What the hell is going on?
 

So my buddy has a vortec supercharged mustang that was being worked on at a performance shop. they tuned it, and some other shit I dont know. To tell you the truth I dident like the way they did things but whatever. So we got it back, and it dynoed a healthy 440hp. Problem is it idled like shit, and the supercharger surged (bov wasent working?).

So I looked around. Seems they moved the recirculating BOV to before the MAF sensor and let it dump to atmosphere. Now it leaks at idle, seems the supercharger is pushing ALOT of air out of the BOV when idleing. Like hair dryer on high powerful. I dident like this, so we relocated it back to after the MAF and recirculated it. Now it ran like total shit, this was not working.

So then I dident recirculate it, and tired to tighten the spring up on the BOV. Still leaked... but ran a little better.

So I tried resetting the ECU and recirculateing the BOV. Now it ran REALLY bad, scared us actually.

So I gave up and put everything back like it was. Funny thing is now the surge is gone, and it runs great. WTF?

I figured maybe it ran like shit when recirculated because they tuned it with the BOV leaking at idle... but I thought that would fuck with the MAF sensor? I dunno what to do, I guess if its running fine now just leave it.

Its a 99 stang with a sean highland 6.1L engine, cams, vortec v1, 10 lbs boost, SCT I think flash tuned, some odd dialbosport maf.ia...

I mean I know the cams can fuck with idle, the motor pulls around 10 to 9 inhg vacuum.


This is why I do my own work....

so is there a question somewhere in there or are these just observations?

I dont know whats up, but that sounds like shit.

lol sorry guys, I was just wondering if you had any ideas as to why the car now runs good, and why recirculating the bov like it should be made it run so shitty.

if it was tuned with that huge leak then recirculating it will make it run lean at idle.

i'd just recirculate the bypass valve to after the filter but before the maf. sure its not quite right, but it should run fine that way.

I have no experience with mustangs, but:
if the car was tuned for it not to be recirc'd it might have been running lean from all the extra air you added to the mix when recirculating the bov. just my .02


*edit:
You beat me by a fraction of a minute:D

um his real problem is he let someone tune it with a flash tuner get something u can realy fuckin adjust. And since he obviusly put alot fo $$ into the car the people who didnt finish the job ie give him a satisfactory product should fix it.

THats what I keep tellin him, we are going to go over there this week. I feel like they are going to be a huge pain in the ass.

And I assumed it would run lean, dident think it would change as much as it did tho. The car couldent even move. Fuckin shops, they said its supposed to leak.