GU series 6 - 3ltr- exhaust /boost question.

[BENNNO]

Hi everyone, as some may know i have a nissan 3ltr.
I recently put a 3" mandrel bent exhaust system in from turbo back, it has a 3" kat and 3" muffler.

PROBLEM i am facing is that between 1000rpm and 2000rpm under full throttle the boost seem to bounce between 15psi and 10psi a couple of times before settleing.

Now it only started doing this after i put the exhaust on, the only thing i can think of is that it has something to do with the varrible vane turbo and the lack of back pressure ( 3" to big) is causing it, has anyone heard of this before and can you give me some advice on how to counteract this bloody anoying problem.

Thanks, Ben

[tweak'e]

reset the ecu. poor mans way is to leave the battery disconnected over night.
this will erase the old learned data and it will relearn everthing from scratch. that way it wil take into an account of the bigger exhaust.

if that dosn't fix that it may be a problem with the MAF sensor. if its dirty it can react to slow and the ecu will have trouble controlling the turbo.

edit: out of interest what cat have you got on it ?

[Dzltec]

When we fit exhausts to zd30 gu's we have to adjust the vnt actuator to stop boost spiking. As you said, you are taking the restriction out of the system. It can be done on the road or on the dyno if your operator knows what they are doing.



Andy

[tweak'e]

proberly better to block egr then adjust turbo to suit.

also see how much oil is going through the intake. the extra fuel causes a few problems which can go unnoticed. a good catch can is highly recommended.
heaps of info on http://www.patrol4x4.com/forum

[Yom]

blocking the egr will only make the boost spiking worse

if fine tuning the vnt actuator does not cure the spiking you will need to fit a setup which smooths the spiking out. its called a dawes valve and the setup of these devices is located, as tweake said, on the www.patrol4x4.com/forum

goodluck with it. fingers crossed you're not the first to blow up a CRD zd30 (assuming you do actually have a series 6).

[j-top paj]

reset the ecu. poor mans way is to leave the battery disconnected over night.

doesnt need to be overnight. its only about 5 mins or so. i had to do it once when the sub tank wouldnt pump into the main

[tweak'e]

reset the ecu. poor mans way is to leave the battery disconnected over night.

doesnt need to be overnight. its only about 5 mins or so. i had to do it once when the sub tank wouldnt pump into the main

i'm told 5-10 min is not enough. overnight is fairly easy to do tho it wouldn't hurt to try 5 min if your pushed for time.

[j-top paj]

reset the ecu. poor mans way is to leave the battery disconnected over night.

doesnt need to be overnight. its only about 5 mins or so. i had to do it once when the sub tank wouldnt pump into the main

i'm told 5-10 min is not enough. overnight is fairly easy to do tho it wouldn't hurt to try 5 min if your pushed for time.

i think i read 7mins on here once before..

i have only had to do it once when i first got the car and it was my first trip with it so my memory isnt the best from 2 years ago.
overnight would obviously work if you werent worried about time and wanted to make sure it definately reset.

[chunderlicious]

disconnect and hold your foot on the brake or with the lights on for a few minutes. thats what it is for commondores and works with a few others ive done it too.

[j-top paj]

or sterio on when you disconnect the battery etc...
helps with cap charge in the electrical items

[Nuttaa]

I think this is the valve $30.

http://www.3barracing.com/product_8.htm

Cheers.

[BENNNO]

thanks for the info guys, i got the exhaust put on at about 1500km so its been on since new and its done it from the second i put it on there. perfect before. It has a second hand catt on it wich is pretty small im told, and a pretty small muffler.

ill try the battery thing and let you's know.

[tweak'e]

It has a second hand catt on it wich is pretty small im told, and a pretty small muffler.

whats the cat off? its not a cat off a petrol motor ??

small muffler is ok provided its straight through !

[msjc38]

Ramove the varible actuator & turn the VNT stop screw in 1/2 to 1 turn you will not stop the problem but will improve alot as this is a standard thing for this type of turbo

[chunderlicious]

any luck benny

[BENNNO]

na did'nt work, just gonna put a 2 1/2 inch zaust on it with a good quality cat, work from there!!

Deffinately not going to change shit like blokeing e.g.r valve or adjusting turbo!! im worried enough having a chip in it!!

Thanks for all the help everyone!!