Spark plugs and gaps and also running rich

Discussion of tuning specific to MAZDASPEED3/MAZDASPEED Axela/Mazda 3 MPS vehicles
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Ianstattoos
Posts: 18
Joined: July 19th, 2020, 2:11 am

Spark plugs and gaps and also running rich

Post by Ianstattoos »

Hi it’s time again to change my spark plugs so I’m looking for spark plug and gap recommendations for a gen 2. I’m currently running the high load tune and the only current mods are hpfp internals, corksport stage 2 short ram intake and gfb recirc valve.

Also I don’t have much knowledge but the car is running rich atm, I can smell fuel in the cabin after a pull and sometimes when idling , I also get a puff of black smoke after hard acceleration, I have recently had the intake valves cleaned and fitted cs injector seals. I have checked the fuel rail pressure I think is fine (roughly 500 psi at idle, 1800 psi at full throttle) if you have any advice or suggestions I’d appreciate it thanks.
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Spark plugs and gaps and also running rich

Post by mituc »

If the fuel rail pressure is 500psi at idle then you probably have a small problem somewhere, assuming we're talking about warm idle, no AC.
If you suspect the car is running too rich then please take a log and post it somewhere here. Please use this logging preset to take the logs: https://www.dropbox.com/s/i0ndre5umzanz ... vtpre?dl=0
Take 2-3 logs 1 minute each driving normally and one with the car idling for at least 20 seconds, plus one 3rd gear WOT log, let's see what's up.

As for the spark plugs, in your case stock heat range should work just fine. I recommend NGK spark plugs: 3787/ILTR6A-8G, 6509/LTR6IX-11 or if you can find them LTR6BHX.
You can also go a step colder: 6510/LTR7IX-11 or better the 95605/LTR7BHX.

As an alternative and only if you can't find NGKs in a reasonable amount of time you can go with the Denso ITV20 for OEM heat range or Denso ITV22 - one step colder.

Some of these spark plugs need to be re-gapped to 0.7mm (the 6510 are by default gapped to 1.1mm).
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Ianstattoos
Posts: 18
Joined: July 19th, 2020, 2:11 am

Re: Spark plugs and gaps and also running rich

Post by Ianstattoos »

Thanks for the reply, I’ll get some plugs plugs ordered, I found NGK 95605/LTRBHX they sell them gapped to 0.711mm for a me 3 focus st would this be okay?
I’ll get some logs tonight and check back in.
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Spark plugs and gaps and also running rich

Post by mituc »

0.711 is really 0.7 realistically speaking :) Probably they gave the gap in inches and when converting you ended up with a few more decimals :D
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Ianstattoos
Posts: 18
Joined: July 19th, 2020, 2:11 am

Re: Spark plugs and gaps and also running rich

Post by Ianstattoos »

hi theses are the logs. if you could take a look id appreciate. thanks.
Attachments
Full-3MPSBL-Logging - 2023-03-02 09.33.23.vtlog
(679.69 KiB) Downloaded 54 times
Full-3MPSBL-Logging - 2023-03-02 09.35.13.vtlog
(733.36 KiB) Downloaded 57 times
Full-3MPSBL-Logging - 2023-03-02 09.35.53.vtlog
(275.69 KiB) Downloaded 56 times
Full-3MPSBL-Logging - 2023-03-02 09.39.25.vtlog
(626.99 KiB) Downloaded 44 times
Full-3MPSBL-Logging - 2023-03-02 09.45.14.vtlog
(424.6 KiB) Downloaded 47 times
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Spark plugs and gaps and also running rich

Post by mituc »

Ok, one at a time:
1. your car seems to be working decently.
2. the gas smell in the cabin may be due to an exhaust leak. Possibly you have an exhaust leak before the O2 sensor because I can see it's reading weird at times (fuel trims are possitive while the AFRs are slightly richer than commanded);
3. Under load everything looks ok;
4. do you have a pops&crackless maps? This is how it looks like...
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Ianstattoos
Posts: 18
Joined: July 19th, 2020, 2:11 am

Re: Spark plugs and gaps and also running rich

Post by Ianstattoos »

Thanks for looking, I am not running the crackle and pop map just the normal high load, I have changed the lowest idle rpms to 800 to reduce flywheel chatter, I don’t know if this would affect the reading?
Good to know it’s nothing serious though, I’ll try nvestigate an exhaust leak that would make sense.
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