We just did an engine swap on my blazer and it sounds like it has a dead miss and it is running lean. The block we used was orginally TBI but we used my injector assy. to make it CPI. We cleaned out the injectors, swapped to platinum plugs, check the firing order about 10 times, checked the valves, ran new gas, octane booster, and gas treatment through it, as well as triple checked the timing. We cleaned out everything before putting it back together. Nothing seems to fix it. We noticed that cylinder 4 was weak but there were no other problems. Any ideas?

 

Have you checked fuel pressure? I know that w vin with cpi requires 59 to 63 fuel pressure and z vin with tbi is like 12 to 14 psi.

 

Sorry it took so long to get back, I think they did but I guess with 5 million different things going on it would be easy to forget that.