I somehow missed that post entirely. My appologies.
First you need to turn up the fuel. Once you get it enough to drink, its time for some timing
I would increase your fuel delivery substantially. I tuned a truck with the same cam you have and iron 217 marine aka 083 TPI heads and had to run the 61# injectors at 20 psi to feed it.
Hi Fast,
In your spark table screen shot what does the Equivalence Ratio refer to?
I was just wondering the same. Spent some time looking at available parameters I can modify with TunerPro last night. I didn't get through all of them yet. Just too much to calculate/change.
Originally Posted by Kitch
Air/Fuel ratio
The PE spark adder in a factory black box Vortec PCM is based off of Air/Fuel ratio and RPM.
Soichiometric /Equuivalence ratio =Commanded Air/Fuel ratio
14.1/1.2 = 11.75:1 and 14.1/1.15 = 12.25:1
As I was going through the tune I modified the timing table as suggested. I do have a question. I updated tune for the 100 lb injector rate. I also updated the displacement value for the engine. I calculated what BPW needs to be with the new flow rate and engine size. I entered the new BPW in the tune in the cold start parameters. I am curious why I need to enter a BPW when I'd think the computer would calculate this based on injector size and displacement?
Is the cold start BPW its own value so that a program can increase fuel at startup?
I think the factory has it set to some value near 134 with 61 lb injectors. My calculated value with 101 lb injectors is closer to 82.
Some of the pcms that I’ve poked around in, I’ve noticed that there were redundant items in the scalers. I.e. gms/sec and inj lbs/hr. Well i say redundant being if you open each one press F2 the line address and the bit value were the same, so you’re not wrong in asking of BPW, displacement and injector size.
So I have been messing around with data logging today and trying to get the truck to run better. Each change seems to improve it, but I am still not where I need to be. I am getting a surging. Happens at idle and holding a constant speed. But under throttle it seems to do ok. The surging has crazy swings on the AF Ratio, more toward the lean side. Bouncing between 12 and 18+. BLM is showing they are slightly off like 140 range so each time I have gone out. I have updated tunes with these small changes, but the surge is not improving.
Any thoughts on what I am missing?
Is it just still too lean?
The hunting is bad enough that it triggers acceleration enrichment when idling. The other weird thing is that during logging, it shows that its at stable idle condition True, for all rpm. Why/how is the stable idle condition met at 2400 rpm?
Last edited by only_1; 05-21-2018 at 11:55 PM.
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