Mach 10

I had my Vortech V-2 supercharger installed a couple months ago...it took my times from 15.47 down to 13.754 on an uprepped track and crappy tires. Internal 255 lph fuel installed and it has the FMU.

So while I was on vacation I installed new 24lbs injectors, a C&L 73mm cal'd for the 24 lbs injectors, an adjustable fuel pressure regulator and a fuel pressure gauge attached to the fuel rail schrader valve...I adjusted the fuel pressure to 42lbs.

After the install the car drove with no problems for about a week...but I don't think I ever floor it or got on it really hard.

I let it set for week...so I took it out the day before the drags to test it out.

Here's the problem...under normal or slightly aggressive (less than 50% throttle) acceleration the car pulls and runs normally, but under hard or full throttle acceleration the car losses power and has trouble getting above 3,000-4,000 rpm.

I went to check the fuel pressure but the gauge I had just installed was internally unravaled, I adjust the pressure up/down and it made little or not difference...I have a new gauge on order.

I didn't notice any fuel or any other obviuos leaks, we adjusted the TPS up since it was at .90 but this didn't help, and it read 4.67 fully open.

I had a friend drive it and he said that it didn't sound or run like it was detonating.

Any ideas or suggestion of what I should check?

stanglx2002

have you checked the timing?

luckythirteen13

your a/f ratio could be way off. you dont have to have to hear the ping to be running lean. i was running 26:1 before i got my wide band o2 kit and i have absolutely no ping. never heard any and the spark plugs looked/look perfect. gave it a lot more fuel and that fixed it right up. have you had it dyno tuned. without a wide band o2 at the very least for tuning, you shouldnt even be driving it will a supercharger on it

94Cbra

Is the FMU set at the right ratio for the new 24lb'ers?

EDIT: I would sugest you get rid of the FMU and get it on a dyno. Some 36-42lb injectors and a dyno tune would be plenty to run without one.

Mach 10

How do I get the FMU set to the right ratio? Send it back to Vortech?

I'm stationed in Germany and don't have access to a dyno that can tune

sc94gt

What about the MAF? Maybe it's hitting it's limit.

Mach 10

How do I check this and what should it be reading? How can I adjust it?

I bought the C&L 73mm MAF cal'd for 24lbs injectors, but it still uses the stock electronic MAF sensor.

vfast

so I take you had 19's using that fmu..correct..what you need to do is get another disc for it with a different ratio or just use a set of 30 and no fmu.......what is happening is it's either too rich or lean at that rpm.....because of the wrong fmu disc..also your tps should be alil closer to 5

uedlose

does it start bucking and act like it is missing? Did you close up the gap on the spark plugs?alot of times the added pressure of the charger will blow out the spark under full boost you should also drop back 1 or 2 heat ranges on the plugs also to help keep spark knock at bay.worth a try as I have had this problem in my early days of tuning on our superchager.

Mach 10

What should I gap the plugs to? I'm going to pull the plugs and see what they look like, then replace them with new ones.
Edit: the plugs where gapped to .035

Edit: the car only bucked and acts like it's missing when I have the fuse in for the T-Rex external fuel pump, I've had the the fuse pulled since the supercharger was installed because of this, the car ran fine on the stock 88lph pump and also on the 255lph I installed later.

I got my new fuel pressure gauge installed and adjusted it to 39-40 psi and the car is still doing the samething.