2000 GT w/ Vortech wont run HELP!

[spodeboy]

I have a 2000 Gt that we just put a Vortech V1 back on, had it rebuilt because of a bad bearing, and drove it around no problems for 15 minutes without making boost, it had like 17lb vacuum at idle. We then drove it again, gave it a little gas to see what boost we were making, and it started missing and running bad, no boost and now no vacuum and wont idle. I have to hold like 1/2 throttle in it to make it run at all and the whole time its missing and backfiring. We checked some lines but can't find any issues. Lots of fuel pressure, checked it too. Can anyone help?

 

[fiveohwblow]

Spin the supercharger by hand? Does it freely spin? What about the tune? Do you have a custom tune in it with a handheld? If so, check to make sure the tune is still in place?

 

[screamin gt]

plug blown out?

 

[spodeboy]

Supercharger spins fine, I took off inlet pipe and it really has a lot of air flow. I checked spark plugs, they are all ok. I have a tune on it, l did not check the tune, i will now.

 

[joshjwc9]

No check engine light? My vote is for a misfire, something that's not connected to the TB/Plenum correctly to cause a vacuum leak or bad IAC.

 

[trinity_gt]

Check the compression. Are you sure it's running on all 8 holes?

 

[JymboSlice]

did you unhook the MAF? if the MAF is unhooked you're car will run like that

 

[warment]

I blew off one of the silicone connectors on the air inlet pipe once and my car did the same thing.

 

[spodeboy]

No check engine light, maf is good i think. Its definately connected. I am going to do compression check tomorrow and see i guess. Doesnt make any BAD noises like its blown up.

 

[screamin gt]

iac sensor get blown out the discharge pipe? did you change to cooler plugs than before? need more info, what was done to the car? what was the car running with before you put the s/c back on? etc.

Lots of good guys on here but you got to give them more info to work with....

 

[spodeboy]

yes, your right ok here's the story. Put on used vortech and 42# injectors, colder ngk plugs, along with focus pump and vortech's installation kit. Then took it and had it tuned made right at 300hp at wheels. Drove it for couple months fine, and was driving it back from work one day and just died. Found supercharger bearings completely shot. Pulled supercharger back off and sent to magnusun tp rebuild. Put the supercharger back on and drove it around for 15 minutes just fine, at low throttle positions, before before putting a vacuum/boost gauge on it. Put gauge on and started car, everything good 17+ vacuum and idling great. Took it out to see what kind of boost we were making and it drove fine at low throttle, got on it a little bit(less than 3/4 throttle) vacuum went to 0 and no boost. And then would not idle or run without 1/2 throttle in it at all times.