A few days ago my car suddenly started boosting late during full throttle (3800 - 4300 PRM instead of the usual 3000 - 3200 RPM). It also seemed to me that it was also a bit more sluggish than normal and that the boost didn't taper as much. I suspected a boost leak and took it to the dealership. The tech took if for a drive alone and then came back and took me along. He said that it felt normal, even though I felt otherwise. He tested the boost and it was running 12 psi under less than full throttle. I still was hesitant so he sprayed down every hose with something, explaining that if there were a leak the substance would be sucked in and cause the RPM's to increase. I guess this is the usual way to test for a leak. Anyway, it all checked out fine. I asked if it were possible that the throttle body seals were degraged enough to cause a leak (as discussed in a how-to thread in this forum). He said it was possible.

Anyway, my question is this: Could the problem be my custom tune? Al tuned my car back in September. I have no other mods except for a K&N drop-in. I'm not showing any error codes of any kind. So do tunes sometimes go bad suddenly? If I had my car reflashed back to stock, would that normalize it? Or am I just being paranoid about the whole thing? Thank you...

 

Sounds like your wastegate may be going bad and opening too early which would cause slow spool and irregular boosting.

 

Thank you. My car has 56,xxx miles on it. Has anyone else had to replace a wastegate this soon?

 

Boost leaks are tested by pressurizing the boost system with 21 psi of compressed air

Try that and report back !

 

Also does your car have a boost gauge? If so what does it read at full throttle around 5k rpm?

 

Use this tutorial and do a boost leak test yourself.

http://www.vfaq.com/mods/ICtester.html

Then let us know

 

" I still was hesitant so he sprayed down every hose with something, explaining that if there were a leak the substance would be sucked in and cause the RPM's to increase. I guess this is the usual way to test for a leak."
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^^^^That is a double edge type of test. The test the tech performed shows leaking internally through suction(actually vacuum), he is missing the boost test which is maintaining boost pressure through the piping.

For that matter, you could also spray that die fluid into the air filter and make the rpm drop.

The real boost leak test consist of pressurizing the system and puting some soapy water in the brackets and piping connections all along from the LICP all the way to the TB and extending a visual inspections to other parts such the BOV, BOV hoses,waste gate actuator/ solenoid etc.

In several ocasions I ridiculed senior master mechanics from dealerhips showing them that the ASE certification is just a badge that you get from a dollar store.

Case one#1. The dodge dealer master mechanic told me that my turbo driveshaft were snapped by starting the car after I fueled my car at a gas station thus reversing the rotation causing the shafts to snap. I felt like I want it to punch the guy in the face.

Case two #2 [/B]. A senior mechanic advisor from Renault told me that in order to boost leak a turbo car the turbo must be fully tested on a bench. He completely disregard any possible piping leak or loose bracket on the engine piping route. I insisted it could probably be a partially broken hose, I was correct.

Case # 3 TEC turbos corporation owner rejected my claim maintaining that I overboost both turbos on my Stealth R/T causing the shaft to snap during extreme boosting. Ironically when I put a set of oem used turbos from a junk yard I never overboosted them nor I ever had any sort of boost device. He forgot to secure the turboshaft nuts coming these loose under boost thus destroying my brand new 13G turbos I just bought from them(9 years ago)

Botton line, take it to a friend that knows about turbos, there are a bunch of people around this business that don't deserve the job/position that they represent.

Tshooting a faulty boost is in my opinion one of the simplest and easiest jobs. Go section by section and you will slowly but surely 100 % encounter the issue.

my .2c

Carlos