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4.9L Cadillac with Allante Intake Manifold (Page 1/2) |
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sanderson231
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JUN 23, 02:54 PM
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This topic got broached in another thread I recently started on poor mileage with my 4.9L. I am planning to install an Allante intake manifold. Raydar brought up the different MAT sensor locations and the fact the Allante had no EGR while the 4.9L does. Without EGR and a MAT sensor location less prone to heat soak from the cylinder head, the Allante MAT will run much cooler
Tunercat has the definition files for both engines. After looking at the documentation there are 6 tables that relate to the MAT:
MAT Spark Advance Correction Factor Vs. MAT MAT Spark Advance Compensation Vs. MAT at Idle Base Pulse Compensation Vs. MAT Sync. A.E. MAT Correction Vs. MAT (not sure what Sync A.E means) Heavy Load Spark Retard Vs. MAT in Low Gears Heavy Load Spark Retard Vs. MAT in High Gears
The equation for fuel injector Base Pulse Width is:
BPW = BPC * MAP * MAT * A/F * VE * BVC * BLM * DFCO * DE * CLT * TMB
where:
BPW = base pulse width BPC = base pulse constant MAP = manifold absolute pressure MAT = manifold absolute temperature A/F = air fuel ratio for other than closed loop VE = volumetric efficiency BVC = battery voltage correction BLM = block learn mode DFCO = decel fuel cut-out DE = decel enleanment CLT = closed loop i.e. the value from the integrator TBM = turbo boost multiplier
It would seem like values in all six of the above tables need to be changed when swapping to the Allante intake[This message has been edited by sanderson231 (edited 06-27-2022).]
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Raydar
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JUN 24, 12:21 AM
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I imported the Allante IAT tables to the 4.9 PROM image. Don't think I messed with those other tables. Since both applications use 19# injectors, I just multiplied the 4.9 BPW (thought I remembered Base Pulse Constant, but I could be wrong) by 1.1 (Which is, essentially, 4.9 divided by 4.5.) to accommodate for the increased flow of the Allante intake system on the 4.9. It's a crap shoot, but those two changes give me BLMs of 127-129, in part throttle cruising.
I want to say I imported the Allante VE and spark tables, too, but it's been a long time, so I'm not really certain. I was chasing a "phantom ping" which turned out to be intake noise, so there's no telling what I changed. (I actually made notes, with every change, but it's been a long time.) Of course, all the "EGR ON" tables were stuffed with "EGR OFF" values. EGR Enable parameters were set to something absurd, so that EGR would never be commanded.[This message has been edited by Raydar (edited 06-24-2022).]
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sanderson231
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JUN 24, 09:53 AM
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Raydar,
I am going to get the Allante definition file and do a side-by-side to the 4.9L. If the spark advance vs MAT table was not changed that may explain why you had to advance the base time to 20 degrees. I think I've go this under control now so don't spend time looking for old notes. Thanks for your help
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Raydar
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JUN 25, 03:06 PM
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quote | Originally posted by sanderson231:
Raydar,
I am going to get the Allante definition file and do a side-by-side to the 4.9L. If the spark advance vs MAT table was not changed that may explain why you had to advance the base time to 20 degrees. |
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I had (have?) both files as well. I'm not sure there were any changes (at least on the face of it) that would warrant an additional 10 degrees of lead, but I could be wrong. Please let me know what you find. There are at least two other 4.9/Allante installations, besides mine, running ~20 degrees base timing. One of them was even "massaged" by a well known chip tuner.[This message has been edited by Raydar (edited 06-25-2022).]
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Will
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JUN 27, 10:18 AM
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quote | Originally posted by sanderson231:
Sync. A.E. MAT Correction Vs. MAT (not sure what Sync A.E means)
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AE is typically Acceleration Enrichment... Makes a little sense that that would be calibrated to IAT/MAT because AE is basically a calibrated guess, empirically determined, anyway.[This message has been edited by Will (edited 06-27-2022).]
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sanderson231
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JUN 27, 01:54 PM
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Thanks Will - acceleration enrichment makes sense.
Just ordered hardware and software from Tunercat. I'll use the compare feature in tunercat to check differences between the two definition files. It may make sense to use the Allante definition file and just change the base pulse constant (BPC) from the 4.9L to account for larger displacement.------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
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sanderson231
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JUL 01, 06:07 PM
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Got the hardware and software from Tunercat and realized the difference between a definition file and a calibration file (.bin). The definition file just configures the tunercat program to work with a certain PCM. The calibration file is what contains all the data. I did not get a definition file for the Allante from tunercat. Does anyone have an Allante calibration file either broadcast code ATTL or AUMF. I can buy a new prom from Autozone for $55 but just trying to save the bucks.
