Lean at full throttle.

[ThE_mOnKy]

Hi, i'm having problems with my car, but im not sure where is the problem.

Im running 740cc injectors, z32 maf, blacktop sr20, my car is an S13, the car works great at low revs, if i put down the gas pedal when i hit 15 psi approx the wideband starts to read lean (13.5 - 15.0 afr) and the nistune software disconnects from the ecu. But if i partial throttle everything works great, good afr, and almost never disconnects nistune. I checked almost everything, replaced fuel pump, sensors voltages, and i dont have any idea.

Can you help me, or should i burn my car? :(

[Dboyizmlg]

Did you get a new fuel filter?
Also, check you airflow meter, dirty airflow meter can cause it to lean out as well.
Make sure you have the correct fuel pressure.
Faulty wiring can also cause an engine to lean out.

[Dboyizmlg]

SR20 Setup Tips (http://www.plmsdevelopments.com/sr_setup_tips.shtml)

Read section 12, second paragraph.

[ThE_mOnKy]

Did you get a new fuel filter?
Also, check you airflow meter, dirty airflow meter can cause it to lean out as well.
Make sure you have the correct fuel pressure.
Faulty wiring can also cause an engine to lean out.

I replaced the fuel filter, cleaned the airflow meter, im going to check with another MAF, the fuel pressure is ok, i think im going to need to check the wiring with a multimeter, how much ohms must read approx each wire from sensor to ecu?

I was using a walbro 255, i believe that was the problem, i replaced with an aeromotive, and the problem was the same, then i checked fuel pressure, and it is ok :(

[Dboyizmlg]

Then most likey it's going to be the Nistune program.
You should have that checked out first.
Or if you still have old set up ( stock ecu, injectors, turbo, and maf), swap with that and check if issue still exist.

[ThE_mOnKy]

I checked the program twice, then i build another program taking the oem base tune, then, i get programs from the internet, and stills the f***ing problem.

I dont have the old setup, but i noticed something, if i low the boost by 2 psi, the problem dont appear (or i think), if i raise the boost 3 or 4 psi, it starts to going lean (14.0 - 15.5)

[Croustibat]

fuel pump issue ... or fuel pump WIRING issue.

Or both. The oem wiring is maybe 1mm² . I juste replaced mine with a 5mm² cable, the difference was immediate.

(I also had to change the pump because it was crappy, but i first did the wiring and got approx 10% less injector duty for the same AFR)

I see you have a nistune, try to up a little bit the dwell time, and put a smaller gap on your spark plug (smaller like 0.1 or 0.2mm smaller)

There is no reason the nistune would disconnect, except if the voltage drops a hell lot... it did not disconnect on mine before, and it dropped to 8-9V when cranking.
Are you sure your alternator is in good condition ? No slipping belt either ? This could be related to low fuel pump flow.


Edit: how did you check pressure ? not enough fuel flow gives low pressure at WOT. I had correct fuel pressure on idle, but then it dropped like hell on WOT...

[ThE_mOnKy]

I put a relay and a 10 AWG wiring for the pump, my fuel pump have 2 months, is an aeromotive in tank pump, the alternator works great, and the volts showing the nistune software is ok.

I feel is something related to wiring, how can i check all the wiring on my engine harness?

dwell times (volts 2 - 17)
255 255 255 255 255 255 255 183 134 107 89 76 67 59 54 49
my gap is 0.028"

changing the dwell times what i'm doing? or what benefit im getting?
again, checking each wire from ecu to sensor harness what resistance the multimeter should show?

[Dboyizmlg]

Try searching a bit....

MAF/ECU wiring question : SR20DET Forum (rear-drive) (http://forums.nicoclub.com/maf-ecu-wiring-question-t491720.html)

[ThE_mOnKy]

Ok, i try to double check again all of this points, volts of the ecu and fuel pump, maf and sensors, check resistance between grounds and sensors, and change the fuel filter again...

[Croustibat]

I put a relay and a 10 AWG wiring for the pump, my fuel pump have 2 months, is an aeromotive in tank pump, the alternator works great, and the volts showing the nistune software is ok.

I feel is something related to wiring, how can i check all the wiring on my engine harness?

dwell times (volts 2 - 17)
255 255 255 255 255 255 255 183 134 107 89 76 67 59 54 49
my gap is 0.028"

changing the dwell times what i'm doing? or what benefit im getting?
again, checking each wire from ecu to sensor harness what resistance the multimeter should show?

The dwell time is the time used to "fill coils", basically. The longer you do it, the better the spark, to a certain extent. But the higher the coil temp goes.

On old coils, extending that time helps to do the job. Using a smaller gap is nearly the same, smaller gap requires less energy to spark.

0.028" should be ok though, although you can go lower if it misfires. I am running 0.6mm at the moment, but boost is at 1.2bar.

Anyway, when you say it leans out, do you mean it never did before at the same boost level ?

[ThE_mOnKy]

Sometimes do, and sometimes not... Im confused...

Sent from my Galaxy Nexus using Tapatalk 2

[4x4le]

If consult is disconnecting you are having an electronic noise problem. Usually a ground issue. This is usually remedied by adding engine grounds. You may not be havinging as powerful of a spark as you need, or spark blow out due to the lack of ground which could be giving you a false lean. This could be a compound issue with just one fix being necessary, however it also could be a basket of things needing fixed. My first suggestion would be to get better engine grounds so that consult will quit disconnecting but you may find that that this will help other things as well.

[ThE_mOnKy]

I feel is something like that (noise) i ground the ecu grounds at manifold direct to battery, but the problem stills there...

[4x4le]

Do you have good engine grounds from engine to chassis to battery?

[ThE_mOnKy]

I dont remember the number, but the multimeter shows low resistance from some engine and chassis points to battery...

But i feel is something like you says, electrical noise, because, if it dont go lean, the consult dont lost the connection with the software, do you have mor tips for me?

[ThE_mOnKy]

BTW, this if my first try, im a beginner in this...

Primeros aracles - YouTube (http://www.youtube.com/watch?v=4mlVW6pVAYU)