Long Term Fuel Trim = 0.0%, always
05-19-2015 | 10:29 AM
#22
Thanks again for everyone's thoughts. The cam is a Comp Cam 229/239 .627"/.621" 111.5+3. TrickFlow 220s, FAST 102 with a LS2 90mm TB (ported).
coSPEED, I'll have to look more at "forcing" closed loop when you say
I thought I was in closed loop b/c I have rear 02s but that may just show I don't know much about open vs. closed loop and forcing things.
I do plan on changing out the 02s and plugs. I've also read that my deka 60lb injectors are problematic and may need the minimum injector pulse reduced.
Question: my 02s get their sensor and heater "grounds" from the PCM. As a test, can I run those straight to a known good ground?
coSPEED, I'll have to look more at "forcing" closed loop when you say
If you force the car into closed loop via the live hpt controls, you will see them change. They are likely not registering because the car is somewhat smart enough to know when you have insufficient switching and stay on open loop. change the spark plugs and O2s with new and start over.
I do plan on changing out the 02s and plugs. I've also read that my deka 60lb injectors are problematic and may need the minimum injector pulse reduced.
Question: my 02s get their sensor and heater "grounds" from the PCM. As a test, can I run those straight to a known good ground?
05-19-2015 | 07:34 PM
#23
No. do not do that. the sensor doesnt ground like that. Check your sensor fuses under the hood.
otherwise force the car in closed loop with hp tuners and see what happens. but also turn it back in in the tune.
otherwise force the car in closed loop with hp tuners and see what happens. but also turn it back in in the tune.
05-19-2015 | 07:56 PM
#24
I'll look into forcing closed loop. I'm also going to test all 4 wires on both front sensors for resistance back to the PCM. Same with the grounds from the block to the PCM.
? I've also read things may not reset until 3 cold starts and a full tank of gas(?)
05-28-2015 | 08:34 PM
#26
I put in 2 new AC Delco O2 sensors just for the heck of it. I used VCM Scanner to "force" closed loop. Still no LTFTs.
O2 wiring tests: I tested both continuity and resistance of all four wires (from the O2 end of the extensions back to the PCM and, for the heater (+) wire, from the O2 back to the fuse box) and all tested continuous and .2 or .3 Ohms resistance. I also tested the O2 extensions themselves and they showed continuous and .2 or .3 Ohms resistance.
I applied the tune to a different OEM ECU/PCM and that didn't solve anything either, so it's not the ECU/PCM.
Still no LTFT values (when the engine is over 115 degrees or otherwise)... STFTs are at like -1.8 and O2 hz are around 825 each. I'm at a loss.
O2 wiring tests: I tested both continuity and resistance of all four wires (from the O2 end of the extensions back to the PCM and, for the heater (+) wire, from the O2 back to the fuse box) and all tested continuous and .2 or .3 Ohms resistance. I also tested the O2 extensions themselves and they showed continuous and .2 or .3 Ohms resistance.
I applied the tune to a different OEM ECU/PCM and that didn't solve anything either, so it's not the ECU/PCM.
Still no LTFT values (when the engine is over 115 degrees or otherwise)... STFTs are at like -1.8 and O2 hz are around 825 each. I'm at a loss.
05-28-2015 | 08:42 PM
#27
change the tune then. add 4 to the ve table. see what happens. at -1.8 stft the ltfts don't have to show anything.
by hz you mean voltage right? the fronts should oscillate between 950 and 200 or so. back and forth. the rears (if you have cats) will nearly stay static. they can vary their voltage range by a little.
I've had to use both pids turned on to force the computer to comply before. why dont you post up a scan?
by hz you mean voltage right? the fronts should oscillate between 950 and 200 or so. back and forth. the rears (if you have cats) will nearly stay static. they can vary their voltage range by a little.
I've had to use both pids turned on to force the computer to comply before. why dont you post up a scan?
05-28-2015 | 09:13 PM
#28
I can't tell you how much I appreciate the feedback.
Yeah, I should have said mV instead of hz. I only see the mV change from mid 700s to high 800s, never lower. Couldn't that be a consequence of being very, very rich? Rear O2s are there but turned off.
