Hello to all. This is also cross posted on Rennlist.

I have searched the archives but can't seem to determine where I should go next...

I have an 01 TT, with an Upsolute ECU, Baileys, K&N, and open (no muffler or cat) exhaust.

These mods were done all at once with about 17K on the car. For the first few thousand miles thereafter, I would see 1.0 bar and hold 1.0 bar till redline in all gears, and even see 1.1 flash for about a second in 4th-6th.

Now the car was about 25K miles. Here is what I observe during hard acceleration.

- .8 bar in 2nd until about 6000 RMPs then .9 till redline;
- .9 in 3rd thru redline;
- in 4th and 5th, 1.0 bar initially for a second or so, then dropping to .9, then back to 1.0 at about 6000 and holding to redline.

When not accelerating hard, I can get 1.1 bar spikes in 4th - 6th at lower RPMs and especially when the engine is loaded (going uphill, etc.)

I think I have ruled out a boost leak (based upon inspection of the hoses, etc and also my mechanic pressurized the system and could not detect a leak.) I have new plugs within the last 1000 miles and this did not seem to help.

I would like a few suggestions on which route to go next. I think I should be seeing 1.0 bar based upon my configuration. Maybe a new MAF? ALso I have heard about bent wastegate actuator rods. Is there an easy way to check for this?

Thanks to you all.

 

I might not worry too much about that. I understand the gauges are not very accurate. Does the car drive any different? If you dynoed it or have a quarter mile run back from when you saw higher boost you might repeat those again now. Unless the car is performing at a noticebly lower level I wouldnt do anything.

 

Do you have stock dump valves? YUou really should get aftermarket billet ones when running an ipgraded ECU...Call Stephen at Imagine Auto

 

I think he said he has Bailey DVs.
msindi- Did you get you Bailey DVs installed under warranty?

 

You shouldn't see any lower boost pressure due solely to the dense air.

 

The only other variable I can think of is the grade of the particular road you were on, as boost is also a function of load.

I haven't noticed any change in boost due to the cold weather. I also have the Baileys.


Did you run the Z06 from a roll?

 

Yep, I have an '02 6spd, and I see a peak boost of 0.6 or 0.7 depending on what RPM I start the pull and depending on if I'm going up hill or down hill. Up hill the RPMs obviously don't build as rapidly and there's more time for the boost to build. By red line the boost is on average 0.6, but I have seen 0.5 and 0.7 too.

I'm not always watching the boost though when I'm hammering it, so my responses should be judged a "random survey".

 

Did you get my PM?

 

I'm thinking that you guys have it all backwards...

I think you should see higher boost pressure with cold temperatures. Cooler temperatures mean higher engine performance due to the increased air density of the intake charge.

With a more dense/cooler intake charge, I would expect better performance and higher boost pressures than with less dense/hot air AND less timing retardation due to excessive operating temperatures in the engine itself.

Here in Arizona when the temperatures soar, my performance AND boost pressure drop substantially (well... substantially enough to actually FEEL the performance drop).

Joe West

 

The boost is "above atmosphere", so at max. boost the ambient pressure is boosted another ~0.7 bar (no matter what the ambient pressure might be, within reason. My take at least). Maximum boost can't be exceeded becaues of the "pop off" valves.