My car runs good, but I can't seem to get my tune dialed in after 6400rpm. My afr is nice at 12.9 throughout the rpm range, but once it hits 6400 rpm it starts to take a nose dive down to about 11.9 @ 6900-7000.
I have tried to adjust the last PE vs rpm number down, but it doesnt do much. Recently I tried to lower my Open loop AFR vs Map and car still goes rich. I have tried a regular $8D and the SAUJP V4 mask's to no avail.
Is there something I am missing here? Is there anything else that can cause the AFR to nosedive after the dreaded 6400 rpm ecm limit.
I have a very stout solid roller 383 with a short runner that likes to rev, but I'm leaving power on the table and possibly washing down the cylinders with too much fuel.

Any help is greatly appreciated. I have learned a lot from this forum, but this has me stumped

 

you have reached the ecm limit , the saujp has increasing rpm limit to 6400 rpm from 5600 rpm on the Extended VE Tables.

 

You should have been able to go to 8K on the PE table in SAUJP V4 1026.
Be sure you had the bit set to enable it.

 

Why wouldnt it just hold the last value in the table? I swear my maf 6e did this but now i am on $59 with 730 and i have been past 6400 with same air fuel held. Ve table only goes to 6400 and spark goes to 4800.

I would have thought ecm would just hold value. I know my buddy is reving 7300 i think on his 406 on 730 ecm and doesnt seem to have issues

 

hmm I didn't know that orr89rocz, need to make a harness for my test bench and look at the 730.

(rbob)PE/WOT mode is open loop, or more correctly a pseudo open loop mode. The INT is locked at 128 and BLM learn is disabled.

Unless the ECM thinks that the TPS is bad, it can then drop out of PE mode.

 

Just what i am seeing but i could be wrong. I dont seem to have a sudden enrichment beyond 6400 but i have an issue on high boost not alllowing me over 6000-6200 now which may be valvesprings so i cant test it further.

 

I have used both the standard $8D and the SAUJP 8K table checked and it seemed like AFR went down at about 6400-6500 ish, the car went rich, approx 12.1 even with 0 entered in the 7000 and up entries.. I was at about 10% at the 6500 entry
I agree, I have gone to 7300, but AFR gets richer with RPM after 6400

TPS is good, as I can see the TPS voltage in the datalog from my datamaster datalog
This is why I was wondering if the open loop AFR % table would affect if I was in true PE mode
I used to think I had bad springs and/ or my hyd roller was the culprit. So I went to a solid roller cam with plenty of spring pressure. I CAN tell you though over the last three years I have replaced EVERYTHING that could possibly affect revving ability. I noticed that my Digital MSD boxes werent even close on the rev limit. I used to have my rev limit set to 7000rpm and the car would start to break up at 6600. So I moved it up with not much difference until I moved it to 8000rpm. NOW I have the MSD limit set to 8000 and the fuel cutoff in my bin set to 7350 and return at 7200. NO more problems with rpm limits, the car "sings" easily to 7000+ rpm, but it gets rich over 6400-6500

 

Check the injector PW in the data log. Likely it should be decreasing once over 6500 RPM. This would be due to a decrease in volumetric efficiency of the engine.

Also look at the injector duty cycle. Make sure that it doesn't go over 85%. And 90% maximum.

RBob.

 

Have you tried a negative value?
The PE table can remove fuel also IIRC.

 

I thought I read somewhere that you couldnt enter negative values in the PE table... not sure if that applies to the 8000 rpm PE table in SAUJP V4. To be honest I haven't tried a negative number.. only zero...

 

Also wondering if I can edit the adx file for that particular function and re-number the last three RPM values to 6750, 7000, and 7250 instead of 7000, 7500 and 8000. I would hope to get a better grasp on fueling from 6500 to 7250.. Just not sure on the flexibility of modifying the adx file... I'm using TunerPro V5
Thanks

 

i'm also going to throw my hat into the "your engine starts running out of steam after ~6400RPM" group. that would cause an excessive amount of fuel to be calculated for the amount of air that's actually in the cylinder, hence a rich condition.

and you would be modifying the XDF, not the ADX.... and even then, it's not as simple as just changing the table breakpoints, you would have to modify algorith to change the real breakpoints.

 

I need to correct my last example. My buddy also sees richness after 6400. Its not terrible but it does go rich. So maybe it is the ecm code

 

looking at the hac, and I'm not the best at reading it but it looks like the int is locked at 128.

If I'm reading this correct then, I think I remember Rbob posting somewhere that 445 is FAR for 14.7 (or somthing like that), now assuming it's using 14.7 (or stoich maybe?) into the PE formula, then L860D and LB617 are added to the locked 128 to give the AFR, so it has to be using the last VE cell it see's before, then adds to PE.

 

The stock AUJP table has negative values so I believe the entries are valid in the 8K table as well.

 

One thing I have not seen mentioned that is easily overlooked. INJECTOR DC%, if the injector goes static it will dump extra fuel and run rich suddenly.