Ronny

iTrader: (1)

Hooked up Aeromotive VAFPR for first time today.

Observations:

Cold cold start was similar to w/o unit enabled. Due to my lack of IAC(port plugged) on a cool morning (45F) can wants to struggle running and frequently dies but restarts nicely. During initial cruise A/F OL appears much leaner than my tables per WB. May be due to manifold cold. I will leave that alone for now. Enrichened and using 95% of EBL.bin values for that table.

Once it flips CL the reported A/F shows 15.1/1 in cruise.

With coolant at 185 deg idle A/F at idle (OL)is lean at 16/1 to 17/1. W/O the VAFPR was 14.9/1 or so.

Are the OL A/F tables completely controlled by the BPC with VAFPR connected? I idle at 40 MAP which I believe is 60 KPA in BPC vs VAC tables. At 60 kpa I have a value of 121 BPC. that table is scaled from 0 kpa value for BPC is 86 and 80 is 138 BPC. (80 lbs inj at 19 lbs FP 350 CID).

scale changes about 3 ticks for BPC per 5 change in KPA.

Should I decrease the BPC in those areas of 50-70 kpa so as to enrichen OL tables?

RBob

iTrader: (1)

An increase in BPC will enrich the AFR (larger PW). The BPC value is just the injector flow rate and the engine displacement rolled into a single value.

Check the MAP are key-on, engine-off. That will be barometric pressure. Then subtract the current MAP from that value for the vacuum. The Analysis Dump Log also shows the baro and vacuum values.

What has been found is that the FPR are not always linear. Dominic put a curve on the BPC vs VAC table to help in matching what the real fuel pressure is. You could do the same by changing the BPC to bring the AFR in line.

Or have the VE tables make up for the non-linearities of the system.

RBob.

Ronny

iTrader: (1)

Quote:
An increase in BPC will enrich the AFR (larger PW). The BPC value is just the injector flow rate and the engine displacement rolled into a single value.

I will assume this is true only for the OL A/F tables. CL will be corrected with NB feebback and not be affected. I believe it affeects the AE as well.

Quote:
Check the MAP are key-on, engine-off. That will be barometric pressure. Then subtract the current MAP from that value for the vacuum. The Analysis Dump Log also shows the baro and vacuum values.

My MAP is like 98-100. So kpa for idle would be 58-60 in tables.

Quote:
What has been found is that the FPR are not always linear. Dominic put a curve on the BPC vs VAC table to help in matching what the real fuel pressure is. You could do the same by changing the BPC to bring the AFR in line.

non linear. That is what I expected. Should I increase the values in the BPC vs VAC accross the board by 5% to affect the OL A/F CTS VAC tables OR just 40 Kpa thru 80Kpa? So if I read this correct the FP is being reduced more that the tables are set to by the VAFPR?

Dominic Sorresso

Ron,

Here's the VAFPR table I used on my motor. This was based on using the
20-60psi spring on the Aeromotive 13301. FP was set at 20psi for WOT and the values I used were based on calculations after using a MityVac to get the actual Fuel Pressure dependent on Vacuum. One other thing is that I increased the BPC Base Pulse filter Constant to .78. This appeared to have the effect of causing the ECM to react more quickly to changing vac and so change the BPC more quickly. The result was a much better throttle response.

Ronny

iTrader: (1)

Thanks Dom greatly appreciated. I knew there had to be a scientific approach to the VAFPR tables!

Yesterday afternoon I did my second and third VE Learn. As I stated my BLM with the intial run yesterday morn were pegged 150-160 and my OL cold start was quite poor. WB showed in OL I was running extremely lean and car had difficulty seeing fuel on cold manifold(Holley Projection 7.4L TBI). Air temp 45d F.

The Learns dropped the BLM to 140's this morning with cool temps again. As stated my OL tables are a bit richer than the EBL.bin stock tables. Last night I also increased the VAFPR tables for BPC in areas 50-80 Kpa. That helped my cool coolant initial ride this AM and also my warm engine idle came in at 15.0/1. May be some reversion occuring as my WB sensor is just in front of the rear axle. 15/1 OL idle may in fact be richer.

BPF constant? Never thought to look at that. Will do. Seems like it is a match for VAFPR use.

Any idea how many of the TBI guys run the VAFPR?

ps might be at Joliet Friday June 6.

Dominic Sorresso

Ron,

I didn't use the BPC table to "tune" VE. Rather, I made sure the BPC was correctly calc'd then tuned from there. If the issue is IAT, then I would adjust that to match the conditions you're experiencing.
Too bad about the 6th. I out of town that day. We may go to Great Lakes in the near future. Maybe you could meet us there.

Your WB is pretty far back there. I had mine in a collector bung next to the NB.

Ronny

iTrader: (1)

Dom and RBob.

I changed the BPC v VAC tables to yours. Also changed the BPC filter as you suggested. It appears the car runs better.

I idle at 40 MAP or 58 VAC. In my prior tables I had 117 at 60 VAC. I noticed that my VE1 tables had a few 100's(1400-1600rpm 40-55 map) as a result of a few VE Learns. Learn kept adding fuel. Globally the tune was very lean in table 1. Using your table the tune enrichened and I am this morning after 2 learns sitting at 128-132 in most cells under 3200 rpms but yet seeing 140+ in those cells I previously saw the 100 in table. Not sure if the table is maxed again. will check this PM. It appears in your table 55-80VAC your BPC increases significantly. You stated your tables were a result of "using a MityVac to get the actual Fuel Pressure dependent on Vacuum".

