My original k16 oem stock porsche 996tt was dammm stable and linear on a road-course track. When in a turn, i could be half throttle down and it was consistent and didn’t fluctuate power.

Now, i had my gt640 kit for about a year, great full throttle power, however, if you try to go halfway throttle over 4k rpm its unstable, inconsistent, erratic.

Did anyone here have the 640 then go to 700 ? Did the Hitachi mafs make a difference in this regard. ?

 

Interesting perspective that I would like to hear others response as well.

I'm about to endeavor the GT640 or 700 myself - would be interested to hear what others have to say from their experiences.

Rich

 

I believe the difference between 640 and 700 is the fuel system. Turbos are the same...

 

My 640 was the same.. almost on off, no real control in the middle. UMW stg 2 ZC gives you complete control, it's almost like driving an NA car.

 

the old MAF for GT700 was stable. the new Hitachi MAF is *very* erratic as you describe, in 4k rpm+ at mid boost levels - almost to the point of being dangerous. in a curve, where you may not be full throttle, it will start acting erratic, bucking almost, and you can imagine how that could lead to dangerous situations.

the new MAF is *very* fast but this and my LWFW stalling problems are not making me very happy. while i don't want to give up the speed, i may revert back to the old MAF.

- chuck

 

Sounds like some tuning tweaks still needed with the new MAF?

 

I went from the 640 to the 700. I thing I hold the record for fried MAFs. The 640 is a little problematic, particuliarily with the Bosch MAF (which can only read air flow up to 480 HP). The new H=-MAF has full resolution to redline and the file is much more refined. The compensation (IE RICH TUNING) required with the BOSCH MAF is no longer an issue. The H-MAF provides WAY smoother off idle stability and a much more accurate air/fuel mixture at WOT (doesn't need to make adjustments from the 02 sensors as the MAF can properly meter the air). This = more power and superior drivability. The fuel system upgrades in the 700 kit make me feel much more comfortable.

 

Zippy, you don't have problems w/ 4k+ rpm and mid-boost levels? My car bucks and becomes quite violent when i begin to lift the gas slightly (if memory serves me correct.) It feels like a tuning problem but I was told the new MAF acts like this.

- chuck

 

Chuck,

Boy oh boy, SO I am not the only one!...I have exactly the same problem, I have had this issue since installing the new Hitachi MAF and software. You are spot on, it is bloody dangerous at times going into corners..

Chuck, I am PMing you about this.

BBB

 

This is not good news. Looks like EVO fixed one problem but caused another. Who else has the new HMAF + SW and having problems?

Can someone from EVO chime in?

Jag

 

I think you are experiencing turbo surge. I used to get it a lot on my set up (which was similar to the GT640). I since installed the Proto Fuel system and the surge is reduced.

 

Dr-jitsu, it does feel like turbo surge (or what i think turbo surge feels like) but there are no noises. In my Supra, i had a similar feel and it was errors in the fuel map.

I'm not sure how a fuel system would solve a turbo surge problem; it's not related afaik.

- chuck

 

Chuck - I do get this at times. When I constantly drive the bag off the car it seems to adapt and not do it. Periodically whe I simple think about getting off the gas it feels like power dissapears 100%. I've had this several times. I find when I'm driving aggressively, it seems to not really happen at all? Strange!

I had a track day for the first time in a long time last month in Calgary. Never happened once.

I'm glad to see it's not a "Canadian gas" issue. You ever get any codes?

 

Interesting info... why doesnt someone call or email Todd and ask. They usually make improvements as time goes by.
I can tell you all that a proper MAF is the solution to most tuning issues.
regards,
markski

 

Mark...
Who's Inga?