As I plan my return from hibernation, I'm stuck with a confusing problem that plagued me all of last season. Last year, I ran my 2000 I built with some of the components (including engine) from the '99 I wrecked in 2014. Just a quick summary of the drama with that car...Early in the season I had a bad misfire that was likely due to the fact that I had the cam timing wrong. After having the cam timing corrected I got rid of the misfire, but then had an issue with the engine running lean with decreased power. We had to turn the fuel pressure up to 60+ psi to make max power, and were still a bit lean.
I posted this back in May...http://mazdaracers.c...+fuel +pressure, but never really figured out the problem.
Unfortunately, we determined that some of the valves were damaged from cam timing being off. I got that repaired, and was hopeful the above problem would be resolved. Though we dyno'd the car at the same power this motor made in the '99, we had to do it with over 60psi of fuel pressure...and the 5500rpm AFR was over 13. Prior to this I also swapped fuel pumps (not new) and installed rebuilt injectors (from Dave W.). From there, I just ran a few races, and did the Runoffs. I did swap in another MAF meter, but no difference.
So, I've got a car that needs over 60psi to get maximum horsepower with the AFR about 13.2 at 5500rpm. I get great fuel mileage (but don't run enduros). At Mid-Ohio I averaged about 12.3mpg.
I've been studying fuel systems, but nothing jumps out at me. The car starts fine, runs fine, but clearly something is wrong. I data log the fuel pressure in the loop of hose that comes from the fuel line into the engine bay, before it gets to the pulse dampener thing. I get a drop of about 1.5psi from 5000rpm to redline.
Any help is appreciated.