Low boost and high EGTs on ZD30 Y61

[DickieO]

Hi all,

I was drivimg home this afternoon, when all of a sudden, unexpectedly my boost was struggling to peak over 8psi (set to 15). EGTs we rising alot quicker than usual under acceleration.

Im fairly new to my patrol. Owned it for 6 months or so and still getting use to maintaining and repairing a diesel. Its got dawes and needle valve but i havent touched or adjusted them since buying it.

So some investigating and checking is in order. I would like to start with the easiest and work my way to the more complex possible isses.

This is what im going to get started on tomorrow.

Check the MAF and clean,
Check for intercooler or leaks in turbo system
Block the EGR, originally wasnt done. But got the plate made a while ago and was waiting to install it.

Going to research some more into throttle position sensor and the vacuum solenoid or vacuum sensor.

If anyone has other helpful tips or ideas, or if you would like more info please let me know.

Cheers
Richard

Edit:
Question:
Is it a bad idea to drive it? Even if i baby it and keep egts low?

[Hodge]

Hey DickieO
Driving it around at 8PSI isnt a good idea i reckon, until you get it sorted.
Start with easy things first... And you've already got the right idea.
Check all air hoses, pre and post intercooler. Check that the needle and/or dawes valves havent "undone" or come loose in some way shape or form. Vacuum hoses etc...
It is super common for the factory IC to leak, thus releasing valuable boost before the motor entry. I'd be checking all that first and then rip the MAF out and clean it while you're at it.

[DickieO]

Will do Hodge.

I got a cross country intercooler installed but ill check it anyway.

[AB]

Yep as above my money would be on a leak somewhere and not ideal to drive it too much.

Idle in your carport and check all fittings, pipes and IC, even put soapy bubbles around if you can't visually see any leaks as a starter.


Sent from my iPhone using Tapatalk

[mudski]

Sounds like a boost leak. Or a vacuum leak on the Vacuum side of the Dawes. As mentioned, check all the boost hoses and clamps. If all that fails to improve anything. Pull the MAF out and give it a good clean. If the MAF is buggered, a clean wont do anything.

[Wilburnator]

Hi mate, had a similar thing happen to mine.
Turns out the ball and spring in the Dawes got stuck not allowing it to build up boost pressure. Happened pretty sudden, but easily fixed by loosening the Dawes, perhaps even pulling it apart and cleaning it.
Just mark the threads first to get a rough idea where to set it back to.
It's a simple job and worth a shot!


Sent from my iPhone using Tapatalk

[DickieO]

Thanks all for all the help,

Woke up early this morning after leaving the battery disconnected all night to have a sticky beak.

I could hear a leak (hissing sound) coming from the needle valve under the dash while idling and noticed the grub screw had come loose. When i closed the valve completely the hissing stopped, backed it off half a turn to where i could just hear the hissing again and tightened up the grub screw. Test drove and was getting 15psi of boost.

Spool rate was super quick, so adjusted it while making my way to work. Till i was getting more normal reading.

I did loosen and retightened the dawes valve as mentioned, i didn’t clean it though. This may of done it. Not completely sure just yet.

Seems to be driving fine, Boost and EGT looking normal but i will do some more investigating.

Thanks all.

[mudski]

Thanks all for all the help,

Woke up early this morning after leaving the battery disconnected all night to have a sticky beak.

I could hear a leak (hissing sound) coming from the needle valve under the dash while idling and noticed the grub screw had come loose. When i closed the valve completely the hissing stopped, backed it off half a turn to where i could just hear the hissing again and tightened up the grub screw. Test drove and was getting 15psi of boost.

Spool rate was super quick, so adjusted it while making my way to work. Till i was getting more normal reading.

I did loosen and retightened the dawes valve as mentioned, i didn’t clean it though. This may of done it. Not completely sure just yet.

Seems to be driving fine, Boost and EGT looking normal but i will do some more investigating.

Thanks all.

The hissing is just the negative air pressure (vacuum) passing through the valve. Good to see is was an easy fix.