Supercharged cars-Vac guage...

Red1990Lx

Member
Nov 2, 2006
82
0
7
Ohio
I am currently having issues with the stang and was wondering what a boost/vac guage reads at idle? Mine currently reads 0 at idle but if I remember correctly when it was actually running like it should be, it was near 20 on the vac side not the boost side at idle...
 
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This unfortunately has been an on going problem for three days now. I woke up this morning and fired the stang right up, no problems. It idle perfect, vac was at say 16-18 oil was at 55 and the fuel pressure was at 42. After about ten minutes, the car acted up like it has been, no throttle, acts like it is missing, vac drops off the wall to 0 oil pressure is about the same and fuel pressure goes between 34-42 at idle (if it idles at all). I have changed the fuel filter, the plugs, wire, cap rotor, added octane booster, iso heat for water (?) and checked the FPR vac line to see if there was gas in it and it was clean. I do not know of anywhere else to look. I have sprayed some brake cleaner around the intake, SC hoses and vac lines with no spike in idle. You can push the gas to the floor and it will hesitate for a second then it will stumble up and then rev with a backfire. I haven't the slightest idea what is happening something is over heating or is on its way out causing this, I just cant figure out what i might be.... No codes or check engine light either!!! :mad:


P.s. It started about three miles down the road after filling up with 92 at a speedway location.

Got any codes?

I would think the gauge isn't reading right if it is at 0 - car would not run. Look for a vacuum leaks, make sure the discharge tube didn't pop off.

Wes
 
make 100% sure your intake tube is on and sealed. i had a similar problem where my air filter/maf fell off and un-metered air was going into the engine. it was okayish at idle, but the second you gave it any gas, it would crap out.
 
The stumble and backfire sure sounds like it is rich to me, check after the MAF in the intake to make sure nothing came loose - when an engine torques over under power it's not uncommon to pop a tube slightly off if one is loose.

For it to be running that rough all of a sudden I would think it would have to be something fairly substantial that went wrong.

Keep us posted, troubleshooting over the Internet sucks. :)

Wes
 
After a few bucks, and new parts, the symptoms seemed to reveal themselves. It turned out to be a bad or "going" bad stator in the dizzy. What a pain it was trying to figure it out. The timing after filling up with gas was so coincidental (SP) that I assumed it was bad gas or something with the fuel. Boy was I wrong!!! Thanks for the input. Vac is back up to 14-16 at idle and everything else checks out.


The stumble and backfire sure sounds like it is rich to me, check after the MAF in the intake to make sure nothing came loose - when an engine torques over under power it's not uncommon to pop a tube slightly off if one is loose.

For it to be running that rough all of a sudden I would think it would have to be something fairly substantial that went wrong.

Keep us posted, troubleshooting over the Internet sucks. :)

Wes