Curious????? Sr20de+t aif flow problem look here!!!

[Aquarius]

Congratulations!!!!!
You have been chosen to help me solve my problem.
although i can't give you any prizes, all comments would be appreciated.

here's the rundown.
over the weekend i started my car normal, then as i put it in drive it cuts off!!!

no check engine light, just tumbling

as suspected, the ECU was fried....when i opened it up i saw burnt traces.(f*ck me!!!!)

and it wasnt an orignal sr20det ECU.
we installed a daughterboard to run a 300zx MAF (mass air flow) so (double f*ck me!!)



i got to thinking, what if i revert to my original sr20de ECU and MAF, it should work....so i tried it and it worked!!!!!

but....in order to do that i had to splice back the orginal MAf harness.


so tuners....here's what's happening. the car starts, but it's very rough and my engine almost sounds like a subaru and i'm not taking the chance of going into boost

i'm a DIY (do-it-yourself) guy, so i rather try and fail thant fail to try!!! (or maybe i'm just too cheap )

Anyways, i'm open to suggestion to what could cause that and rectify that problem.

**Please note, Images used are not my own. it's just to give you a general idea of what's going on**

thanks for your comments

[FugiTECH]

it will happen if you still have the 370'ccs working with the DE ECU and Air Flow, get back a regular DET ECU and Air Flow , i have a DET ECU if interested, PM me or call 292 1701 ,

if you upgrading your ECU Again consult JWT.

[Anil_Sooknanan]

wait your saying your using a stock DE ecu and a DE maf? if so yes the car will start but it will run rich. A DE MAF voltage output is increase via change of vacuum pressure, while a DET changes via forced air. So what your actually doing is forcing air though a Vacuum type MAF automatically sending the voltage to MAX.

[Aquarius]

thanks for the input guys. this really helped me understand my car a bit more.

[sentraman]

u need a det maf and ecu??

[THE SYNDICATE]

wait your saying your using a stock DE ecu and a DE maf? if so yes the car will start but it will run rich. A DE MAF voltage output is increase via change of vacuum pressure, while a DET changes via forced air. So what your actually doing is forcing air though a Vacuum type MAF automatically sending the voltage to MAX.

good info

[Mosaic]

I recently built a MAF interceptor to correct a/f mix on Nissan type Voltage based maf/map.
Specifically I had a WOT rich prob on an Xtrail GT cruise mode.

So rather than ecu or Maf work I simply inserted an automated control with calibration capability.

The interceptor ONLY pulled the A/F into closed loop (using o2 sensor) stoich a/f mix when NOT in boost..I allowed the sr20 to run rich when boost was sensed.


In order to know if that's what u need u gotta do the following:

Go get yourself a 10K ohm potentiometer ...the three wire volume control kind.....about 25bux.

U have 3 wires coming from the MAF....a ground, a 5V power and a signal. Use a voltmeter to figure out which is which. On most nissan the orange wire is the signal. Signal will be around 1 volt or so when idling.

Connect the Potentiometer with One end wire to ground, other end wire to MAF signal and the middle wire to ECU. SO u have to disconnect the regular MAF to ECU signal, u must leave the ground and 5V connected to MAF.

Now b4 u start, rotate the shaft of your new control all the way to the the MAF signal side wire. That puts the car into "stock" position. Imagine the pointer of the shaft rotating inside the curve of the potentiometer body and stopping at the wire connection to know how to turn it.

Startup...u should have no change in performance...yet. Now slowly turn the control away from the MAF signal wire. Not all the way! As u turn u are leaning out the A/F mix. If u can get good idle with this u can try a drive around to see how it goes.

Of course this may not be perfect cuz u not monitoring the o2 for closed loop. But it is a cheap way to see whats required. IT might be all u need though if the adjustment puts the signal into the ballpark so the ECU O2 sense closed loop A/F correction can work. Then u are fixed.


Based on your results I can construct a smart interceptor for ya. I also have consult II data logging capability to see how things work b4 & after a mod.

If u screw up the connection the ECU will throw a code...no biggie.

[Aquarius]

I recently built a MAF interceptor to correct a/f mix on Nissan type Voltage based maf/map.
Specifically I had a WOT rich prob on an Xtrail GT cruise mode.

So rather than ecu or Maf work I simply inserted an automated control with calibration capability.

