Ok, so I was thinking about this as I was watching my fuel trims driving today.
The idea is to keep the LTFT's as close to 0 as possible when under WOT right? Wouldn't it be preferable to have the PCM pull fuel out rather than a piggyback in some situations? Let me give an example.
If I have the SAFC pulling -35% fuel out at say 4000rpms & the LTFT is says the PCM is pulling -5%, that's quite a bit of timing being added due to the altered Map signal. This may be bad on low octane & high boost.
Now lets say you are only pulling -15% on the SAFC & the PCM's LTFT says it's pulling -25%. Either example there's -40% total being taken out, but with the PCM pulling more of that fuel in the 2nd senerio, the SAFC isn't having to alter the Map as much therefore keeping the timing down a bit more.
Maybe I'm way off here?
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and a Standalone would solve this by allowing you to change short and or long fuel trims withouth the computer re-adjusting it back to how it should run?
and a Standalone would solve this by allowing you to change short and or long fuel trims withouth the computer re-adjusting it back to how it should run?
A SAFCII or DTEC will allow for corrections/adjustments of the LTFT in either the LO or 25% columns respectively. Just use a scan tool to view the LTFT and use the afc to correct the negative/positive LTFT in the ecu with a corresponding entry in the afc.
FYI,
Marion
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inovate has the system for you! it is a wide band you can program out puts to send back to the computer and trick the ecu they have a great website very informative and videos to boot!
Quote: Originally Posted by -ND4SPD-
Soooo how would someone go about trying to tune the trims in closed loop?
It seems that since there are so many different sensors constantly adjusting everything based on load, speed, temps, O2, etc.... that you can't really account for every situation with something like a SAFC? There's just too many variables?
Also do you just drive down the street at a constant rpm & speed looking at the trims. Then go into the piggyback at that rpm range & make your adjustments?
The Innovate Motorpsorts wideband and data acquisition systems are a very powerful tool, and are one of the most accurate low to mid-range automotive widebands. You can even physically log timing advance now without having to monitor via OBD-II, which might be helpful for anyone using an aftermarket ignition system like an MDS that's taking timing out after the PCM. But you still need something to interface with the OBD-II port to read the fuel trims.
Like a lot of other variables, you can't tune a car alone using just fuel trims, just like you shouldn't use only A/F readings either (although you can and people do). That's where a nice data logging system that you can collect and easily interpret your information can be just as important as the data itself. To make the best adjustments you've also got to look at the big picture and understand how every variable effects other variables and overall operation.
As an example, maybe your A/F looks ok but you have to use a piggyback to pull (remove) excess fuel across the board, and the PCM is adding fuel back in under certain areas as shown in the fuel trims. If you were also getting minor knock from detonation (verified by running race gas and it going away), looking at the data you might come to the conclusion that you need to raise the fuel pressure to richen the mixture while inversely having the piggyback pull less fuel. The A/F may stay the same and look as good as ever, and the fuel trims may even get closer to zero correction. And because you're altering the MAP signal less by not using the piggyback as much to change the signal you may solve the knock/deto issue and have an overall better timing curve. Of course I'd also be looking at other variables like coolant temp, EGT's, and the IAT sensor during all this to make sure other things that could affect the knock threshold are under control.
The best solution right now would be to have a data acquisition system that can log various sensors and external inputs (including the wideband, which is what many of the data logging systems like the Innovate and PLX Devices offer) while also being able to interface with the vehicle's OBD-II diagnostic and sensor data. Unfortunately I don't think you'll find any reasonably priced solutions like this yet. So the best you can do is be able to log and monitor your data as easily as possible for interpretation as a whole. What you do with that data is up to you.
Been doing a lot of reading – AND I have a bit of a dilemma
Anyway Mod are in sig (include PTP 75psi static FPR Mod & SFAC2)
I have a very ruff Idle 13-16afr (LTFT was at +28 when pulling 13% with sfac 800-1200rpm)
Anyway — >Did the battery reset to clear my LTFT and also set sfac to ZERO all the way across RPM board (LO setting)
After about 5min of idle my LTFT was at +25 and STFT was (-2 to +5)
Driving around for ½ an hour did nothing to change this (as while as resetting the battery again), (this is my second PTP FPR the old one was installed incorrectly and had to be removed, anyway I dug up some old data logs from when the old one was installed and the I had the same + LTFT (+26)
Questions:
1. What do you think the problem is?
2. How can this be corrected?
3. Is there any long-term bad side effects from this other then the idle
4. I'm a little confuzed after read all the posts like 3times does not having the LTFT set close to zero change power levels a lot?
