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A/F ratio tuning
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924RACR  



Joined: 29 Jul 2001
Posts: 8422
Location: Royal Oak, MI, USA

PostPosted: Tue Mar 09, 2021 10:12 pm    Post subject: Reply with quote

Yeah, that'll ruin your day.
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'79 924 #77 ITB racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2224
Location: MI

PostPosted: Wed Mar 10, 2021 5:46 am    Post subject: Reply with quote

MikeDanger wrote:
Fasteddie313 wrote:
MikeDanger wrote:
are there any videos of someone driving with both the AF and boost gauge in the view? so i can compare??

thats another thing, hard to drive around while staring at the gauges!



I can enrich the WOT/FullBoost with the "brass plug" port I thought 12 was pretty good

I just want to make sure I don't burn up the motor/blow HG.

It actually pulls surprisingly well for only 7Psi


is there any way to adjust the labmda?


https://m.youtube.com/watch?v=POVuP3VRAlg

https://m.youtube.com/watch?v=UoVKeAE8rRA

Heh
Wouldn’t try that without an IC


Unfortunately those dont show a steady Mid throttle.


Ugh..

Check out the rest of my videos man..

Here is cruising..
https://m.youtube.com/watch?v=zZryUQxY24M
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11556
Location: PacNW

PostPosted: Wed Mar 10, 2021 7:43 am    Post subject: Reply with quote

12 not enough, IMO, especially if you increase boost.
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MikeDanger  



Joined: 21 Nov 2002
Posts: 636
Location: Denver

PostPosted: Wed Mar 10, 2021 8:03 am    Post subject: Reply with quote

Its all stock for now, Boost wise. However I just put the fixed injector back in, started it and I backed off the "boost enrichment" screw in the WUR and it also lowered the control pressure. So We'll see.

It seemed to be running a little better, and the with the injector not leaking air, and is NOW getting richer when opening the throttle, were as it wasn't before.

The other Minor change I did was re route the Vacuum line to the WUR. Previously it was coming from the front port on the throttle. But now I swapped it to the Decel valve line (as its marked on the Factory diagram)
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MikeDanger  



Joined: 21 Nov 2002
Posts: 636
Location: Denver

PostPosted: Wed Mar 10, 2021 8:08 am    Post subject: Reply with quote

BTW can any one List the Accurate:

Cold (non running) Control pressure
Cold (just after starting) Control pressure
Warm Control pressure

Im finding several different Numbers. Don't know which is most accurate.

Even in some factory Literature.

thanks!
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MikeDanger  



Joined: 21 Nov 2002
Posts: 636
Location: Denver

PostPosted: Wed Mar 10, 2021 10:29 am    Post subject: Reply with quote

here are the numbers i have found for the S2 (s1 slightly different)

Cold 34-40psi
warm 50-56psi


can anyone tell me what their Cold start AFR is? and how long it takes to increase? Mine is fairly quick goes from about 10-11 at start to 14.5-15 (idle)
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11556
Location: PacNW

PostPosted: Wed Mar 10, 2021 2:20 pm    Post subject: Reply with quote

Exactly what mine did, with rebuilt WUR and fuel dizzy... WUR warmed up very quick (in moderate ambient temps).

Also got close to 10 under boost.
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MikeDanger  



Joined: 21 Nov 2002
Posts: 636
Location: Denver

PostPosted: Wed Mar 10, 2021 3:56 pm    Post subject: Reply with quote

Well so Close YET SO FAR!
Nother test drive, Nother problem.

I took it out, made some adjustments and seemed better, drive around my hood for about 1.5hr Got out about 10 times to adjust.

Heres what I seemed to find. If I made it Richer (in an attempt to enrich mid range/part throttle) It seemed like the Car/computer tried to lean the mid ranger even more!!, SO I did the opposite (I think Costanza might be onto something!) I leaned the idle to about 15, and that seemed to keep the Mid/part around 14-15, except when boost began to build it would start to to 13.7-14, untill boost got over 5lbs or WOT then it would dip under 11.


BUUUUUUT near the end all of a sudden car started to miss comming to a stop/take off.
WTF now!!?!?!, seemd ok once the turbo started to spool, but on initial Tip in the AF was going to 17, then would richen up. Nursed it back home, running as many stop signs as I could (on a closed course!)

Well I found the Throttle pivot is leaking, when i spray Carb cleaner the engine almost dies. Im assuing it was leaking before, and may have been a contributing factor, but now it must have completely broken.
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