no power when cold

my engine has no power when it is cold,it just falls on it's face and stalls if you let off the gas.if you ease in to it without boosting it will run fine.soon as you try to boost it looses all power and has to fight to gain speed.soon as it warms up it shreads the tires and no issues.i also have low vacum only 10-13 at idle but idle is smooth and if i rev it up to 2k it sits at 18-20.

now things i've changed to fix the prob are ECT,plugs,wires,cap and rotor,all vac lines,timing is set at stock 10. all done when the motor was rebuilt 8k ago and this problem has been there since then .i even tried advancing the timing with no change.there are no codes when i test it so what am i missing as it has to be something stupid i am missing.

You might have a vacuum leak that tends to seal itself up as the engine warms. The only vacuum reading that matters in a case like this is idle vacuum and yes, 10-13 is seriously low unless you got a radical cam

it has a mild cam but i am begining to think the engine builder put in a bigger cam then i wanted.as for vac leak i have blocked off all vacums and even tried a vac test off the main line with the same result

Does vacuum increase, at idle, when the engine is warm?

as for vac leak i have blocked off all vacums and even tried a vac test off the main line with the same result

That indicates that is is not one of the vacuum subsystems, off the vacuum tree. It could still something directly on the engine, like the lower intake to cylinder head. Maybe the gasket slipped. Or the upper to lower intake or the throttle body. Does the IAC have a gasket between it and the TB. Is the pcv connected on both ends of the valves.

it has a mild cam but i am beginning to think the engine builder put in a bigger cam then i wanted

Even so that does not explain the situation you describe.

nope no change that is noticable if any at all.

i forgot to mention that when cold and trying to boost while it is running really gutless if can you hit 3k it acts normal and takes off like it should but if you drop below 3k while still cold it will fall on its face again.

Kind of a long shot but have you checked cam timing.

You said you tried advancing ignition timing. Did that help the vacuum at all?

It still appears that you have a vacuum leak on the engine itself. Try the tricks for looking for one.

Kind of a long shot but have you checked cam timing.
the timing has been played with by adancing and retarding a tooth to see if it made a diff but no good so it is set back to stock.

You said you tried advancing ignition timing. Did that help the vacuum at all?

no difference at all in the vacum reading

It still appears that you have a vacuum leak on the engine itself. Try the tricks for looking for one.
i have tried every trick i can think of to find a leak with no luck.i even ran around all the seem with a propane torch to see if there was any change in idle and nothing.



[This message has been edited by phyxius (edited 10-19-2005).]