I have had some difficulty getting my post EBL tune in order. as i have posted the VE learn has created some areas cells the were over 100. my only option was to fudge my bpc from 82 to now over 115 to get those cells under 100.

possibly a result was my A/F WOT went from 12.9/1 to <11/1 in four seperate WB logs of event. I am commanded to 12.5 and now to get my WOT in the 12's I am forced to fudge the commanded PE to a high number of 13.7/1 and retest. will do next week.

another issue of having a 115 BPC is my OL idle is now 16.7/1 and was 14.5/1 last year. again have to move table to very rich #'s

i thought replacing the fuel filter was a good idea and did with no help.

another issue is that if i accellerate onto xway from 10 mph and attempt to accellerate faster than normal the engine stumbles-bogs and I witness a spike on the WB. this is a loaded pull at 2000-2800 rpms 2nd 3rd of 5. TPS goes from 10-50 or so and the MAP jumps from 40 to 80-90 and get this the NB02 drops like a rock to like 20-50 mV. my thought is i need a much stronger AE as far as MAP goes as my MAP values during event move quickly very high. now the WB sensor puked again and i think due to excessive heat at sensor(has heat sink to move out of ext stream). so WB is now kaput. I am adding to AE MAP and am now 50% higher on values with no help.

Is the AE MAP needing a mega shot?

another question. I am looking at EBL tables for SA. I recall in my pre EBL i had a table for PE SA? i see EBL has same but PE-SA- gear/rpm. those are zeroed and i did not account for PESA in my main tables so looking at my SA tables i see at 2400 rpms where the issue on AE develops my SA is 20 and at 2800 it is 25 and the area 2400-2800-50 map to 90 map it ramps down to about 14 deg. my cam comes on right around 3000 where the issue is just under 3000. should i add in 5 deg 2400-4800 at 50 to 90 map to help the AE issue and recover PESA i neglected to bring back in? and also in extended SA table?

 

If its always lean on tip-in, then it likely needs AE. Both too little and way too much AE can cause a lean spike. The thing that seperates them is that the wideband will quickly go to <9:1 and then have an apparent lean condition when theres too much AE along with smoke out the exhaust. What units are the AE tables in? When cold, the manifold needs ALOT of AE. In cold weather, I max out the injectors in AE and it still barely meets the demand. Also, the AE requirements change with temperature unless the manifold is fully heated, which makes things even harder. Cold you need alot, hot, barely any since the gas cant settle out on the manifold walls.

Also, what size injectors are you using? Still sounds like the BPC isnt right if the VE table is maxing out. Also, might want to talk to RBob and see if the BPC is still the same as before. The TBI ECMs had a whole bunch of stuff like the air density, injector flowrate, cylinder volume, etc. rolled into that one byte constant rather then breaking everything out individually like the later systems.

 

WB shows lean spike followed by enrichment. EXCEPT in that area 2400-2800 when rolling on the throttle under a load. if i hit that dead area and then floor it (PE) it seems to be able to recover. almost seems as if no gas flows at 2400 yet flows at 2800. I can accellerate slowly thru the 2400-2800 spot if i do so slowly. grandma style.

as far as BPC it is based upon formula that uses FP at 23 lbs. GM @ 80 lbs(2560).

i hesitate to add VAFPR if i cant get this under control.

OL on temps under 160 it seems the AE is better. but i never accellerate that briskly as no opportunity or need to. i hope it is just needing mega AE MAP. would not he NB falling like a rock show lean?

 

If you start from a stop, does it still stumble through that area while accelerating? it may be a general issue with the VE tables.

 

from a stop i will say yes if i accellerate brisk but not ***** out. YES if i am at red light awaiting my turn to get on xway when cars are moving 60 mph and i want to grap a spot and merge it will dog. since i moved my bpc to a higher number to get <100 my blms are now 120-126. RBOB did do a smoothing last fall and this is my 3rd VE learn in a week this first ride. so I will need to resmooth as the hits are in cells easily populated. in fact i think it was pulling some fuel and adding some maybe 3%. but there is no area 60-90 map that i can label as out of line in tables. i believe they are in fact global rich 3-5%.

last season i must have done 50 learns.

 

Almost my exact words to RBob before he called me a chicken. And precisely why you SHOULD go to VAFPR. Right now the BPC is an overall compromise because you're running 23psi. Using the VAFPR and the BPC v VAC table optimizes injector sizing based on need. You should take a ride down 94 and come see me. A bunch of Vettes are going to Byron on Cinco de Mayo BTW.

 

One thing about the VAFPR is that it can make transients harder to tune. Although if the filtering matches the response time, it shouldnt be an issue.

