Cmoney100g

I have a 1999.5 A4 1.8TqTip and recently installed a center vent boost gauge. I have the 150HP model and was making sure this boost level is correct. I am getting a max of 5 PSI of boost under full load. From what I read I should be spiking to 6-7 PSI, but the weird thing is it holds at 5 PSI and never gets higher. I did some searching and found that limp mode limits you to 5 PSI. In some posts I have read that nDBW cars dont have limp mode.. some say they do. If you are in limp mode does the CEL always come on?

I have no CEL, and since I bought the car only 8000 miles ago I have no idea if the car has had issues all this time. The car seems to pull fine and keeps the PSI through out all gears.

I was told by the shop where the car was serviced before that the DV was replaced with the one from the Audi TT. Could they have installed it wrong? Could I just have a boost leak issue? or are these boost levels correct for a stock 1999.5?

I plan on chiping this car ASAP and I need to make sure its in A+ shape before I do so.

Justin517

limp mode, boost leak, or shot waste-gate/wastegate actuator...

kenny (dremel)

That's the first thing I'd do after a boost gauge, then chip it.

Monkeyboy

I had a tough time getting correct readings until I redid connections @3 times.
Similar results as you - showing low boost (psi)#s - never over 5, and a boost leak sound at one of my connections.

I thought my connections were tight - but obviously they were not. Zip ties did not do the trick. Ended up getting smaller than normal single use clamps (tightened with the special tool) and that did the trick. McMaster part number 52545k26 and 52545K38 (I forget which one I used). Let me know if you want a few, I got a whole bagfull

Does the car feel normal? What vac readings are you getting?

Cmoney100g

My vacuum at idle is roughly 15-16 hg.. while driving and letting off the gas my vacuum is 20ish hg.

So my 1999.5 nDBW does have limp mode? Like I said before... does the CEL always come on when you enter limp mode?

I guess the car feels normal.. the turbo spools around 3k rpm and it holds the boost well.

Also monkey did fixing the boost leak fix your problem or was it the connections 4 the boost gauge? or both?

Monkeyboy

I did not have a boost leak (technically) - my leak was with the tubing to the boost gauge.

My car felt normal. I forget the vacuum numbers, but I think it was at @15 or so when I should have been at @25-28 at idle. My car ran fine otherwise.

I tested by removing the boost gauge and going directly from the boost gauge to the intake on the front of the engine block. This showed me better vacuum numbers...therefore, I could conclude that my gauge was working and the problem was with the rest of the run.

First thing I checked was the 3 way splitter (I had the no buzz) that branches one line to the boost gauge. I tried a tee fitting with a bigger opening to the boost gauge and that gave me better numbers - but I had the buzz. I worked on the no buzz connector...I stuck a hot pin thru the opening of the connector that went to the boost gauge. This is a restricted opening and there was a possibility that there was some crud in the gumming up the flow. No real change.
I eventually went down the road of improving my connections. I got smaller diameter clamps and did all 3 connections on the no-buzz connector. What made the difference, I think, was the connection where the nylon hose went into the vac tubing. I got the smallest diameter clamp I could use. I actually sanded down the end of the rubber vac line so that the clamp would fit then tightened it down (the white nylon line was fed into the vac line @6". That got me to accurate boost levels and no leaky sounds. I can't believe some people just use zip ties...I don't see how this could give a tight enough connection.

Cmoney100g

hehe i actually didn't have anything for clamps or zip ties on the t-fitting.. I guess i'll be getting some clamps then.. see if that will fix the problem