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Raydar
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JUL 02, 11:54 AM
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quote | Originally posted by sanderson231: Does anyone have an Allante calibration file either broadcast code ATTL or AUMF.
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Check your email.
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sanderson231
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JUL 04, 06:25 PM
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Thanks Raydar for the Allante .bin file>
The Base Pulse Constant is 167 for the 4.5L and 183 for the 4.9L. These differ by the ratio of the displacements
Concerning the tables that involve MAT:
]MAT Spark Advance Correction Factor Vs. MAT[/b} there is no difference between the 2 engines
[b]MAT Spark Advance Compensation Vs. MAT at Idle[b] there is no difference between the two engines if the MAT is above 20 'C
[b]MAT Spark Advance Correction Factor Vs. MAT neither engine uses MAT to correct spark advance
Base Pulse Compensation Vs. MAT there are minor differences in the compensation factor
MAT 4.5L 4.9L -40 'C 0.066 0.057 -28 'C 0.061 0.054 8 'C 0.056 0.052 32 'C 0.053 0.051 56 'C 0.049 0.049 80 'C 0.045 0.047 104 'C 0.044 0.046 128 'C 0.043 0.044 152 'C 0.043 0.043
This basically accounts for the decreasing air density at higher temperatures
Sync. A.E. MAT Correction Vs. MAT (synchronous acceleration enrichment means pulse widths are widened during acceleration there are differences but not sure how much difference this would make - this is a multiplier - not sure what the difference between a multiplier and a factor is
MAT 4.5L 4.9L -40 'C 0.352 0.656 -28 'C 0.352 0.656 -16 'C 0.332 0.645 -4 'C 0.301 0.625 8 'C 0.281 0.586 20 'C 0.281 0.508 32 'C 0.254 0.430 44 'C 0.195 0.352 56 'C 0.117 0.285 68 'C 0.059 0.250 80 'C 0.020 0.203 92 'C 0.000 0.156 104 'C 0.000 0.156 116 'C 0.000 0.156 128 'C 0.000 0.156 140 'C 0.000 0.156 152 'C 0.000 0.156 Heavy Load Spark Retard MAT Factor Vs. MAT in Low Gears
MAT 4.5L 4.9L -40 'C 0.250 0.996 -28 'C 0.250 0.996 8 'C 0.250 0.996 32 'C 0.500 0.996 56 'C 0.996 0.996 80 'C 0.996 0.996 104 'C 0.996 0.996 128 'C 0.996 0.996 152 'C 0.996 0.996
Heavy Load Spark Retard MAT Factor Vs. MAT in High Gears
MAT 4.5L 4.9L -40 'C 0.250 0.996 -28 'C 0.250 0.996 8 'C 0.250 0.996 32 'C 0.500 0.996 56 'C 0.996 0.996 80 'C 0.996 0.996 104 'C 0.996 0.996 128 'C 0.996 0.996 152 'C 0.996 0.996
In conclusion there does not seem to be an apparent reason why the 4.9L with the Allante intake likes more timing advance.
There are significant differences in the Volumetric Efficiency Tables. Here is a comparison around WOT (wide open throttle) conditions
4.5l
RPM kPa 90 95 100 4000 84.8 87.1 87.1 4400 88.3 90.6 90.6 4800 89.1 90.2 90.2 5200 84.8 86.3 86.7
4.9l
RPM kPa 90 95 100 4000 83.2 82.8 82.0 4400 84.4 84.4 84.4 4800 84.4 84.4 84.4 5200 82.8 82.8 82.8
Despite the higher volumetric efficiencies for the 4.5L, the 4.9L flows more air under all conditions because of its larger displacement. Interestingly, the 4.9L flows more air at 5200 RPM than at 4400 RPM where the HP is peak at 200. So at higher RPMs the percentage of fuel getting burned must be less.
Some of the volumetric efficiency difference is probably due to the fact that both engines use the same head and thus the head is relatively larger for the smaller displacement engine. Obviously the rest has to be due to the better intake for the 4.5L.
Sorry about the tables. The spacing was not maintained when I posted ------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged[This message has been edited by sanderson231 (edited 07-04-2022).]
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Raydar
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JUL 12, 02:56 PM
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quote | Originally posted by sanderson231: ... The Base Pulse Constant is 167 for the 4.5L and 183 for the 4.9L. These differ by the ratio of the displacements
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BUT... both engines use 19# injectors, and are rated at 200 HP, out of the box. So, with the additional airflow of the Allante intake, on top of the additional displacement, I figured that the BPC should be increased by that ratio, yet again. Check the BPC of the tweaked 4.9 file I sent. My BLM at an "easy cruise" hovers right around 127-128, so I have to believe I'm close.
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