Stutter in boost that goes away when warm

08Speed3

08Speed3

Greenie N00B Member
Year/Make/Model: 2008 Mazdaspeed 3
Mileage: 240000kms body 140000kms engine
Location: Alberta / Canada
Concern: Every morning when I start to leave lately the car stutters while under part throttle and im in boost. It bucks but stops if I let off and go easier on the gas. Its happening on really low boost say 5psi in the beginning of the drive. As the car heats up it gradually gets better and better. Once I get into the city after 40min highway drive I can go WOT and it seems fine. Leave work after it sits for 8 hours and same deal, bucks going into boost at part throttle and seems fine by the time I get home. Datalog attached, boost is low because car has a CX-7 ko4. I have a proper mazdaspeed k04 waiting to go in but I want to get this fixed before that. happened at 10.8 sec mark. I was 3/4 of the way to work and it acted fine on the WOT pull up to about 5k rpm and then fell on its face like it does at lower rpm when its colder. I can try to get a cold start datalog today. Thank You.


DTC's: Intake runner code stuck open.

Modifications:
-Short ram intake stock maf housing.
-HKS SSQV knockoff VTA
-Muffler/ Resonator delete
-Autotech HPFP


ECU/Tuning Software: Accessport V3

Tuner: Freektune OTS+

Is the concern intermittent? No

Can you duplicate the concern? Yes

Recent Repairs: Brand new plugs gapped to .026 yesterday. issue persists.

Correction:
 

Attachments

That code has been on since I bought the car over a year ago. This just started in the last few weeks. Little plastic arm on the actuator is broken.
It’s been about 0c during the night and around +10c during the day. I’ve been meaning to delete the vcts eventually but havnt got around to it yet. I did the PRV test today and watched it climb to 1850 and hold so that should be fine. I’m starting to suspect a coil acting up but I’m not sure. That’s probably where I’m headed next but I’m open to any ideas. It’s annoying merging onto the highway in the morning and it bucking trying to get up to speed then act fine later.
 
Is the bucking present in this log? If yes, does it happen at the end of the WOT pull?
Also, set the AP to display the coolant temps, and see what temp it stops bucking at. Also, while you do this, pull a good WOT log of the issue not happening for comparison.

As for analysis, I see KR and heavily pulled timing, AFR goes super lean, followed by super rich. Boost and load also spike on that lean row, so might be a loss of spark or some kind of spark or fuel cut.

Edit: Pull the negative cable off the battery to reset trims and see if there's any difference. Also, you probably shouldn't beat on it if the engine is cold; wait for at least like 60c temps on the water, because by then the oil should be starting to warm up a bit (it's more important for the oil to be warm than the coolant).
 
Yes it was present on that log at the end of the pull. The pull was done 20 mins into the drive, coolant temp was 190. Car seems to want to be at 190-200 for around 15-20 mins before it doesn’t happen anymore. It still can just very rarely compared to when cold and doing it all the time. I can try and get some different logs to show what it does in comparison being cold to hot. I can also reset trims. My LTFT always stays between -5 +5 right now but I can reset and see if anything changes.
 
There are more than just fuel trims that get cleared when resetting the ECU. There's WGDC, load, etc.

Also, sitting at normal temp for 20 mins would suggest to me that oil temps are still coming up, but I don't see how that should matter for this issue.
 
Sorry for no update. Figured I would update in case it will help anyone else.
I replaced the coil packs, reset ecu and issue cleared yup. Im almost positive i had a coil going out, engine was on the original set.
All is good now. Thanks for the help!
 
08Speed3 said:
Sorry for no update. Figured I would update in case it will help anyone else.
I replaced the coil packs, reset ecu and issue cleared yup. Im almost positive i had a coil going out, engine was on the original set.
All is good now. Thanks for the help!
Click to expand...


Is she still running strong?
I’m having the same exact issue. I just upgraded my MAP sensor to a Bosch 3.5bar & pigtail. Got my revised tune and during the test drive your explanation is exactly what happened to me. I have a set of OEM coils coming assuming my current set is the original set as well. Car has 157k miles on it.
 
cavsfan2 said:
Is she still running strong?
I’m having the same exact issue. I just upgraded my MAP sensor to a Bosch 3.5bar & pigtail. Got my revised tune and during the test drive your explanation is exactly what happened to me. I have a set of OEM coils coming assuming my current set is the original set as well. Car has 157k miles on it.
Click to expand...


