this car.


« Reply #10 on: June 11, 2016, 11:53:14 PM »

I have a random hiccup with my hydra system as well.  Happens once every 5-10 minutes of driving.  FM says it's no big deal and that it's a known issue with the Hydra ECU.  Good luck finding a solution.
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2014 Acura ILX Dynamic- 6 Speed, A Peppy DD
MSM #2452- Velocity Red Mica
Engine Mods- 700cc Deatschwerks Fuel Injectors, Hydra 2.7 ECU, FM Front Mount Intercooler, FM Intake, FM Throttle Body Inlet Pipe, FM Dowpipe, FM Midpipe and Exhaust, TurboSmart Boost Controller, TurboSmart BOV
Drivetrain Mods- FM Level 1 Clutch, FM Level 1 Flywheel, FM SS Clutch Line, Corksport 3.63 Ring and Pinion
Audio/Electronics Mods- GROM Audio Adaptor, Cobra SPX5500 Hardwired Radar Detector, USB Charging Adapter
Suspension/Wheel/Tire Mods- TEIN Street Advance Coilovers, Advanti Storm S2s, Dunlop Direzza DZ102s
Brakes - Porterfield Carbon Pads
Safety - Harddog Hardcore M2 Double Diagonal Rollbar
Chrisbee
Fourth Gear
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Posts: 254


« Reply #11 on: June 12, 2016, 01:29:14 AM »

I have a random hiccup with my hydra system as well.  Happens once every 5-10 minutes of driving.  FM says it's no big deal and that it's a known issue with the Hydra ECU.  Good luck finding a solution.

This is what I mentioned several comments up. Your issue sounds similar to mine, which sounds like the known Hydra hiccup. But that known issue shouldn't happen when in hard acceleration like OP is saying his is doing.
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2004 TI #3021. Purchased Oct. 2014 with 56k miles.

Engine: FM 2 kit with Hydra 2.7, 700cc injectors, and full 3" exhaust.
FM Crossflow radiator w/stage 2 airflow kit.
Suspension: Fox Racing with FM sway bars.
Wheels: 15x8 Enkei PF01s running 215/50 BFG G-force Sports.
Misc: Custom Speedhut boost gauge in place of stock oil pressure gauge. Temp gauge mod. ScanGaugeII. Blue instrument panel lights. Eclipse dash vents.

Definitely a work in progress!
Titus69
First Gear
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Posts: 44


« Reply #12 on: August 02, 2016, 02:27:23 AM »

Late to the party for this thread but I also have the slightly misfire with hydra. I am going to try turning off what was mentioned in this thread and I will send the findings to FM.

I'm in contact with them now for a high boost misfire. Much like the op problem.
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barmato
Fifth Gear
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Posts: 743


« Reply #13 on: August 02, 2016, 04:26:13 PM »

Just to update since the thread was just revived, my issue seems to be resolved since switching back to R85 firmware.  I can't explain why though.  I still get the occasional light load misfire but the high load one seems to be gone.  One of these days I'm going to flash a new copy of R87 onto the Hydra and see what happens but for now I'm just enjoying the car running well and working on the tuning.  Maybe there's something with my Hydra that doesn't agree with the individual cylinder knock detection that was updated between R85 and R87, who knows.
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redmist
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Posts: 9


« Reply #14 on: August 30, 2016, 07:46:53 PM »

That is one of the issues I have as well (Finished install last week). Switching to the FM "Big Spark" kit to see if that makes a difference as well as putting in a better fuel pump. Also taking it to Evans Tuning and see if he can diagnose/fix the issue.
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