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I am by no means an expert tuner, but I do have a little experience using HP Tuners on the LS engines. I also have a BASIC understanding of fuel and timing curves, torque management, and data logging. Very basic! That being said, I have a couple of questions about the Predator and Hemi tuning.

1. I recently did some logging on my 2010 RT AUTO and noticed that the command afr @ WOT was 11.8. That seems ridiculously rich to me. I liked to see 12.8 on my brand X junk. Is 11.8 too rich and is the only way to set the commanded afr through the CMR software? On a related note, i noted that the LTFT's were in the -1.8 range. Should I reduce fueling in that RPM range?

2. I thought (key word thought) that there was a wide band O2 sensor that could replace/emulate the factory narrow band and act as a wide band as well. Again this was when I was working on Brand X stuff. Has anyone else heard of something like that or did I dream it? I guess there isn't anything like that available for the Challenger. Could I replace one of the rear O2's with a wideband and have a CMR tuner turn them off since I don't have to pass inspection?

3. I have scoured this and the Diablosport boards for Hemi tuning tips. I have found the best PID's to monitor and such, but haven't really found anyone sharing much detailed info. I know the Predator is limited compared to the HP Tuners suite (thanks to Chrysler) but I am wondering if anyone has any general info to share on tuning the Eagle motors. For example add 1% fuel and 2 degrees spark in the mid range etc... Is the Predator so limited (not knocking Diablosport) that it is best to just run a canned tune and let someone with CMR interpret the logs and tune where they can turn more knobs so to speak? I know there are many great Hemi tuners, but half the fun to me is doing it myself (and being VERY careful along the way).


Thanks for any and all tips/comments!
 

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I am by no means an expert tuner, but I do have a little experience using HP Tuners on the LS engines. I also have a BASIC understanding of fuel and timing curves, torque management, and data logging. Very basic! That being said, I have a couple of questions about the Predator and Hemi tuning.

1. I recently did some logging on my 2010 RT AUTO and noticed that the command afr @ WOT was 11.8. That seems ridiculously rich to me. I liked to see 12.8 on my brand X junk. Is 11.8 too rich and is the only way to set the commanded afr through the CMR software? On a related note, i noted that the LTFT's were in the -1.8 range. Should I reduce fueling in that RPM range?

2. I thought (key word thought) that there was a wide band O2 sensor that could replace/emulate the factory narrow band and act as a wide band as well. Again this was when I was working on Brand X stuff. Has anyone else heard of something like that or did I dream it? I guess there isn't anything like that available for the Challenger. Could I replace one of the rear O2's with a wideband and have a CMR tuner turn them off since I don't have to pass inspection?

3. I have scoured this and the Diablosport boards for Hemi tuning tips. I have found the best PID's to monitor and such, but haven't really found anyone sharing much detailed info. I know the Predator is limited compared to the HP Tuners suite (thanks to Chrysler) but I am wondering if anyone has any general info to share on tuning the Eagle motors. For example add 1% fuel and 2 degrees spark in the mid range etc... Is the Predator so limited (not knocking Diablosport) that it is best to just run a canned tune and let someone with CMR interpret the logs and tune where they can turn more knobs so to speak? I know there are many great Hemi tuners, but half the fun to me is doing it myself (and being VERY careful along the way).


Thanks for any and all tips/comments!
I would post these questions on the DS website under the Dodge gas section.
 

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Check out the forum on the Diablosport website lots of good info, search back a few pages ;) But it is my understanding that you need a Wideband to see your actual FA ratio, you can have a muffler shop weld in a bung to install wideband. Also the only thing you can do with out CMR software is add or reduce fuel and spark at WOT in different RPM ranges to manage ST Knock. They also recommend installing a catch can to keep the oil vapors from going back into the intake contributing to ST knock. If you have any questions post them up on the Diablo forum and Mike or Johan will be happy to answer your questions.
 
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1. I recently did some logging on my 2010 RT AUTO and noticed that the command afr @ WOT was 11.8. That seems ridiculously rich to me. I liked to see 12.8 on my brand X junk. Is 11.8 too rich and is the only way to set the commanded afr through the CMR software? On a related note, i noted that the LTFT's were in the -1.8 range. Should I reduce fueling in that RPM range?

It is my understanding that fuel trims are used for Closed loop operation only... I wouldn't reduce fueling without a wideband, but that's just me.

2. I thought (key word thought) that there was a wide band O2 sensor that could replace/emulate the factory narrow band and act as a wide band as well. Again this was when I was working on Brand X stuff. Has anyone else heard of something like that or did I dream it? I guess there isn't anything like that available for the Challenger. Could I replace one of the rear O2's with a wideband and have a CMR tuner turn them off since I don't have to pass inspection?

The LC-1 controller can use a single wideband sensor and simulate a narrowband (and still provide you with wideband functionality). It just seems overly complex to do this since the ECU also monitors the o2 sensor's heater curcuit. It's just easier to weld another bung and add a wideband. I put my added bung before the cats on the driver's side.

