Ski Bum
15+ Year Contributor
- 231
- 3
- Nov 17, 2005
-
Citrus Heights,
California
Before you jump to conclusions, I'm not turning on a cold engine and going straight to WOT and wondering why it has no power.
What is happening just started within the last few weeks. When I start the engine cold I'll let it idle for 30 seconds or so then gently begin driving. Before and even when the coolant temp indicator reaches normal operating temp the engine surges and feels absolutely gutless. Obviously I am not flooring it and only gently let the rpms rise. While this is happening and I get into boost I can really hear the turbo spool loudly. After a few minutes the engine goes back to normal.
I havent modded anything recently enough to contribute this to. My engine however has low compression and recently I have noticed a slight oil leak on the oil feed line on the turbo, both at the banjo fitting on the head and turbo. There is also a layer of carbon deposits on top of the center section of the trubo where the banjo fitting are. All of the crush washers are new and torqued to spec. The carbon deposits should indicate and exhaust leak right? I have not been able to locate a leak by listening with a stethescope and hitting the gas. I realize that under boost the leak may appear.
I have done numerous boost pressure tests and can hold 20+psi, aside from the oil cap and dipstick leaking, which do so above 20psi.
Its worth mentioning that I do have another longblock that I am in the process of rebuilding and when finished will swap with existing mootor, my concern is, for the time being are these symptoms an indication of something major that will cause me to expedite the rebuild? For now I just want the existing motor to be reliable enough to last untill the rebuilt motor is finished.
Edit: This morning I hooked up the datalogger to see what was going on while the surging and power loss occured during cold operation. During idle everything appears normal but when I accelerate (normally) and the power loss begins my knock count goes sky high, up to 40 counts. The knock count only rises when I feel the power loss and surging, and the timing, according to the logger drops to as low as -10. So obviously the power loss and surging I'm feeling is the ECU pulling tons of timing but what is causing it? As I mentioned earlier I am not in boost when this is happening, just easy accelerating while the motor is cold. When theengine is warm and I do real datalogging passes at WOT I rarely get any knock 1-2.
What is happening just started within the last few weeks. When I start the engine cold I'll let it idle for 30 seconds or so then gently begin driving. Before and even when the coolant temp indicator reaches normal operating temp the engine surges and feels absolutely gutless. Obviously I am not flooring it and only gently let the rpms rise. While this is happening and I get into boost I can really hear the turbo spool loudly. After a few minutes the engine goes back to normal.
I havent modded anything recently enough to contribute this to. My engine however has low compression and recently I have noticed a slight oil leak on the oil feed line on the turbo, both at the banjo fitting on the head and turbo. There is also a layer of carbon deposits on top of the center section of the trubo where the banjo fitting are. All of the crush washers are new and torqued to spec. The carbon deposits should indicate and exhaust leak right? I have not been able to locate a leak by listening with a stethescope and hitting the gas. I realize that under boost the leak may appear.
I have done numerous boost pressure tests and can hold 20+psi, aside from the oil cap and dipstick leaking, which do so above 20psi.
Its worth mentioning that I do have another longblock that I am in the process of rebuilding and when finished will swap with existing mootor, my concern is, for the time being are these symptoms an indication of something major that will cause me to expedite the rebuild? For now I just want the existing motor to be reliable enough to last untill the rebuilt motor is finished.
Edit: This morning I hooked up the datalogger to see what was going on while the surging and power loss occured during cold operation. During idle everything appears normal but when I accelerate (normally) and the power loss begins my knock count goes sky high, up to 40 counts. The knock count only rises when I feel the power loss and surging, and the timing, according to the logger drops to as low as -10. So obviously the power loss and surging I'm feeling is the ECU pulling tons of timing but what is causing it? As I mentioned earlier I am not in boost when this is happening, just easy accelerating while the motor is cold. When theengine is warm and I do real datalogging passes at WOT I rarely get any knock 1-2.
