Poor Fuel Economy Troubleshooting Help Needed
11-25-2016, 08:32 AM
#21
A mail order tune to kill VATS and emmissions crap is a completely different thing from a live tune. That being said, with a basically stock engine a mail order tune will usually be fine, although you may be leaving a little on the table. My question is why is yours so bad? How many miles have you driven it? You really cant get a good accurate idea of mileage on only a couple tanks. Also maje sure your speedo is accurate, given that its a mail order tune, it could be off and giving you inaccurate mileage readings.
11-25-2016, 09:40 AM
#22
A mail order tune to kill VATS and emmissions crap is a completely different thing from a live tune. That being said, with a basically stock engine a mail order tune will usually be fine, although you may be leaving a little on the table. My question is why is yours so bad? How many miles have you driven it? You really cant get a good accurate idea of mileage on only a couple tanks. Also maje sure your speedo is accurate, given that its a mail order tune, it could be off and giving you inaccurate mileage readings.
I have right at 1500 miles on it since the swap. I calibrated my Intellitronix speedo and it reads within .1 mph of GPS and drove a loop and it was dead on for distance.
The other thing I notice is it just smells really rich too. Not sure if that is normal or not.
11-25-2016, 09:56 AM
#23
It shouldn't smell really rich. Maybe a little more than a late model car due to not having cats, but if it smells that bad, it probably is. Your best bet is going to be to find a local competent tuner to do a good live tune on it. Don't just go to the first guy you find, do some research, talk to your car buddy's and their buddy's, word of mouth is a great advertisement. Bad "tuners", and I use the term loosely, are a dime a dozen. Spend the time to find someone who really knows their **** and will work with you to make the tune right. 
11-25-2016, 10:05 AM
#24
It shouldn't smell really rich. Maybe a little more than a late model car due to not having cats, but if it smells that bad, it probably is. Your best bet is going to be to find a local competent tuner to do a good live tune on it. Don't just go to the first guy you find, do some research, talk to your car buddy's and their buddy's, word of mouth is a great advertisement. Bad "tuners", and I use the term loosely, are a dime a dozen. Spend the time to find someone who really knows their **** and will work with you to make the tune right.
I 100% agree with this.
11-25-2016, 10:48 AM
#25
It shouldn't smell really rich. Maybe a little more than a late model car due to not having cats, but if it smells that bad, it probably is. Your best bet is going to be to find a local competent tuner to do a good live tune on it. Don't just go to the first guy you find, do some research, talk to your car buddy's and their buddy's, word of mouth is a great advertisement. Bad "tuners", and I use the term loosely, are a dime a dozen. Spend the time to find someone who really knows their **** and will work with you to make the tune right.
I looked locally and there's not that many choices for tuners. One shop a couple towns over does drive tunes and does dyno tunes too. Seems competent from the reviews so we'll see. He charges $300 for a drive tune.
Thanks for the replies. It is greatly appreciated.
11-25-2016, 11:57 AM
#26
This was a budget tune from a gentleman that has a popular site with tons of pinout info and general info on Gen3 stuff. I'm a little disappointed nothing was mentioned about getting this stuff fixed after the swap. I suppose he wouldn't sell a lot of tunes if he told everyone they had to get another one after it was running.
And just so I can start learning:
PE - Power Enrichment table? What does this do?
VE - Volumetric Efficiency? Does this have to do with intake tube sizes and filter box pre throttle body?
Thanks again for the replies. Sincerely appreciated.
And just so I can start learning:
PE - Power Enrichment table? What does this do?
VE - Volumetric Efficiency? Does this have to do with intake tube sizes and filter box pre throttle body?
Thanks again for the replies. Sincerely appreciated.
To answer your previous questions...
Mail order tunes are just to get you going with pretty much stock equipment. They are really a guess that should get you moving in the proper direction. I've done a few unlocks (remove VATS, codes, etc.) for people with the caveat that any changes they make outside of stock will affect how the swap runs. If they want it to run properly I need to actually road tune the vehicle with a wideband and make changes from there.
Power Enrichment - this is simplest to describe as the fueling for the secondaries on a four barrel carb. It gives you that extra shot of fuel when you go wide open throttle (or clear whatever set points are programmed to enable this table). This is the difference between the VE table (stoichiometric) and whatever air / fuel ratio you need for the RPM and air velocity you're running. This needs to be adjusted after VE.
Volumetric Efficiency - This is a map of the airmass per cylinder in percent that drives your fueling compared to air flow through the engine. Since this is a calculated measure of air volume through the engine, it is affected by anything that will change airflow. This means any air inlet, intake, throttle body, heads, headers and sometimes even exhaust will affect this table. This is what keeps your engine at the stoichiometric (proper air fuel) ratio for the fuel you have programmed in that you're using.
I'm including an image captured from HP Tuners below. The on the left is a table view of the VE table for my Impala and on the right is the visual of the same. Most find the visual format easier to understand how a change relates to the rest of the data.
11-25-2016, 12:14 PM
#27
To answer your previous questions...
Mail order tunes are just to get you going with pretty much stock equipment. They are really a guess that should get you moving in the proper direction. I've done a few unlocks (remove VATS, codes, etc.) for people with the caveat that any changes they make outside of stock will affect how the swap runs. If they want it to run properly I need to actually road tune the vehicle with a wideband and make changes from there.
