C5 Personal Tune

Dannenbergcorvette · Post by **Dannenbergcorvette** » Thu Mar 05, 2009 10:26 pm

I have the U7198, v9r10 that I am using on a 2001 C5 Corvette. I have a K&N Filter, BBK throttle body and Corsa X-pipe with the Pace Car Exhaust. I have been trying to understand the Long Term Fuel Trim Bank 1 & 2 that I see "Sticky" talking about. I took my car on a run in 6th gear at 75 miles per hour and couldn't get it above 1600 rpm's (manual). After that I ran it home in 5th gear at about 68 mph and ran about 2200 rpm's.
6th Gear Run:
LTFT Bank 1 - 10.16%
LTFT Bank 2 - 8.59%
Intake Air Temp - 55 Degrees
Spark Advance 33.5
Knock Retard 0.0
Abs. Throttle Pos. 21.5%

5th Gear Run:
LTFT Bank 1 - 7.813
LTFT Bank 2 - 7.813
Intake Air Temp - 53.6
Spark Advance - 38.5
Knock Retard - 0.0
Abs. Throttle Pos. - 21.96

What does all this mean?

The bottom line is - What would a custom tune do for me and do I need one based on the numbers you see above?

Dannenbergcorvette

Post by **06MonteSS** » Thu Mar 05, 2009 10:37 pm

did you record the logs and save them to your PC that you can post up here???

if not, based on the numbers you posted above, and the knowledge of the mods you said you have and other tunes I've done with similarly equipped vettes, I would say you need to adjust your injector slope to -8%... and then you'll be good to go...

Dannenbergcorvette · Post by **Dannenbergcorvette** » Thu Mar 05, 2009 11:42 pm

Thank you for the quick reply. I don't know how to post it. In addition, I don't understand what it is that I am actually affecting by changing "it" to -8. Can you give me a little background into injector slope?

Thanks for your time.

Post by **06MonteSS** » Fri Mar 06, 2009 12:03 am

k... your LTFT's are positive.. Long Term Fuel Trims... when they're positive, that means you are running lean, and the PCM is adding in additional fuel to keep your stoich AFR value at 14.7... and it fluctuates/bounces around...

so, you adjust your injector slope negative (tells the PCM that your injectors to spray more fuel) so that it doesn't have to search around as much to figure out how much fuel to spray....

the more negative the injector slope, the longer amount of time your injectors spray fuel...

the more positive the injector slope, the less amount of time your injectors spray fuel...

if LTFT's (long term fuel trims) are positive, that means you are running lean and the PCM is having to figure out how much fuel to ADD....

if LTFT's (long term fuel trims) are negative, that means you are running rich and the PCM is having to figure out how much fuel to SUBTRACT....

i.e. if you're running lean, your ltft's will be positive--- +8... if you're running rich, you're ltft's would be negative--- -8....

so, the less time the pcm has to spend figuring out what your fueling is doing, that will transend into quicker throttle response, quicker accleration, etc etc...

also, if at WOT (wide open throttle), and your ltft's are positive, the pcm will dump in extra fuel on top of the PE (power enrichment) fueling table, which you DON'T want to happen - cuz then it makes you too rich at WOT and you lose power...

but, if your LTFT's are 0 to slightly negative (i.e. -1 or -2), then the PCM does NOT add any additional fuel on top of the PE fueling table during WOT, so you get better performance/power...

so this is why you want to get your average LTFT's dialed into the correct range of 0 to -2... not only will this give you better throttle response, quicker acceleration, stronger/harder pull at part throttle, but it will also give you more power at WOT since it won't be adding any additional fuel on top of the PE fueling table for WOT....

get it??

Dannenbergcorvette · Post by **Dannenbergcorvette** » Fri Mar 06, 2009 7:27 am

Ok. I understand that I am running lean and I need to make it run a little more rich.

