Bucket o' turbo lag

[NevTheNav]

Hey guys, recently I've noticed a pretty big change in my nav (08 stx), it seems very subdued, when taking off and general driving it seems to have huge amounts of turbo lag, and smoke pours out the back when you change gears.

Its always had an amount of smoke but this is considerably more than usual. I suffer from the limp mode "issue" of going into limp mode past 4500 rpm that is a seemingly semi-regular issue on these forums, but this is different.

I've tried resetting the ECU but it didn't help at all, does anyone have any ideas before I drop it into a mechanic for some expensive fault finding?

Thanks in advance

 

[nuckin futs]

check ur actuator is working. check ur vacuum hoses and intake hoses. do u have a catch can and egr block. is it serviced regularly. might be sucking air somewhere or be starting to get blocked up with crap. do u have a hot pipe or just the stock rubber one. give the maf sensor a clean.

 

[kernels]

Yep, first thing to check is vacuum lines.

 

[shr1mpy]

check ur actuator is working. check ur vacuum hoses and intake hoses. do u have a catch can and egr block. is it serviced regularly. might be sucking air somewhere or be starting to get blocked up with crap. do u have a hot pipe or just the stock rubber one. give the maf sensor a clean.

How can the hot pipe cause turbo lag issues?

 

[BMGTZ]

check for boost leaks{split hose}. tighten all boost piping clamps.

 

[Old.Tony]

How can the hot pipe cause turbo lag issues?

Particularly in the early V9Xs, the hot pipe would balloon under turbo pressure (remember the air is at 200C or so). The time taken to fill the balloon then squeeze the rest out into the intake contributed to the lag.

I'd check the actuator first. At idle, make sure it's moving up and down (in and out of the turbo) about 3-5mm almost randomly. If it's not, your car's old enough to have aged the vac hoses and they may be cracked, hardened or split.

There are two other areas involved with the actuator - the solenoid itself, which is located under the turbocharged air hose in front of the turbocharger (between the turbo and the radiator). This particular item has failed a fair bit in the past. The other is the brake booster, which works on vacuum. I've read 2 reports where the vacuum valve in the brake booster has failed and the vacuum is lost in there - but so is braking performance, so you'd know if it happened.

A dirty MAFS - or worse, a damaged MAFS - will cause faults in reading the air quantity entering the intake and it can make the car blow excessive smoke and perform poorly. Try cleaning it: use an electrical circuit cleaner or MAFS cleaner (they're the same thing) and make sure you never make physical contact with the innards. If cleaning it doesn't work, it may be damaged - oil-based filters that are over-oiled will deposit small particles of oil on the wire which is then heated and carbonises the oil. The MAFS will need to be replaced if this is the case. If you don't use an oil-based filter you can probably not bother replacing the MAFS and just look elsewhere. Don't replace the MAFS straight away - Nissan want about $400 for them, see if you can borrow one first.

A stuck EGR valve will also cause issues. First, the pressure inside the exhaust will be reduced preventing the turbo from spooling as well as it could. With that much exhaust gas entering the intake, the fuel won't burn as well = lots of black smoke. All the extra exhaust in the intake will dramatically affect performance, including idle & start.

Boost leaks can cause issues like this too. Look for black oil around the air hosing between the turbocharger and the intake manifold. If you see it, you've got a leak.

 

[nuckin futs]

watched a video the other day of the pipe ballooning. couldnt believe how much it ballooned. and this is the cheap fix they used to stop it

 

[nuckin futs]

the good ol zip tie. is there anything it cant do

 

[rastik86]

the good ol zip tie. is there anything it cant do

Zip tie / cable tie fact:
If someone tricks you into having your thumbs zip/cable tied together then there is not much you can do until someone cuts it off for you.

Silly apprentices, they only fall for it once lol

 

[rastik86]

watched a video the other day of the pipe ballooning. couldnt believe how much it ballooned. and this is the cheap fix they used to stop it
http://s1284.photobucket.com/user/b...06_2133099314539955614_o_zps34d62758.jpg.html

Isn't there an aftermarket pipe kit to replace that with a solid one?

 

[mike1303]

Clean the maf?

 

[nuckin futs]

Isn't there an aftermarket pipe kit to replace that with a solid one?

yeh. plazaman make em.

 

[rastik86]

yeh. plazaman make em.

Thought it was somethingman lol.
Wrong section but do they make anything like that to replace the poxy joiners between the stock D22 solid piping?

 

[nuckin futs]

i think supercheap do a silicon pipe joiner. dunno what theyre worth or what sizes but a few ppl have used em

 

[benchrisfennell]

Is that rubber pipe a problem?? I just purchased the plazaman hotpipe.... What benefits will i notice?

 

[rastik86]

i think supercheap do a silicon pipe joiner. dunno what theyre worth or what sizes but a few ppl have used em

Cheers

 

[Old.Tony]

Is that rubber pipe a problem?? I just purchased the plazaman hotpipe.... What benefits will i notice?

Less lag, mostly. The rubber hoses will expand because of the heat. It's usually not a huge drama because the hoses used from factory have the webbing inside (like radiator hoses do). The early V9X didn't have that - no idea why, it's a silly thing to do.

 

[d22dave]

Thought it was somethingman lol.
Wrong section but do they make anything like that to replace the poxy joiners between the stock D22 solid piping?

i think supercheap do a silicon pipe joiner. dunno what theyre worth or what sizes but a few ppl have used em

I paid $14 each for silicon hoses for my d22. Just go to any hydraulic hose supplier like enzed or hydratec

 

[benchrisfennell]

Hey guys, recently I've noticed a pretty big change in my nav (08 stx), it seems very subdued, when taking off and general driving it seems to have huge amounts of turbo lag, and smoke pours out the back when you change gears.

Its always had an amount of smoke but this is considerably more than usual. I suffer from the limp mode "issue" of going into limp mode past 4500 rpm that is a seemingly semi-regular issue on these forums, but this is different.

I've tried resetting the ECU but it didn't help at all, does anyone have any ideas before I drop it into a mechanic for some expensive fault finding?

Thanks in advance

I dont think you should rev a diesel to 4500 rpm... Unless in reading wrong. That can't be good

 

[Old.Tony]

There's a governor that limits the engine to 5000rpm which is a reasonable maximum for our engines with our fuel's combustion rate. Higher cetane rated fuel may allow for a slightly higher RPM and I believe that the Audi TDi race cars rev to around 5500rpm, but with a burn rate as slow as diesel is, revving it any faster would cause the fuel to still be burning forcefully as the exhaust valve opens (there's always some residual burning).

With that said, I agree with you. 4500rpm is a lot - and to get those revs, you're dumping a considerable amount of fuel into the motor. I'll take a look at mine later and see if I can get a reading on fuel rail pressure and flow rates at those RPM.

In this situation, I wonder if any DTCs are being generated? Does the CEL come on?