Dyno diagnostics and dawes valve, is it necessary?

[muz muz]

too true about the dawes sweet spot.

[WA-Waz]

Seems that they maybe unfamiliar with ZD30s, dawes valves and VNT turbos??

Time will tell really, they are happy to "fine tune" so we get a good result, so I can't complain. One thing I have found since, is that it seems to be quite slow in 1st and 2nd (lower rev range). I know that it has never been a ball tearer off the line, but I would have thought that with mods made and a tune that this would have changed and I would have had some sort of performance increase in this area????

[threedogs]

Seems that they maybe unfamiliar with ZD30s, dawes valves and VNT turbos??

Time will tell really, they are happy to "fine tune" so we get a good result, so I can't complain. One thing I have found since, is that it seems to be quite slow in 1st and 2nd (lower rev range). I know that it has never been a ball tearer off the line, but I would have thought that with mods made and a tune that this would have changed and I would have had some sort of performance increase in this area????

Couple of things ,,,what size tyres are you running and at what pressure??
When was the last time you had the MAF sensor cleaned, ??
I think mine goes great off the lights......do you have the needle valve fitted.???

[mudski]

Hi Just a quick one,
I have my car (2002 3ltr Di) at a fuel injection place getting checked over after I had an exhaust, chip and upgraded intercooler fitted. He called and said that the dawes valve is unnecessary and in fact reduces power, possibly significantly? I mentioned that it was to stop boost spiking and that this is a possible issue with these vehicles, which he responded by saying yes it is to stop overboost, but that they don't believe in using them. So should it be removed permanently?

Any advice/comments??

cheers

I had a little chuckle to myself reading the mechanics opinion. I would think they are just not familiar with the dawes function and variable vane turbos. Reminds me of a comment a local mechanic said about blocking the egr. He said you will only damage your motor blocking it. A big lol from me on that one.
Fitting the dawes is only half the job. All it does as mentioned, is limit boost. So not a lot of performance gain will be had by just that. The needle valve is where the performance gains are made mostly. This adjusts the spool up rste of the turbo in a nut shell.
I know for a fact when i had the ZD30, after i fitted the dawes and needle valve, i decided to remove them and go for a spin and notice what the boost and egts were doing. I reckon i got about 5ks before i turned around and refitted the valves. The motor ran no way near as good without the two valves.

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[WA-Waz]

I have 33" Mickey T MTZs (285s) on it running at 36psi. I would expect a reduction in overall power output because of running these(?) Its funny you mention cleaning the MAF as I did this when I installed the new intercooler, and after doing so and having the results I did, thought I had broken it... no I don't have a needle valve, it wasn't offered when the dawes was fitted.

When adding intercooler and catch can I thought it would be a good idea to swap the MAF housing for one from HP Diesel. Looked bling and I thought it's only a bit of tube, oh how wrong I was. It seems that this was causing me a great deal of trouble. It was causing the huge spikes in boost apparently. Not sure why, maybe caused the MAF to misread or something like that? The injection mob took out this housing and put back the original and the car went back to having a much smoother boost that maxed out at 18psi without the dawes. The car is back to driving as it was drivability wise and the performance seemed to be how it was plus some after having the exhaust and chip done. It's now sitting on 80kw at the rear wheels, which probably isn't a lot but is still a huge increase from where it was.

As for dawes and needle valve, I didn't realise that the needle valve was such an important part in the whole scheme. I didn't really want to know either to be honest... as I thought it was best left to the pro's.............

For my own interest I think I will look into it further though, just can't help myself... and I'm sick of wasting money

[threedogs]

When I ran 305 MTZ's the mighty patrol was slow off the line even with 40 psi.
I don't run them now. You'll need to fit a needle valve to control your spool up rate.
Not a huge cost, give Mudski a PM and talk to him about it.
When it warms up i'll be fitting a bigger intake,,,lol

[WA-Waz]

Just a tad bigger :-)
Went for a drive in the country over the weekend, so gave the old girl a good run. started off okay, but I found that it kept going into limp mode. I'd be sitting on 100 and if i applied a bit more of the loud pedal it wouldn't respond at all, until I took my foot off and put it back on again. I found it did this at 80, 90, 100 & 110km. My first thoughts are get the chip removed my second thought is get my hands on that needle valve mentioned earlier and put the dawes back on.

On its own would refitting the dawes set at about 15psi stop the car from going into limp mode or is it the spooling up too quickly that would be causing the issue?? I'm getting in contact with the chip installers today to try and clear things up.

[Dr Gary]

Just a tad bigger :-)
Went for a drive in the country over the weekend, so gave the old girl a good run. started off okay, but I found that it kept going into limp mode. I'd be sitting on 100 and if i applied a bit more of the loud pedal it wouldn't respond at all, until I took my foot off and put it back on again. I found it did this at 80, 90, 100 & 110km. My first thoughts are get the chip removed my second thought is get my hands on that needle valve mentioned earlier and put the dawes back on.

On its own would refitting the dawes set at about 15psi stop the car from going into limp mode or is it the spooling up too quickly that would be causing the issue?? I'm getting in contact with the chip installers today to try and clear things up.

When you fit needle valve and dawes, the flow through the MAF housing accelerates, and the MAF sensor thinks there is a problem, hence limp mode. I fitted an HP Diesel housing (bigger tunnel) and fixed the limp mode.

[WA-Waz]

Hey Dr Gary,
I had the same MAF housing fitted and apparently it caused the boost to spike through the roof. So it was suggested to pull it out, which they did and it seemed to settle it down? Maybe that also needs to go back in but with the addition of the needle valve to control the spool up rate of the turbo. I think the missus is gonna kill me buying extra stuff definitely don't want to do half a job though. LOL

[threedogs]

with the egr blocked and a dawes an needle fitted "YOU" will be controlling the boost.
I take it you have a boost and EGT gauge fitted, at this price buy one as they are normally $60 Plus.
At least with it you can run a line into a gauge on a temporary basis
http://www.ebay.com.au/itm/Quick-Fit...IAAOSwsB9WDzLX

What chip and what is it set on ????
Dis-connect your battery, overnight if possible but 1/2hr is OK
that will re-set your ECU memory