1. I don't know how to actually change the parameter on my U7198 to download it to my car.
2. What other parameters would / should be changed in conjunction with this change?
3. I also downloaded the dslogredux on my pc and when I try to start the program it gives me an error and won't start - What am I doing wrong?

Thanks again for all your help.

Dannenbergcorvette

Post by **06MonteSS** » Fri Mar 06, 2009 9:43 am

are you using windows vista 64 by any chance????

Dannenbergcorvette · Post by **Dannenbergcorvette** » Fri Mar 06, 2009 2:39 pm

No. I am using XP.

Post by **06MonteSS** » Fri Mar 06, 2009 3:35 pm

wow, first time I've heard of that issue with XP.. . I know it doesn't work for Vista 64...

what does it do when you try to start up the app after installing it?? does it give you any kind of error message???

does it do the whole install process ok??

hmmm... have you tried uninstalling it, downloading it again from the site, and then try reinstalling it???

Dannenbergcorvette · Post by **Dannenbergcorvette** » Fri Mar 06, 2009 3:39 pm

I will work on the reinstall. What about actually reprogramming the u7198 to accept the change to-8 for ltft?

Post by **06MonteSS** » Fri Mar 06, 2009 4:12 pm

hook up to your car like you did when you installed the tune before...

select the same tune that you installed before...

then choose Modify Tune...

scroll down to and select Fuel Injectors...

in that submenu, select injector slope...

press the left arrow till the slider gets to -8%...

press the center button to save the adjustment...

then press the ESC button a few times until it asks you "Install tune now?"

answer YES and the adjusted/modified tune will be installed to your car...

Grumpy_Aero_Guy · Post by **Grumpy_Aero_Guy** » Fri Mar 06, 2009 4:23 pm

Dannenbergcorvette wrote:No. I am using XP.

Have not encountered one problem with XP thus far. What is the error? What is it telling you?

Are you installing from an account that has "Administrator" priviliges?

If not, it WILL complain. If NOT, log on to the Administrator account and install from there.

Betcha it will work !

Dannenbergcorvette · Post by **Dannenbergcorvette** » Fri Mar 06, 2009 7:48 pm

Thanks for the info on the tune - I will try it right now.

The error is DSLogRedux has encountered a problem and needs to close. We are sorry for the inconvenience.

If you were in the middle of something, the information you were working on might be lost.

Be right back with re-install comments and new tune.

Dannenbergcorvette

Dannenbergcorvette · Post by **Dannenbergcorvette** » Fri Mar 06, 2009 8:34 pm

Ok - I changed the injector slope to -8. It resulted in the following:

LTFT Bank 1 - 1.78%
LTFT Bank 2 - 0.00%

It did go negative a few times as the vehicle was going up / down a very modest grade.

I think I am getting quicker "throttle response" but it could be just in my head.

Also tried to re-install the DSLogRedux and it didn't work again. Same error message. I will try it on another computer we have

Dannenbergcorvette · Post by **Dannenbergcorvette** » Fri Mar 06, 2009 8:42 pm

I was able to install the program on my other PC. Sweet!

Is the next logical step to go to the Power Enrichment tune??

Not a Predator Question - Can I bypass the throttle body (the coolant running through it) so the incoming air temp is cooler?

Dannenbergcorvette

Post by **06MonteSS** » Fri Mar 06, 2009 9:14 pm

Dannenbergcorvette wrote:Ok - I changed the injector slope to -8. It resulted in the following:

LTFT Bank 1 - 1.78%
LTFT Bank 2 - 0.00%

It did go negative a few times as the vehicle was going up / down a very modest grade.

I think I am getting quicker "throttle response" but it could be just in my head.

Also tried to re-install the DSLogRedux and it didn't work again. Same error message. I will try it on another computer we have

excellent! yeah, quicker throttle response is what you should get, as well as quicker acceleration, stronger/harder pull, and better mileage...

after getting 50-75 miles on the tune with the adjustment, re-check the ltft's again...

after making slope adjustments, you need to drive for 50-75 miles to let the fueling get relearned by the ECM....

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