Actually funny you just posted, the issue just came back within the last week and has been getting progressively worse. It did do away for awhile though so im stumped.
When I leave in the morning I have to baby it or it will hesitate and shake under throttle. As the car warms up, driving it for maybe 20mins issue resolves and feels normal besides this time being richer then normal in boost.
I just pulled my injectors and dropped them off to get flow tested and cleaned today. New seals will also be installed, and im going to clean my intake valves. they are pretty gross. Injectors have never been serviced so i'm guessing it could be the issue, either one leaking, or clogged or something. combustion seals looked like they were ok and not leaking. If that doesn't resolve the issue i'm going to probably look at o2 sensors, but it feels like injectors are the most likely culprit right now, i'm not sure though and i'm just going through the list of likely issues while getting up to date on all the maintenance items. I will post when I get the injectors back and installed and let you know if it fixed it or not.
 
I had a similar problem on an older car that still had plug wires so it was easier to have this problem. There were cracks in the wires that would get damp overnight and dry out once the car got hot. Was able to determine by squirting the wires with water when the car was running

Might not be possible with coil on plug but worth checking
 
08Speed3 said:
Actually funny you just posted, the issue just came back within the last week and has been getting progressively worse. It did do away for awhile though so im stumped.
When I leave in the morning I have to baby it or it will hesitate and shake under throttle. As the car warms up, driving it for maybe 20mins issue resolves and feels normal besides this time being richer then normal in boost.
I just pulled my injectors and dropped them off to get flow tested and cleaned today. New seals will also be installed, and im going to clean my intake valves. they are pretty gross. Injectors have never been serviced so i'm guessing it could be the issue, either one leaking, or clogged or something. combustion seals looked like they were ok and not leaking. If that doesn't resolve the issue i'm going to probably look at o2 sensors, but it feels like injectors are the most likely culprit right now, i'm not sure though and i'm just going through the list of likely issues while getting up to date on all the maintenance items. I will post when I get the injectors back and installed and let you know if it fixed it or not.
Click to expand...

The car drove normal with the old setup it had(eBay turbo, shitty fmic setup, no-name cold air intake, Cobb ots tune believe it or not). All at once I did a serviced set of injectors, overspeed seals, GB seals on the Rail side, walnut blasted my valves, NGK colder plugs gapped at .026 (didn’t do new coils due to these being OEM although they looked old) BNRS3, Damond 3.5in intake, Damond PCV plate & valve w/ their catch can also. MAC 3port EBCS, CXRacing FMIC, new starter, new Oil drain line from Turbo to pan. New pressure relief valve, Autotech internals were installed by last owner on HPFP. EGR & VTCS deletes. The fuel resistor under the intake was bypassed by previous owner as well. Car ran great for 350/400 miles now it’s hiccuping/bucking when going into boost. Oddly do remember it started after I hand washed the car. But nothing electrical got wet. Did just replace my MAP with a Bosch 3.5bar due to p0069 code which is no longer there. Tuned by Farhan @ Damond. We’ve had contact off & on about this build. Compression is 168-167-149-160 warm. I figured the engine is getting tired. 157k miles. I just want to push 20psi of boost & cruise. I don’t drive hard really. Eventually I want to build the engine but I want to enjoy the car first. Had it a year & have only put 700 miles on it between the setups. Did see someone with same exact issues end up having a failing throttle body on the Facebook pages. But once I put coils in I’ll go from there
 
cavsfan2 said:
The car drove normal with the old setup it had(eBay turbo, shitty fmic setup, no-name cold air intake, Cobb ots tune believe it or not). All at once I did a serviced set of injectors, overspeed seals, GB seals on the Rail side, walnut blasted my valves, NGK colder plugs gapped at .026 (didn’t do new coils due to these being OEM although they looked old) BNRS3, Damond 3.5in intake, Damond PCV plate & valve w/ their catch can also. MAC 3port EBCS, CXRacing FMIC, new starter, new Oil drain line from Turbo to pan. New pressure relief valve, Autotech internals were installed by last owner on HPFP. EGR & VTCS deletes. The fuel resistor under the intake was bypassed by previous owner as well. Car ran great for 350/400 miles now it’s hiccuping/bucking when going into boost. Oddly do remember it started after I hand washed the car. But nothing electrical got wet. Did just replace my MAP with a Bosch 3.5bar due to p0069 code which is no longer there. Tuned by Farhan @ Damond. We’ve had contact off & on about this build. Compression is 168-167-149-160 warm. I figured the engine is getting tired. 157k miles. I just want to push 20psi of boost & cruise. I don’t drive hard really. Eventually I want to build the engine but I want to enjoy the car first. Had it a year & have only put 700 miles on it between the setups. Did see someone with same exact issues end up having a failing throttle body on the Facebook pages. But once I put coils in I’ll go from there
Click to expand...

