ding ding ding... We have a winner. The only way you are going to boost higher is a stand alone mgt system like haltech or something similar.

 

let me ask a simple question here and then state why I'm asking.

Is the MAF before or after the turbo on these setups? I've not been able to really get a good loke at one so I don't know.
If it's mounted after the turbo and is getting pressurized air then that may be the problem all together when running a stock MAF. On most setups I've seen the MAF is mounted before the inlet on the turbo ie: Filter, MAF, Turbo, Throttle Body.

Just a question.

 

The MAF is mounted after the IC on both our cars.

EDIT - We dyno'd again yesterday and Skidazzle's car did not go into limp mode at 8psi+. The MAF reached 100% airflow at 5500 rpm's.

EDIT 2 - My MAF was custom mounted in the piping coming off the IC and it was removed from the factory piping. Appears that this may be the issue with my MAF reading 100% too early. Could be location, placement in the pipe, or the metal pipe. We will be putting it back in the factory housing to see if this resolves the issue.

Thanks for everyone's input on this. This is still an issue that CAN happen on the car. 4th gear on the highway, the car is under heavy load and it can go into limp mode. If this happens to anyone boosting, pull over turn off the car, disconnect the MAF, restart. Turn the car off again, and plug the MAF back in. Car will come out of limp mode. PITA, but may be helpful!

 

Ok here's the problem. Obviously the stock MAF is not intended for inline boosted use. Your best solution is to get a MAF that is setup for inline boosted use, or to mount the MAF before the inlet on the turbos (however in a twin setup they would have to share a Y or split type pipe as a single air inlet for both). Based on my work with Mustangs and Camaros years ago, I used to see a problem with them though not a limp mode issue. My suggestion, call someone like Pro Flow who makes a MAF for virtually anything and everything and have one made for inline useage on your Z. This should solve the problem, if you go through the trouble of explaining your research here to them.
Once again I've seen similar issues on other makes and models, the light came on about this last night because I'd assumed that you guys had mounted the MAF before the turbo inlet much like we've always done on blown or turbo mustangs. Based on my previous experience I'd almost put money on an inline design MAF fixing this problem. I think setting up a resistor would probably only be a band aid, and I can't help but wonder if the stock MAF isn't damaged if not ruined by the boosted application.
You guys are incredibly sharp on digging as deep as you have into this problem, I hope that an inline MAF is all you really need because it's a simple fix that anyone and everyone can use.

Don

 

you can't just replace the MAF. The stock ECU is tuned for the stock MAF and has a table that relates MAF voltage to airflow. Replacing the MAF will make this table completely invalid and most likely, the car will run terribly lean.

You can always get TS to try and set you up with a different MAF table, but I'm not really sure of what their capabilities are with the Z's ECU. Either way, you'd probably have to bring the car out to California to get them to tune it. Not a particularly convenient scenario.

 

TIM-
i got to drive the Z today (its been tuning all week and Tadashi and i met up at a socal meet)-

my turbo setup is @8.5psi with the HKS EVC with a peak warning set at 9psi...

i did several street runs at WOT, in 3rd and 4th gear... i didnt have my CMX-100 to monitor A/F voltage.. but nothing occurred.. no limp mode...

will repeat in a closed environment again soon- sorry for not having any more conclusive data- Tadashi has had the car for the past two weeks tuning for each stage of boost and recording ECU map readings...

--Cheston

 

cheston:
my 8.5lbs runs didnt do it either..

i think the problem with tim is the MAF transplant from the OEM black tube into a metal tube custom made. we think its too deep in the pipe or not 100% straight... this would mean the MAF is reading too much air because its more exposed, perhaps?

either way... in my 8.5# runs, i was hitting 100% at 5500... not even close enough to trigger the problem... you probably are experiencing exactly what i am...

hopefully we get tim's all figured out this week.

m

 

Actually if you have a MAF that is calibrated for the Z's ECU then you would be able to change to an appropriately calibrated MAF that tells the ECU how much incoming air you have.
It's always worked with other applications that we've done it on here with a stock ECU and no plug in chips, etc.
Not trying to argue, this is just based on my own experiences with cars that use a MAF system.

 

don:

the Z ecu interprets 5v as 33.827 pounds/min of incoming air..
this is the limit... doesnt matter what MAF you put there, if its calibrated to what the ECU wants to see.

as an example: get a MAF that outputs 1/2 the voltage as stock... then when there is 33.827 pounds/min, the ecu will only see 2.5v.

Now the ecu will only add fuel for 16.9 pounds/min of air...

see the problem..?

the only solution I see is getting injectors with double the output... this way the air/fuel ratio will work itself out!

 

Does Technosquare have the ability to change the MAF mapping?

Could they create a reflash that would work in conjunction with a higher capacity MAF to solve this problem?

-D'oh!

 

they "should" be able to make the ecu work with another MAF sensor...
i would rather have them make it work with a standard GM 2bar MAP sensor output...

 

If they could do that, I'd buy it. My biggest reservation with the ECU and running boost has alsways been the capacity and accuracy of the MAF.

 

hello everyone, I have an IS300 and I think I might have a solution to your problems. First off, I'm not an expert on e-manage or tuning of a vehicle so don't expect any miracles. First thing that caught my eye is that you guys are getting over 5 volt readings. With the e-manage, what did you set the VOLTAGE CLAMP to? With the IS's we had to set it to about 4.98 to avoid going limp like you guys. Even with that though, all of us with piggyback controllers have had problem with the stock ECU relearning and leaning us out at boost. Our newest solution is a product called the SPLIT SECOND ESC1. It forces the ECU into OPEN LOOP when it senses just 1psi of boost. When it forces the system into OPEN LOOP it allows altered signals(like from a piggyback) to take over. This is about the only way you can get the stock ECU to stop learning and going into limp mode.


www.splitsec.com

They make some pretty good stuff.

Hope this helps,
-Spencer-

 

Just so you guys don't have to go searching for the product link...

http://www.splitsec.com/products/esc1/esc1ds.htm

 

This approach might work quite nicely. Moving the MAF in front of one of the turbos would effectively halve the airflow reading without any voltage tweaks. Too bad I've never heard of any 880cc injectors for the Z.

 

How exactly does it force the ECU into open loop? I believe the J&S can do something similar by outputting a voltage when it detects boost. My question would be, how would the ECU react to getting that voltage on the TPS. It's never been tried by a 350Z owner AFAIK.

 

I have no clue how the device does its thing...I guess if you knew that little trick the people @ Split Second wouldn't be too happy! All I know is that a few IS Turbo owners with piggybacks have used this device and all their troubles went away.

 

The problem you guys are having sounds very similar to what the MKIII Supra guys ran into. The solution that seemed to work well for them was to take an AFM off of a V8 lexus, which has the same output as the stock supra sensor (it's a variable frequency square wave on those, not just a dc voltage, so emanage couldn't do anything with it). Then, they'd put on 550cc injectors instead of the stock 440's. This way the motor is getting more air, and more fuel, but the ECU was none the wiser, and no lean condition. Could you guys take a MAF off of a V8 titan, and go to larger injectors?

 

isnt jwt's turbo kit gonna mount the maf before the turbos? maybe he already knew about this problem and has a solution for it as well?

 

From the pic in the news section on the JWT website it looks like the MAF is close to the same location as stock.