Power Enrichment - this is simplest to describe as the fueling for the secondaries on a four barrel carb. It gives you that extra shot of fuel when you go wide open throttle (or clear whatever set points are programmed to enable this table). This is the difference between the VE table (stoichiometric) and whatever air / fuel ratio you need for the RPM and air velocity you're running. This needs to be adjusted after VE.
Volumetric Efficiency - This is a map of the airmass per cylinder in percent that drives your fueling compared to air flow through the engine. Since this is a calculated measure of air volume through the engine, it is affected by anything that will change airflow. This means any air inlet, intake, throttle body, heads, headers and sometimes even exhaust will affect this table. This is what keeps your engine at the stoichiometric (proper air fuel) ratio for the fuel you have programmed in that you're using.
I'm including an image captured from HP Tuners below. The on the left is a table view of the VE table for my Impala and on the right is the visual of the same. Most find the visual format easier to understand how a change relates to the rest of the data.
Mail order tunes are just to get you going with pretty much stock equipment. They are really a guess that should get you moving in the proper direction. I've done a few unlocks (remove VATS, codes, etc.) for people with the caveat that any changes they make outside of stock will affect how the swap runs. If they want it to run properly I need to actually road tune the vehicle with a wideband and make changes from there.
Power Enrichment - this is simplest to describe as the fueling for the secondaries on a four barrel carb. It gives you that extra shot of fuel when you go wide open throttle (or clear whatever set points are programmed to enable this table). This is the difference between the VE table (stoichiometric) and whatever air / fuel ratio you need for the RPM and air velocity you're running. This needs to be adjusted after VE.
Volumetric Efficiency - This is a map of the airmass per cylinder in percent that drives your fueling compared to air flow through the engine. Since this is a calculated measure of air volume through the engine, it is affected by anything that will change airflow. This means any air inlet, intake, throttle body, heads, headers and sometimes even exhaust will affect this table. This is what keeps your engine at the stoichiometric (proper air fuel) ratio for the fuel you have programmed in that you're using.
I'm including an image captured from HP Tuners below. The on the left is a table view of the VE table for my Impala and on the right is the visual of the same. Most find the visual format easier to understand how a change relates to the rest of the data.
That's great info. Thanks for the explanations. The 3D view is really cool. It will help having a slight idea what this stuff is when I have it tuned so I can try and determine if the tuner is BSing me or not...
11-25-2016, 01:19 PM
#28
If you have any interest in tuning your own vehicle I suggest downloading a copy of HP Tuners from their site. You can't read your car without purchasing their interface, but you can look at some included sample calibrations and hopefully understand the logic a bit better.
HP Tuners is a very powerful tool, but it is expensive and has a very steep learning curve.
HP Tuners is a very powerful tool, but it is expensive and has a very steep learning curve.
11-25-2016, 01:20 PM
#29
If you have any interest in tuning your own vehicle I suggest downloading a copy of HP Tuners from their site. You can't read your car without purchasing their interface, but you can look at some included sample calibrations and hopefully understand the logic a bit better.
02-05-2017, 02:09 AM
#30
Just took delivery on HP Tuners and an AEM wideband kit. Pulled my stock tune file. I can upload it if anyone wants to look at it but it doesn't look that different from a stock 5.3 tune I downloaded from the HPT repository.
Last tank was 10.3mpg. I have about 2200 miles on this swap and this is the worst fuel economy yet. It keeps getting progressively worse.
I did however finally buy a fuel pressure gauge and tested my fuel pressure. With key on pump prime I get 50 at the rail. I then re-primed it and clamped the line off and it leaks down from 50psi to about 20psi in less than 5 minutes. I'm assuming that this means I have some leaky injectors. Would that cause a 40% reduction in fuel economy?
I plan on logging some drives in the next week and see where I am although I need to figure out how to wire in my wideband so I can log it as I didn't buy HPT Pro.
I sincerely appreciate everyone's input in this thread so far.
Last tank was 10.3mpg. I have about 2200 miles on this swap and this is the worst fuel economy yet. It keeps getting progressively worse.
I did however finally buy a fuel pressure gauge and tested my fuel pressure. With key on pump prime I get 50 at the rail. I then re-primed it and clamped the line off and it leaks down from 50psi to about 20psi in less than 5 minutes. I'm assuming that this means I have some leaky injectors. Would that cause a 40% reduction in fuel economy?
I plan on logging some drives in the next week and see where I am although I need to figure out how to wire in my wideband so I can log it as I didn't buy HPT Pro.
I sincerely appreciate everyone's input in this thread so far.
02-05-2017, 11:20 AM
#31
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Its also possible for a completely stock LS vehicle (Eg 5.3 truck) to get bad mileage too. It's not necessarily your "Bad tune" that's causing it. Bad IAT readings can put the fueling way off.
02-06-2017, 05:14 PM
#32
Thanks for the idea to check the IAT. I went through and checked ground and to see if it has proper +5v and it does. I added an IAT gauge onto my Torque screen and it appears to be reading correctly within 1*.
02-08-2017, 06:58 PM
#40
I have the 0-280-155-890 injectors from an F body LS1 with an LS1 intake off of a 00 camaro. I tried looking up some info on those injectors and honestly didn't know what I was looking at.
I'm going to try to get my wideband installed this coming weekend and go log some drives and some WOT pulls to see what is happening.