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Old 07-25-2019, 10:31 AM   #1
cebra
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Tuning Advice Needed

I have had my LS in for a couple months now and have put 4k miles on it as is but it will not run with the TPS hooked up at all (replaced TPS even though it shows as working properly and replaced MAF). The last tuner I took it to said the ECU was cutting out and he wouldn't be able to tune it like that and wondered if it was the ECU or my BP Automotive harness as he has had bad experiences with aftermarket harnesses.

With this said I am weighing my options:

1. Get a new ECU and have it tuned and hope it isn't a harness issue
2. Try to find a ECU unlocked to buy and test that one with my harness
3. Get a new ECU and get HPTuners, find a base tune on the web for a stock LS, and adjust it myself...weighing this as most tuners won't touch what I have going on

Thoughts?
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Old 07-25-2019, 02:12 PM   #2
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Re: Tuning Advice Needed

ECU's are cheap. Ebay has a couple guys removing vats for $70 after shipping. Have them do base tune and turn off emission stuff. That way you can rule out ECU.

https://www.ebay.com/itm/LS-swap-tun...YAAOSwSWJXRT65

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Old 07-26-2019, 09:00 AM   #3
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Re: Tuning Advice Needed

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Originally Posted by prodjay10 View Post
ECU's are cheap. Ebay has a couple guys removing vats for $70 after shipping. Have them do base tune and turn off emission stuff. That way you can rule out ECU.

https://www.ebay.com/itm/LS-swap-tun...YAAOSwSWJXRT65
Great idea, that will be my next step. My tuner wanted $100 to bring his ECU over and swap it out which I would have paid for but he has been a bit mia lately (due to selling a house) and I want to get moving on this before I take it to paint.
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Old 07-25-2019, 02:48 PM   #4
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Re: Tuning Advice Needed

Read the post about coolant. I didnít know you had to fill that way either.
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Old 07-26-2019, 09:02 AM   #5
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Re: Tuning Advice Needed

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Read the post about coolant. I didnít know you had to fill that way either.
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Yeah, it makes sense if you think about it as there is no coolant going to the motor if the upper hose is above the radiator fill neck and the bottom hose goes to the t-stat so it is cold water and the t-stat doesn't open. I wish I had read this somewhere or conceptually thought about it but I am not used to the t-stat being on the bottom so I proceeded as I would any other motor and it cost me.
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Old 07-25-2019, 04:10 PM   #6
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Re: Tuning Advice Needed

Have you tried to test the harness for 12+ power or ground interruptions? I would check power and ground in the harness plug to the ECM. Maybe even wiggle the harness to see if power or ground changes voltage while testing.
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Old 07-26-2019, 08:59 AM   #7
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Re: Tuning Advice Needed

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Have you tried to test the harness for 12+ power or ground interruptions? I would check power and ground in the harness plug to the ECM. Maybe even wiggle the harness to see if power or ground changes voltage while testing.
I have not but that is a good thing to check and I will work on that. I have checked the half dozen wires including the ground I was supposed to hookup and those have the correct power/ground. Sucks I may have a harness issue on a brand new harness but the customer experience I have had with BP automotive it wouldn't surprise me. They forgot to turn my fans on when it comes in the base tune and I specifically told them what temperature I wanted.
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Old 07-26-2019, 01:37 PM   #8
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Re: Tuning Advice Needed

If you go with option 3 and you are going to make changes in relation to the fueling of the engine then you also need to factor in the purchase of a wideband o2 sensor.

Trying to do any performance tuning without one is asking for trouble.
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Old 07-26-2019, 03:11 PM   #9
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Re: Tuning Advice Needed

Ideally I would find a stock 00 Silverado (4.8/MT/4x2) ECU and have a tuner remove VATS/emissions and turn on the fans and not touch anything else. Finding that transmission was near impossible and the price was absurd so that ECU if I could find it would probably be out of my price range. I drive a ton so I am solely after gas mileage (3.08 gears, manual trans, small fuel injected motor).
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Old 07-28-2019, 11:46 PM   #10
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Quote:
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Ideally I would find a stock 00 Silverado (4.8/MT/4x2) ECU and have a tuner remove VATS/emissions and turn on the fans and not touch anything else. Finding that transmission was near impossible and the price was absurd so that ECU if I could find it would probably be out of my price range. I drive a ton so I am solely after gas mileage (3.08 gears, manual trans, small fuel injected motor).
I was under the impression that the ecu control of the tranny only matters if itís automatic. Otherwise just donít connect the tranny to the harness and remove tranny codes with a tune.

Iíve also read an Auto tranny will give you 20mpg or so with a 5.3 so long as you donít stomp on it. Thatís great mpg in my opinion for a truck.
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Old 07-29-2019, 08:53 AM   #11
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Re: Tuning Advice Needed

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I was under the impression that the ecu control of the tranny only matters if itís automatic. Otherwise just donít connect the tranny to the harness and remove tranny codes with a tune.

