So the car in question is a evo 9.

Built ported head - Kiggly valve train - gsc s3s - Ams intake
Built block 10.5 cr. Wiseco/ Manley I beams
t4 turbo
2150s , double pumper
E98

Ok So I am having these really weird issue with the car breaking (Almost like a 2 step situation) between 6-7k rpm.

Cruising is fine. The second we hit 6-7k under load it breaks up bad. For a while I was able to free rev past 6-7k but not I can't even do that.

So things we have changed:
Both Cam sensors
Crank sensor
Possible valve float on my gsc springs? Swapped in some Kiggly springs
New Lifters
New Spark plugs
New Ignition. ( was using spark tech, then swapped in boostin cop and stockers)
Swapped 2150s for another set.

Sent a direct signal from ecu to cam sensors.

Verified fuel pressure.

NO boost leaks.

Changed map sensors
Change IAT senor for ****s and giggles

Any other ideas? We are stumped?

Shoot out is a week away

 

Hey Kevin,

Have you gapped your plugs down to .020-0.022 before reinstalling them? This sounds like spark blow out (although it typically wouldn't happen during free rev) , a bad ground, or a timing issue. Have you tried a compression test after changing and bleeding the lifters?

I've also heard that a very dirty fuel sock could cause this. Best of luck!

 

Thanks for the reply buddy!

Plugs are gapped to .20. The car sort of goes into a anti-lag situation so a little bit different than spark blow out but you are down the right path.

New lifters bled before installing.

The car doesn't run lean and pressure is way up where it needs to be so i have ruled out the pumps at this point.

Compression is 145-150 across the board. Leak down test has them all within 10% of each other.

I never thought of a grounding issue but nothing has really changed on the car since last year.

I'll try to add some grounds to see if that helps!

 

What plugs? What gap? Any trouble codes? Is it tuned?

 

Tried ngk iridium and Densos both 1 step colder.

Gap is .20

No codes.

Running same map I used last year. (42psi)

Tuned by me.

Switch Roms.
Switch ECU's. Two OEM and 1 Haltech.

 

Try turning down boost see if it helps?
Have you tried a smaller gap?

 

No, haven't tried a smaller gap yet but boost is only around wastegate pressure when it breaks up. WG pressure is 18psi.

Eliminated the MBC from the car completely. Only running gate pressure until this thing gets sorted out.

 

log??

 

Doesn't show much outside of about 35 knock counts when the car breaks up. On stock ecu.

For that, we changed the knock sensor which didnt help.

On haltech the knock voltage doesn't do much of anything out of the ordinary even when the break up happens.

 

How about a bad mivec gear?

 

Now that is something I didnt think of. I suppose I can log the Mivec and see how its moving. Thanks man, I am definitely going to give this a shot!!

 

Also ssee what timing advance is doing

 

I'm having a similar issue, but my break-up is consistently between 3-4k under load or free revving. Is yours consistently at that 6-7k rpm range? I too have tested a plethora of sensors, bench tested and cleaned injectors, swapped fuel pumps, among other things, all to no avail, but the Mivec gear/solenoid is a good idea.