Show full size 924Board.org
Discussion Forum of 924.org
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
 Technical FAQ924 FAQ (Technical)   Technical924 Technical Section   Jump to 924.org924.org   Jump to PCA 924 Registry924 Registry

Desirable AFR readings (wideband) for stock-ish car?
Goto page 1, 2  Next
 
Post new topic   Reply to topic    924Board.org Forum Index -> 931 Tech.
View previous topic :: View next topic  
Author Message
bureau13  



Joined: 07 Sep 2017
Posts: 266
Location: South Florida

PostPosted: Sat Nov 09, 2019 8:19 am    Post subject: Desirable AFR readings (wideband) for stock-ish car? Reply with quote

I acquired a used Zeitronix wideband sensor and gauge, and installed it on my 931 in place of the narrowband sensor. I did not hook up the narrowband emulation, at least not yet. It is actually running much better this way, so I'm not inclined to mess with that, tbh.

I'm not sure what to expect to see on the gauge, however. At cruise or idle I see mid-11s, at WOT and, well, pretty much everywhere, I seem to be in the 11s. Once at cruise I was at 12 pretty consistently. Even on decel it didn't change that much. I guess I just expected more of a difference between different modes of operation.

FYI it's a Bosch LSU 4.9 sensor, no calibration required (or possible, from what I can tell).
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
Back to top
View user's profile Send private message
morghen  



Joined: 21 Jan 2005
Posts: 8170
Location: Romania

PostPosted: Sat Nov 09, 2019 8:47 am    Post subject: Reply with quote

Maybe you messed up the calibration?
_________________
Ruby-sh 924
Back to top
View user's profile Send private message Visit poster's website Yahoo Messenger MSN Messenger
bureau13  



Joined: 07 Sep 2017
Posts: 266
Location: South Florida

PostPosted: Sat Nov 09, 2019 9:04 am    Post subject: Reply with quote

morghen wrote:
Maybe you messed up the calibration?


No calibration required with Bosch LSU 4.9 sensors, supposedly. Zeitronix manual makes no mention of it.
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
Back to top
View user's profile Send private message
Fasteddie313  



Joined: 29 Sep 2013
Posts: 1962
Location: MI

PostPosted: Sat Nov 09, 2019 6:27 pm    Post subject: Reply with quote

It would probably seem to run real good in the 11s everywhere..

It should be more like high 14s in cruise and 11s in boost, but you say boost isn't further dropping the AFRs?

Sounds like the boost sensing part of your WUR isn't working..
You aren't still running those old original cloth covered small vacuum lines to the things such as the WUR and distributor are you?

If you have replaced those vac lines, and are sure they are good, then maybe you need to test the WUR to see if control pressure is dropping when applying pressure to it's line..


You could also turn your fuel mixture screw on the AFM to get your idle and cruise into the 14s, and then see what that does to your boost..
Boost over like 13 is starting to get unsafe though so watch it..

Crack that AFR screw 1/4 turn lefty loosie at idle and see if it raises your idle AFR.. Idle AFR should be about 14.7..

Boost between 10.8 and about 12 seems to work good for me.. Under about 10.8 I can tell it's down on power from that much fuel.. Leaner makes more power but I don't know how lean is ok so I like to see it under 12..

But I don't have it really dumping on the fuel until like 7 psi of boost.. From 0 psi to about 7 psi I have it tapering from high 14's down to low 13's/high 12s and then after 7 psi I'm trying to get it down to right under 12.. But I think yours should fully drop by time your stock WG spring pressure is reached, full stock boost..
_________________
80 Turbo - Slightly Modified
Back to top
View user's profile Send private message Yahoo Messenger
Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Sat Nov 09, 2019 7:22 pm    Post subject: Reply with quote

Zietronix ZT-2 that I have does not need to calibrate the 02 sensor.

Don't worry about the other fuel discussions in this thread, other than that on boost, the WUR should be enriching the fuel from 0.5bar boost. There are a few ARF tables pulled from my Zeitronix showing AFR changes on boost/WOT

Link http://www.924board.org/viewtopic.php?t=42373&postdays=0&postorder=asc&start=45

Ideally you should be in the 14's on cruise and idle. No need to aim for 14.7 on a non IC'd turbo. The fuel is needed to help cool combustion.

