Ok, here is the issue. i have a serious misfire when i use anymore than say 25% throttle. the car just studders, almost like a seizure?? and will not really accelerate.

It seems the issue is when the car gets into boost. Now i thought maybe it was a faulty coil pack, or wires, etc. i replaced both coils, all spark plugs, wires. I still have a misfire....any thoughts on what this could be?

Any input is greatly appreciated.

 

did you use oem wires and have you boost leak tested it

 

did you gap the spark plugs?

 

I have not boost leak tested it, but all intercooler couplers are tight and no tears.

Wires are identical to OEM, but not OEM.

What would the reason be to gap new plugs?


I can use say 7psi, but anything after that and it just studders and the steering wheel shakes and hardly accelerates. if i control how much boost it makes(throttle) i can rev all the way to redline no problem, just feels like a slower turbo car.

Also my CEL for EGR insuffiecient flow.

 

do a boost leak test there is stuff(vacuum lines,throttle body shaft seals,injector seals ect.) you wont be able to visually inspect and you def need to gap new plugs unless they are iridiums also what plugs are you using NGK bpr7es is what you want(i gap mine at like 27)

 

The plugs are iridiums.

Is there a how to, on boost leak test?

 

https://www.evolutionm.net/forums/ev...er-5-02-a.html

 

try disconnecting your knock sensor and don't boost full throttle.. i've been having the same issue and there are like two threads about this issue that i've found doing a search, i disconnected the knock sensor and my misfire went away but my timing was WAAAAYYY off. so i reconnected it and the misfire doesn't seem as consistent but its still there..

It amazes me how many problems evo 8-10's have... i mean these cars arent even 10 years old yet and people have problems with EVERYTHING from paint to spark! If i can figure out whats up with my evo soon, then i'll let you know..

I'm thinking if you had a bad enough boost leak that your car was shuddering, then you would be running super rich and you wouldn't be building up boost gradually if you took your time on the throttle.. it sounds like many of us are having problems with ignition timing and spark

 

sounds like your having exactly the same issue as me. i was thinking about disconnecting the knock sensor, but wasn't sure what the affect would be.

If anything it seems like its leaning out to much under boost, which if i had a boost leak it would be running way rich, and its not.

if you know how to roll your tongue, thats what my car sounds like once it gets into boost, and quits accelerating.

 

Bad map sensor maybe?

 

hooked up a scan tool and drove it in the live data mode. the timing was advancing 6-8 degrees under load.

My dad thinks everything could be related to the low restriction exhaust.

I have Gt-Spec turbo manifold, HKS 3" dp, HiFlow Cat, HKS Hi-power exhaust. anyone think that the misfire and my EGR code could be related to the less restricted exhaust? possibly needing to be tuned for the mods?

The codes are EGR insufficeint flow, and o2 below thresh hold bank 1. If i remember correctly.

 

These are the two codes i'm getting.

DTC P0401: EGR Flow Insufficient Detected
DTC P0420: Catalyst Efficiency Below Threshold

 

Gapped plugs properly to .020, and then inspected EGR components. whoever the previous owner was, broke the nipples off of the EGR solenoid and then tried to fix it by covering it in silicone and putting the lines in the silicone with a peice of one of those red spray nozzles you get from WD-40, etc.

Misfire Solved.

 

If plugs dont come pre-gapped remember to gap them or that will happen, it happend to me. Oh and good job finding the actuall problem.