S14 SR20DET won't idle with Z32 maf

Discussions concerning the M7790 cpu

Moderator: Matt

Post Reply
motary
 

Posts: 11
Joined: Sat Jun 04, 2011 11:12 pm

S14 SR20DET won't idle with Z32 maf

Post by motary »

I changed the maf to Z32 and also ticked the box for Adjust load scalers. The engine revs nicely to redline, however it will not run at idle at all. Is there a specific maf voltage it should have when it is running at idle when engine is cold?
Last edited by motary on Wed Sep 04, 2013 2:39 am, edited 1 time in total.
skylinegtrhr
 

Posts: 301
Joined: Sat Jun 21, 2008 1:50 am
Location: Croatia
Contact:

Re: SR20DE won't idle with Z32 maf

Post by skylinegtrhr »

if You have B13 without O2 sensor check minimum enrichment afm idle voltage table (or something like this I'm not in front of software at moment) or You will get AFM DTC and bad idle ,
on our turbo SR20DE redtop (gt28rs) with Z32 voltage is 0,9 to 1,2V on idle
motary
 

Posts: 11
Joined: Sat Jun 04, 2011 11:12 pm

Re: S14 SR20DET won't idle with Z32 maf

Post by motary »

It is an S14, sorry for my misinformation, I have now edited first post.
I will try those solutions, thanks!
skylinegtrhr
 

Posts: 301
Joined: Sat Jun 21, 2008 1:50 am
Location: Croatia
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by skylinegtrhr »

Then it's different story,

post a log so someone will help You for sure
PL
 

Posts: 957
Joined: Fri Feb 03, 2006 3:29 pm
Location: Adelaide, South Oz
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by PL »

Your K constant may still need adjustment to get AFR's correct, so try that first. You'll of course need to get K adjusted so both full load and part load mixtures are correct. This is usually a balancing act between K, fuel map values and latency.

Also check plumbing to Z32 AFM. Smooth plumbing into and out of AFM can be critical.

As Mario said, 0.9 to 1.2V is typical for Z32 at idle.

What injectors are you using? S14 is easiest to tune with Z32/550 combo as K constant finishes up close to standard.

PL
motary
 

Posts: 11
Joined: Sat Jun 04, 2011 11:12 pm

Re: S14 SR20DET won't idle with Z32 maf

Post by motary »

I am using S15 spec-R injectors at 3 bar, but the fpr is adjustable.
skylinegtrhr
 

Posts: 301
Joined: Sat Jun 21, 2008 1:50 am
Location: Croatia
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by skylinegtrhr »

One of my customers once bought and install sr20de 250cc instead of 480cc s15 as they are also red ...
PL
 

Posts: 957
Joined: Fri Feb 03, 2006 3:29 pm
Location: Adelaide, South Oz
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by PL »

Yeah, you do have to be careful with injectors. There are some 270's that are red - but the aftermarket JECS (HKS, Nismo, Tomei, Apexi) 740cc injectors are also red! If you have a known injector to compare against you can actually see if they're bigger or smaller by carefully inspecting the size of the 4 holes in the end with an eyeglass. Naturally if some monkey has knocked the caps off and/or drilled them out then all bets are off. Avoid!!!

S15 480cc injectors are a rusty brown colour rather than the bright red of the 270/740's.

http://www.thenismoshop.com/Nissan-JDM- ... _p_37.html

http://www.thenismoshop.com/Nismo-Facto ... _p_33.html

Please note that all manual S15's use 480's. All autos use 370's. If you load the factory images into NIStune you'll see that the K constant is significantly different between auto and manual images.

PL
skylinegtrhr
 

Posts: 301
Joined: Sat Jun 21, 2008 1:50 am
Location: Croatia
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by skylinegtrhr »

You can also google that numbers on injectors, but I first realized because car didn't idle until I move K almost double, and then point that something is wrong with his "sxoc" injectors :)
motary
 

Posts: 11
Joined: Sat Jun 04, 2011 11:12 pm

Re: S14 SR20DET won't idle with Z32 maf

Post by motary »

These are the ones I have so I am sure they are correct:
Image

I also tested the Z32 maf on a Z32 where it worked perfectly so it must be a problem in the program
UNISA JECS
 

Posts: 367
Joined: Wed Jun 04, 2008 3:48 am
Location: USA Socal

Re: S14 SR20DET won't idle with Z32 maf

Post by UNISA JECS »

I took a bunch of pics of my S15 injectors, those are deff S15 injectors

Image

Image

Image

Image

Image
Last edited by UNISA JECS on Sun Sep 08, 2013 4:12 am, edited 1 time in total.
skylinegtrhr
 

Posts: 301
Joined: Sat Jun 21, 2008 1:50 am
Location: Croatia
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by skylinegtrhr »

It is easy to determine, put again S14 AFM and see if K is around S15 OEM K or is it like injectors are 250cc, what AFR are You getting before car "dies" on idle?
Again post log with AFR and someone will spot a problem ...
motary
 

Posts: 11
Joined: Sat Jun 04, 2011 11:12 pm

Re: S14 SR20DET won't idle with Z32 maf

Post by motary »

I had the wiring done wrong and it runs now!

For some reason it goes into limp mode after a while however..

I looked at the TTPmax and fixed the values to standard ones and it went away, but later it came back but values were correct.

The map and log are in the attachments.
siim.bin
(64 KiB) Downloaded 167 times
z32_2013-08-31_2009_35.csv
(663.64 KiB) Downloaded 177 times
Thanks in advance!
motary
 

Posts: 11
Joined: Sat Jun 04, 2011 11:12 pm

Re: S14 SR20DET won't idle with Z32 maf

Post by motary »

Can anyone also point out why when the car is running it is using the knock fuel table? The knock sensor is not connected, perhaps that is the issue?
Matt
Site Admin
 

Posts: 8961
Joined: Sun Jan 29, 2006 1:45 am
Location: Adelaide, Australia
Contact:

Re: S14 SR20DET won't idle with Z32 maf

Post by Matt »

Yep that is the issue. Replace / reconnect the knock sensor

Otherwise turn off knock feedback and the DTC code ... or stub out the knock sensor with 470k ohm resistor
Post Reply