I am new around here but I have a few questions and want to get everyone's opinion. I have a 2006 Grand Prix GXP that I bought new and just turned up 75,000 miles on (Still original trans cross fingers) I recently purchased a Hogan catless DP and Magnaflow exhaust and had previously installed a K&N CAI three years ago.

After the DP and exhaust install I contacted Lew to get the car tuned using my Predator. After doing some data logging my LTFTs were in the plus 10 range. Lew indicated that this was not normal. He made me a no dod 93 octane tune. I had data logged before the DP and Exhaust and the LTFTs were at like plus 7.

Lew asked me to check the CAI and the exhaust for leaks and I found everything to be tight. I then cleaned the MAF which was very dirty. There was a black film or residue almost like soot on the MAF screen so I cleaned it with MAF cleaner and put it back and cleaned the throttle body with TB cleaner as best I could without removing it. I disconnected the battery and drove it to re learn with the clean MAF and data logged again.

On the new data log the LTFTs were between 3 and 4. I sent this to Lew and he advised me that the numbers still seemed high. This time instead of changing the injector slope he adjusted the MAF tables.

After driving it today and observing the LTFTs it seems they are in line at around zero.

My question is: Is a plus 10 LTFT really high or could there be something else wrong. Should I look at replacing my MAF or front O2 sensor (side note when I put the downpipe on I noted the front O2 sensor looked pretty black and sooty as did the entire inside of the exhaust) The car seems to run great I just want it to run its best. I am very happy with the new mods I just want to get it dialed in 100%

Lew has been a big help and is great to deal with. Sorry for the long post.

 

My car has similar numbers, and I also have a Lew tune. It was waay worse before he tuned it. Some of these cars just run very lean and we have to live with it.

As a side note, the stock tune in my Camaro is showing LTFTs of +13 to +23. Can't wait to get Lew to tune that!

 

Lew tuned my Monte as well and I have similar numbers. I think it's just the nature of the LS4, like LS1 Racing said.

 

depends on mods, location/elevation/altitude, etc... cuz my monte is not like that, with high ltft's... mine were about +4 to +5 before my tune... all I have for engine mods is the coldairinductions CAI and the IAT sensor relocate...

and in regards to his post.. with his ltft's at +3 to +4... that would have been good if I hadn't made adjustments already, heh.. so that's why I said it was still a little high.... I had made adjustments already of -5 or -6... so then at +3 and +4 still, I would have had to adjust to -8 to -10... which is too much for these cars going the injector slope route... it makes them a dog and pig rich....

so, I set those back to stock and adjusted the MAF sensor table instead, and voila!

ls1 and jessmo... we may want to take another look at your tunes to see if I did the MAF sensor tables on yours or not... I don't remember...

 

Thanks, Lew! Let me know if I have a new file coming my way!

 

I'm pretty sure you adjusted the MAF sensor tables due to my LTFT being on the high side after installing my catless dp. I haven't sent a new data log for you to review after the new tune but my car is going into hibernation in a couple weeks so I might just wait until Spring to send that to you.

Did you get your power back on yet?

 

Thanks guys you are making me feel better that I am not the only one with this issue.

Lew you are the man and I will get you some new data logs soon!

It is great to have a forum where people are actually nice and very helpful.

Thanks again!

 

Mine jumps significantly when i use 94 oct gas , with a canned ds tune and 91 oct im +1 - +2. With 94 it jumps as high as +7

 

ok who is lew and where is he ?

 

06monteSS post #4