this is 8746-EBL. 80 lbs injectors with 23 lbs FP.

was able to do first datalogging for season on sunday. this is WB datalogging. was trying to get a handle on my current state of tune before i attach the vac line, change .bin accordingly and run with VAFPR(Aeromotive 13301). I was able to do 4 WOT logs to check my current WOT A/F. I found that I was seeing 10.5/1 A/F with a 1st to 2nd and again 2nd to 3rd shift(5 speed). engine feels and sounds like it is very rich. my commanded PE is 12.5/1. this is my question. why am i not seeing what commanded? i have obviously more than enough fuel supply. MAP is showing 90-95 or 4.5V(approx) in logs.

one reason might be that i am fudging my BPC. when i ran my VE learn last year on EBL install i ended up adding considerable fuel with BPC accurately cal'd (approx 80). as i saw areas of the table peg at 100 at each Learn I had to bump the BPC up. I think i did so 5 clicks at a time till I am currently at 110. my VE learn from Sunday showed 100 in a few VE cells around 3000 rpms so need to move the BPC to 115.

it was suggested that i may have a clogged fuel filter causing unreasonably high VE tables. I am replacing FF tomorrow.

Is it possible my BPC is affecting my PE results?

 

Id set the BPC to what it should be and make sure the engine has steady fuel pressure through the operating band. Then redial in the VE table.

At part throttle with TBI, trying to get your target AFR is like throwing darts backwards in the wind. At WOT, though, you should be able to get close if you also use IAT compensation as well.

 

Ron,

Set the BPC at what it is supposed to be then adjust VE. What is your DC% at WOT? If its under 70%, I'd consider dropping the FP. Commanding a certain AFR doesn't make it so.

 

The BLM value can affect the WOT AFR. If the BLM cell 1 is above 128, it will add to the WOT PW.

Try setting up a WB based VE Learn and run the 4 WOT data logs through. If separate logs just run them one after another with the same VE Learn open. See if that helps the VE table learn in some.

RBob.

 

Hi Dom: this is the issue I was struggling with last season after the install of the 8746 EBL'd.

with the standard 7747 i was running 17 lbs FP and seeing 13.4/1 on WB WOT. the BPC i am guessing was like 92 at that time. when i went to the 8746-EBL i believe i left FP at 17 but saw DC% well over 100% day one of install. at that time the VE tables around 2400-2800 rpms at 50-70 map were over 100 in several cells. i swapped springs and upped FP to 23. DC% dropped under 100% for WOT. VE tables were still over 100. only option i had was to up BPC 5 ticks at a time and reburn. i am now at 110 BPC with rich WOT and still have VE tables in some areas over 100.

Question: when i moved my VE tables from 7747 to 8746 i needed to account for higher RPM's in EBL main fuel table #2 with an assumed value. is it possible i have way too large a value around 4500-6000 rpms in main fuel table #2 and that when it goes PE it is looking at those cells(super rich) and calculating a rich PE?

Also: I dont recall my AE last season to be so far off. If i gradually accellerate entering Xway the car goes way lean on WB and accellerates poorly. if i step it down harder the AE-PE(40%) kicks in and it goes. seems the 30-60 MPH brisk acceleration is an AE issue or lack of AE. If I stomp it to floor alll is well just too rich. in the EBL AE TPS is expanded from 25% to 50%. I currently have values AE/TPS starting at 122 going to 610 incrementally in table. should I fatten up the area 5%-35% AE/TPS to allow enrichment on moderate accelleration? will try that wednesday evening.

 

I wouldnt tinker with teh AE untill the main fueling is done. The AE is mainly for the fuel that the manifold holds onto. This is pretty much independant of the steady state fueling and is based on manifold plenum temp and pressure. You may change it only to find yourself needing more.

 

Ron,

My VE starts to drop off after about 4400rpm. If your VE% continues to get higher after the torque peak, then you need to drop it. To go from 10.5 up to a 12.2 AFR, need to multiply VE by 86%.

 

That was an issue I ran into. I had the VE table continue to climb. I would see a 13.2 AFR at about 4000 RPM of so, then go to 12.1 AFR @ 5500-5600 RPM. I started to drop the ve table as it goes up, for getting that once the engine is revved up it needs a little less fuel.

