Wayyy too rich at idle
Thread Starter
Staging Lane
Joined: Aug 2014
Posts: 60
Likes: 9
From: Viera, Florida
Wayyy too rich at idle Hello all,
I have a 2005 Hummer H2 that I recently had the cats removed from and a custom tune by a local shop. One cat was completely missing inside, so I had the other removed as well. I live in FL so its no big deal.
Anyway, the guy used HP tuners to tweak the tune. It runs like a scalded dog now. The only complaint I have is that at an idle, sitting in traffic or the driveway, you can not have the windows or sun roof open due to the fumes. It is just too rich. I took it back and he said he pulled some fuel out of it at idle but I do not notice a difference. He says I'm just smelling what is normal because the cats have been removed. Says its like an old Chevelle.
Now I'm no LS expert and don't know squat about tuning these things but as an old retired gear head, none of my race cars even ran this fat at idle.
Can anyone give me any advice? I'm not prepared to buy HP Tuners because I just don't understand all of it but maybe he missed something really easy to adjust?
Thanks
Tim
I have a 2005 Hummer H2 that I recently had the cats removed from and a custom tune by a local shop. One cat was completely missing inside, so I had the other removed as well. I live in FL so its no big deal.
Anyway, the guy used HP tuners to tweak the tune. It runs like a scalded dog now. The only complaint I have is that at an idle, sitting in traffic or the driveway, you can not have the windows or sun roof open due to the fumes. It is just too rich. I took it back and he said he pulled some fuel out of it at idle but I do not notice a difference. He says I'm just smelling what is normal because the cats have been removed. Says its like an old Chevelle.
Now I'm no LS expert and don't know squat about tuning these things but as an old retired gear head, none of my race cars even ran this fat at idle.
Can anyone give me any advice? I'm not prepared to buy HP Tuners because I just don't understand all of it but maybe he missed something really easy to adjust?
Thanks
Tim
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
Do you have an aftermarket cam installed? If you have overlap, it will smell a bit at idle even if it's lean. The only real way to get the smell down without cats is to delay End Of Injection Timing (EOIT). Even with doing this it won't completely remove the smell.
Another consideration is if you are running in closed loop the computer will eventually readjust the fuel to what it thinks is stoich, no matter what you put in the tune. This is due to Long Term Fuel Trims (LTFT's) which are a result of a long history of Short Term Fuel Trims (STFT's) reading rich or lean. Say your tuner set the AFR lean at idle, so the STFT's read +10 or something like that, the computer will constantly dump fuel trying to correct it. Eventually this becomes a +10 on your LTFT's, resulting in no noticeable change to the "smell" or AFR.
To combat this, adjustments can be made to the O2 sensors and their switching points, but it isn't as effective as doing an open loop idle. In open loop the O2's are disabled, as are all fuel trims. That's the one sure way to "lean it out" in any particular condition. It's done by enabling power enrichment at idle and then adjusting the Volumetric Efficiency (VE) table accordingly.
Hope that helps, but you can ask your tuner or show him this post and he should know how to do it.
Another consideration is if you are running in closed loop the computer will eventually readjust the fuel to what it thinks is stoich, no matter what you put in the tune. This is due to Long Term Fuel Trims (LTFT's) which are a result of a long history of Short Term Fuel Trims (STFT's) reading rich or lean. Say your tuner set the AFR lean at idle, so the STFT's read +10 or something like that, the computer will constantly dump fuel trying to correct it. Eventually this becomes a +10 on your LTFT's, resulting in no noticeable change to the "smell" or AFR.
To combat this, adjustments can be made to the O2 sensors and their switching points, but it isn't as effective as doing an open loop idle. In open loop the O2's are disabled, as are all fuel trims. That's the one sure way to "lean it out" in any particular condition. It's done by enabling power enrichment at idle and then adjusting the Volumetric Efficiency (VE) table accordingly.
Hope that helps, but you can ask your tuner or show him this post and he should know how to do it.
Thread Starter
Staging Lane
Joined: Aug 2014
Posts: 60
Likes: 9
From: Viera, Florida
Do you have an aftermarket cam installed? If you have overlap, it will smell a bit at idle even if it's lean. The only real way to get the smell down without cats is to delay End Of Injection Timing (EOIT). Even with doing this it won't completely remove the smell.
Another consideration is if you are running in closed loop the computer will eventually readjust the fuel to what it thinks is stoich, no matter what you put in the tune. This is due to Long Term Fuel Trims (LTFT's) which are a result of a long history of Short Term Fuel Trims (STFT's) reading rich or lean. Say your tuner set the AFR lean at idle, so the STFT's read +10 or something like that, the computer will constantly dump fuel trying to correct it. Eventually this becomes a +10 on your LTFT's, resulting in no noticeable change to the "smell" or AFR.
