Low Vacuum? Car bogging.

[deputy865]

I'm getting about half the vacuum I should be. I believe the low vacuum is directly causing my car to bog. I can't even drive it, its really slow to pick up RPMs and struggles to get into boost. When it does get into boost, it rev's up pretty quick. But this low end stuff is horrible. All of this has been noticed while the car is sitting. Throttle response is horrible as well. Wideband shows that I'm running rich when I give it some throttle. No CEL.

Also, I'll give it gas, get into a little boost, let off and my boost gauge will show that the vacuum falls down to where it should be, but then slowly falls off and holds at -10.

Car is stock besides a turbo-back exhaust. Compression is perfect, timing appeared to be lined up, I DID NOT check ignition timing though. Car idles just fine. Plugs and wires are brand new, distributor cap and rotor are brand new. Replaced the MAF. I performed a boost leak test and fixed all leaks.

Really confused.. Any ideas?

Shane

 

[volcomsnow245]

Check your BOV make sure it's not leaking and all your vacuum line.

 

[deputy865]

Check your BOV make sure it's not leaking and all your vacuum line.

Wouldn't those leaks be apparent from a boost leak test? I performed one and fixed all the micro leaks I had. In fact, my vacuum was -10 before I fixed the boost leaks.. and was still -10 after I fixed them all

Riddle me that?

Shane

 

[delta448]

When you did the BLT, did you pressurize the IM as well?

Where does the car like to idle?
Idle choppy?
Stock cams?

 

[volcomsnow245]

What kind of spark plugs do you have? And My vac is at 13-14 at idle.

 

[deputy865]

When you did the BLT, did you pressurize the IM as well?

Where does the car like to idle?

I hooked the BLT up to my throttle body and pressurized it. At first, I found a huge leak at my fuel rail, turns out it was loose. So I fixed that, retested and I didn't hear anymore leaks.. Guess it wouldn't hurt to try again as well as clean my nasty throttle body..

Car likes to idle from 800-1000. It isn't choppy or anything. Idle's pretty smooth, but will slowly start to wander.

New NGK plugs and wires.. Gapped correctly. All of them have even wear on them when I pull them.. They all show black, as I'm running pretty pig rich.. 10.0 on the wideband when giving it some throttle.

Shane

 

[volcomsnow245]

what type of ngk's bpr?

 

[deputy865]

what type of ngk's bpr?

NGK BPR6ES gapped to .28.. I don't think my plugs are the issue. They are brand new, never had issues with these before either.

Shane

 

[volcomsnow245]

Yea there fine I was asking because 7es's can cause this. I was having the same problem make sure your safc setting are right and check your ISC mine was cracked off.

 

[delta448]

Did you also BLT from the compressor to the TB?
What on the rail did you fix? Injector seal?
Did you check the FPR? -Might help explain your black plugs too...


BTW, I hope you meant 0.028".

 

[deputy865]

Did you also BLT from the compressor to the TB?
What on the rail did you fix? Injector seal?
Did you check the FPR? -Might help explain your black plugs too...


BTW, I hope you meant 0.028".

I hooked up the BLT to the turbo itself and on the throttle body. Those are the only two places. My fuel rail was loose, not making a full seal to the block. The injector seals were all fine and didn't look worn at all. I was prepared to replace them though.

Yes, 0.028 .. And this is a different car, I don't have an SAFC on this one. Besides some gauges and a full exhaust, this car is stock.

Shane

 

[delta448]

SAFC? You gave me too much credit, I didn't look at your profile until now.

You may want to check your stock Fuel Pressure Regulator though.

 

[volcomsnow245]

^^ +1

 

[miguelmcv]

+2 on Fuel pressure.

Also, check your TPS to be adjusted.

When you did the TBL, Did you check how long it takes for the pressure to be relief?.

If it reliefs the pressure wright away, It means that you have a leak somewhere.

If this is happening, then you have to test part by part, First, Throttle Buddy, Pipes (after the turbo), and at last before the turbo.

Some times is hard to see it or hear it, It happens to me, and was a PIA to find it.

 

[deputy865]

What exactly am I looking for with the stock fuel pressure regulator? Would that cause my messed up vacuum?

 

[delta448]

Fuel coming back through the vac line into the intake mani, primarily. Air leaking through the casing secondly.

 

[deputy865]

Fuel coming back through the vac line into the intake mani, primarily. Air leaking through the casing secondly.

Coincidentally, I have a aftermarket adjustable fuel pressure regulator coming to me already. Won't that eliminate the stock fuel pressure regulator all together?

I work at a dealership, one of the mechanics mentioned having check valves on my vacuum lines.. Needed or not?

Shane

 

[delta448]

The AFPR will solve any issue with the FPR except a bad vac line. Check valves are not needed (and actually will mess up function) for the FPR, but are okay for PCV and crankcase fresh air vent.

 

[deputy865]

The AFPR will solve any issue with the FPR except a bad vac line. Check valves are not needed (and actually will mess up function) for the FPR, but are okay for PCV and crankcase fresh air vent.

Are there any signs inside of the intake manifold that might tell me fuel is going into it? My intake manifold is pretty nasty and grimey looking inside..

Shane