A little background. I just finished the following changes/upgrades to the car. Car was 100% fine prior to the changes.

1. New Pistons/rods
2. New Timing Belt
3. Rear balance shaft removed. I turned down the front shaft on a lathe to remove the weights.
4. Ported intake manifold to match ported TB which is not yet on the car. Stock TB until the new one is done.
5. Removed stock turbo assembly and replaced with 50 trim. New manifold, DP,and a tial 44 mm wastegate and a 19 PSI spring.

Engine runs like a sewing machine. No funny noises. Pulls smooth and revs easy. Changed engine oil after first 20 miles to get all assembly lube out and such. No metal on magnet and all looked good. Plugs seem fine.

Problem. As soon as I get to about 13 PSI the car falls on it's face and feels like it is hitting an ignition or fuel cut. It is only occurs under boost. I can ease into it with low boost and do not get the problem. There is no SES light, no code, and no knock. Never had any ignition problems prior to the changes. The car is not yet tuned for the new turbo, but I doubt that has anything to do with this problem. Any help would be appreciated.

 

tune it, I'd bet money you are lean

 

The tune is not the problem. I would not be posting if it were as simple as that. I have a UTEC and I can mess with the fueling all that I want. Issue is there regardless of what I do to the tune.

 

maybe some kinda of a vacuum leak.

 

my mistake, I saw not tuned for turbo and misunderstood. you logging knock?

 

I log knock and timing with the UTEC. I need a new wideband 02 before I can log AFR's. It is on the way.

 

My car did spmething similar.... but around 18psi..... It would cut in and out.. Mine ended up being the gap in the plugs..... Maybe check that... Sometimes its something so small.... mine are now gapped at .023mm

 

You sure its not a boost leak or something stupid like that, or an ignition wire not connected properly...my bets on a leaky pipe...

 

Personally I would bypass the UTEC and log through evoscan.

 

what is max boost that its hitting?

 

Yea I believe it may be a combination of a boost leak and possible timing issue. Recheck the timing as well. I would do a boost leak test next.

James

 

Change your spark plugs. And check for boost leaks.