That cam is a bit more aggressive than mine. I have comp 08-304-8. I don't know if it's the low injector pulse width? I also see that it's desired afr is in the 13's?
I am ok with the 13's but didn't know if that makes it approach the edge of o2 tolerance quicker?
I just reviewed your idle log file and the idle timing is fluctuating a lot. The PCM uses timing to make fast idle changes instead of trying step the slower IAC valve. Can you post your bin? First thing I would do is adjust the throttle stop screw (minimum air) for about 10 IAC counts with the engine fully warmed up. I would also adjust the VE table to get the BLM closer to 128. You are sitting at 105 which is rich and the PCM is pulling fuel to compensate. If you still have surge, you may have to make changes to the idle overspeed / underspeed spark tables. I zero'd out the idle over/under speed tables to calm my idle surges down a long time ago. I could probably go back and repopulate the tables with some values but overall my idle is decent considering my cam won't have a smooth idle. Attached is a screenshot of the spark tables.
I edited the original post to include the bin file. I have been updating the VE tables per the BLMs with the spreadsheet someone had put together (sorry, I forget who did). I moved the low rpm idle VE values down to offset that 10X numbers.
Take a look at the Bin file and let me know if I am just wrong anywhere. Suggestions and criticism are welcome!
Thanks for all the help!
Didn’t realize you were the op. lol IIRC in another post you’re using 80#s with 20ish psi??? I’d like the experts to chime in on this one as I’ve yet to experience this myself. I too noticed on your log the small pulse widths of 0.xx at idle.Originally Posted by only_1
What adx are you using? I couldn’t see the target AFR while viewing your logs.
I have came in late in the game obviously. If you have 80lb injectors and running them at 20psi, you have approximately 100lb per injector and you may have a little too much injector. You can try to lowering the minimum BPW times under BPW Limits. I don't know how much it will help you. I am running 61lb/h injectors at 27psi currently and idle fueling seems ok. Can you lower your fuel pressure? If so, you may have an easier time tuning this thing. Another thing I noticed is not a lot of spark advance at cruise. How heavy is this vehicle? I'll look at your bin this evening when I come back in.
Brian
Yes, I can adjust the fuel pressure to be lower if that would help.
The truck is a 1994 Blazer Fullsize. I think its around 4600 lbs.
The spark map was something I got from Fast in my other post. I have not changed it much since I got it from him.
I am going to start over with setting the throttle body blades to idle with IAC closed when hot. I wonder if that isn't the part of my problem. Either way, some times its best to start over at square 1.
Twist throttle screw clockwise 1/4 turn. Look at IAC counts. Adjust only when hot. Keep turning clockwise until counts drop to around 10 or a little below in park. Shut off engine for approx 10 seconds (until PCM fully powers down) then restart. See what your counts level out at after a couple of minutes idling. Your counts weren't extreme but it needs a little more air past the blades. This helps the fueling at idle due to shearing action of air going past the blades. I am downloading your bin now and going to look at a few things
Brian
Your datalogged spark doesn't match what is in the bin file. I have been trying to find what is causing the commanded spark advance to be lower than what is in the tables. Most places I checked it was off by approximately 5 degrees . I also notice your egr is commanded on the whole time the vehicle is running. I will dig further as I get time.
I am using the 217_OD_v250 adx
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