yzfr6i

I just swapped from 24lb injectors with and FMU to running 42s by themselves. This is on a SC car running 6lbs of boost. Should I leave my timing and fuel pressure the same as before? The car doesn't pull as hard with the 42s as it did with the FMU installed. I'm currently running 11 deg initial w/ spout and 42lbs of fuel pressure w/o vacuume. Should I increase my fuel pressure up to where the FMU used to spike it (which I believe was around 50 - 52)? Also I did change mass air meters to one that was set up for the 42s.

Thanks for any info.

smacked1

so did you upgrade your maf with the 42lb injectors

yzfr6i

Yes. 76mm calibrated for 42s.

92hatchLX

Why not leave the FMU on? I'm still running mine with 7 lbs of boost, 36lb injectors, no tune, 75mm Pro-M MAF with the open filter/supercharger curve. My car runs great!

yzfr6i

I've just nevet had to run an FMU on any of my other SC cars. And I had heard that they are pretty hard on your fuel pump. I'm going to get the car tuned and have a chip burnt as soon as I do the last few things I'm wanting to my car. Till then I'm just trying to get it to run decent.

92hatchLX

So is your timing 11 degrees w/ the spout removed or in? This is kind of off topic but it sounds like your running your base timing a little too high w/ out a tune. I'd turn it down to 8 degrees. What kind of fuel pump are you running? I've heard that if you're running 42's or anything higher without a tune it's not going to run great. Good luck!

yzfr6i

11 degrees with the spout in. I have everything set up the same as when I was running the 24s with the FMU. I did just go out and turn the fuel pressure up to 48 without vacuume and that seemed to help out quite a bit. But it still doesn't feel as violent as it did with the 24s.

The scary part is when I bought this car a few years ago the kid had the timing set at 16 base with the spout in, and it didn't ping.

93 LX FiveO

so you had the blower on there with the 24lb injectors?

yzfr6i

Yes. I was running the blower with the 24s and the fmu at 11 degrees timing. Spun a bearing in the blower and while I had it off rebuilding it I removed the fmu and was just running 24s on the engine only. Put the blower back on two weeks ago and left the fmu off and was using just the 24s, and set the timing at 8 degrees just to be safe. The car was ALOT slower than before but I expected that with the lower timing and the fmu being gone. Installed the 42s and new mass air, and bumped the timing back to 11 degrees like it was before expecting the car to run as good if not better than it did back before when it had the 24s and fmu. However it just doesn't have the kick that it did before.

I don't know if maybe it's the fact that the fmu would make such a big fast spike in fuel pressure as soon as the vacuume dropped that made it feel really violent.

I'm wanting to go to a 255 pump instead of the 110 it has now and install an AFM powerpipe before I have it tuned.

TrimDrip

I would be careful doing what you are doing and at least have a wideband hooked up.