[RESOLVED] 20psi + WOT = Crap!

[spyderturbo007]

Well, I haven't been around lately because my wife and I just bought our first house and my work decided to purchase a new building and make us move everything.

Anyway, things are calming down now and should be slow for the next couple of weeks until it gets to be time for closing on the house. Alright, enough about my personal life.

I was out last night and I decided to turn up the boost to the 20psi maximum that my gauge will read. I was running about 18psi prior to that and had great looking logs. No flat spots or timing pulls and getting about 19 degrees @ 6500rpm. I took about 2% out on the SAFC across the board and bumped up the boost a couple of turns. Made a nice WOT pull and noticed that I was pulling 20psi. Checked the log and everything looked great except for a small flat spot around 4500rpm. No big deal, I just yanked out another 1% and made another pull.

Everything was running great and the log looked exactly as it should. I saw a 2.5 lb/min increase in my airflow, which is about right for a 2psi increase. Woo hoo.......20psi on an EVO III is much more fun than 18psi.

Anyway, I was screwing around and then noticed that my boost gauge was now showing that the boost would spool to 20psi and then drop to 16psi and then seemed to start climbing again........ Made another pull and recorded the log......WTF, everything looks normal and I didn't notice a stutter when the boost fell off. Got out of the car and looked for anything out of the ordinary and everything looked fine.

Anyone have any ideas what could be going on. I know the tune is good and everything feels fine, so I'm stumped. I know it's not a boost leak because the log didn't change. A boost leak that big wouldn't go un-noticed by the ECU.

Anyone think it's possible that I blew out my boost gauge? I really don't think that's the problem, because VAC and light boost still look normal. What about my BOV? I don't think that would be the problem, because I would notice a fall off in acceleration and airflow increase at the point where the BOV was pushed open. Same thing if the wastegate was sticking open.....I would notice that also.

My brain hurts and this actually kept me up last night till about 3am, laying in bed trying to figure out what is going on. I get the car out for the first time in about 2 weeks and this happens.

Any suggestions are welcome.

 

[andymoraitis]

Nathan,

Welcome back. I hope everything's good on the home front since you owe me cookies. If those aren't sent pronto, it'll be:

No tuning advice for you!

In actuality, it sounds like either the boost gauge is binding up and is on it's way out. I don't know what type you run, but AutoMeter's have been spotty with respect to quality control. I'm on my third one and this unit seems to be working like a champ. I'd start there, re-check the boost source line and see what that nets you.

I don't think it's anything like the flapper blowing open or a boost leak since the log would have shown a crazy drop in airflow and performance. Put a 30-0-30 in there and give it another shot.

Welcome back and congrats on the new home,

Andy

 

[spyderturbo007]

Nathan,

Welcome back. I hope everything's good on the home front since you owe me cookies. If those aren't sent pronto, it'll be:

No tuning advice for you!

I told you that I would have my wife bake some for you and you said that you wanted to wait. So there!!!!!

In actuality, it sounds like either the boost gauge is binding up and is on it's way out.

After racking my brain for a couple of hours, that's all I could come up with.

I don't know what type you run, but AutoMeter's have been spotty with respect to quality control.

Yep, it's an AutoMeter Phantom series. It's been fine for about 5 years, so maybe the extra sweep from upping the boost killed it. Woo Hoo.....If that's the problem I can tell everyone that I blew up a boost gauge.

I'd start there, re-check the boost source line and see what that nets you.

Yep, I checked the line last night and it looks good.

I don't think it's anything like the flapper blowing open or a boost leak since the log would have shown a crazy drop in airflow and performance. Put a 30-0-30 in there and give it another shot.

My thought exactly with the airflow drop. Sucks that I'm poor right now because of having to pay $6,400 in closing costs. We are also looking to finish the basement in the new house before we move in. Oh well, it's my birthday tomorrow, so I think the wife will get over it if I spend a little money. After all, I just bought her a house.

Welcome back and congrats on the new home,

Andy

Thanks a bunch!!!!

 

[andymoraitis]

That's true - well about the cookies at least!

Somehow I don't think $45.00 will cause a stir considering your current expendtures. Either way, let us know if that fixed it or not.

 

[spyderturbo007]

You never know with women what they are going to do.

I just got done ordering this, which will hopefully fix the problem. I went with AutoMeter again just because it's on the cheap end of the scale. That, and I can't see spending $200 on a boost gauge.

http://www.dsmparts.com/customer/product.php?productid=148&cat=70&page=1

 

[andymoraitis]

Those work fine. Like I said, it took three tries for me to get one that wasn't reading 4 in/hg of vacuum with the gauge still in the box. Apparently AutoMeter's been working on their quality control so they should be better now.

 

[daren_p]

Those work fine. Like I said, it took three tries for me to get one that wasn't reading 4 in/hg of vacuum with the gauge still in the box. Apparently AutoMeter's been working on their quality control so they should be better now.

I don't know about their quality control, the first gauge I bought I ran for 2 summers & it was sticking on the VAC side so I bought a new one. When I took it off I found it was now also reading 4 psi low. So I get my nice new replacement, the dial screws are lose so the face slops around, hook it up to check its calibration & it leaks internally. I send it back for replacement & the new gauge still has a small internal leak.

 

[andymoraitis]

I guess I'm luck then if it only took a few tries. Seriously, I replaced mine about 4 months ago and it's been perfect.

 

[spyderturbo007]

Turned out I blew up the boost gauge.

Just marking my old posts as resolved.