3. I have scoured this and the Diablosport boards for Hemi tuning tips. I have found the best PID's to monitor and such, but haven't really found anyone sharing much detailed info. I know the Predator is limited compared to the HP Tuners suite (thanks to Chrysler) but I am wondering if anyone has any general info to share on tuning the Eagle motors. For example add 1% fuel and 2 degrees spark in the mid range etc... Is the Predator so limited (not knocking Diablosport) that it is best to just run a canned tune and let someone with CMR interpret the logs and tune where they can turn more knobs so to speak? I know there are many great Hemi tuners, but half the fun to me is doing it myself (and being VERY careful along the way).


Thanks for any and all tips/comments!
The predator has very limited (read: coarse) adjustments. Diablosport really doesn't want to put too much power into your hands. I agree, the PIDs are not very well defined anywhere.
 

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1. I recently did some logging on my 2010 RT AUTO and noticed that the command afr @ WOT was 11.8. That seems ridiculously rich to me. I liked to see 12.8 on my brand X junk. Is 11.8 too rich and is the only way to set the commanded afr through the CMR software? On a related note, i noted that the LTFT's were in the -1.8 range. Should I reduce fueling in that RPM range?

Never modify your a/f with the handheld unless you know exactly what you are doing and have a trust wideband a/f gauge on there. Some of the aftermarket, cheaper, widebands can be as much as half a point off so if you dial in 12.8, you could actually be running 13.3 from what I've seen. Commanded afr on the HEMI's isn't always what you are going to see the car's motor hit. I know that some of the newer Fords run wideband O2 from the factory and will always correct to the commanded afr but the hemi's don't necessarily work this way. Commanded 11.8 could actually be seeing 12.8 so be careful. The handheld WOT A/F adjustments affect the commanded A/F table, and only at WOT. Any part throttle fuel adjustments have to be made through CMR. If you are seeing -1.8, that would be considered practially dead on on a long term fuel trim.

2. I thought (key word thought) that there was a wide band O2 sensor that could replace/emulate the factory narrow band and act as a wide band as well. Again this was when I was working on Brand X stuff. Has anyone else heard of something like that or did I dream it? I guess there isn't anything like that available for the Challenger. Could I replace one of the rear O2's with a wideband and have a CMR tuner turn them off since I don't have to pass inspection?

You can install a gauge with a wideband O2 sensor in a rear O2 slot and turn off the sensors in CMR since they are there strictly for emissions. Depending on your catalytic converter, you will have to take into consideration that the cats can cause the reading to be leaner than you actually are. I see about half a point on stock cats and really no change at all on high flow cats.

3. I have scoured this and the Diablosport boards for Hemi tuning tips. I have found the best PID's to monitor and such, but haven't really found anyone sharing much detailed info. I know the Predator is limited compared to the HP Tuners suite (thanks to Chrysler) but I am wondering if anyone has any general info to share on tuning the Eagle motors. For example add 1% fuel and 2 degrees spark in the mid range etc... Is the Predator so limited (not knocking Diablosport) that it is best to just run a canned tune and let someone with CMR interpret the logs and tune where they can turn more knobs so to speak? I know there are many great Hemi tuners, but half the fun to me is doing it myself (and being VERY careful along the way).

There's no tricks or safety margins to work with on tuning these engines unfortunately.
In short, those of us that make a living off these vehicles are not going to drive business away by giving away our secrets and knowledge. And free advice is only worth what you pay for it because if you blow up the motor, the person who just told you to make a certain change isn't going to step up and buy you a new motor because they gave you bad advice. The tuning, especially for the variable cam motors, is something that is more complicated than ever and really shouldn't be screwed around with. It should be left to the professionals as HEMI's are not very forgiving... unless you have the money to invest in a stroker motor, then we're all for it. :)

From modifying just with the handheld, you really don't have a lot to gain. You can put your car on the dyno to make sure your a/f is safe and if you run the engine at 11.8 a/f and then lean it out to 12.8 a/f, I'm pretty confident that you won't see one horsepower. But you may see knock retard starting to play a major factor. If you are wanting to mess with the tune, log knock retard and if you consistantly get a few degrees pulled out, take some timing out of your tune in that area - that will probably make you faster. Just make sure that you are removing timing, not adding it and only do it in small increments and log the results each time.

Joshua, HHP
 

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Discussion Starter #7
Thanks for the replies guys. I am in no way trying to become a tuning guru and know that is best left to the experts who have years of experience and major $$$$ worth of equipment. I am just looking to learn more about the HEMI engines and like to tinker with stuff. I am considering adding a wide band and doing a lot of logging. I just want to be educated enough to *maybe* see areas for adjustment and be able to speak intelligently with a REAL tuner. I hate having no knowledge about something and being totally dependent on someone else for advice. If I didn't have a lot of $ (at least for me) invested in the Challenger and it was not my daily driver I would be doing a ton of mods to it myself. I like doing my own work when I can. To me, that's what makes it MY car.

HEMI tuning may be one of those areas that I can't/won't tackle, but I am at least getting educated on the subject a little. I have already learned that 11.8 isn't too rich for a HEMI and KR seems to be a big issue with these engines. Those two things alone make me a lot more comfortable with what I am seeing in my logs. In fact, noticing some long term KR in one of my logs was what prompted this post. I will take Joshua's advice and leave the real tuning to the experts (was going to do that anyway) and concentrate on getting the KR under control. Being able to do that much will give me some sense of accomplishment.
 
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