Low boost high egts after high boost low egts

[Browndogblue]

I did some repairs to my patrol (2001 gu zd30 di) it had low egts but insanely high boost (spiked to 28psi and then cut out to 0) replaced vac lines replaced fuel filter and replaced maf and fixed the intake hose to the turbo (it had a split in it). But now I'm getting max 8psi boost and then cuts out after cruising at 100 for about 5 seconds and just sits at 0 before I take my foot of then back on and we repeat the process and the egts head north of 600 degrees. Vacuum is good at about 95 kpa. Anybody got any ideas?

Mods. egr blocked with 8mm hole, 3" exhaust, catch can, aftermarket intercooler, 33" tyres

[MB]

Bidja John Old Mate, ZD30 Kind Advice [emoji120][emoji120]


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[MudRunnerTD]

The EGTs are up because the boost is Low. Traditionally you'd up the Boost to reduce the EGTs.

You say you had a split intake hose? Pre Turbo? POST air Filter?

It would seem that something you have done, swapped, changed, repaired may not be fitted correctly mate would be my guess?

Where is the Boost being measured from?

[mudski]

Thats pretty much how the Old DI ZD30's run. Not very well. Get rid of the factory boost control solenoid and run a manual boost gauge to limit the boost and a needle valve to control the turbo spool rate and be done with it. Plenty of "how too's" on the net available. Or ask here for help.

[Bidja]

[QUOTE=Browndogblue;833386 Vacuum is good at about 95 kpa. [/QUOTE]

Where did you measure this vacuum, ie 95kPa (28"Hg) which is what I expect @ vac source. In your case guess from under IC at front?

Check,@ idle the VNT actuator rod should be lifted up and lever should be resting against the vane limit stop screw?
Same @ idle pull vac hose off actuator and the rod should drop?
Genuine replacement MAF sensor and connected correctly?

Best show a pic of the boost control setup (or diagram).

[Browndogblue]

Vac measured under intercooler and at boost solenoid and when measured at turbo is 60-70 kpa from memory
Yeah split in hose was just before turbo and have double and triple checked everything is back together and in right spot yep turbo is against stop and when I take vac line off it drops. Have aftermarket maf and oem maf both doing the same thing. this is why it's driving me crazy I've got no power up hill egts spike and then temp gauge follows especially up the range.

[Browndogblue]

Boost gauge is between i/c and throttle body

[Bidja]

Ok I agree with mudski, it is a well known fact that ZD30 DI has poor boost control using the stock ECU/Vacsol operation, so also suggest install manual boost control (Dawes or Tillix with a needle valve). Can also improve on this by adding another needle valve downsteam of the boost controller (Dawes or Tillix).

[mudski]

Vac measured under intercooler and at boost solenoid and when measured at turbo is 60-70 kpa from memory
Yeah split in hose was just before turbo and have double and triple checked everything is back together and in right spot yep turbo is against stop and when I take vac line off it drops. Have aftermarket maf and oem maf both doing the same thing. this is why it's driving me crazy I've got no power up hill egts spike and then temp gauge follows especially up the range.

Whats the condition of the intercooler? It is original? Does it have any oil deposits on it? Especially on the underside. If yes to the last two Q's. Replace it. It will be leaking, there for thats where your boost pressure is going.

[PeeBee]

The EGTs are up because the boost is Low. Traditionally you'd up the Boost to reduce the EGTs.

You say you had a split intake hose? Pre Turbo? POST air Filter?

It would seem that something you have done, swapped, changed, repaired may not be fitted correctly mate would be my guess?

Where is the Boost being measured from?

Hey Darren, I dont understand this. I would have thought higher boost would add more air, better combustion of the given fuel, which generates more energy and thus more heat - much like less air, lower combustion potential, lower energy, less heat? What am I getting cocked up?

[MudRunnerTD]

Hey Darren, I dont understand this. I would have thought higher boost would add more air, better combustion of the given fuel, which generates more energy and thus more heat - much like less air, lower combustion potential, lower energy, less heat? What am I getting cocked up?

Not sure to be honest. Definitely turning Up the Boost will drop the EGTs. Complete burn, efficiency, more air. No Bog.

nissannewby will be able to explain I'm sure.

100% I uave played with the GU a fair bit and turning Up thr boost allowed everything to work more efficiently and dropped the EGTs

[Browndogblue]

Brand new welded i/c

[mudski]

Brand new welded i/c

Well then I go back to my original suggestion and ditch the factory boost control setup for a manual control setup. Factory is absolute garbage. Being 2001 your should have the vacuum canister thats mounted to the top of the motor next to the intercooler. If you do. Piss that off, Nissan realised it did nothing but only leak vacuum so they canned it in 2002.

[nissannewby]

Not sure to be honest. Definitely turning Up the Boost will drop the EGTs. Complete burn, efficiency, more air. No Bog.

nissannewby will be able to explain I'm sure.

100% I uave played with the GU a fair bit and turning Up thr boost allowed everything to work more efficiently and dropped the EGTs

I dont know anything.....

[Bidja]

But now I'm getting max 8psi boost and then cuts out after cruising at 100 for about 5 seconds and just sits at 0 before I take my foot of then back on and we repeat the process and the egts head north of 600 degrees.
Mods. egr blocked with 8mm hole, 3" exhaust, catch can, aftermarket intercooler, 33" tyres

Sounds like hard Limp to me.
Noted you blocked EGR when and maybe this cause the issue?
Why use blocking plate withe a hole _ defeats the purpose. Plate/EGR block may be impacting MAF volts signal to ECU. Remap is the best option (turn EGR function off).
Normal accepted practice with EGR block is to install manual boost control to eliminate spiking.

Concerned with 60-70kPa (18-20"Hg) vac at actuator to lift rod (lever to vane limit stop) can cause it to be very laggy (normall 13-14 "Hg).
Has the actuator rod length been changed?
Does the paint marks across actuator arm frame and adjuster thumb wheel line up?

If you wish to continue with VNT Vacsol / ECU control check that it is connected right. The sketch is a guide and the damper can also be fitted between vacsol and turbo actuator diaphragm.

[phdv61]

Blocking EGR and adding a 3" exhaust is the perfect recipee to get limp, in that it reduces back pressure (3" exhaust) and increase MAF voltage ( both EGR blocked and 3" exhaust do that).

MAF voltage exceeding for more than a few seconds the following voltage values before a high enough RPM value is reached, generates limp ( fuel is cut by the ECM) :
3.55V before 2000RPM
3.90V before 2500RPM
4.00V before 3000RPM
4.15V before 3500RPM.

As Bidja mentioned : you can go for a remap to suppress Limp, or, you can add a needle and reduce the initial spool-up (which is equivalent to screw down the lever limiting screw).

As soon as you modify your Patrol, your ECU gets "lost", and the way it manages the turbo vanes is no longer adapted. No surprise here.