7427 $0E cold start tuning
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7427 $0E cold start tuning
Still working on dialing in my most recent and most ambitious TBI build. Been chasing my tail for a while with the VE, flow rate and other parameters while tracking down exhaust leaks and other little nuisances that pop up when ironing out the bugs on something.
What parameters are you guys using to make cold starts not so crazy rich on a 7427 $0E???? Can this all be done in the VE table in time??? I have to pedal it to get it started cold, and it chops pretty bad from being way too rich, but it cleans up and holds a real nice idle after a minute or so, even if it is still way too rich....
What parameters are you guys using to make cold starts not so crazy rich on a 7427 $0E???? Can this all be done in the VE table in time??? I have to pedal it to get it started cold, and it chops pretty bad from being way too rich, but it cleans up and holds a real nice idle after a minute or so, even if it is still way too rich....
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: 7427 $0E cold start tuning
Looks like there are two tables to work with:
The first one is in affect during idle. The second table is always in use during open loop. Note that there are some crank tables for fueling.
RBob.
Code:
;---------------------------------------------
; OPN LOOP IDLE AFR NUMERICAL LIMIT (MIN LEAN)
;
; Dissassemby of BJKZ, LINES = 13
;
; TABLE = AFR * 10
;---------------------------------------------
ORG $4BAB ; AFR DEG C COOL
;---------------------------------------------
; OPEN LOOP AFR Vs Vac Vs cool
;
; 05-25-1999 Dissassemby of BJKZ
; 9 COL x 13 BLOCKS = 117 BYTES
;
; TBL = 10 * AFR
;---------------------------------------------
ORG $4BB8 ; RBob.
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From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 7427 $0E cold start tuning
Idk what xdf you are using but mine has open loop tables
open loop idle lean limit vs temp
open loop afr vs temp vs vacuum
and these may work too
choke afr vs temp
choke afr decay time vs temp
choke afr decay time multiplier vs airflow
open loop idle lean limit vs temp
open loop afr vs temp vs vacuum
and these may work too
choke afr vs temp
choke afr decay time vs temp
choke afr decay time multiplier vs airflow
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Re: 7427 $0E cold start tuning
Thanks RBob and Orr89RocZ.
I will look around at those tables. Maybe the crank tables are what I need to focus on. It starts pretty easy now and holds a decent idle, but I almost always have to give it gas to start it, much like a carbed car would be.
I will look around at those tables. Maybe the crank tables are what I need to focus on. It starts pretty easy now and holds a decent idle, but I almost always have to give it gas to start it, much like a carbed car would be.
Joined: Sep 2003
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From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 7427 $0E cold start tuning
Yeah crank to run and crank pulsewidth adjustment should help that.
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Re: 7427 $0E cold start tuning
Well this morning was the coldest it has been in a while around here. about 19*F..... The thing did not want to start at all.. Struggled with it for a few minutes and had to keep giving it pedal, and even then once it got started it was chugging very bad and showing VERY rich on the wideband.....
Of all the tables mentioned what would you guys suggest I do to them?
Would taking those two tables mentioned: open loop idle lean limit vs temp and open loop afr vs temp vs vacuum, and increasing the AFR a full point in every cell below 40*C help this?
Of all the tables mentioned what would you guys suggest I do to them?
Would taking those two tables mentioned: open loop idle lean limit vs temp and open loop afr vs temp vs vacuum, and increasing the AFR a full point in every cell below 40*C help this?
Joined: Sep 2003
Posts: 25,895
Likes: 429
From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 7427 $0E cold start tuning
If i recall those afr numbers in the choke tables are subtracted out of the commanded open loop table, so if the value is 4.5 that means its taking 4.5 out of the open loop table which probably reads 13-14.5 or so. So that would mean closer to 10 afr commanded. Not sure tho i dont have my laptop handy. I believe of of those tables does that, choke afr maybe. Try 1 point out of those or just try leaning out the commanded open loop vs temp vs vacuum.
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Re: 7427 $0E cold start tuning
Well I tried monkeying around with those tables and it didn't help. Seems to have made it worse. I also bumped the whole AE MAP and AE TPS tables up by 30+ percent since I'm still having a lean pop or bog when you snap the throttle open. But changing the AE tables hasn't helped that either. Not sure what to do at this point?
Here are the latest two BINs and datalogs I have from trying to get this thing to work correctly. I'm hoping someone will take a look at this and point me in the right direction with the cold start rich issue and the lean pop on throttle opening
Here are the latest two BINs and datalogs I have from trying to get this thing to work correctly. I'm hoping someone will take a look at this and point me in the right direction with the cold start rich issue and the lean pop on throttle opening
Last edited by Cdeez; Feb 7, 2019 at 08:05 PM.
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Re: 7427 $0E cold start tuning
Update if in case anyone else finds this in a future search. I used the 350 4L80 BIN I found since I figured it would be the closest starting point, BJDR.bin.
For whatever GM's reasoning was, they fudged the open loop AFR table in this particular BIN..... Was commanding CRAZY rich AFRs compared to say a basically identical BIN for 350 4L60.. The only difference being the transmission.....
I looked at a BIN for a 454 $0E codemask and basically used a lot of the values in those two tables to lean out the BJDR BIN....
For whatever GM's reasoning was, they fudged the open loop AFR table in this particular BIN..... Was commanding CRAZY rich AFRs compared to say a basically identical BIN for 350 4L60.. The only difference being the transmission.....
I looked at a BIN for a 454 $0E codemask and basically used a lot of the values in those two tables to lean out the BJDR BIN....
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