To combat this, adjustments can be made to the O2 sensors and their switching points, but it isn't as effective as doing an open loop idle. In open loop the O2's are disabled, as are all fuel trims. That's the one sure way to "lean it out" in any particular condition. It's done by enabling power enrichment at idle and then adjusting the Volumetric Efficiency (VE) table accordingly.
Hope that helps, but you can ask your tuner or show him this post and he should know how to do it.
Another consideration is if you are running in closed loop the computer will eventually readjust the fuel to what it thinks is stoich, no matter what you put in the tune. This is due to Long Term Fuel Trims (LTFT's) which are a result of a long history of Short Term Fuel Trims (STFT's) reading rich or lean. Say your tuner set the AFR lean at idle, so the STFT's read +10 or something like that, the computer will constantly dump fuel trying to correct it. Eventually this becomes a +10 on your LTFT's, resulting in no noticeable change to the "smell" or AFR.
To combat this, adjustments can be made to the O2 sensors and their switching points, but it isn't as effective as doing an open loop idle. In open loop the O2's are disabled, as are all fuel trims. That's the one sure way to "lean it out" in any particular condition. It's done by enabling power enrichment at idle and then adjusting the Volumetric Efficiency (VE) table accordingly.
Hope that helps, but you can ask your tuner or show him this post and he should know how to do it.
I'll get this info to the tuner. He also eliminated the post cat o2's, I think but I don't know about it being in open or closed loop. I have no idiot lights on, even though I am one when it comes to this...lol.
Tim
Whats the wideband say,
and how many milliseconds are coming out of what size injectors at what pressure
Is what you would need to know whether it was "rich" instantaneously or not.
aside;
If you have duty cycle, injector size, and fuelpressure, you can calculate fuel used / time (for example 1 gallon per hour) and then if you also happen to know speed in miles per hour you combine them to cancel hours and get miles per gallon from the computer.
and how many milliseconds are coming out of what size injectors at what pressure
Is what you would need to know whether it was "rich" instantaneously or not.
aside;
If you have duty cycle, injector size, and fuelpressure, you can calculate fuel used / time (for example 1 gallon per hour) and then if you also happen to know speed in miles per hour you combine them to cancel hours and get miles per gallon from the computer.
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TECH Enthusiast
Joined: Dec 2011
Posts: 531
Likes: 5
I went through a similar problem trying to get my decapped truck injectors to not be stupid rich at idle.
ChoperDoc, ddnspider and Lsxford all helped me figure it out.
To lean out fuel at idle from the crazy rich scenario I was dealing with it helped to adjust "Min Injector Pulse", " Default Injector Pulse", and "Min Fuel Milligrams". Like mentioned.
ChoperDoc, ddnspider and Lsxford all helped me figure it out.
To lean out fuel at idle from the crazy rich scenario I was dealing with it helped to adjust "Min Injector Pulse", " Default Injector Pulse", and "Min Fuel Milligrams". Like mentioned.
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Verdad Gallardo So how do you know how far to reduce the min fuel milligrams. Every thread I've read about it says something cryptic like "It sets a low Injector pulse limit" or "just cut in half" something, and yet the number appears somewhat arbitrary.
Im about to start messing with it but was hoping an expert would give another perspective based on what they've seen it do.
Normally I would just test it until I had it figured out. however, the lack of real time tuning is a huge turn off for this sort of approach. I don't want to burn up my ECU by re-writing it over and over and over again searching for data. Even if it is just a $40 computer. What happens if I set it to 0 or 0.001 or something tiny?
Im about to start messing with it but was hoping an expert would give another perspective based on what they've seen it do.
Normally I would just test it until I had it figured out. however, the lack of real time tuning is a huge turn off for this sort of approach. I don't want to burn up my ECU by re-writing it over and over and over again searching for data. Even if it is just a $40 computer. What happens if I set it to 0 or 0.001 or something tiny?
So how do you know how far to reduce the min fuel milligrams. Every thread I've read about it says something cryptic like "It sets a low Injector pulse limit" or "just cut in half" something, and yet the number appears somewhat arbitrary.
Im about to start messing with it but was hoping an expert would give another perspective based on what they've seen it do.
Normally I would just test it until I had it figured out. however, the lack of real time tuning is a huge turn off for this sort of approach. I don't want to burn up my ECU by re-writing it over and over and over again searching for data. Even if it is just a $40 computer. What happens if I set it to 0 or 0.001 or something tiny?
Im about to start messing with it but was hoping an expert would give another perspective based on what they've seen it do.
Normally I would just test it until I had it figured out. however, the lack of real time tuning is a huge turn off for this sort of approach. I don't want to burn up my ECU by re-writing it over and over and over again searching for data. Even if it is just a $40 computer. What happens if I set it to 0 or 0.001 or something tiny?
Hey thanks man. And remember a year ago when you said 400 would be a slam dunk? lol This is the moment I was thinking of when you said that, that tomorrow I would be looking for 400 tire and somehow I knew you would be right there, as if we are drawn to it. Strange how time works sometimes, cross your fingers