Just would like to say that in the last week I have learned alot from this forum on the LNF.
I appreciate all of the info that is here....

On that note, I would like to know exactly where the LTFT's and STFT's should be with our engines for enhanced performance. From what I can gather, am I correct in assuming that the LTFT's should be @ 0 or more on the + side, rather than the - side???
I have an 08 HHR SS Auto w/PPC tune. I have noticed that when I clear codes, that upon startup my LTFT's will start @ 0 on the Aeroforce gauge and that the engine responds much better, I imagine because it is running richer. As I continue to drive over a period of a day or so, my LTFT's start to climb up to about a + 14 to a +18 depending on where I am driving, highway driving as opposed to city driving. Would the same settings hold true for the STFT's as well?
I also check the KR, Timing and other parameters, but need to know exactly in what range they should be at for increased performance. So any guidance on where to obtain this info would be great.
I also have a blank ECM for the SS, that would need the GM software installed, was wondering if any of the tuners can install that program with my serial #, then add their tune to it, that way if I want to change out ECM's, it should be a snap.

I also placed an order with Forge for their BPV, which is on backorder until the end of next week. I am anxious to get that installed as per the reviews on this forum and the fact that I have had the P2261 code a number of times over the last year. I also have the Dejon spring installed, which may over time cause the valve to be stuck in the closed position and thus setting the code at times.

I also need to learn how to datalog, I also have the DashHawk, but it is disconnnected at this time. If there is an adapter out there where I can use the DashHawk and the AeroFroce gauges at the same time, let me know, or if I can spice one gauge into the other, so there would be one connection, that would be the way to go.

Know I am asking alot, but you guys seem to have all of the answers

Thanks again............................................. ...........................Tom

 

Yes, with LTFT/STFT, the closer to 0, the better. If you have to be off, negative is better, meaning that you're a bit rich and that the ECU is subtracting fuel. Being within 5 is nice, being within 10 is considered highly recommended for good driveability. Once you get to 15, you may throw a code, due to it being so off.

Knock: 0. All the time.

Timing: Depends. As long as you aren't getting knock.

If your fuel trims are that off, I would highly recommend getting a custom tune. It will have better driveability, safer on the engine, and faster when you can get those fuel trims under control.

 

Your ltfts reset when you clear the codes or disconnect the battery or flash a new tune, you need to have your maf calibrated since it is straying positive over time, this is no good for perfornance and can cause kr! That ppc tune is garbage you need to find a REPUTABLE hptuner such as terminator2 or byt ss turbo. The dejon spring is crap

 

FYI - This particular ECU (Bosch E69) likes to run with the STFT's in the -0.8 to -1.6 range and will pull the LTFT's around until it gets the STFT's there. For that reason I tune for my LTFT's to run a wee bit positive, around 0.8 to 1.6 so that they null out with the STFT's.

As was posted earlier, if they have to be off, it's better to err slightly negative, that means it's a bit rich and pulling some fuel.

If yor spare ECU has never been programmed, you need it flashed initially with a Tech II at a shop or dealer that has access to one.

 

thanks for the info, always learning.....is it possible with the BPV not working properly to alter the LTFT's? I have to take note of the other parameters and see how they are in conjunction with everything else. I am sure that you are right in getting a custom tune, but I want to install the new BPV when it arrives before I go with another tune.
BTW, enjoying your thread on the EVAP Purge Solenoid........thanks again.....

Your advice is also well taken.....hptune sounds like the way to go with one of the two people that you mentioned.......thanks

Some more good advice, it is appreciated..... No, the spare ECU has never been programed. Have to see if any dealer in the area would do it, or just find someone who has a Tech II. I will have to check out my STFT's and see where they are and take more notes.....
I just have to learn to datalog, I am sure it would make things easier.........

 

I utilized this info as well thanks all

 

are you running a k&n in the car because rallycobalt06 had the same problem when he add his filter after the car was already tuned

 

Not to thread jack but i also have a few questions on this matter. I monitored the car on the dashhawk on the way home. The LTFT's never went above +8.6% the STFT's usually ran in the low negatives except on a WOT pull in jumped to a -30%+.

Mod are K&N sri, charge pipes, MPx i/c, catted dp, and hahn exhaust, HPtune. Now before any questons are asked, NO i have not had it retuned since i put the intake on, the car was tuned with just the k&n drop-in. Thanks for any help on this guys

robk

 

LTFTs are what is most important here. if they are showing +8.6% then your in the clear, just running alittle too lean for my liking. Its not till LTFTs hit like 18%+ that CELs start appearing.

also when you say jump... does the STFTs jump and then hold? might be why your LTFTs are leaning towards the positive.

 

haven't post on here in a while, no not running a K&N filter anymore, but found out that the K&N was not the problem......my fuel line was leaking and causing all types of problems.....it wasn't until I replaced the line that it started running good again. (I know CudaJoe is answering "robk" in his response, but this is what my LTFT's are doing now) I also put back in the BSR tune and the LTFT's have fell right into line, have been as low as 4.6 high as 9.2, usually runs in the 5.6 or 6.2 area, so the BSR tune seems to be fine. I still loose boost after a heavy pull, which throws a P0234 overboost code, but I believe it is the Turbo Bypass solenoid that is defective, I should be changing that out in a few weeks. Other than that the HHR SS is running fine and getting great gas mileage at that. Approcahing 79,000 miles, I have the bug for another C3 Vette (81-82) for a DD, so I am looking to either sell or trade the SS for one of those, so we shall see what happens....

 

The LT or ST number is just the correction it is applying to the table. It isn't actually running rich or lean.. Its just commanding in that direction and applying the change to bring it back to the commanded AFR.

 

What I've learned during experimentation and from others teachings is that the closer your trims/MAF tune are to being "in-line", the less likely chance the ecm will over shoot the correction. Really helps with keeping the random kr minimized and throttle response peppy.