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View Full Version : PLEASE HELP, strange problems(SR20det).


owned by pandas
07-13-2014, 11:34 AM
Ok I have been experiencing a problem with my car for about a week now and I can't come up with a solution. Im usually pretty good at diagnosis but this one has me stumped. Before I start, let me just say that this literally came out of no where, and I didn't change anything in between the transition time of it running fine and it running bad.


The problem doesnt seem to matter weather the motor is cold or hot. If I start the car when it is cold/hot at idle it will go super lean(past 18 and wants to die), and I have to keep my foot on the gas a little and wait about a min and it will go to a normal idle afr. Now sometimes when I start it, it wont change no matter how long I sit and wait for it to go back, so I literally have to change the idle tune on the AFC, sometimes just to idle at 13 afr i have to move the fuel to +50 on the AFC. It seems to go back and forth with this problem and I cant seem to figure out why. Also other times when the car decides it wants to be friendly, when the idle goes back to its normal percentage on the AFC its at about +20 which is what I have always ran before. So basically I am having to change the idle tune from +50 or +20 back and forth on separate occasions just to idle correctly.

Second problem, after dealing with changing my idle tune almost every time I drive the car, sometimes while driving(which it runs good when it drives), there are spots where if I push on the gas just a little (cruise) the AFR goes to 10 flat. Then if I let off just a hair or apply just a hair of throttle it goes back to running normal.

I am confused with this. It has gotten me stranded twice so far(once it just would not start at all). I have checked and change a lot of parts and nothing seems to fix the problem, they only made it just a little better.

Things I have tested/changed:
-Fuel pump(changed when I got stranded)
-MAF(changed)
-Boost leaks(checked couplers and starter fluid spray)
-Wiring(grounds and power at ecu)
-Fuel pressure(Read 45 at idle)
-Cleaned plugs(just put them in a month ago), and regapped to a short gap.
-Checked all injectors and coils
-Replaced Ignition coil
-Checked PCV(ball moves freely)
-Changed Coolant temp sensor
-Swapped out BOV


My engine setup:
-SR20DET Redtop
-550CC injectors
-GT3071R turbo
-Nistune
-AFC neo
-JGY fuel rail
-Walbro 255 fuel pump
-Greddy front mount
-HKS SS BOV(on hot pipe, before the MAF)
-N62 MAF(I've always ran the maf blow through, about a foot and a half from the Throttle body on cold pipe.)

cotbu
07-13-2014, 01:51 PM
Your tune is f'd up for 1 and you probably have a messed up setup all around. I just glimpsed through your post. So I'll point out what I do see wrong first before I go back and reread.

Fuel pressure at idle is wrong, you are over fueling. 36psi/ 43.5psi with out vacuum. The AFC not needed with nistune, but again you are over fueling +20 and +50 will make an s13 sr20det run rich at idle with 550cc injectors, you would have to have a tune for 740cc for that to make sense.

The z32 mafs is not designed to be run blow through, check out
Precision Flow Labs Z32 Blow-Through maf
They function extremely well blow through or draw through. I tested both!

Is the afc setup correctly, is the ecu tuned for the z32mafs? If the ecu is tuned for the z32 mafs then the AFC needs to be 2in and 2out.

Nistune needs a tuning!

Sent from my Highly Tuned Galaxy S3.4!!!

owned by pandas
07-13-2014, 01:59 PM
Your tune is f'd up for 1 and you probably have a messed up setup all around. I just glimpsed through your post. So I'll point out what I do see wrong first before I go back and reread.

Fuel pressure at idle is wrong, you are over fueling. 36psi/ 43.5psi with out vacuum. The AFC not needed with nistune, but again you are over fueling +20 and +50 will make an s13 sr20det run rich at idle with 550cc injectors, you would have to have a tune for 740cc for that to make sense.

The z32 mafs is not designed to be run blow through, check out
Precision Flow Labs Z32 Blow-Through maf
They function extremely well blow through or draw through. I tested both!

Is the afc setup correctly, is the ecu tuned for the z32mafs? If the ecu is tuned for the z32 mafs then the AFC needs to be 2in and 2out.

Nistune needs a tuning!

Sent from my Highly Tuned Galaxy S3.4!!!

I have always ran my mafs blow through and never had an issue before, but I will look into that precision flow labs test you're talking about.


The AFC and the ecu are working correctly as far as I know. The nistune is tuned for 2871r, z maf, and 550. Which is everything I have except I upgraded to a GT30 recently. The nistune was on my friends car that had the same set up basically except he had a aftermarket intake manifold and mine is stock. Although i can understand how that might be an issue at one point, but for me to drive the car around for almost a year with that setup and no issues and all of a sudden start running like poo leads me to believe it has nothing to do with AFC on Nistune.

Its interesting you said to run the in and out at 2 and 2 b/c I have messed with different settings and the only reliable one seems to be 6 and 6, which is what I have been running with no issues for a while now. I will change it and see how it goes though.

As for the Fuel pressure being to high, after changing the fuel pump and fuel filter I will look at the FPR as a possible suspect, it might be causing the car to run erratic?

owned by pandas
07-14-2014, 01:14 PM
I recently checked the TPS and MAF wiring, everything is fine. Then i decided to open up my nistune and after looking at the type 3 chip this is what I found.

http://i302.photobucket.com/albums/nn112/ownedbypandas/20140714_143915.jpg (http://s302.photobucket.com/user/ownedbypandas/media/20140714_143915.jpg.html)
http://i302.photobucket.com/albums/nn112/ownedbypandas/20140714_144033.jpg (http://s302.photobucket.com/user/ownedbypandas/media/20140714_144033.jpg.html)
http://i302.photobucket.com/albums/nn112/ownedbypandas/20140714_143906.jpg (http://s302.photobucket.com/user/ownedbypandas/media/20140714_143906.jpg.html)
http://i302.photobucket.com/albums/nn112/ownedbypandas/20140714_144016.jpg (http://s302.photobucket.com/user/ownedbypandas/media/20140714_144016.jpg.html)