Colder Plugs Cold Start

[shittyg70]

I’ve scoured the forums over at stinger forum and here and am yet to find this problem. I just installed HKS M45iL plugs about a week ago. Closed em to a .022 like recommended by BMS and the car wasn’t running too bad. Couple sputters when idling (i read that’s the nature of the cold plugs) but felt a bit lack lustre in map 2 so I checked logs and it was pulling timing, specifically tons of timing in ign3 (I think it got up to 7.5°). I regapped the plugs (turns out some were too tight) so they’re all sitting at about .023 now, checked logs and the highest timing pull was 0.8 in ign3 and every other cylinder was clean.

Thought I fixed my problems but yesterday after work and this morning (both cold starts) car wouldn’t start until the 4th crank. About 3 seconds of turning over and had to do that 3 times before it finally started up. I live in Canada and it’s the summer, if it’s fighting me this hard on cold start in the summer I physically can’t run these plugs in the winter. I’m going to recheck the gap on ign3 and if it changed regap all of them again.

Anyone have a similar issue to this or can anyone give me insight as to how to fix this. Thanks

2021 G70 3.3T Sport

 

[Cashby]

0.8 correction isn't much to worry about. If you just recently reset the ECU (unplugged battery) then that could just be the adaptive timing correction left over and it will go away.

The plugs themselves should have nothing to do with your cold start issue. Especially if its warm there. I had a similar issue as you and it was intermittent at first but then got worse over time. Turned out my starter was going out and it finally died. Dealer replaced it and never had an issue again.

 

[shittyg70]

0.8 correction isn't much to worry about. If you just recently reset the ECU (unplugged battery) then that could just be the adaptive timing correction left over and it will go away.

The plugs themselves should have nothing to do with your cold start issue. Especially if its warm there. I had a similar issue as you and it was intermittent at first but then got worse over time. Turned out my starter was going out and it finally died. Dealer replaced it and never had an issue again.

The corrections aren’t a concern the timing graphs look good now. I spent back in yesterday to check cyl 3 plug and it looks fine and i swapped back cyl 3 and 5 coil packs again to how they were originally (thought it might mess with the ignition timing memory) and it seemed to medially help but the problem persists. Talked to my genesis tech he said i can take it in to get it checked out but that’s weird how my starter was perfect after installing the plugs but after regapping then it just got shot. My idle is also rougher and sputters but not sure how much of that is the just the cold plugs or if it’s whatever this problem is. Thanks cashby

 

[APS]

I am curious. By cold plugs I presume you mean colder than recommended by Genesis. Why would you do that?

 

[shittyg70]

I am curious. By cold plugs I presume you mean colder than recommended by Genesis. Why would you do that?

Running above stock boost increases heat by a lot in the cylinders causing detonation and blowout. When running tuned you normally run 1 step colder plugs at a tighter gap (stock is i think .036 but recommended is between .024-.022) to avoid the previously mentioned problems. But i’m pretty sure it’s as Cashby mentioned being my starter.

 

[TheBeginning]

It’s really easy to damage te ceramic in the plugs when torquing them in. Some performance shops toss the plugs after being installed because of this. Could be your issue. Those HKS’s aren’t cheap though.

 

[Volfy]

It is possible to have cold running issues when you deviate from the stock heat range, which was selected by the OEM engineers to balance between too hot (pre-ignition) and too cold (plug fouling) for the stock tune. Contrary to popular belief, closing the gap tighter doesn't compensate for too cold a plug. That is not the reason why tighter gap is recommended.

Running 1 heat range colder typically won't create much of a fouling problems, but 2 heat range colder can cause problems, especially if you spend a lot of time idling in traffic and/or do a lot of cold starts and short runs. That said, while your symptoms are consistent with plug fouling, that in and of itself doesn't mean that is the only possible cause. Easiest way is to pull a plug or two to check directly. Or even easier way to diagnose... you can also just run your car "spirited" for a bit to blow out the carbon fouling. In the old days, this was referred to as an Italian Tune-Up. If your symptoms go away right after a good ITU, then it is quite likely your engine does have a tendency for cold plug fouling. The symptom will probably return after a while of more idling and cold starts, but at least you know.

 

[19 G70 3.3T]

Very good explanation @Volfy. I'd also like to chime in and say that the reason for running a tighter gap is to reduce spark "blow-out" at high RPM. This happens because when you increase boost (cylinder pressure), the coil no longer has enough energy to create a strong enough spark to jump the air gap between the ground strap and electrode. IMO, closing the gap is a band-aid and not the cure. Running a stronger coil is the real solution for "blow-out". Remember, a stronger (aka hotter) coil won't cause any issues at lower RPM, lower demand conditions. The plug will only use as much energy as it needs to jump the air-gap... but, when demand increases due to higher cylinder pressures, it has the reserve to be able to make the spark. In the end, run the largest gap you can without blowing out the spark. A larger flame front creates better combustion and a more complete burn.

 

[ominousone]

Can someone tell me the stock plug for my 2019 3.3T, plz? I'm having a little trouble finding a definitive answer.