Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Go Back   Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum > General > Tech Talk

Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars


Reply
 
Thread Tools Display Modes
Old 12-04-2022, 01:37 PM   #1
Quiche2192
 
Join Date: Oct 2018
Location: FL
Age: 32
Posts: 47
Trader Rating: (0)
Quiche2192 is an unknown quantity at this point
Feedback Score: 0 reviews
Lean AFRs

My SR20DET seems to be running lean according to my innovate wideband.

I've checked fuel pump (hardwired to battery), fuel pressure (50psi no vacuum), injectors are good, no exhaust leaks, cleaned MAF, calibrated O2 sensor.

My AFRs used to be 11.3 at WOT, now it's like 11.7 pretty consistently, and I am getting a knock sensor code 34. I do remember the car running bad after I cleaned the engine bay. I think some water may have gone into the intake. I did clean the MAF, but still.

Could the MAF have gone bad?
Quiche2192 is offline   Reply With Quote
Sponsored Links
Old 12-12-2022, 09:21 PM   #2
slider2828
Post Whore!
 
slider2828's Avatar
 
Join Date: Oct 2004
Location: San Francisco, CA
Posts: 5,992
Trader Rating: (13)
slider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfectionslider2828 is close to perfection
Feedback Score: 13 reviews
You can just check the reading on resistance to see if in spec. I would do the same with the TPS sensor and the ECT sensor..... Its all in the manual.
__________________
Turn and Burn!
slider2828 is offline   Reply With Quote
Old 12-13-2022, 08:29 AM   #3
Kingtal0n
Post Whore!
 
Kingtal0n's Avatar
 
Join Date: Jul 2005
Location: South Florida
Age: 40
Posts: 4,827
Trader Rating: (17)
Kingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond repute
Feedback Score: 17 reviews
Send a message via AIM to Kingtal0n
Get an AEM wideband without stupid calibration.
A difference of .5AFR is negligible if the reading is in the 11's any 11 is fine
I've seen some sr20 stock ECU run 12.5 in the boost
Replace the knock sensor, check the timing, basic maintenance.
Very unlikely maf is bad. Could be dirty but rarely they go bad.

They do get old though and that seems to influence more than anything.

I tried 5x different mafs once and all of the give difference AFR at wide open throttle.
only real way to control is to use a stand-alone like Power FC

make sure maf is installed right, no air leaking around it, straight tubes in front and back. Recirculated bypass dumping after the maf. If there is open blow-off or if the blow-off closes prematurely or at low rpm the backflow into the maf will cause problems.
Kingtal0n is offline   Reply With Quote
Old 12-15-2022, 09:15 PM   #4
Quiche2192
 
Join Date: Oct 2018
Location: FL
Age: 32
Posts: 47
Trader Rating: (0)
Quiche2192 is an unknown quantity at this point
Feedback Score: 0 reviews
Thanks for the advice guys. I have yet to find the problem. I haven't tested other MAF's yet. Knock sensor is new, timing is good. I have an open blowoff, but didn't have problems before. 11.7 isn't bad at all, but it used to be 11.3 so something happened to cause it to go to 11.7 and that's what I'm trying to find out
Quiche2192 is offline   Reply With Quote
Old 01-14-2023, 09:57 PM   #5
tunermt
Zilvia Junkie
 
tunermt's Avatar
 
Join Date: Aug 2008
Location: MT, AZ, Seoul, Bangkok
Posts: 389
Trader Rating: (0)
tunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to beholdtunermt is a splendid one to behold
Feedback Score: 0 reviews
(Assuming MAF is ok/nothing was damaged during engine bay wash)

If the pump is on its way out it will still make fuel pressure at idle just fine but will not be able to keep up under full load/high rpm.
You may just have a tired pump and or dirty fuel filters. You can check by logging a fuel pressure sensor or monitoring a gauge through a WOT pull. *Fuel pressure should rise/fall 1:1 with boost\manifold pressure.
__________________
GTR PartsBuy JDM Cars
tunermt is offline   Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 06:24 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
vB.Sponsors
Copyright ? 1998 - 2022, Zilvia.net