About the BPC, why is it a compromise, just out of curiosity? Are there limits imposed on how large the injector can be in the calibration? Im running that much injector on my setup with little issue.

 

Dim,

Something I wrote about recently was the BPC filtering. On the stock EBL bin it was set to 39% or so. I played with it and found that at least on my modded motor, increasing the filtering to about 70% made a significant improvement in throttle response. I think liquid8 also had the same results. Possibly the issue regarding tuning for transients has something to do with how closely and quickly the ECM adjusts to MAP deltas. In any case, I haven't found that to be an issue. As a general rule of thumb, I have been looking at the filtering of all the parameters (TPS MAP, Coolant, etc). I suspect that a modded motor reacting more quickly to change requires the filtering of various inputs to take that into account. So I am looking at various filters and setting them to react more rapidly to changes. Overall, this strategy seems to be working.
As for the "compromise", setting the proper BPC because of FP for WOT creates an issue at low rpm conditions. The PW just doesn't get small enough to manage areas like idle. Using the VAFPR with variable BPC allows me to have the "correct size" injector for all the various engine operating conditions. I'm sure that RBob can chime in with a better explanation.

 

I agree with both things.

I currently idle with 0.8 msec of injector pulsewidth, without issue. I am running a VAFPR as well. My idle fuel pressure is 25 PSI on 68# injectors. WOT the pressure jumps to 34 PSI.

 

Im about where fast is as well, but with 28 PSI all the time. I havnt noticed anything in peticular, but one day Id like to build an injector test bench to calibrate the short BPW offset table, and genereally see how they react at very low pulsewidths.

 

Why not find the short BPW offset table in the $0E code used with the HD 350/454 truck engines. In 1994-1995 they used 4.3 injectors running at 26-28 PSI STOCK.

 

Whenever I've experienced issues getting a VE table into line, and/or issues with tip in and WOT leaness. It has been a mechanical problem. Usually exhaust leaks prior to the O2 sensor, and/or fuel delivery issues.

If the fuel delivery is solid, and the O2 reports correctly, the VE Learn will be consistent. That is is will keep pulling from the rich areas and adding to the lean areas, until it balances out. Each drive the tune will get better.

Any issues in either area and the tune keeps moving around.

A weak fuel delivery system will also explain the higher then normal(?) BPC you are using.

Ronny, you have mentioned the exhaust heat before. It may be that the SA timing is off. Not enough advance will cause a lot of heat to be dumped into the exhaust. It may be worth while to verify the damper mark lines up with the tab and TDC. Not only does the outer ring slip, but there are several different mark and tab combinations.

RBob.

 

Good stuff. Dont overlook the ignition system, either. A weak ignition will dump alot of unburned gas and O2 into the exhaust stream and really cause the car to act funky. It will also cause the car to sumble under hard acceeration and cause WOT issues. A good spark is needed. If the spark is weak, it may not jump the gap very well or at all at high cylinder pressures.

I think we often assume that the posters car is in proper working order, but Im as guilty as the next person of inadvertently compensating for something through the tune rather then finding out what the real problem is.

 

Recently went to a vafpr on my setup. adjust the bpc filter did help, but still fighting a different problem.

Too much AE. Mostly from a dead stop, like at the track. Slowly making progress, but it seems to be real touchy. Not as bad at speed, say 50 or 60,with a punch, but still there. Will drop down to 10.5:1 or so, then work its way back up. Just upped filter to 75%, from 60%. It was dropping below what the ZT2 would read, for about a second. Now it doesnt drop below 10.5

Also, besides the Map/AE Pw's, I started making some progress when I started adjusting the AE vs RPM multiplier. It had real large numbers down low, and zeros up top.

So, at least i am going the right way.

98% dc before the vafpr, now about 75%, 27 psi WOT, 20 psi at idle.

 

I want to second this. I just went through this exact scenario. Had a leak at the back where the Magnaflows met up with the rear Y-pipe. For the longest time, Learn VE kept adding fuel in the low MAP/low RPM areas. Bracket on muffler finally broke and when I fixed it, the very next datalog showed fuel being reduced in those same areas. I would not have thought that a exhaust leak all the way at the back would have affected the O2 in the header collector and ahead of the cat. Went through many burns with inconsistent Ve learns. With exhaust leak fixed, now I can see a consistent progress to where many of the VE cells are showing no adjustment required. Both BLMs and INT are much more consistent and range +/- 3 units. Finally have the C/L tune dialed in and the motor is running pretty sweet right now. I've activated Hiway Cruise and next will be CCP enable. Going to the track in 2 weeks.

