Powerloss after Valve Job and Ported Intake Valves

[BlackdOutGST]

for a 1g 6-bolt 4g63 Turbo

Just had the head resurfaced, valve job done, and intake valves opened up a little. Now having massive mid, high and WOT powerloss. Idles fine. 12lbs boost no matter what the controller is set at. Any ideas?

 

[yokotabrat]

This inquiry is for a 1g 6-bolt 4g63 Turbo

Just had the head resurfaced, valve job done, and intake valves opened up a little. Now having massive mid, high and WOT powerloss. Idles fine. 12lbs boost no matter what the controller is set at. Any ideas?

Have you verified all mechanical timing marks are correct? Verified ignition timing is correct? Compression and leakdown tests done? Boost leak test done?

 

[BlackdOutGST]

Timing was the first thing we checked, Mechanical timing is perfect. How do you check ignition timing? (Does that mean making sure the spark plugs in correct order?)

 

[yokotabrat]

For a 1g, the procedure can be found at the vfaq.com site:

Base Timing Adjustment

 

[Bud92gsx]

Your going to need some kind of logging device or some kind of tuning device. Your stock ecu is seeing an increase in air flow and doesn't know how to compensat. Or is compensating but can't go that far..Also when you get your head resurfaced, you must get a thicker head gasket. Why. When you take material away from your head or block, your compression goes up a bit. As to why it goes up and how much it goes up, at this moment I can't remember..

 

[BoredDSM]

Your going to need some kind of logging device or some kind of tuning device. Your stock ecu is seeing an increase in air flow and doesn't know how to compensat. Or is compensating but can't go that far..Also when you get your head resurfaced, you must get a thicker head gasket. Why. When you take material away from your head or block, your compression goes up a bit. As to why it goes up and how much it goes up, at this moment I can't remember..

From what I know that depends how much you remove. If you only removed 1 thousandth of an inch then it's fine. A lot of people resurface and don't use thicker head gaskets. Was the porting professionally done? Check your base timing as stated

 

[1timehondalover]

Check for boost leaks. If you can only muster 12 psi regardless of controller setting you either have a leak or a dying turbo.

 

[xreaction122]

Check for boost leaks. If you can only muster 12 psi regardless of controller setting you either have a leak or a dying turbo.

not every problem on a dsm is related to boost leak

 

[1timehondalover]

not every problem on a dsm is related to boost leak

Who said it was?

I think it's reasonable advice considering mechanical timing is good. I've had my cas slip before and although it retarded the timing considerably, I was still able to make +12 psi.