The interceptor ONLY pulled the A/F into closed loop (using o2 sensor) stoich a/f mix when NOT in boost..I allowed the sr20 to run rich when boost was sensed.


In order to know if that's what u need u gotta do the following:

Go get yourself a 10K ohm potentiometer ...the three wire volume control kind.....about 25bux.

U have 3 wires coming from the MAF....a ground, a 5V power and a signal. Use a voltmeter to figure out which is which. On most nissan the orange wire is the signal. Signal will be around 1 volt or so when idling.

Connect the Potentiometer with One end wire to ground, other end wire to MAF signal and the middle wire to ECU. SO u have to disconnect the regular MAF to ECU signal, u must leave the ground and 5V connected to MAF.

Now b4 u start, rotate the shaft of your new control all the way to the the MAF signal side wire. That puts the car into "stock" position. Imagine the pointer of the shaft rotating inside the curve of the potentiometer body and stopping at the wire connection to know how to turn it.

Startup...u should have no change in performance...yet. Now slowly turn the control away from the MAF signal wire. Not all the way! As u turn u are leaning out the A/F mix. If u can get good idle with this u can try a drive around to see how it goes.

Of course this may not be perfect cuz u not monitoring the o2 for closed loop. But it is a cheap way to see whats required. IT might be all u need though if the adjustment puts the signal into the ballpark so the ECU O2 sense closed loop A/F correction can work. Then u are fixed.


Based on your results I can construct a smart interceptor for ya. I also have consult II data logging capability to see how things work b4 & after a mod.

If u screw up the connection the ECU will throw a code...no biggie.

pm sent

this sounds deep though!!!!

[Aquarius]

sentraman,

u need a det maf and ecu??

just in case do you have one???

[krack korn]

Aquarius, this is what to do:

get a contact number for Victor Whibby (yellow pages), he owns and operates an electronics repair shop in Sando on/off rushworth street. You can go to any other good electronics person as well but I can only recommend victor from experience. He has lots of ECU repairs under his belt.

Most likely he will be able to repair your old ecu, the burnt trace looks like the main power supply to the ecu, its an easy fix. he is very good and reasonable as well. One note here is that that ecu damage doesnt happen by itself, you have a short somewhere or had a short or had a mad electrician connect something wrong or he trying to run the fans tru the ecu circuit or something retarded like that. Any alteration done recently is suspect and you should get it checked asap. As a guess it seems like a high current load has been added to the ECU circuits maybe on the ECCS relay circuit causing the burn on the board.

At the worst victor can take any old model DE ecu and transfer the daughterboard from the old one to the "new" one and you good to go. Only if your DET is a GTiR 4 throttle then you should get a GtiR ecu. Reason being is the other ecus run high impedance injectors and the GTiR runs low impedance. You can use resistors on the low impedance injectors but that is rubbish and I dont want to get into that now.

The explanation given by anil is not the best, but he is a good fella and does excellent work. Doh lash im.

The fact is if you are using a DE ecu and DE MAF but DET injectors you will run pretty rich. The ecu is expecting to run 259cc injectors but is actually running 370cc, that is an increase in gas flow of about 43% but the ecu can only correct for about 15% plus or minus.

The MAF sits before the turbo intake and as such is always in a vacuum state, unless of course you are running a blow through setup, but that dont work too well with the 300zx maf unless u modify it lil bit.

If you change the injectors to 259cc red ones, your engine will run fine but only up to 0 psi boost, as you go into positive boost you will run progressively leaner because the maf/ecu/injector combo is not setup for boost(specifically the load and timing tables). This will result in early retirement of your engine without a VESEP package, very bad buisness.

Just spend a lil small change and do the right thing, victor is honest as well he will tell and show you what was done, not like some ppl will change a fuse and tell u the flux capactior had short out and drain the dilythium crystals and he had to fly in the parts from the cygnus galaxy and they hit a black hole on the way and loss 2 spinners and so the cost is one meeelion dollars.............................................CIF......................................... plus duties and vat.

[Aquarius]

get a contact number for Victor Whibby (yellow pages), he owns and operates an electronics repair shop in Sando on/off rushworth street. You can go to any other good electronics person as well but I can only recommend victor from experience. He has lots of ECU repairs under his belt.

my dad told me about him as well, but i didnt know how to find him... will look into that.

thanks a whole lot!!!!!!

[bluesky]

Great info here for another sr man like me.....had me researching the net all night trying to understand the greek. Learnt a lot
Thanks