WOT/full boost should be in the low to mid 10's. Again a non IC'd turbo needs the fuel to avoid detonation

For non IC'd turbo on mid throttle boost AFRs' of 11's would be OK. 12's starting to go into lean area. Above 13's would not be ideal unless very low boost/cruise
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
Back to top
View user's profile Send private message
CÚdric  



Joined: 27 Aug 2004
Posts: 1977
Location: Sweden

PostPosted: Sat Nov 09, 2019 8:09 pm    Post subject: Reply with quote

Steve, i don't think the us cars goes that rich on the low boost that they run an full load. Mid 11s should be fine. My car has always been in the 14s at cruise, something seems a bit of. Probably a measuring of the fuel pressure would be good here.
_________________
┤80 924 Turbo
Back to top
View user's profile Send private message MSN Messenger
Fasteddie313  



Joined: 29 Sep 2013
Posts: 1962
Location: MI

PostPosted: Sat Nov 09, 2019 9:35 pm    Post subject: Reply with quote

US cars have lambda so they idle at 14.7 if the lambda is operating..
If you set them correctly with a dwell meter to 50% duty on the FV your idle is set to a natural 14.7 and the rest of the fuel curve is correct from there given a properly operating system..
Though it is often set to like 45% to put the whole curve safely a bit on the rich side, the act of the FV going to 45% makes it idle at 14.7 but the natural/WOT curve is still bumped rich..
Cruise too to some extent, lambda will fight it to 14.7..

With the original O2 unplugged the lambda should operate in failsafe mode, and it needs to keep operating in failsafe mode for the overall fuel curve to be correct, or it will go very lean with no reduction of lower chamber pressure and you lose a lot of flow capability..

So, set the idle to 14.5-14.7 with the lambda operating in failsafe (because unplugged O2), and the rest of the fuel curve should be right from there..

If it does not richen in boost it is probably the WUR not doing it's boost richening job, or you are running out of fuelpump due to a poor pump or clogged filters..


I recommend a full CIS pressure test and pump flow test but what really needs tested for is control pressure drop when pressure is applied to the WUR line and maintaining full system pressure at full injector flow..
If you can maintain full system pressure during full injector flow into bottles then your flow is good enough..
Or you can do the fuel flow test like the book says if you are willing to do a FULL CIS pressure checkup by the book, which would be best..


Maybe you should be running in the 10's on boost in a stock car and not 11s, I don't really know, but I do know that 10.5 and down is losing a lot of power and by 10.0-9.8 it's basically misfiring for me..

High 11s to about 12.2 is the fastest but might be too lean for having no intercooler.. Might even be too lean for having an IC but it friggin rips like that..
And crossing into the first couple psi of boost in the low 14s to high 13s makes it spool better than dumping to the 11s immediately when crossing into boost..


Want your car right?
Full CIS tests by the book..


I have a foot and a half of snow.. My car is put away for the year.. Excited to swap the legals over to the Subaru.. I miss the Subaru, it's been awhile..
_________________
80 Turbo - Slightly Modified


Last edited by Fasteddie313 on Sun Nov 10, 2019 6:01 am; edited 1 time in total
Back to top
View user's profile Send private message Yahoo Messenger
bureau13  



Joined: 07 Sep 2017
Posts: 266
Location: South Florida

PostPosted: Sun Nov 10, 2019 12:22 am    Post subject: Reply with quote

Wow, lots of good info in here, thanks guys. I need a bit to digest it. I don't have the equipment to do a full CIS test I think, but it's probably something I should get and learn how to do.

Btw, I know SOME of my vacuum lines are old and brittle, and some are not. I just broke one for the emissions the other day. That's the first thing I'll check out...
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
Back to top
View user's profile Send private message
Fasteddie313  



Joined: 29 Sep 2013
Posts: 1962
Location: MI

PostPosted: Sun Nov 10, 2019 5:46 am    Post subject: Reply with quote

bureau13 wrote:
I don't have the equipment to do a full CIS test I think, but it's probably something I should get and learn how to do.


100%
It is the only way to really know it is right and doing it will probably really help you understand the system..
And dude, injector flow tests are really a lot of fun.. https://youtu.be/sO6pZjnv450

bureau13 wrote:

Btw, I know SOME of my vacuum lines are old and brittle, and some are not. I just broke one for the emissions the other day. That's the first thing I'll check out...


Just replace ALL of those little cloth covered vacuum lines, no question..
Dissect one and I bet you'll be shocked at the actual condition inside.. I was shocked..

They can throw off your vac/boost compensated ignition timing and your boost compensated AFR drop via the WUR.. Important stuffs to not explode the engine..

If you don't get that boost signal right you won't get the fuel enrichment for boost from the WUR, or the ignition timing pull for boost from the diaphragm on the distributor, and that itself could be dangerous for the engine, especially a non-intercooled engine..

You want to make sure that WOT and idle switch on/under the throttle body are working too for your boost enrichment via the lambda system..

WOT switch enriches by dropping the lower chamber pressure in the fuel distributor, increases the duty cycle of the frequency valve from the lambda computer, which increases the differential of the pressure between the upper and lower chambers in the fuel distributor under the injector ports, lowering the diaphragm to create a bigger opening to the injector ports, thereby allowing more fuel to flow out the injector ports given the same airplate position and system pressure, at WOT..
Another enrichment compensation..