Hmmm...
The only other time I had this happen my intake had a leak by the filter and my MAF couldnt read incoming air properly causing the car to buck and go haywire. What I have happening felt very similar to that. I just don't know why it gets better as it warms up. Maybe its a leak in the intake somewhere that seals up when it gets hot, leaks cold. coupler or something...Maybe its even the MAF going bad...

I got my injectors back and what you said tracks, they were not bad at all, they cleaned up a bit but they were not leaking or out of whack at all. Im in the middle of hand cleaning my valves, no walnut blaster so its taking me a bit but i'm hoping to have it back together tonight. I will try to clean out the throttle body and see if it makes any difference too, maybe even grab one from the junkyard if the issue is still around since swapping one to see is fairly easy if that fixed it for someone else. I deleted VTCS with the manifold off, and I will go over all my couplers and intake connections and see if I can find anything suspicious when it all goes back on. I haven't compression tested. Definitely a frustrating issue.
 
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08Speed3 said:
Hmmm...
The only other time I had this happen my intake had a leak by the filter and my MAF couldnt read incoming air properly causing the car to buck and go haywire. What I have happening felt very similar to that. I just don't know why it gets better as it warms up. Maybe its a leak in the intake somewhere that seals up when it gets hot, leaks cold. coupler or something...Maybe its even the MAF going bad...

I got my injectors back and what you said tracks, they were not bad at all, they cleaned up a bit but they were not leaking or out of whack at all. Im in the middle of hand cleaning my valves, no walnut blaster so its taking me a bit but i'm hoping to have it back together tonight. I will try to clean out the throttle body and see if it makes any difference too, maybe even grab one from the junkyard if the issue is still around since swapping one to see is fairly easy if that fixed it for someone else. I deleted VTCS with the manifold off, and I will go over all my couplers and intake connections and see if I can find anything suspicious when it all goes back on. I haven't compression tested. Definitely a frustrating issue.
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Yeah I’m tossing in a set of OEM coils** & throwing in some Denso ITV22 plugs. I guess those plugs were the original colder plugs these cars ran before the NGKs & some still swear by them. Hopefully that will fix my issues. Keep me posted on what you find! Hope we both get back on the road smoothly
 
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Hello, sadly i can't view your log right now, However
Enki said:
...As for analysis, I see KR and heavily pulled timing, AFR goes super lean, followed by super rich. Boost and load also spike on that lean row, so might be a loss of spark or some kind of spark or fuel cut.

Easter Bunny said:
I had a similar problem on an older car that still had plug wires so it was easier to have this problem. There were cracks in the wires that would get damp overnight and dry out once the car got hot. Was able to determine by squirting the wires with water when the car was running
Click to expand...

Enki's and Easter Bunny's comments, and the fact that you got better after changing coils, but then got worse again later, make me think you have an ignition issue. Also since it seems your injectors weren't an issue.
Before throwing more parts at it, I think I would test your old coils to see if any are out of tolerance, If they are within tolerance it could be you just had a single weak coil. Then I would check the coils you have now, and the signal going to the coils. If you find that a new coil is now week slide in one of the old ones that tested good. If there is improvement, Look at the signal for that coil.
It is possible the coils were not the issue and a failing coil was the result of the signal to the coil being incorrect, for example shorting some where in the harness, when cold (damp) this would be an analog to what Easter Bunny was saying.
If after that there is not improvement, Do again what Enki suggests and pull the negative battery cable to do a reset of some parameters.
If there is improvement, it is likely an issue with one or more parameters. You might at that time ask your tuner to verify they are correct in your tune. If so, test the corresponding sensors, maybe there is a failure or a signal issue.
All this costs is time.
If the issue continues, it is time to look for air leaks after that MAF, Clean and test the MAF and MAF signal. If the MAF is feeding incorrect air volume, you will have fueling issues as described by Enki from you logs.
Also it is possible that you have an issue with the knock sensor, it could be loose, it could be failing or as mentioned a lot of times above it could be an improper signal, that could be happening when cold (Damp).

