hello. ihave 87 iroc the engine is a vortec 5.7 with 305 heads lt4 factory HOT cam stock tpi with 24 lb injectors . it surges from 1500 to 1900 rpm. there are no codes any body know of a cure?

 

Well... that is a WHOLE LOT of cam for a stock tune/stock intake setup... which won't help any minor problems there are. I'd try to see what the ECM see's and go form there... maybe your running lean and knocking (ig. retard).

If that looks OK - which is all it will - you are way out of tune, check the TPS for any dead spots, etc. Does this happen all the time, warm cold, part throttle full throttle?

I doubt this will be easy to diagnose given your mismatched combination.

 

thanxs for the reply . the tune up is fresh. the tps is new from gm,set up as per service manual. the car hits hard thru the whole rpm range. a little lopey at idle. would a new prom help? it is not a bad surge just noticeable. ive been a mechanic my whole life but this is the first chevy with fi that ive built.mosty street rods thanxs again

 

Anyone else doubletake on this or am I just too tired?