Iíve also read an Auto tranny will give you 20mpg or so with a 5.3 so long as you donít stomp on it. Thatís great mpg in my opinion for a truck.
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Yeah, you can change anything in the tune but after spending so much money on tuning/harness/ecu's I would like to keep peoples hands out of it as much as possible is all I was getting at.
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Old 08-05-2019, 01:23 AM   #12
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Re: Tuning Advice Needed

What'd you end up doing? Was the overheat condition the reason it was running bad?
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Old 08-07-2019, 12:31 PM   #13
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Re: Tuning Advice Needed

I ordered a new ECU from ebay and then sent it off to get flashed by an ebay tuner (which cost maybe $120 total rather than having a tuner bring a known good ECU to hook up for $100). We will see if this resolves any of my issues, should be able to install it this weekend assuming it has arrived by the time I return to the US.
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Old 08-07-2019, 06:28 PM   #14
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Re: Tuning Advice Needed

Is the engine stock?
Is the harness new or old and reworked?

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Old 08-12-2019, 10:35 AM   #15
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Re: Tuning Advice Needed

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Is the engine stock?
Is the harness new or old and reworked?

Clint
Stock motor, new standalone harness.
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Old 08-12-2019, 11:04 PM   #16
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Re: Tuning Advice Needed

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Stock motor, new standalone harness.
Easy thing about ls harness, easy to wire test. Nothing in a stupid crazy hard location to get to. You could wire test the harness, get pinouts online and know for sure if the harness got damaged from manufacturer, install, or wear and tear from abrasion...

If you check, ohm wire to wire. Wire to ground and wire to power. Each test wiggle the harness from connector to ECU to see if there is a problem. Lots of YouTube videos on wire testing.
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Old 08-15-2019, 08:54 AM   #17
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Re: Tuning Advice Needed

Luckily I won't need to test the harness as the new ECU/tune seemed to resolve my TPS issue. I had 3 main issues with the first tune: not running on TPS, speedo way off, no fans.

Now I have the motor seemingly running fine and the speedo resolved but my fans now kick on at like 170 (asked for 210) so they run nonstop but that I can resolve easily. My tach is also now about 2x the readout of the ECU, I am hoping that I need to just switch it from 4 cyl to 8 cyl though.
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Old 08-15-2019, 09:25 AM   #18
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Re: Tuning Advice Needed

LS engines run on a 4cyl signal so you need to change the tach resolution, that was probably done on your last PCM. But if you have a programmable tach you can just set it to 4cyl and it should be fine.
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Old 08-16-2019, 01:29 AM   #19
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Re: Tuning Advice Needed

Awesome to hear! I still haven't started the swap on my truck. I want to get on it because I want to start driving my truck!
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Old 08-16-2019, 08:42 AM   #20
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Re: Tuning Advice Needed

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LS engines run on a 4cyl signal so you need to change the tach resolution, that was probably done on your last PCM. But if you have a programmable tach you can just set it to 4cyl and it should be fine.
Yeah, I had it on 4 cylinder and it was reading 2x on this new tune. Switched it back to 8 cylinder and it reads correctly now according to my Fusion app. The tuner must have changed the signal.

All issues now resolved less e-fans. I will probably just get an external controller for this as I am 0 for 2 on tunes getting these to work correctly and I don't want to pay for a real (in person) tune just for e-fans. Thanks for all the guidance and I really came out ahead on cost by just getting another ecu and ebay tune.
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Old 08-16-2019, 11:02 AM   #21
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You could ask the eBay tuner to fix it for you. Maybe offer to help with shipping?
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Old 08-16-2019, 04:51 PM   #22
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Re: Tuning Advice Needed

I bought a fan controller as I don't want to cause more issues with another box tune and I do not want to pay $400 for a live tune just to resolve the fans. Would this relay setup work? I am getting + from Controller but would like my - Trinary signal to kick on the high fan as well.
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Old 08-25-2019, 10:55 PM   #23
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Re: Tuning Advice Needed

I'm sorry to hear about your issues, but it makes me feel good about thinning out my own harness, building my own fuse block, buying HP Tuners ($300) and paying ($100) for two credits to tune my own PCM, and running the mechanical fan, not trying to rub it in, but you already spent this much on the harness, original re programming, a new PCM, and still need more mods for the fans.

I bet if you saved the file from the new PCM and wrote it to your original it would work as well, as I think it's the tune that's jacked on it.
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Old 08-27-2019, 10:36 AM   #24
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Re: Tuning Advice Needed

Yeah, I may buy HPTuners if these last 2 tunes don't resolve my e-fans. According to everyone I have talked to (3 tuners), the e-fans are very difficult to get working on a box tune as you "click the button" and don't know if it takes or not where as a live tune you can click, no work, click, no work, click, ok they work....that would be the equivalent of sending it out for 3 box tunes...my understanding of the issue.
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Old 08-27-2019, 12:26 PM   #25
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Re: Tuning Advice Needed

I'm pretty sure the ebay tuner will fix this for you.
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