Hey guys so this my first thread so I apologize if I mess something up. My problem is when driving and getting on the gas at higher rpms my car starts to miss pretty bad. I've just replaced the spark plugs and also replace a coil as it was out of the specified resistance range. The car runs great at crusing and just casual driving speeds. Also it holds boost and just had a boost leak check done. Any help or thoughts would be greatly appriciated as I'm trying to avoid taking it to a shop!
Evolving Member
any mods done to the car? Have you had it tuned? what is your AFR at high rpms?
The car has a bbk full turbo pte 1000cc injectors gsc s1 cams, k&n intake, ams turbo back exhaust high flow cat, ported exhaust mani, Megan 02 housing. It was tuned in January by CBRD. The car has being running excelent until about a week ago. I was running copper plugs when the problem first started and thought they were just fouling out. I replaced them with stock iridium plugs but that didn't help at all.
It's like it cuts out or is back firing under heavy throttle. I haven't done a compression test yet slightly because it does feel like something in ignitin system but I'm kind of new to the turbo scene as far as trying to diagnose things
The car is tuned for 27psi. With the iridium plugs could I be blowing the spark out as the boost gets higher? And if so I am under the impression that you shouldn't change the plug gap on the ir plugs is that correct?
Evolving Member
the NGKs come pregapped but its always good to check. What is your AFR when doing the pulls?
Here what im thinking... you were tuned in January when the weather was cold and the air was dense meaning more oxygen per cc of air. now since its hot and humid there is less oxygen per cc meaning a rich AFR. you could have to much fuel in the chamber that ur not igniting and choking out the engine. Have you fouled out any plugs?
Have you datalogged the car at all? are you picking up knock
Here what im thinking... you were tuned in January when the weather was cold and the air was dense meaning more oxygen per cc of air. now since its hot and humid there is less oxygen per cc meaning a rich AFR. you could have to much fuel in the chamber that ur not igniting and choking out the engine. Have you fouled out any plugs?
Have you datalogged the car at all? are you picking up knock
Evolved Member
I know that the stock ignition can handle that power without a problem. I had the same issue with my evo 8 and i just put a bandaid on it by installing a ignition amplier. I was running 28psi on evo 8 stock turbo with alcohol injection.
The cheapest way to do things is to mess around with spark plug gaps 0.026- 0.020's. It should get better eventually.
The cheapest way to do things is to mess around with spark plug gaps 0.026- 0.020's. It should get better eventually.
Evolved Member
as stated, new plugs and gap them. they are supposed to be pre-gapped but i had a problem with my last set so will gap myself always.
Thank you guys for the input! I'm actually just leaving class so I'll check out my af ratio inmy way home
Evolving Member
I had a similar problem. I just run some cheaper ngk plugs (br8es or something like that) gapped to .023 and it got rid of the problem. I do have to change my plugs more often but they are inexpensive so i don't mind
Evolved Member
Are you using the stock heat range plugs? That'll do it. +1 on Ericks response.
Newbie
Is this on the stock ignition? If it is, when was the last time your spark plug wires were changed? I had the same problem awhile back on stock boost and swaped out my plugs twice with a gap of .024 and nothing changed. So I decided to do a full tune up with new iridiums(had to gap to .024 cause from the box they were at .032), 8.5 magnacore, and complete fluid change and never had the problem since.