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#1
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Factory PCM vs. Aftermarket
So, I've been trying to learn late model tuning with HPTuner. It's more complicated that I thought it would be. I removed the torque management, changed PE, etc. on my '04 GMC 2500HD. I still haven't messed with fuel VE map, MAF, and timing tuning. Watched a lot of videos and read a lot. Partly being lazy I guess. So how much easier is tuning with systems like Holley Terminator X and similar?
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#2
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I've never tried to use a stock ecu, but I think probably the main difference is the freedom to choose how you want to tune the engine. You mentioned MAF, and with the aftermarket standalone stuff you can eliminate that if you choose and use speed density instead(or alpha n, blended alpha n and speed density or ITB for that matter). Traction control can be tailored to suit, or turned off, easily. There's nothing that's "locked", except the limits of hard coding on some units. My MS3 has open source code, so those with the computer skills (not me) can even change that.
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'65 Tempest 467 3650# 11.30@120.31 |
#3
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#4
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The only guy I personally know that makes really good, but street able horsepower (620 @ the crank N/A) says they moved away from MAF for easier tuning and made better power to boot. Just fyi, maybe don't get too hung up on keeping the MAF, especially if it makes your life more difficult...
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'65 Tempest 467 3650# 11.30@120.31 Last edited by Scott65; 06-03-2022 at 11:50 AM. Reason: Addition |
#5
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The Following User Says Thank You to JSchmitz For This Useful Post: | ||
#6
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Bang for the buck the LS platform wins hands down. The corrections for driving conditions with regards to changing temps (MAT correction)and even elevation (barometric correction) is easily handled in speed density. When I have a minute I'll take some screenshots of my tuning software showing how adjustments are handled even without MAF.
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'65 Tempest 467 3650# 11.30@120.31 |
#7
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Ok. Cool! |
#8
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So, I'll attempt to keep this explanation in order of the screenshots. I don't have the ability to put the photos inline( or the skills anyway) There will be two of the air density correction, and the reason requires a little detail, that may be relevant to you no matter whether you decide to tune the stock ecu or go stand alone.
The factory engineers put a lot of thought into the sensor arrangement and the location to take intake air from. Then they calibrate for that and it works well. We the hot rodders take either a factory engine and stick it in a different car(your case) or add efi to a car that never had it(my case). In either case, we've changed the factory engineering, or never had any in the first place and the air intake temps ( or MAT if you prefer) can be inconsistent, or inaccurate, or both. One of the air density tables I'm showing is the default table, and it's based on the Ideal Gas Law which covers the effects of changing air temps on air density(and other things, if you solve for different variables) Makes me once again wish I'd taken science more seriously... Anyway, if you have a well engineered system with accurate temps, and adequate airflow, you probably can run very close to the default curve. In my case( and many others doing retrofit stuff) the default curve doesn't play well, and you get lean conditions where it "should" be ok to have the curve leaning things out. And thus the reason for my curve having a slight "bell" shape as opposed to the default. Also availe is MAT/CLT correction which corrects for low airflow high temps. I haven't messed with that much... Baro correction is there, but needs to be tuned in actual conditions. I rarely go 100 miles away from sea level, so I don't mess with it. I use the feature that allows the sensor to compare pre start up MAP sensor reading and handle it internally. You can also add a second map sensor(1 bar) and constantly compare the two. Over my head, and unnecessary in my case... I also have the ability to run a MAF sensor, but choose speed density instead. Hopefully this is helpful. ETA: screenshot of menu where these options are
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'65 Tempest 467 3650# 11.30@120.31 |
#9
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Stock LS1B or E40 ECU = Use EFI Live to get control of air temp modifiers through custom OS tweaks. Can run speed density no issues.
Stock E38 ECU = Use HP Tuners for the same air temp. Can run speed density no issues. Stock ECU's are pretty complicated to understand for the beginners, but they're also the easiest to get the car started and running. Aftermarket ECU's are much easier to understand for the beginners, but they're harder to get the car started and running. The cost of aftermarket ECU's and support from vendors, community, base map availability is much better than using the stock stuff IMO and the cost difference isn't that horrendous between the 2.
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'71 Holden HQ Monaro - 3850lbs race weight, 400c/i - 11.4 @ 120 '66 Pontiac GTO - 389, 4 speed street cruiser |
#10
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#11
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#12
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Yes, that I know of anyway.
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'65 Tempest 467 3650# 11.30@120.31 |
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