ksattic

iTrader: (5)

I have a Zeitronix ZT-2 with 3.5 bar MAP (boost/vacuum) sensor, now calibrated for this altitude (5000ft) and I am also able to log RPMs and the TPS.

I have noticed that if I accelerate in 6th gear (s-sport mode, in manual) from approx 2.3k rpms, the car will build boost to just over 20psi and then dump to anywhere between 13 and 11psi. I can clearly hear the dump. My DV is pretty loud and it sounds exactly as if I took my foot off the accelerator. When this happens, you can even feel the rpms drop. It'll then build back up to 20psi rapidly and will continue building. I logged this tonight on my ZT-2 and you can clearly see it.

Right before the boost is dumped, you can see a bit of flutter in the log. I can also hear the flutter. It'll do this almost every time I do a pull in 6th across this rpm range.

Altitude:5000ft
Temp: 3F (yes, 3F)
Octane: 91
Mods: none (stock)

Note that this is a logarithmic graph so the dip that is highlighted with the line starts at 20.5psi and ends at 11.8.



This is a 3rd gear pull. You can see there is a dip in the boost - it drops from 20.5psi to 18.10 and then creeps back up again before tapering off. It does this in 4th too.



Onto the big questions - is my DV faulty? Is something else faulty? Should I even bother for a warranty repair? I am still 100% stock so this could be a sensible option. It is easy to demonstrate the problem even without logging since it is clearly audible and the rpms clearly drop.

For those interested, here is the original Zeitronix Data Logger log file and csv:

http://simonrules.com/temp/stock_6_6_3_4_2009-01-26.zto
http://simonrules.com/temp/stock_6_6_3_4_2009-01-26.csv

The pulls in order are 6th gear, 6th, 3rd, then 4th. They are easy to spot - look for TPS of 98 or greater.

stokEd

iTrader: (3)

So to clarify, you've been having problems regardless of the weather? This wasn't just something that came up yesterday when the temps were low?

And wasn't it like 70* a few days ago? I threw a P1235 (overboost) yesterday because of the cold. Need to do some logging myself to see what's going on.

If you're 100% stock then I'd take it back to the Dealer and make a warranty claim. Sounds like it could be something with the DV. If the problem is easy to demonstrate I wouldn't expect them to give you much hassle.

Who is your dealer btw? PM me if want.

Spunkysandoval

iTrader: (7)

I wonder if this some sort of contrived fuel strategy design of Mitsu. 6th gear in that rpm range is clearly highway speeds. It's hard to tell what is causing you to dump boos like that.

Is the DV electronicaly controled through a boost solenoid?

ksattic

iTrader: (5)

The fluttering happens when accelerating regardless of the weather. I have only just noticed the boost dump issue in the last few days, though I only did a pull in 6th across this RPM range since getting my ZT-2, so I wouldn't have noticed it before. Flooring it in 6th at 2.3k rpms isn't something I regularly do, but I'd still like to determine the cause.

Before returning to the dealer, I have an IX DV that I can try (assuming it fits).

Spy007

Is 6th the only gear this happens on?

ksattic

iTrader: (5)

I have only tried pulls in 3rd, 4th and 6th. In 3rd and 4th, the log does show a similar boost dip at a similar rpm range, though not near as great (only 2psi or so instead of 10).

I will try 5th tonight.

Spy007

How long is the car holding boost by the time it drops boost?

BTW.... what is the RPM drop that you are logging when it dumps?

ksattic

iTrader: (5)

Sorry, the pics are down temporarily because my domain host is having issues.

In 6th, the car builds 17psi of boost by 2500rpms. There is then some kind of flutter sound, at which point I see boost vary between 19 and 16psi from 2500 to 2700rpms. The car hesitates during this time and I see rpms fall a little at points. The rpms only drop about 50, but the car has decelerated at this point and they hover around the 2700 mark for a while. The log shows that the flutter/dump caused the car to stop accelerating for a whole second. However, the dump itself took just a fraction of a second. The flutter appeared to cause more of a problem.

Then at almost exactly 2700rpms, boost is dumped all the way to 11.8psi. The log shows I am still WOT. RPMs drop slightly again but boost builds up rapidly to 18psi again and then continues to rise. Boost will peak at about 21.5psi and hold steadly.

When my web host comes back up, I can post a graph showing the rpms over time during this process.

boostin20

Do you have an AP or a scan tool that can read and log engine parameters?

Evo Tengoku

iTrader: (22)

My guess is that the car is just seeing too high of a load. (high gear, low rpm). I know that happened to me in my 6 speed IX (the dv would flutter). Just downshift if you want to pass someone. Should be pretty easy with paddle shifters right?

ksattic

iTrader: (5)

I have the ZT-2 and ZChip (currently not installed), but nothing else to log with, at the moment. I'll get an OpenPort 2.0 cable when EvoScan works with it properly.

I realise I can downshift, but having this problem bugs me. I am at high altitude, so I don't think I should see this problem at all - what if I was at sea level where I can build boost more rapidly in the same conditions?

I'll see if swapping the DV fixes the problem.

spdracerut

iTrader: (2)

Sound like it could be compressor surge. If it does not do it in the lower gears, then compressor surge is my guess.

ksattic

iTrader: (5)

OK, here's a linear plot (ignore the x-axis, the numbers are just the row numbers from excel). The y axis is of course psi (positive) and inches of mercury (vacuum).



Now you can *easily* see the flutter and massive dump.

Note, this is the exact same data as above.

Apologies for the crap quality, all I have at work is MS Paint.

philamthebest

iTrader: (4)

i have the same problem but it is at a constant accelaeration. Not overly hard, (normal driving) but it still flutters..... any ideas?