 

OK. i have not driven the car since my last post. I think I am over the edge on AE. I believe the car is under a load when it bogs and is drowning in fuel. I looked at my AE tables and a 25% TPS movement at 60-80 MAP I was adding too much fuel in my opinion. I believe I am seeing the WB sensor and NB sensor read the unburned oxygen in a super rich mix that is not being burned. that lead me to think lean but was very rich. fooled me for a week. I am starting over with lean AE #'s and work up rich.

that brings another question? I believe tuner pro can only accept increments of 61 mSec of AE. so that makes it difficult to calibrate AE with large inj and high FP. will adding the VAFPR provide more lattitude in AE tune as well as idle stability which i believe was said is the main benefit? does VAFPR somehow help control overall fueling with the rapid changes in MAP I see?

I idle 1.2 mSec pulse width BTW. idle is very stable synch 875 rpms.

the header to ext pipe was tightened up just before end of last season so i dont believe any leak there as was suggested. that however may have been the culprit with earlier EBL tunes. no vac leakes at header flange nor TBI. I will look at muffler to ext pipe this evening on cold start and see if any vapor exists. dist cap and rotor are new about three years ago. all new good mallory wires same time. it has a stock replacement Acell high energy coil and module about 2 seasons ago. BLMs are stable at 124. i am gonna assume mechanical OK.

I did bump SA 3 deg at 2600 and higher rpms at 60-100 MAP in first table and 2 deg in extended table. Knock counts went ballistic so pulled out in bin last night. my spark is same as Doms last I looked.

i am getting high speed internet this week so may send some data logs that my dial up could not handle last season.

Dom I most likely will drive down some weekday PM later this spring if that would work for you. Hands on advise I could greatly benefit from.

 

Ron,

Yeah. Bring her down some day. I checked and my PW at idle is right where yours is at, 1.1 - 1.2. As for the exhaust leak, the telltale sign for mine was the exhaust popping after rapid acceleration and then a closed throttle decel.
MAP was 40kPa and under.

 

i idle 40-41 map at 875 rpms.

how long does you WB02 sensor last? i replaced new half way thru last season and it appears it is dead again. Innovate LM1. It starts showing erratic A/F with extremely lean readings and real read back forth on display till it finally shows error message it is cooked.

now another issue. past 2 weeks WB was showing lean OL idle of 16.0/1. which I thought was accurrate. I assumed my OL idle tables were being affected by the fudged BPC being higher than it should. so I enrichened the tables 10%. did not seem to drop the idle A/F? also at the end of a prolonged deaccelleration engine is dying at a stop. seems that started about 2 weeks ago. stall saver is functional but cant get job done. it looked as if engine was not seeing fuel. restart and idle was fine.

 

Ron,

My idle is at 47-49kPa. I use Idle State SA feature of EBL with 23d.
As for the ZT-2 WB, I have had it for 18 months and its still working very nicely.
At what point does your bin take you back out of DFCO when you decel?
Mine comes out at 1000rpm. I may bump that up a bit.
What are the specs of your cam again? @ .006".

 

I need to check my setting on that. laptop is at home. i will check tonight and report tomorrow. i dont think i changed it from where it was working prior. I will assume DFCO is different than Deacceration Enleanment. DE is functional and the "off" I believe is 30 MPH which I set high.

Idle State SA? is that to lock idle SA to prevent it from drifting between cells? I idle 19 SA and it does not vary.


Cam is 224/230 @ .05 114 LSA. show vacuum at idle of 15 on vac gauge.

 

Ron,

I'm interested in determining amount of overlap. I think you're using Trick Flow 23d heads, correct? And what do you figure the power rpm range is for the manifold you're using? Is the cam in a catalog and what number is it?

 

pretty sure this is it:
Part Number 12-268-4
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS XE268H-14
Description

--------------------------------------------------------------------------------

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.479 0.48
Duration At 0.006 Tappet Lift 268 280

--------------------------------------------------------------------------------

Valve Timing At 0.006
Open Close
Intake 24 64
Exhaust 78 22

--------------------------------------------------------------------------------

These Specs Are For The Cam Installed At 110 Intake CL
Intake Exhaust
Duration At 0.05 224 230
Lobe Lift 0.319 0.32
Lobe Separation 114

--------------------------------------------------------------------------------

Recommended Valve Springs 983-KIT

Edelbrock aluminum RPM heads 64 cc chambers non emissions 170/60cc rated up to 6500 rpms.

holley projection manifold rated to 6500 rpms.

 

OK. So its not a roller. Looks like it has 46d overlap. My roller has 53d overlap and it benefitted from lowering the idle window terms. But seems like yours is doing fine as is.

 

FOLLOWUP. I was super rich on the AE. i went over the edge. i believe i am still rich on AE(WB is crapped out currently) so i will pull some AE fuel out right where i see still a bit rich and retest.