hey guys. I've worn out my search button for the last few months on this issue. Found ton of great ideas but nothing has worked.

Problem : at WOT starting around 14-17psi my evo 8 starts to stutter/miss. It's not violent like fuel cut, but it's enough to not be able to boost. It doesn't matter the gear or mph, anytime under WOT it happens. Also here and there at cruising speeds both low and high, it will also happen but not nearly as bad/often. Please help as I've invested a ton of money chasing this down and still nothing.

Mods: Buschur 2.0l full built
Custom 2.5" ic piping
BR fmic
Gtx3076r ported dual ball bearing
Ported mani
Turbosmart bov
BR clutch
COP setup
Slowmotion tune at 530whp at 30psi

Tried: coil packs from stock to COP
cam sensor
16 years worth of plugs gapped from .019-.025
Boost leak test
Vac line replace
Turn down boost
No codes. No cel. No other problems. Just a stutter/miss. Some one please help before I roll this off a cliff and go back to subarus 😫😱

Thank you

 

Had that. My cables were shot.cables from coils I mean.

 

OK so not saying this is whats happening but I lifted the head on my Evo VIII and it would studder horrifically at wot (a few times before i realized i lifted the head) ALSO what are your AFR's at wot? Are your plugs fouling when you pull them out?

ALSO my new tuner said my previous tune- timing advance had a lot to do with why i was missing. I chased this issue for a long time before i lifted the head as well... it was in the toon. My coils also were shot and switching to a COP system really helped and cleared it up... EDIT- just realized i missed you have a COP system. one of your coils COULD be bad?

Hope this helps!

 

Thanks guys. So far I just put in a new cam position sensor and has seemed to fix my problem at WOT. I now have a slight stutter at 1/4 with low boost but am chalking that up to the tune. At least until I get retuned and they tell me differently. My plugs seem to be ok, but do go bad fairly quickly. Assuming that's from e85. For $13, I'm not really worried about that. I do not have a wideband now as it was completely destroyed. Will be getting a new one soon. Thanks for all the help, any other input is welcome and considered. Thanks guys

 

What plugs are you running? mine was missing at wot when i used coppers for more than 1k miles and running one step colder plugs. What fixed my issue perm. was switching to NGK iridium stock heat range plugs, tho im not sure with you running 100 hp over me if youd wanna run a step colder and iridium.

 

trade for my 04 sti? lol

 

Send me info! Bc the stutter is still there. Only left I can think of is the clutch. don't know what else it could be.

Has anyone ever heard of stock clutch chatter? There is an even rattle from the trans but when clutch pedal is pressed in it stops. Thanks again for the help fellas.

 

Ok. So I've done some other stuff to try to figure out this problem. I pulled all my Injectors and 2 of them had a good amount of black gun on the ends. I cleaned these and found that 3 of the o rings were cracked/broken/dry and they only have about 2k miles on them. I also replaced all vacuum lines. The stutter is still there although not as prominent. This seems to be hit or miss on when/if the stutter occurs and also seems to get a bit better with everything I do and then suddenly return. So I'm left with replacing the clutch and/or getting retuned......

 

I honestly think it's your plugs, plugs can foul quickly if your running rich or burning a little oil, but most of all, iridium can go bad fast.

I would pick up some ngk copper plugs, they're the best for your car and cheap, like $12 for all 4,

Gap them to .022-.023 and use a feeler gauge to check, not a plug gapper.

I've had the stutter misfire under load a few times, and surprisingly frequently, once cuz a leaky headgasket that fouled my plugs fast.

Last week I got towed home because of this, I knew it was plugs from the stuttering and misfire, replaced them and the car is all good.

I just feel like if it was your clutch then it would slip and rev way up when you get on it.

Other than that, check your fuel filter/sock on your fuel pump hanger

 

I agree compression seems good, do a leak down different from a compression test and see if there are any leaks. I would also check the plugs as well. Are you on the MAF still or on SD? Their is allot of checking to do to see if their is chatter I would say a bad TOB, I am glad to be gone with the TOB and Clips I am on a Quartermaster 8 leg. I eat oil as well but I don't really stutter except the norm on the car and I know what is causing mine and it will be fixed on the 30th with new Injectors and fuel rail and a tune.

 

I'm on SD. As for the plugs, I have literally tried almost every plug that will fit in my head! Everything ends with the same result, still stuttering. I'm looking into the CC twin disk. I want to say it's not my clutch bc the rpms never go up without my speed going up. I just don't know what else to try and have heard of weak clutches causing stutters. Thanks for all the help, but I'm still wanting to roll this thing over a cliff and be done!

 

Do you have any idea what heat range to go with? I've called 7 different parts stores and they said all the ngk bpr8es, br8es, bpr7es, br7es and the like are all iridium. I only ever use feeler gauges. I've tried gapping from .019 to .025. This even happened on my stock coil system so I went COP to try to eliminate it, to no avail.

Also I cleaned my Injectors and sock yesterday. Only 2 Injectors had a small amount of black gunk. Nothing changed after cleaning them and replacing the o rings. Btw I'm running bosch 1200cc no impedance injectors.

 

Not sure what heat range they are, I'm pretty sure they're the stock heat range.

Google TPG Tuning and give them a call , they carry the ngk copper in stock and they could easily tell you which heat range they are, or the product number. The stuttering and missing has happened to me a few times and I'm still pretty sure it's your plugs.

Bad gas can cause it, but it's more likely to cause intermittent knocking. Stutter is from not firing. Which is either spark, or other related ignition problems... Try to get those plugs !

 

Well forget any other problem I had. I now need someone who can rebuild a gtx3076r. Well I just need a new compressor wheel. When slowmotion put my turbo on, they ran the oil line against my coupler to my intake and it melted it, send a piece at my compressor wheel. If I knew how to attach pics I would. I thank you guys for all the help, but I think this is the last straw.

 

daaaaaaamn!!!! thats not fun. update us on what happens. sorry for the bad news man!