Other INFO:
SFAC works great @ WOT and is set up per forum instruction (with MAP) & LO settings set at Th point 20% & Th point 50%
Timing @ idle is +11-16% (at WOT 25-30% pulling 15% with SFAC @ 20PSI and then falling)
oh I checked plugs for signs of Dectonation none there I could see....
Coil, Wires, Plugs are fine (changed) No boost leaks
The vacuum does not change just steady, healthy 20 @ idle
AFR and trim are FINE at WOT and regular driving (althou from my understanding of some of the posts here LTFT will still be used by the PCM at WOT?
Also I tried pulling fuel untell the idle was fine (-38% on safc) and then LTFT was about +32 and STFT was + about 32 idle was fine, but of course from reading all the other posts this is not a good idea and when I shut the car off it clears out STFT and then start it again it idles really, really lean for a bit (by guess would be bad for the car from a cold start)
I didnt read through all of it but now you can add the tempature difference from ambient (sp) temp to the IAT sensor and figure out how it changes the timing as well. There are several factors to use when calculation timing not just fuel trim. What you have said may work very well on one car but much worse on another and the only changes between them could be the weather in your area. Just something to think about, thanks.
I dont really care about the ruff idle it does not bother me a bit, my only consern was after reading all the posts in this thred was if it affects power when they are off...
But anyway my timing seems to be good: 25% @ WOT and then in3 3rd it climes towards redline up to about 28% <<----- this is stock timing levels but I'm runing 21psi falling down to 16psi with an AFR of about 11.8
Anywho I'll just contine to tune and learn as I go...
Been doing a lot of reading – AND I have a bit of a dilemma
Anyway Mod are in sig (include PTP 75psi static FPR Mod & SFAC2)
I have a very ruff Idle 13-16afr (LTFT was at +28 when pulling 13% with sfac 800-1200rpm)
Anyway — >Did the battery reset to clear my LTFT and also set sfac to ZERO all the way across RPM board (LO setting)
After about 5min of idle my LTFT was at +25 and STFT was (-2 to +5)
Driving around for ½ an hour did nothing to change this (as while as resetting the battery again), (this is my second PTP FPR the old one was installed incorrectly and had to be removed, anyway I dug up some old data logs from when the old one was installed and the I had the same + LTFT (+26)
Questions:
1. What do you think the problem is?
2. How can this be corrected?
3. Is there any long-term bad side effects from this other then the idle
4. I'm a little confuzed after read all the posts like 3times does not having the LTFT set close to zero change power levels a lot?
Other INFO:
SFAC works great @ WOT and is set up per forum instruction (with MAP) & LO settings set at Th point 20% & Th point 50%
Timing @ idle is +11-16% (at WOT 25-30% pulling 15% with SFAC @ 20PSI and then falling)
oh I checked plugs for signs of Dectonation none there I could see....
Coil, Wires, Plugs are fine (changed) No boost leaks
The vacuum does not change just steady, healthy 20 @ idle
AFR and trim are FINE at WOT and regular driving (althou from my understanding of some of the posts here LTFT will still be used by the PCM at WOT?
Also I tried pulling fuel untell the idle was fine (-38% on safc) and then LTFT was about +32 and STFT was + about 32 idle was fine, but of course from reading all the other posts this is not a good idea and when I shut the car off it clears out STFT and then start it again it idles really, really lean for a bit (by guess would be bad for the car from a cold start)
SORRY FOR LONG POST! REALLY
your pulling fuel when your LTFT is +25?????
do you not know what a + means
somethings goofy with your car if its adding +25 or more to the LTFT
Been doing a lot of reading – AND I have a bit of a dilemma
Anyway Mod are in sig (include PTP 75psi static FPR Mod & SFAC2)
I have a very ruff Idle 13-16afr (LTFT was at +28 when pulling 13% with sfac 800-1200rpm)
Anyway — >Did the battery reset to clear my LTFT and also set sfac to ZERO all the way across RPM board (LO setting)
After about 5min of idle my LTFT was at +25 and STFT was (-2 to +5)
Driving around for ½ an hour did nothing to change this (as while as resetting the battery again), (this is my second PTP FPR the old one was installed incorrectly and had to be removed, anyway I dug up some old data logs from when the old one was installed and the I had the same + LTFT (+26)
Questions:
1. What do you think the problem is?
2. How can this be corrected?
3. Is there any long-term bad side effects from this other then the idle
4. I'm a little confuzed after read all the posts like 3times does not having the LTFT set close to zero change power levels a lot?