If this is the case with you, I'd do like has been said, leave AE last, get your WOT straitened out, and then you normal driving. That's what worked for me.
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That was an issue I ran into. I had the VE table continue to climb. I would see a 13.2 AFR at about 4000 RPM of so, then go to 12.1 AFR @ 5500-5600 RPM. I started to drop the ve table as it goes up, forgetting that once the engine is revved up it needs a little less fuel.

If this is the case with you, I'd do like has been said, leave AE last, get your WOT straitened out, and then you normal driving. That's what worked for me.

 

my VE table 2 >100 is right at the area that i stated around 2400-2800 rpms at 50-70 map. maybe 2400-3200 rpms. i never see much VE learn at areas above 3200 rpms or above 80 map. as was said in other posts by others it is difficult to get a learn or BLM change in those areas. so maybe this is a manual adjustment of tables?

so what i will do is drop by main fuel table 2 by a set percentage (10% or .90 as Dom stated) in those higher rpm areas as apparently it is affecting my PE fueling. then will rerun WOT to witness the change.

last night i was looking at my WB log and my .bin and i see i have my AE tables in EBL that run to 50% TPS. yet my PE is set to invoke at 40%. should not i se my PE at a minimum of 50% TPS so as not to overlap?

also my LM1 has an output available to patch to ECU. It will then appear in my logs and will allow me to do as RBob said. How to input to 8746(it is buried under dash currently)? Is this a simple plug in?

Also looking at the WOT logs with MAP data I can see consistent 90 map max. key on eng off is obviously 100. Sooo it appears a restriction exists. Does that contribute to WOT rich condition(pe set to 12.5/1)?

OK i understand to leave AE alone for now but is is so easy to adjust it.

 

Ideally, you should have AE past 50% TPS. Even at high loads, there can still be some pressure differential, which means youll need at least a little AE. If its a differential, then it may not reflect the maximum pressure drop you can have.

From my experience, the MAP works the best for the AE since the MAP and manifold temperature are the driving factors in the need for AE. The TPS will also work, but needs to be formatted to represent the pressure drop with throttle opening. MAP for the long duration AE for manifold wetting and short TPS AE to cover for delays in the system as well as manifold filling seem to work fairly well.

 

Dimented: that makes sense as far as AE MAP being the "best for AE". that was stated elsewhere and I thought it was something to consider. I did run with my tables flipped. I but the majority of AE in the AEMAP table and pulled out AE from AE TPS. This was early last year. Unfortunately it did not work for me. BUT my setup as evidenced in my WB logs with MAP data as well as WU logs show a rapidly spiking MAP even with moderate throttle opening. Sooo maybe I should reapproach AE and use MAP as my main contributor to AE fuel? Is this what you are suggesting?

this is my map pw table 549-488-427-366-305-244-183-122-61

this is my tps pw table 549-549-488-488-427-427-244-244-244-183-183-122-122-122-122-61-61

so on a 25% throttle tip in MAP might contribute 488 and TPS 244. that seems to work on a quick movement of pedal more that a lazy movement currently.

I thought somewhere I read the AE or TPS sensor can deliver fuel lets say quickly to TPS movement and the MAP sensor as far as AE is concerned is LAZY? If so can MAP get the fuel in and get it in quick? My logs always showed a lean spike and a delayed enrichment for AE event. Like nothing can be done as this is TBI design constraint?

Now I am going to the VAFPR in a couple days. that will add another variable. Before i I do that I wanted to get my underlying tune closer and I am replacing the fuel filter today.

 

The main restriction in the MAP sensors response is the oraface on the inlet, and possible filtering in the circuity of the MAP itself. The MAP still responds quickly in spite of this, though. One reason you may see a momentary lean spike is that there is manifold filling as well. There is a large inrush of air on tip-in. Even with speed density, this would always cause a split second lean spike. same problem with the MAF. Due to the way its read in, there is some filtering built in, so the sudden inrush gets lost in the shuffle. The easy solution was to provide TPS AE to cover for that. This method works fairly well, for me at least, and is easier to tune then using a blend of both TPS and MAP AE, as theyre both seperate and distinct. The TPS AE also helps to cover for any delay in the response of the MAP sensor and fueling routines.

 

So for a specific AE event would you say the contribution of fueling volume of TPS vs MAP is 50/50?

Or does one contribute more fueling than the other?

I was thinking that balance might be the same for most GM TBI vehicles?

In most of the stock GM bins I have seen and the modified ones posted by members see to larger #'s in the TPS tables.