These CIS engines are sooo cool


When I was still running the stock CIS I made and ran a permanently installed CIS pressure test gauge setup..

I thought it was very cool

To make one you just need to figure out how to put a pressure gauge and a valve in that middle line from the fuel distributor to the WUR..

Pretty simple.. I had the Hoffman tester but wanted to make a permanent one so I did..
3mm compression-Tee with gauge-valve-3mm compression, and a mount..

FD-gauge-valve-WUR
Simple..

https://www.google.com/shopping/product/14379187049982734566


https://www.partsklassik.com/p-1685-banjo-fitting-m10-to-m6-hose-fitting.aspx


IIRC that it is m10X1.0 then you just need those, hose, gauge on a Tee, and a Valve.. To make a tester..

Or buy one for $100
http://www.specialtauto.com/node/18
_________________
80 Turbo - Slightly Modified
Back to top
View user's profile Send private message Yahoo Messenger
bureau13  



Joined: 07 Sep 2017
Posts: 266
Location: South Florida

PostPosted: Sun Nov 10, 2019 2:26 pm    Post subject: Reply with quote

You mention a "Hoffman Tester." I think I've heard of that before...that's just a specific brand of tester for the CIS system, right? Is it basically the same thing at the link below? I've thought about buying something like that before but was never sure if the various kits I saw were actually what I needed. Also, until I got this AFR, fuel is the one area that seemed to be working OK. I'm now thinking it's pretty silly to assume that, especially on a car from the early '80s!

Fasteddie313 wrote:

100%
It is the only way to really know it is right and doing it will probably really help you understand the system..
And dude, injector flow tests are really a lot of fun.. https://youtu.be/sO6pZjnv450


When I was still running the stock CIS I made and ran a permanently installed CIS pressure test gauge setup..

I thought it was very cool

To make one you just need to figure out how to put a pressure gauge and a valve in that middle line from the fuel distributor to the WUR..

Pretty simple.. I had the Hoffman tester but wanted to make a permanent one so I did..
3mm compression-Tee with gauge-valve-3mm compression, and a mount..

FD-gauge-valve-WUR
Simple..

https://www.google.com/shopping/product/14379187049982734566


https://www.partsklassik.com/p-1685-banjo-fitting-m10-to-m6-hose-fitting.aspx


IIRC that it is m10X1.0 then you just need those, hose, gauge on a Tee, and a Valve.. To make a tester..

Or buy one for $100
http://www.specialtauto.com/node/18

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
Back to top
View user's profile Send private message
Fasteddie313  



Joined: 29 Sep 2013
Posts: 1962
Location: MI

PostPosted: Sun Nov 10, 2019 5:54 pm    Post subject: Reply with quote

bureau13 wrote:
You mention a "Hoffman Tester." I think I've heard of that before...that's just a specific brand of tester for the CIS system, right? Is it basically the same thing at the link below?


Yes and yes..

How to connect & operate the Hoffman CIS Test Kit
http://www.924board.org/viewtopic.php?t=35734
_________________
80 Turbo - Slightly Modified
Back to top
View user's profile Send private message Yahoo Messenger
bureau13  



Joined: 07 Sep 2017
Posts: 266
Location: South Florida

PostPosted: Mon Nov 11, 2019 3:55 am    Post subject: Reply with quote

Perfect...thank you!

Fasteddie313 wrote:
bureau13 wrote:
You mention a "Hoffman Tester." I think I've heard of that before...that's just a specific brand of tester for the CIS system, right? Is it basically the same thing at the link below?


Yes and yes..

How to connect & operate the Hoffman CIS Test Kit
http://www.924board.org/viewtopic.php?t=35734

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
Back to top
View user's profile Send private message
Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Tue Nov 12, 2019 6:49 pm    Post subject: Reply with quote

CÚdric wrote:
Steve, i don't think the us cars goes that rich on the low boost that they run an full load. Mid 11s should be fine. My car has always been in the 14s at cruise, something seems a bit of. Probably a measuring of the fuel pressure would be good here.


I forgot, again, the differences on US turbo v's RoW. A good reminder to self ....

US speed


RoW speed



_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
Back to top
View user's profile Send private message
Fasteddie313  



Joined: 29 Sep 2013
Posts: 1962
Location: MI

PostPosted: Wed Nov 13, 2019 6:53 am    Post subject: Reply with quote

Are the euro speedos not green?
I somehow have a green 160 speedo..
_________________
80 Turbo - Slightly Modified
Back to top
View user's profile Send private message Yahoo Messenger
Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
Location: Somerset, UK

PostPosted: Wed Nov 13, 2019 7:41 am    Post subject: Reply with quote

Fasteddie313 wrote:
Are the euro speedos not green?
I somehow have a green 160 speedo..


S1 = green, S2 = white
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    924Board.org Forum Index -> 931 Tech. All times are GMT + 10 Hours
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group