Other INFO:
SFAC works great @ WOT and is set up per forum instruction (with MAP) & LO settings set at Th point 20% & Th point 50%
Timing @ idle is +11-16% (at WOT 25-30% pulling 15% with SFAC @ 20PSI and then falling)
oh I checked plugs for signs of Dectonation none there I could see....
Coil, Wires, Plugs are fine (changed) No boost leaks
The vacuum does not change just steady, healthy 20 @ idle
AFR and trim are FINE at WOT and regular driving (althou from my understanding of some of the posts here LTFT will still be used by the PCM at WOT?
Also I tried pulling fuel untell the idle was fine (-38% on safc) and then LTFT was about +32 and STFT was + about 32 idle was fine, but of course from reading all the other posts this is not a good idea and when I shut the car off it clears out STFT and then start it again it idles really, really lean for a bit (by guess would be bad for the car from a cold start)
SORRY FOR LONG POST! REALLY
your pulling fuel when your LTFT is +25?????
do you not know what a + means
somethings goofy with your car if its adding +25 or more to the LTFT
interesting who is helping you tune your car?
Thanks for the post I forgot about this post~~
I’m just tuning myself by doing research on what’s safe (ish) trying to keep it within those parameters and get the most power with out having to “push” it to much—
About my LTFT, I’m still learning and about this stuff but anyway, I reset my LO sfac settings to Zero all thou the RPM band (LO setting only) and now my LTFT is about 7-10 at an Idle and it goes to Zero or –7 when regular driving.
The only problem is my idle it should be in the (-) LTFT with my fuel mods/fuel, I’ve tried a lot to fix
Changed PTP FPR
Swapped out to old coil
New plugs
New plug wires
Only ever put good gas so not that
Checked my FPR more then once….
Just can’t get the idle to be smooth, and its not that it has to much fuel because it LTFT is (+) at idle but at the same time I’m getting enough fuel at WOT and cruise…
I’m checked around the wires everything seems ok, its only done this since my PTP FPR install so has to be something to do with that.
Anyway I gave up (thought about swapping my injectors out but figured if one was bad would affect cruise and WOT)___ its just a large AFR sweep and a miss or stumble (exhaust makes little pops)
Thanks for your help though it is appreciated, if you have any ideas id love to hear them!
I am running S3R w/toys and am considering a DTEC FCBC to sqeeze out a few more ponies when on pump gas and do some data logging etc. Thanks to all that have posted in this thread so far, great info. Just have a few questions to make sure I understand it all.
1. STFT and LTFT only affect closed loop ECU ops correct? They do not change the amount of fuel during open loop ECU ops, that is done only with the preprogrammed open loop maps in the S3R ECU correct?
2. If I were to go up to 750cc injectors (Deatch Works) to get a little more fuel would the S3R ECU be able to adjust fuel trims to maintain smooth closed loop ops since the injectors only flow 9% more fuel than the s2/3 682cc's?
Thanks for any thoughts and advice,
Phil
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2004 Silver SRT-4 Stage 3, best run 12.9@113.6 -- Gone
Now I have 700hp 720ftlbs sitting in my driveway...STOCK
First i want to say thanks to all ya'll out there putn this good info on these threads. helpn me out a lot.
My srt4 has been of the road for bout 3 1/2 months due to crystlizes antifreeze in the water ports to the head. In turn over heating the head maken it warp. So while i had it apart i went ahead and built the top end. I had it machined, then i ported in./ex. ports, got BC valves, DCR springs, crane 16 cams. I have stage 2 (pcm, sensors, 682cc inj.). I have also swaped to the AGP 50 trim goodies. Including all the other stuff in sig. But ive been driven the car gently, every once in a while i getn on her a lil. Say 6-9psi just to see what the A/F gauge is readn. So at idle its around 14.7 like it should be (bouncing a lil because if the lope anlong with vac. bouncing at 11-13 in vaccum). But in boost its still in the 14s leaning out like crazy dont exactly know why. So needless to say i dont do that very often if anymore until I get it right. Also hesatates during normal acc. when cold (guessn o2 sensors not at running temp. giving in accurate signal for fuel demand maybe cam timing might have somen to do with it too not sure). But when warm seems to be ok. I figure 682 inj. good for bout 15-17psi depending on tune but obviously havent got the chance to tune it.
