Sean

Hey, have not posted in a while.

Here is the problem, I noticed after my supercharger install I get an occasional backfire through the intake ( only under small load around 2000 RPM). I still need to get it tuned, but other than this problem it runs great! It is a vortech s trim (from summit) pushing 8-10 PSI. I have a 73mm C&L meter 19# injectors 65mm TB. way too many other mods to list. I am thinking I need to get my meter recalibrated for the supercharger. Other than that the car runs insane, first and second gear are pretty much useless! Feel free to chime in with any thoughts on the backfire. It also smells rich.

Thanks,Sean

Sean

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Anyone?

Sean

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Slingshot

I'm not sure, but I would guess that it is because at that certain RPM, the pressure in the runners is less than the absolute pressure across the intake valve. So the unburnt air/fuel takes the path of least resistance back into the intake and ignites.

Are you sure it's in the intake manifold? It may just be afterfire (in the exhaust) Especially if it's running rich. This is commonplace in turbo cars with no cats. Again, I'm not positive, but I think afterfire occurs in catless turbo cars when the exhaust is rich, and hot coming out of the turbo, heat + fuel = ignition.

Sean

Thanks for the reply.

I am positive it is in the intake. If I rev it a little from the throttle body while under the hood, the sound is distinctively coming from the intake.

Timing?

I have it set at 10* and the BTM set at 1 on the dial, so total timing should not be any more than 16* at WOT.

I also have heard of guys ditching the BTM and running 19* to 25* with the spout out?

Slingshot

Are you running an off-the-shelf tune of some kind?

Casper98GT

If youre backfirng in the intake id say fireing order.

Slingshot

If the firing order was off, he'd have misfire over and over again. This is just an occasional "detonation" in the intake.
Maybe it's a bad coil?

Redline03GT

you are running supercharged with 19 lb/hour injectors? Dude im suprised your car hasnt died yet...you are running wayyyyyyyyyyy too lean...need AT LEAST 30 lb/hour...

Sean

The kit comes with FMU and a T-REX in line pump. I also checked the plugs after about a week of beating on it and there was no sign of it running lean, if anything it is running rich. I am going to set the base timing at 12*- 14* and pull some more out with the BTM a WOT/full boost and see if it goes away.