Should I increase the BPC proportionately 60-80 VAC to get my lower tables under 100? No vac leaks.

Dominic Sorresso

Ron,

Just to review, the BPC table I provided was based on 20psi FP at WOT. If you are using a different FP, you'll need to re-calc the table.
Do you have enough pressure to provide 12:1 AFR at WOT with a 70-75% Injector Duty Cycle? If not, bump up the FP and re-calc the table.
One other thing is to boost the Injector Bias. I ran my 80# injectors at about .700+mv. The desired AFR and calc'd AFR were much closer this way.
Increasing the IB will make the the VE tables richer allowing you to be under the 100% VE number.
I wouldn't be surprised if you had an exhaust leak. If VE learn is continually adding fuel in the lower rpm/lower MAP region, I would be suspicious. Mine did that until the rear muffler fell off. When I reattached it, all of a sudden VE Learn was taking fuel back out. I had used band clamps for the muffler to cat back pipe. On decel, it was sucking fresh air into the exhaust and all the way back to the O2 sensors. I wouldn't believe it unless I saw it for myself, but that's what was happening.

Ronny

iTrader: (1)

My FP is 19 lbs with 80 lbs injectors. Pretty close to yours.

DC at WOT is under 85%(80%) and reads 12.3/1 on calibrated WB.

Boost injector bias? I will see where mine are vs the stock.EBL .bin. I will search for info as well on "IB".

EXT is welded and only place for leak is at ext header gasket or at collector to ext pipe(duals). I dont hear any leaks and last time on rack the bolts at collector flange were tight. Using Felpro gaskets. I will check again.

It seems the maxed VE table 1 is only in a few cells at a low rpm. At 1800-3000 at cruise they are all well under 100.

Dominic Sorresso

I'd re-calc them anyway. Call me finicky.

Its the Injector Bias v Volts table. Set everything to the same Injector Bias. If I remember right there may be an additional constant for Idle too.

Exactly the situation I had. But the leak was at the muffler not the collector. Are you saying the mufflers are welded on?

Ronny

iTrader: (1)

no. mufflers can be removed. dual exhaust with a crossover welded in all one piece. no emishions here. I will double check the header flange to ext pipes as that area was problematic until I realized there were no lock nuts.

Injector bias. Is that InJ correction offset? Voltage 0-25 V att are set to 732 usec in my .bin. I bet that is it.

Dominic Sorresso

Yep. Inj. Correction Offset. That's it. I think mine were set at 732msec also.
You could bump that up or increase FP by #1 to try and minimize those 100VE points. But take a look at the exhasut first.

Pre-Tuner

iTrader: (2)

You set all of them to 732 usec? I can't imagine the voltage ever getting even above 16, but you don't see the need to have it vary at all?

Also, is there a reason you chose 732 usec versus something else?

I have a similar setup to you guys with some minor differences. Aeromotive VAFPR with 18 psi @ WOT on 75# injectors and I don't have any VE cells above 90.

Dominic Sorresso

Pre-tuner,

The 732msec came from RBob. Its approximately the amount of time it took the BBC injectors to open based on his measurements.
I ran 20psi on my motor in order to get an Injector Duty cycle of 70-75% at WOT. That's where I started from then tuned Part Throttle from there. The VE you need would be partly a result of the heads, cam and exhaust you're running so I would expect your van not to have the same fuel requirements my Xfire did. Mine was at about 300+ rwhp @~5000rpm.

Pre-Tuner

iTrader: (2)

Oh ok. I wonder if I should try decreasing it a tad since my injectors are only 75#. I should be somewhere close to 300 hp, but I plan on taking it to the dyno on the 9th to see what she'll do with a little more tuning. I have vortec heads, intake, exhaust, mild cam, EBL, etc., so it's not exactly a stocker.

Is the 732 usec dependant on FP also, correct?

Dominic Sorresso

As I understand it, the ~732msec is dependent on the type of injector.
RBob could give a much better clarification. Injector Bias or Compensation is like Spark Advance. It will have more of an effect at low rpm than high because the injector opening time is a much higher percentage of overall pulsewidth. Am I right RBob?

RBob

iTrader: (1)

It is as Dominic states, the higher the fuel pressure the longer it takes for the injector to open. The lower the voltage the longer it takes for the injector to open.

The bias value is added right onto the PW before the hardware is programmed. So if the calculated PW is small, say 1 msec., adding .732 msec to it is a 73% increase in PW.

If the PW is large, say 4 msec., then the additional .732 msec is only a 18% increase in PW.

So as adjustments are made to the injector bias values, the changes will affect areas of low PW greater then areas of high PW.

If there isn't enough bias then the VE table starts an upward curve at lower MAP. You don't want this as then the VE table is being used for the wrong purpose. And, the injector operation gets erratic. {Note: this is erratic in the sense that the injector action at low PW is inconsistent. Instead of the PW being compensated for exactly the same each and every time. It will only be compensated for by the VE table. This causes the actual compensation to be inconsistent, as there are other factors involed in calculating the PW. Such as AFR and ~T.}

The picture shows what I am currently using for 81 #'ers at 22 psi (with a VRFPR). Last summer I made adjustments based on lower vehicle voltage. The lug on the alternator broke and was running on battery for about 20 minutes. I could feel the engine running leaner, and was fotunately data logging at the time.

One could do the same, but just disconnect the alternator ouput cable. Then start the engine and drive while data logging. Then adjust the bias and multiplier to get the fueling back in line.

RBob.