Overboosting NJ

Post by **fazza81** » Tue Feb 10, 2009 8:19 am

Hi all,

My pajy is doing something funny, Usually the boost guage will go up to 11 -12 psi but now it will boost to 14-15psi and when towing a trailer you can hear the pop off valve vent. So I assume it is overboosting but why. I have changed the line between the turbo and wastegate which should controll the boost what else could it be?

Thanks

Post by **-Scott-** » Tue Feb 10, 2009 5:43 pm

Model?

Post by **jonnyjtop** » Tue Feb 10, 2009 6:10 pm

hi mate...i dont think there is a major problem....the weather usually affects turbo cars if its been colder than usual that could be the reason its boosting more...the pop off vent is actually turbo backspin that your hearing usually it will get louder if boost pressure is increased/ or there is extra load put on the engine...to fix the problem you could get a boost controller and run the pressure you want...also sometimes inside that pipe you said you replaced is a little nipple inside the pipe (on some cars) removing that or replaceing the pipe with a slightly longer/shorter one will affect the boost pressure....

Post by **hudson44** » Tue Feb 10, 2009 7:12 pm

The actual wastegate could be sticking within the turbo- they are subject to lots of junk and deposits. Is the vacuum diagram (assuming its vacuum/boost operated) worn. If you suck on the line does the actuator move. But as Scott said, a model would help.

Post by **REDNUT** » Tue Feb 10, 2009 7:21 pm

how much boost should a nj be running?

mine sits about 7psi, but when i put my foot down it goes up to 12psi,

im told mine is standard, although i have removed a muffler

Post by **j-top paj** » Tue Feb 10, 2009 11:31 pm

mine used to run an average of 10PSI most times.. but on some cold winter nights i noticed it up to 18PSI without anything sounding any different. if i didnt have a boost guage i wouldnt have known at all

Post by **fazza81** » Wed Feb 11, 2009 9:36 am

Ok

It is a 1996 NJ GLS 2.8td with a 2.5inch exhaust.

The pop off valve has only just started venting in the last 2 days started when I towed a car trailer on Saturday but with out a trailer turbo goes to 14 psi (it was at night) but the valve stays closed.

I might pull the turbo off and check the waste gate is sealing properly sounds like that could be the drama

Post by **REDNUT** » Sat Feb 14, 2009 9:43 am

j-top paj wrote:mine used to run an average of 10PSI most times.. but on some cold winter nights i noticed it up to 18PSI without anything sounding any different. if i didnt have a boost guage i wouldnt have known at all

did u happen to notice if your guage ever went to the vacume side or always sat on boost?
mine always seems to be around 1 -2 psi untill its turned off

Post by **j-top paj** » Sat Feb 14, 2009 11:46 am

guage would go back to 0 but never into vaccum..

Post by **fazza81** » Mon Feb 16, 2009 9:24 am

My guage always always sits on 1 psi never into vacum.

Only just touches 14 psi now and that is at about 5000rpm not sure what is happening.

Cheers

Post by **j-top paj** » Mon Feb 16, 2009 12:00 pm

fazza81 wrote: 5000rpm

how hard are you pushing it?

Post by **fazza81** » Tue Feb 17, 2009 10:28 am

That was only in testing. normal driving is up to 3000 - 3500 and if you accel had it is still boosting over 15psi time to pull the turbo off.

Post by **HotAe92** » Tue Feb 17, 2009 6:15 pm

fazza81 wrote:That was only in testing. normal driving is up to 3000 - 3500 and if you accel had it is still boosting over 15psi time to pull the turbo off.

Yeh I would be careful taking it to 5000rpm, those things hate being revved the crap out of (and you don't have no power up there anyway)

Post by **j-top paj** » Tue Feb 17, 2009 8:34 pm

HotAe92 wrote:(and you don't have no power up there anyway)

i found mine was good up to 4000rpm and then there was no point pushing it any further.. 5000, no point at all

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Overboosting NJ

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