I know I threw a lot at you, and I wasn't able to even view your logs, so just going off comments, But I hope this is helpful.
I have a supercharged 2000 Miata that I put COPs on and it acted like this, first I found that one of the coils was cracked and shorting to the Valve cover, got a new coil and thought that was the end of it, sadly no. turned out to be the signal generator and a short to ground in one of the signal wires, and that short caused the coil failure.
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gives me some ideas...
got the car back together, cleaned injectors, clean valves and all. also deleted VTCS, cleaned the intake manifold out. Car drives better, feels smoother but issue persists. Im going to try and run to the junkyard and pull a new MAF and maybe primary 02 sensor, since its easy and cheap. If no change I will look over the whole harness and see if its shorting anywhere. from what I had apart just now it looked good, but I didnt pay a ton of attention to it. I will reset the ECU on the way home and see if any improvement happens. Freek sent me a new revision last week so I just loaded that today and it hit 22psi and ran great after the regular 15-20 min warmup. It did stutter when cold though getting into boost same as before though.
 
Step colder plugs with what fuel? I know high corn mixes do NOT like colder plugs, and that plug temp can be part of your issue. Ideally, you should only run colder plugs if your tuner specifically tells you to.

Edit:
You also shouldn't go beating on it till the oil is up to temp.
 
Enki said:
Step colder plugs with what fuel? I know high corn mixes do NOT like colder plugs, and that plug temp can be part of your issue. Ideally, you should only run colder plugs if your tuner specifically tells you to.

Edit:
You also shouldn't go beating on it till the oil is up to temp.
Click to expand...

I definitely don't beat on it cold. issue happens even at 190 coolant temp, takes maybe 5-10 min of driving at 190 to finally act normal so ya oil needs to heat up. I live out of town and i'm on the highway as soon as I leave so its sitting in 6th warming up. its getting up to speed merging onto the highway where the issue usually happens.
Im tuned for 93 octane,usually fill with 94. Stock temp plugs NGK 6509.
 
Coolant temp rises much faster than oil, so it's possible the issue is related to piston temps specifically, as the oil would be cooling them down until it comes up to temp.

Hate to say it, but this might just be something you have to learn to drive around. Not real sure why this would be happening if stock pistons, since they are hypereutectic and shouldn't change size much if at all based on temps, but I could see how cold pistons could hamper combustion quality (especially since fuel sprays on the piston directly, further cooling them).

Super strange that you would be having this issue, though, unless the pistons are not stock or have some kind of non-stock coating on them, especially one that might act as a thermal barrier.
 
Enki said:
Coolant temp rises much faster than oil, so it's possible the issue is related to piston temps specifically, as the oil would be cooling them down until it comes up to temp.

Hate to say it, but this might just be something you have to learn to drive around. Not real sure why this would be happening if stock pistons, since they are hypereutectic and shouldn't change size much if at all based on temps, but I could see how cold pistons could hamper combustion quality (especially since fuel sprays on the piston directly, further cooling them).

Super strange that you would be having this issue, though, unless the pistons are not stock or have some kind of non-stock coating on them, especially one that might act as a thermal barrier.
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Ya it is a real head scratcher...
Im pretty sure its a JDM CX7 motor in the car, I bought the car with a "new motor with only 110000kms" on it. It would be all stock though. Car had a cx7 turbo on it, but i switched it out for the proper k04. Justin says my logs look great , no issues. Your right though, Im running out of options. Like I said I will replace the MAF and if that doesnt do it maybe the primary 02. Last things I can think of besides a wiring gremlin somewhere. I went through all the couplers, and vaccum hoses while it was apart and made sure everything was good. Just annoying having to baby it until it runs for awhile. Not that I want to beat on it cold but merging onto the highway without it bucking/ boost cutting/ whatever its doing. Maybe I will try and get a video of it happening and post it, maybe that will help with something. I do appreciate all the help.
 
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