no boost on my A4 turbo ???
 

hi all as i suspected before i wasnt getting any boost so then decided to buy a boost gauge . today i fitted the boost gauge on idle it sits at -6 on vacum and when accelerated under load it wont go past 0 boost no matter what revs i am at can anyone help with my problem as it is really starting to get me down any help appreciated thanks kev :mad::mad:

You are getting boost!!!!!!!! You are not getting "FULL" boost. If you were getting no boost, your vac. reading would decrease slightly not go to 0. Only under full throttle should it go to 0 with no boost. You might have a boost leak somewhere (or a wastegate problem, but no need to worry just yet). Start with the obvious. Take out the DV (Diverter Valve) and inspect it. If it is torn or stuck open you will see a no boost situation. The pressurized air will just recirculated back to the intake side of the turbo and little to no pressure will be created at the intake manifold. I found a write up once on boost leak testing rig..... It consists of three pvc pipe ends and a tire valve stem. You can pressurize the system from the turbo compressor outlet up to the throttle body. If any leaks were to be present you would know.

I would scan the ECU for "positive deviation" codes and any other codes like the N75 Valve etc. Let us know what you find out from a quick scan and a once over on your DV... I will try to find the write up for the boost leak tester.

Adam

I found it.... Easy, cheap and effective way to start diagnosing your problem.

CLICK THE LINKS TO VIEW PICTURES FOR REFERENCE

I put this kit together some time ago more as a Saturday project. I'd say the hardest part was finding the right size parts, but Home Depot had more than enough PVC end caps to go through.

Bear in mind that the typical disclaimers apply. In using a kit like this, you're intentionally pressurizing the air intake system and I will not take responsibility for those of you who get bonked in the head when a pvc end cap flies off because you didn't tighten it right. Also, make sure you keep an eye on the pressure to which you are filling the intake system. I wouldn't go above 10psi, even though most of us are generating almost 2x that or more, simply because even at 7-10 psi, you can hear a leak if one exists. I'd hate to hear that you screwed something up by failing to regulate pressure appropriately. That said, here's my kit:

Starting on the left and going clockwise:

1. PVC endcap with an NPT fitting and tire valve stem. Outer diameter of cap = 2.72" verified with calipers.
2. PVC endcap, same size as 1, but unmodified
3. Air compressor (mine runs off 12v power plug)
4. Small PVC endcap, Outer diameter = 0.85"

http://home.earthlink.net/~andrewaranda/audi/kit.jpg

One of the endcaps is modified using the following items

5. 1/8-27 NPT thread tap
6. 17/64" drill
7. tire valve stem
8. 1/8-27 NPT to 1/4" hose barb fitting
9. hose clamp (not shown)
10. thread sealer (not shown)

http://home.earthlink.net/~andrewaranda/audi/parts.jpg

Drill a hole in the top center of one of the caps and tap the threads. Insert fitting in the cap with thread sealer. Once this cures, then insert the tire valve stem onto the hose barb and clamp with hose clamp. I put some thread sealer in here as well to make sure I had a good seal.

The finished product looks like this:

http://home.earthlink.net/~andrewara..._stem_plug.jpg

This modified cap goes in the turbo intake hose, item 4 below, at the opening where it is usually connected to the air cleaner box (where the hose clamp is shown next to the number 5).

The smaller cap goes in the opening where the PCV valve #10 goes (so we don't pressurize the crankcase).

http://home.earthlink.net/~andrewara...di/intake1.gif

Lastly, the unmodified cap goes into the hose (#4 below) that connects to the throttle body at the point where it connects to the throttle body.

http://home.earthlink.net/~andrewara...di/intake2.gif

That's it, once all 3 caps are in place, connect the air compressor to the valve stem and turn it on until it gets to 7-10 psi. It should hold most of the pressure when you turn the compressor off. The intake tube has additional ports leading to the wastegate regulator and EVAP purge regulator valve, so it won't hold the pressure like a basketball would, but at that pressure, you will hear any leaks.

you for sure have a boost leak somewhere. at idle, the hg level should be anywhere from -16 to -20. Is your gauge mechanical?

How did you plumb your boost gauge. Off of the FPR?

off the vacum pipe from the dv to the inlet manifold

you definately have a leak, you should be pulling way more vaccum then that. either there is a large leak around where you installed the gauge which is causing it not to read correctly, or you have a pretty good size hole in one of your hoses somewhere.

at idle i get about -24lb and while coasting in gear i get about -28lb.

also in order to get the car to make max boost, you have to have your gas pedal on the floor.

+1 when i start my car my gauge reads around -21 then when i put it in drive it moves to around -15. there is a cheaper way to check for leaks with a tennis ball, check www.audidiy.com

edit: heres the topic http://audizine.com/forum/showthread.php?t=64411

what about at idle, vacuum is around -18 and then full throttle wont go past 1psi??!?!?!

If my turbo is just plain dead will it cause the car to not start? Cause it is crqanking but it wont start.

i believe it is getting like 20 lbs of pressure.


please refer to a thread with my story and whats wrong: https://www.audiforums.com/forum/sho...d.php?t=125710