URGENT HELP! Loss of Boost should I be driving the car?????

[macca86]

I would isolate your problem then fix it before doing the nads as these affect your boost and delivery and need to be adjusted back to what they should be if you did them now it would be doing it blind. How's the intercooler and egr valve leaking there? also have you checked play in the turbo? If there's play it's an expensive job to replace I done mine 10 000km ago. are you using oil or have heaps of blue/ black smoke from the exhaust more than usual and if it smells oily that's another sign of a blown turbo

[Rusty86]

I would isolate your problem then fix it before doing the nads as these affect your boost and delivery and need to be adjusted back to what they should be if you did them now it would be doing it blind. How's the intercooler and egr valve leaking there? also have you checked play in the turbo? If there's play it's an expensive job to replace I done mine 10 000km ago. are you using oil or have heaps of blue/ black smoke from the exhaust more than usual and if it smells oily that's another sign of a blown turbo

Thanks Macca,

There are no leaks at all around intercooler and egr, and the turbo is fine too. Not using oil, no smoke at all.

He tested straight into the turbo and the boost showed the typical boost curve with higher levels (as before problem), so it looks like it may be the ecu is cutting the level for some reason. It's not throwing any fault codes though so it doesn't think there's a problem. We thought that by doing Dawes, needle and egr block this would be bypassing the ecu anyway and would probably fix things.

[macca86]

it would help you'll just need to test and tune using chaz info and see how it goes

[Rusty86]

Been speaking with Chaz, who thinks it's most likely a faulty MAF caused when the mechanic cleaned it which could've made it worse. Although a faulty MAF causes overboost usually under heavy throttle, it can cause low boost under light throttle, which is more like what I'm experiencing, as I'm driving like a grandma because of the problems I've been having and rapidly rising EGTs when you try to push it.

I'm going to test it with a new MAF before buying one, just to make sure this is the problem.

Chaz also mentioned he wouldn't be surprised if the egr valve was stuck open or having problems, so blocking the EGR will fix this.

I'll let you know how I go with the new MAF, hopefully this sorts things out!!

Cheers

[Rusty86]

Met up with Chaz yesterday, and I'd like to thank him for his time and knowledge, we spent a while talking about his set up and why he's done mods he has etc, it was great seeing such an awesome rig, it's definitely a goal to have a rig half as capable as his!!

We tried a few things, new MAF didn't change anything but I'll keep the new one in there and the old one as spare, as, although the old one seems to work, the sensor looks pretty dodge so it's good to know you've got a newy in there to start with after doing the other NADS.

We isolated the problem to probably being the ecu solenoid giving an incorrect reading, maybe caused by the MAF but not immediately fixed with a new one. I'm gonna disconnect the battery for a bit to see if that helps clear any faults. We checked vacuum and that all seems fine and the turbo is definitely working as it should too.

Dawes and Needle and EGR block should fix all this up (fingers crossed)

Will update soon, waiting on delivery of Dawes.

[boots]

Good to hear you are sorting your issues out Rusty . Where you gunna mount your needle valve ? or are you that keen its already done mate .

[Rusty86]

haha, nah mate it'll be done when dawes and egr block is done, not sure exactly where it'll be best to mount, I'm after the more 'set and forget' so under the bonnet somewhere rather than in the dash.

[Rusty86]

Dawes FINALLY arrived the other day and everything will be installed tomorrow, getting the manifold cleaned at the same time. Boost has still been odd and low but I'm used to it now and know how to drive it to get the best levels while keeping EGTs low.

Had a moment last week driving up the freeway where I pretty much had no power and the EGTs would skyrocket to 550+ when I tried to accelerate. I actually had to back off the throttle a little and get the revs back to around 2000rpm where the boost would sit at about 10psi lowering the EGTs. But under such a load (steep hill) I could only crawl up at about 40-50km/h in the left lane, about the same speed as semis!! Had to stop once or twice, bit embarrassing really, but once I was over the first couple of big hills and on the down hill near Crafers exit, I could get up to speed and get some momentum and keep it around 100km/h.

Can't wait for this to be fixed....

[Rusty86]

Everything installed on Friday and wow what a difference! Honestly feels like a different car!! Boost problems all solved, constant power throughout the revs, much more get up and go, no lag etc. And EGTs are down to about 230 deg 60km/h around town, rather than 350-400. This would also have something to do with the manifold being cleaned, which did contain a heap of gunk built up.

I've been fiddling a little with the Needle valve but it's pretty much set up to Chaz's guides so it's probably about right. It spools up quite quickly to 15 psi but won't go above that, unless under heavy load I guess where I might get a few more PSI. Cruising it will sit around 5-7 PSI under a bit of load around 10-12.

Thanks heaps to everyone for their help and suggestions, I'm stoked I've got this sorted out.

Cheers,

Rusty

[ZD30 victim]

A whirring and hissing sound is not something you want to hear from a turbo engine. Hissing I could get over until I got home but markedly lower boost levels combined with a distinct variable whirring sound would have me pulling the turbo intake elbow and exhaust outlet for a look and feel ASAP. Compressor and or turbine impeller / mainshaft bearing failures can turn ugly $$$$ pretty quick. Typical turbo shaft tolerances are measured with micrometers / dial indicators, any impeller damage or contact with the housing snails is a stop operating immediately condition, if you don't want your engine to ingest a good dose of metal. Any dramatic unexplained loss of performance needs to be investigated. ZD30's pre 07 need some post nissan TLC toensure reliability.