Rebuild Runs Rough

plymouth4onthefloor said
fluctuation on a fuel injected engine is mostly the problem of a vacuum leak speak lean mixture. check it with a brake cleaner for vacuum leaks. If everything is Ok, i would highly recommend ( in any case ) to to run the EFI in the closed loop mode ( wide band sensor running ) and tune the mixture new, like you bought it new. Every engine needs his own calibrating and you changed a lot of the basic engine! Run a good matching ignition curve matching to your cam, compression ratio and fuel you're using. Good luck.

Yeah this is a weird one. Vacuum leak is again, plausible, maybe it’s affecting only 1 or 2 cylinders instead of all 8. I ran the same map and curve as before but it’s just giving me such a hard time. I thought I already had a pretty good map. I shouldn’t be having this issue. Even advancing the timing at idle to 13,14,15 it begins to act sickly. I don’t have a closed loop system. I have full authority of fuel, ignition. I was also thinking of fueling up with gasoline and trying that. Get it back to basic.

teringer said
do a leak down test on cylinders /compression is low even for a 7 to 1 eng check pushrod length

A leak down was on the list for sure. What fools me is the compression numbers are all average. I was certain I’d have a cylinder <100. I do live high altitude and the pressure last night (with thunderstorms too) was 78kpa. Pushrods were the same as before and I adjusted the rockers per Hughes tech.

diymirage said
2 plug wires swapped?
what is it, 5 and 8?

also, is the mega squirt self learning?
should you reset it for this build?

I had 1&3 swapped for the first startup:BangHead:

It’s been triple checked, now. I originally thought I had washed out 1&3 with E85 and that was the result of the shitty idle. 1&3 are the lowest compression numbers. 5 psi below the rest. Maybe it is still the issue. I’ll try a wet compression test, Ive only done a dry one.

Mega squirt is not self learning, it is calculated using speed density. I am using The same maps as previous engine build. Only hard parts I’ve changed was the crank and crank bolts - I went to studs. Everything else is the same.