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Are these readings while cruising, part throttle or wot?
Not sure. I had been assuming ST was additive (to LT), meaning that a WOT condition (ST) would add that temporary positive value to the average value (LT).
You will need to do some data logging to really see what your ST is doing because it is constantly changing. It can be -8 one second and +8 the next. STFTs will be all over the place during acceleration. At idle, when the car is warm, ST should stay close to 0%.
heres 2 examples, one is good, the top one which is a 273 engine on an 221 s 550 w/ 130k mi.
The other is mine lol, i guess the cel was disabled from being turned on, on the cluster. They are quite a ways out, looks like i have a problem too damn it, more work i didnt need.
Theres no listing for short term adaptations with the sds. Short terms aren't important and are constantly going to be changing as that is instantaneous fine tuning. Lets say your car needs 10 more fuel units, first stft will make the instant correction, slowly overtime as it sits with 10 more fuel units the long term will start to climb and allow the short term to go back to zero.
These are both long term values on the sds. The idle one has a larger range as the idle range is much more sensitive as less fuel is being consumed. The mid/upper load has a much smaller threshold because it really shouldnt be changing much and a larger amount of fuel is being used so a smaller change nets larger results.
Last edited by roadtalontsi; Jan 7, 2015 at 12:36 AM.
Timing will sometimes spike like that when I let off the accelerator quickly after WOT. I think it is just a quirk in how the app reads the data, as I was told timing does not actually go that high. The highest timing I have recorded with my foot in the pedal was 29-30 degrees with a tune for E85.
You will need to do some data logging to really see what your ST is doing because it is constantly changing. It can be -8 one second and +8 the next. STFTs will be all over the place during acceleration. At idle, when the car is warm, ST should stay close to 0%.
+1
I still think his trims are normal for a tuned C63.
These are my fuel trims on my Caddy via Dashboss while idling and than some light acceleration.
The car idles and drives perfect but as you can see the trims jump around. At wot, the trims should read 0 if the tune is correct. I expect a C63 to be similar.
Caddy probably goes into open loop at wot while the c63 will stay in closed loop and use O2 feedback so the trims will still move around.
short terms are always going to bounce around that's what they do. Is the caddy mass air flow or speed density the tuning is totally different? not to mention the ecu and it's algorithms and tuning trims are going to be totally different. Personally i wish it was the same as gm so i could use my 500$ efi live tuner. Comparing a 500hp n/a motor to a supercharged 500hp engine of similer size is 2 totally different animals. One is working its *** of with high compression, the other is hardly being stressed with a few pounds of boost.
short terms are always going to bounce around that's what they do. Is the caddy mass air flow or speed density the tuning is totally different? not to mention the ecu and it's algorithms and tuning trims are going to be totally different. Personally i wish it was the same as gm so i could use my 500$ efi live tuner. Comparing a 500hp n/a motor to a supercharged 500hp engine of similer size is 2 totally different animals. One is working its *** of with high compression, the other is hardly being stressed with a few pounds of boost.
It's mass air. I use HP Tuners but I'm still learning. My tune was done by a professional and I make very minor tweaks. I love being able log and make changes so easily, something I couldn't do with my C63.
Hi
I know this is a old thread, but I have an momentarily power loss (Jerk) on my Mercedes Sl55 AMG R230, almost like the fuel pressure is lost for a millisecond, this is intermittent.
I have educated my self some what about fuel trims in % against rpm. I have access to STAR XENTRY system, which I find overwhelming, and cannot find STFT & LTFT menu. The next best thing I can find is self adaption values in ms.
So have attached photos with car in idle, then in a higher rpm, can anyone please advise what the readings are saying, and if it gives any clues to the issue with the car ?
Is any other tests I should be doing, as the Quick Test on STAR is showing no errors, and clearly something is going on
!
The quick test may be insufficient. Go to modules and test them individual, start with the engine control unit .
There is no short or long trim that the ECU cares about. There is a self adaptation for fueling that is shown above.
I personally think that even people that think they may know something about fuel injection, have to start from scratch with full time closed loops cars. I think full time closed loop cars may not need trims. The question is, if they don't and the ECU doesn't even have trim tables, then what are the OBD2 scanners showing under trims? Maybe whatever it is they show should be disregarded...
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damn it, more work i didnt need.
