My LTFT at low RPM seem kinda high after going through the tutorial on the wiki for changing injectors. I'm running DW 750's at 58psi FP with an AGP Return line. They're around +14 to +20 range from idle to about 2500 rpm, then they don't really go above +5. I had a nasty stumble at 2000 rpm when running 43psi but now that I've bumped it up to 58psi its moved to about 1500 rpm and is not as bad.
Now for the question. What would cause this at low RPM only? Is it my injectors pushing a lot more fuel during low Pulse widths then what i told it to compensate by?
My LTFT at low RPM seem kinda high after going through the tutorial on the wiki for changing injectors. I'm running DW 750's at 58psi FP with an AGP Return line. They're around +14 to +20 range from idle to about 2500 rpm, then they don't really go above +5. I had a nasty stumble at 2000 rpm when running 43psi but now that I've bumped it up to 58psi its moved to about 1500 rpm and is not as bad.
Now for the question. What would cause this at low RPM only? Is it my injectors pushing a lot more fuel during low Pulse widths then what i told it to compensate by?
It could multiple different things... Your fuel mass tables may be incorrect or your VE table at those RPM's may be off.
Have you tweaked your VE table at all yet? I find it rather strange that the PCM is adding fuel with those 750's after nothing more than a fuel mass correction... Are you sure your fuel mass tables are correct? Have you tweaked anything else that related to fuel?
__________________
- Nick Chestnut
* 2004 Dodge SRT-4, GT3076R, SCT Tune, 408 WHP w/o SCT and waiting on new numbers with SCT!
"Don't argue with an idiot. They bring you down to their level and beat you with experience." - Unknown
My LTFT at low RPM seem kinda high after going through the tutorial on the wiki for changing injectors. I'm running DW 750's at 58psi FP with an AGP Return line. They're around +14 to +20 range from idle to about 2500 rpm, then they don't really go above +5. I had a nasty stumble at 2000 rpm when running 43psi but now that I've bumped it up to 58psi its moved to about 1500 rpm and is not as bad.
Now for the question. What would cause this at low RPM only? Is it my injectors pushing a lot more fuel during low Pulse widths then what i told it to compensate by?
On the low end, I noticed I had pull fuel in the low end (after adding fuel) to get the fuel trims correct in the fuel mass table. Top end, I am still working on it. I won't be able to continue until monday though. Once I am done, I am posting my work up... That was a lot of work. I don't know when it's going to be done though.
I haven't touched anything else yet. I'm really trying to do one thing at a time so I don't have to trouble shoot too many changes at once. I haven't even set it up for rising rate yet.
On the low end, I noticed I had pull fuel in the low end (after adding fuel) to get the fuel trims correct in the fuel mass table. Top end, I am still working on it. I won't be able to continue until monday though. Once I am done, I am posting my work up... That was a lot of work. I don't know when it's going to be done though.
hmmm in my case it looks like i'd have to add more fuel so i'll have to lower my multiplier. I made a nice little spreadsheet that does all the work for me
hmmm in my case it looks like i'd have to add more fuel so i'll have to lower my multiplier. I made a nice little spreadsheet that does all the work for me
Exactly. You add fuel for the computer to see by decreasing the multiplier
This is a stupid question, but did you try resetting the ECU? Like actually unplugging the negative from the battery and leaving it unplugged for a while?
I had a similar issue, thinking that every time I falshed the ECU was getting reset, and it kind of is, but its not resetting teh LTFT's. After I reset it, my fuel trims went from 20+ to +5 and have been there for a while ( I could probably tune them closer to 0, but I don't really care since the car drives so nice now).
Sorry if you already tried that step, Im just throwing it out there
hmmm in my case it looks like i'd have to add more fuel so i'll have to lower my multiplier. I made a nice little spreadsheet that does all the work for me
Want to share it with everyone? I can add .xls files as a supported filetype on the wiki so you can upload and host it there if you would like
This is a stupid question, but did you try resetting the ECU? Like actually unplugging the negative from the battery and leaving it unplugged for a while?
I had a similar issue, thinking that every time I falshed the ECU was getting reset, and it kind of is, but its not resetting teh LTFT's. After I reset it, my fuel trims went from 20+ to +5 and have been there for a while ( I could probably tune them closer to 0, but I don't really care since the car drives so nice now).
Sorry if you already tried that step, Im just throwing it out there
Nick
That is absolutely correct, everyone needs to know this, you have to disconnect the battery or if your scanner has the capability reset the LTFT everytime you make a change.
A better way would be to lock out of closed loop to prevent LTFT from affecting anything and just work with the STFT.
you guys are spot on about resetting the battery, I've already had figured that out the hard way. I made some changes and was totally confused as to why my LTFT hadn't moved as much as they should have, so I pulled over disconnected the battery while I went for coffee
How are you guys locking out the closed loop? I was thinking about it and the only thing I can come up with would be to change the Min coolant Temp for Closed Loop value to it would never hit.
As for my spreadsheet its kinda only useful to people runing my ECU code but i'll clean it up and post it if you'd like.
I also have been unplugging the battery everytime I tune. I am also curious how you lock it out of the LTFT's. That would be useful since that is what I am working on right now. Thanks :-)
to attach files you have to be an upgraded member ...
and probably mtf files would have to be added to the list of correct extension
Well when posting the file, just inform that you are changing from xxxx.mtf to xxxx.gif so whoever downloads it has to switch it back... this will allow you to post it up.... i'm pretty sure you can share zips though too...
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Ltft?
but not like the stock one
Linear Mode