Basicly my questions are:
1. Why would the stage 2 pcm keep the A/F so lean?
2. Why hesatation when cold?
3. If this is common will a fuel contoller cure this issue?
NOTE:
Do not have fuel controller (probably a SAFC NEO) but getn one in the next week or soo.
BOUGHT CAR USED AND IT HAS THIS BLACK WIRE THAT APEARS TO GO TO THE BLACK PCM PLUG (BOTTOM PLUG) WHICH IS CUT DONT KNOW WHERE IT WENT TO OR WHAT IT WENT TOO HAVENT FULLY DIAGNOSED THIS YET.
does anyone else have any problems with oil pressure switch leakn and i got alot alot alot of srt4 stuff FS pm me if interested im needn money haha
Getting no love in a separate thread...here's the skinny. Big turbo 650 injectors returnline at 46psi static LC-1 wideband SAFCI etc etc etc. At idle the car is 14.7 all day long and lovin it. On the freeway it drops down to 13.8-14.2 and stays there...won't go back up to 14.7 at all. I've gone from pulling 5% in my low throttle settings from 1000-3000rpms to now pulling 20% and there's not one bit of change. Any thoughts?
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My srt4 has been of the road for bout 3 1/2 months due to crystlizes antifreeze in the water ports to the head. In turn over heating the head maken it warp.
It's nice to bump the thread for others to see, but since the questions aren't related to fuel trims it might be best to start a thread in another section. With that said, I'm not sure what you're talking about that happened to your engine. Was your water-to-coolant mixture off so much that you had pure water and it froze and cracked something or did you run low on coolant, get air in the system, and overheated the car warping the head? Whatever the cause, if you lost a head gasket and the head was warped you probably burned coolant or had some go out the exhaust. The silicate in the coolant will ruin your stock O2 sensors and cause the sensing cell in them to not work correctly. If you didn't change them you probably want to. Stick with the dealer or try to get an NTK sensor (they have a faster switching/response rate than Bosch narrowband O2's).
If you're building boost at partial or low throttle it probably will stay a little lean but should go a lot richer if you're at WOT. If it's that lean under full throttle you've probably got other issues. Since you bought the car used and it's modified and has a possibly cut/damaged wire who knows what else is wrong. The first thing you should do is go over the car with a fine tooth comb and sort out any problems or issues before trying to throw parts at it. If you're not sure what to look for then I'd try to find another knowledgeable owner in your area or a shop that's really experienced with the SRT-4's.
Quote: Originally Posted by Turbocruiser13
Getting no love in a separate thread...here's the skinny. Big turbo 650 injectors returnline at 46psi static LC-1 wideband SAFCI etc etc etc. At idle the car is 14.7 all day long and lovin it. On the freeway it drops down to 13.8-14.2 and stays there...won't go back up to 14.7 at all. I've gone from pulling 5% in my low throttle settings from 1000-3000rpms to now pulling 20% and there's not one bit of change. Any thoughts?
There's nothing to say that it will always cruise at 14.7:1 at idle and under light load cruising conditions. Just like if you're watching fuel trims they will always be at zero on a stock car. If you're in closed loop mode at cruise (using the O2 feedback) there's a lot of variables such as the computer's programming, O2 sensor age, other sensor inputs, etc. that will determine how rich or lean it runs. If you haven't free air calibrated your wideband in a while that would also be another thing to verify. And for those who don't have an Innovate or the newer TurboXS wideband's that can be free air calibrated to compensate for sensor age your wideband can be off up to a point or more as they age.
Thanks in advance for any info.
helpn me out a lot.
. So while i had it apart i went ahead and built the top end. I had it machined, then i ported in./ex. ports, got BC valves, DCR springs, crane 16 cams. I have stage 2 (pcm, sensors, 682cc inj.). I have also swaped to the AGP 50 trim goodies. Including all the other stuff in sig. But ive been driven the car gently, every once in a while i getn on her a lil. Say 6-9psi just to see what the A/F gauge is readn. So at idle its around 14.7 like it should be (bouncing a lil because if the lope anlong with vac. bouncing at 11-13 in vaccum). But in boost its still in the 14s leaning out like crazy dont exactly know why. So needless to say i dont do that very often if anymore until I get it right. Also hesatates during normal acc. when cold (guessn o2 sensors not at running temp. giving in accurate signal for fuel demand maybe cam timing might have somen to do with it too not sure). But when warm seems to be ok. I figure 682 inj. good for bout 15-17psi depending on tune but obviously havent got the chance to tune it.
Linear Mode
