Fault Code PO123 - Came about after Exhaust change from stock to 3"

Hi ALL,

I have searched hi and low in the forums for this code or similar faults but couldn't find anything , sorry in advance if I have doubled up on a previous post

I have a 2012 Telstra spec Ute with a ZD30ddti.

Quick history:
When I bought the vehicle 1.5months ago it came up with a maf sensor earth fault, changed the maf , didn't fix it, ran a wire from the maf earth to the earth point on the engine , all fixed no further issues. then,

I changed the exhaust out to a 3" with a single muffler and after that code PO123 came up, the light comes and goes but the problem remains.

The engine loses all power and boost goes down to nothing , then it picks up and drops off, can feel the engine surging, mainly happens at low speed going through gears but can pretty much notice it through out the range.

when surging the boost was spiking around 20psi so I built and fitted a spring & ball type boost controller and thought I had fixed it but no its still there, although the engine runs better now (maxs out at about 13psi) and feels to have more power.

Nissan told me the throttle body was U/S and they could get me a new one for RRP $2700 but could probly do it for $2400.

Surely there is a better / cheaper fix

Thanks

3inch too much for a 3lt patrol, 2.3/4 inch is the preferred size to keep required back pressure
Did you use the original piece just under the manifold You will need it to be in place

Thanks Fwdpatrol,

No I put a complete system on and don’t have the original anymore , if I replace a section along the line with 2 1/2 or 2 3/4 will that fix the issues ??

P0123 is a TPS fault code, bugger all to do with the 3 inch exhaust.

Google is your friend or you could try this...
http://www.nissanpatrol.com.au/forum...osition-Sensor

Does seem weird everything was fine till the exhaust went on ?? , surely the throttle body cant be stuffed ??

the must be plenty on here that run 3" full exhausts without issues ??

Quote:

---

Originally Posted by R055IE

Does seem weird everything was fine till the exhaust went on ?? , surely the throttle body cant be stuffed ??

the must be plenty on here that run 3" full exhausts without issues ??

---

Yep, but a some only from the dump pipe back and Fwdpatrol is correct in that purely from an engineering view 2.75 is optimum...

Anyhoooo, fooling around with boost is treating the symptom not the fault IF the TPS is dodgy.
You could see if resetting the fault code makes it go away in that it may simply be a latching fault code and the TPS glitched and is actually OK and you do really have overboost issues triggering limp mode.

The fault code will reset / erase when I goes out , but it comes back again.

The boost was bouncing all over the place up over 20psi sometimes , I put a boost controller on it and it now doesn't go over about 13psi

I did notice earlier that it takes a bit longer to get the revs / speed / boost up when taking off, not much happens till it gets up to about 3000rpm.

Fuel / Fuel filter / air cleaner etc have all been changed

???

Quote:

---

Originally Posted by R055IE

The fault code will reset / erase when I goes out , but it comes back again.

The boost was bouncing all over the place up over 20psi sometimes , I put a boost controller on it and it now doesn't go over about 13psi

I did notice earlier that it takes a bit longer to get the revs / speed / boost up when taking off, not much happens till it gets up to about 3000rpm.

Fuel / Fuel filter / air cleaner etc have all been changed

???

---

That would be the low boost. 13psi is waaaaay to low. your EGT's would be through the roof. I would set it to 18 atleast. Add a needle valve in with the boost controller and this will enable you to control the spoolup rate of the turbo too. I just googled P0123 and TPS was the first hit...

Check all the vac hoses. Especially ones under the intercooler , I would replace them all , doesn’t cost much. Get a roll of blue SAAS silicone hose at Autopro
I found with my car which was a Di, 16 psi was it’s max before the maf threw a limp , but Di and CRD are different


Proud BTrol Owner
Sent from my iPhone using Tapatalk Pro

Quote:

---

Originally Posted by mudski

That would be the low boost. 13psi is waaaaay to low. your EGT's would be through the roof. I would set it to 18 atleast. Add a needle valve in with the boost controller and this will enable you to control the spoolup rate of the turbo too. I just googled P0123 and TPS was the first hit...

---

^^^^

Wot e says x 2

Thanks all, will check everything, replace vacuum hoses, and adjust the psi, post back results

Quick update,

I have fixed some issues I had with the boost controller, re adjusted the boost psi and replaced the vacuum and boost lines.

The fault code and throttle response issue are still happening but only randomly now ??

Have found a replacement throttle body for $700 which is heaps better than Nissan price but still aren't ready to buy it,

Thinking I might pull this one out and try and clean it all up , maybe its a bit gummed up with carbon and stuff ??

Any ideas ??

Thanks

many people run catch cans to remove most of the blowby going into the inlet manifold . if the throttle body is gunked , after you clean it up , you might want to consider this as it will help keep your maf sensor and intercooler cleaner as well as the throttle body

Good idea , I was thinking of a bigger intercooler aswell so might do both at the same time, start off fresh and clean...

Hi All,

Update , I ended up fitting a SH throttle body last night and all problems seem to be gone.

The vehicle drives and responds like a whole different beast , it’s never driven as smooth since I have owned it.

Ended up getting one for $220 from a wrecker in vic.

Hopefully it’s the end of the electrical dramas

Quote:

---

Originally Posted by R055IE

Hi All,

Update , I ended up fitting a SH throttle body last night and all problems seem to be gone.

The vehicle drives and responds like a whole different beast , it’s never driven as smooth since I have owned it.

Ended up getting one for $220 from a wrecker in vic.

Hopefully it’s the end of the electrical dramas

---

Throttle body or Throttle position sensor, thats fitted to the acc pedal?

Hi Mudski , I changed the throttle body on the engine

Quote:

---

Originally Posted by R055IE

Hi Mudski , I changed the throttle body on the engine

---

Sweet. Was the original one full of oily black soot?

Had a bit in it but not caked up , butterfly still moved freely with no obvious sticking points , air pipe from intercooler had a bit of oil in it aswell , not heaps but enough to be leaking out around the clamps , bit of obvious oil and crud in the intake manifold after the throttle body