I'm new to HPT & know how to add pre-defined PIDs - what do you mean by 'use both PIDs turned on'?
If I put aside the lack of LTFTs - and considering I'm not getting any MILs - my issue with intermittent surging coming off the throttle could be related to my Deka 60lb injectors' tune which, reading Greg Banish's posts on HPTuners.com, could definitely be off.
Yeah, I should have said mV instead of hz. I only see the mV change from mid 700s to high 800s, never lower. Couldn't that be a consequence of being very, very rich? Rear O2s are there but turned off.
If I put aside the lack of LTFTs - and considering I'm not getting any MILs - my issue with intermittent surging coming off the throttle could be related to my Deka 60lb injectors' tune which, reading Greg Banish's posts on HPTuners.com, could definitely be off.
05-28-2015 | 09:41 PM
#29
Dont get stuck on that until you can fix the issue with your fuel trims.
ideally you can use a wideband to tune your fuel trims but i dont like that path honestly. too many variables.
i did not mean pids i meant parameters. you must "green box" both fuel trim learn and closed loop in the vcm controls > fuel/spark tab. The short term fuel trims would at least be at -18 to -25 if they noticed a rich condition. if they are working also.
ideally you can use a wideband to tune your fuel trims but i dont like that path honestly. too many variables.
i did not mean pids i meant parameters. you must "green box" both fuel trim learn and closed loop in the vcm controls > fuel/spark tab. The short term fuel trims would at least be at -18 to -25 if they noticed a rich condition. if they are working also.
05-29-2015 | 12:37 AM
#30
Post your tune and a log using the Imperial default config. We'll get to the config eventually, but for now I'd like to see what your PCM is doing.
I'd leave LTFTs off. I'd leave closed loop off as well until you can use a wideband to tune your fueling - you can use STFT/LTFT to tune, but it's only when PE mode is not active in the lower load/rpm ranges. And you can use your narrow bands to tune idle.
I'll look at your 60lbs injector data. I'll see if it's right. If the IPW is too high, there's a couple of things that we can change to get it down.
I'd leave LTFTs off. I'd leave closed loop off as well until you can use a wideband to tune your fueling - you can use STFT/LTFT to tune, but it's only when PE mode is not active in the lower load/rpm ranges. And you can use your narrow bands to tune idle.
I'll look at your 60lbs injector data. I'll see if it's right. If the IPW is too high, there's a couple of things that we can change to get it down.
05-29-2015 | 06:24 AM
#32
Jesus why are people replying with "answers" that are completely incorrect.
LTFTs are commonly turned off so you don't get any rogue locked fueling adjustments at WOT and it keeps it more consistent that way. If you have STFTs that are updating but no LTFTs then that is more than likely the case. I have never seen nor heard of anybody turning off LTFTs to prevent "false trimming" of rich idle conditions, especially since your STFTs will also adjust fueling. Also LTFTs update just about immediately when in closed loop unless they are turned off, no time or mileage restrictions.
If your STFTs are moving around and close to 0 then your problem isn't fueling related more than likely, other parts of the tune would definitely be involved. You didn't say what cam you have so I'm going to assume it's a tune issue but not because of the fuel trims.
Having a gas smell and sooty tips is a given no matter what if you don't have cats and have an aftermarket camshaft of any consequence. Hell you can make a stock car smell gas like by just removing the cats and high flow cats don't filter for ****.
If you want a real educated guess post up more information like the cam specs and the tune.
LTFTs are commonly turned off so you don't get any rogue locked fueling adjustments at WOT and it keeps it more consistent that way. If you have STFTs that are updating but no LTFTs then that is more than likely the case. I have never seen nor heard of anybody turning off LTFTs to prevent "false trimming" of rich idle conditions, especially since your STFTs will also adjust fueling. Also LTFTs update just about immediately when in closed loop unless they are turned off, no time or mileage restrictions.
If your STFTs are moving around and close to 0 then your problem isn't fueling related more than likely, other parts of the tune would definitely be involved. You didn't say what cam you have so I'm going to assume it's a tune issue but not because of the fuel trims.
Having a gas smell and sooty tips is a given no matter what if you don't have cats and have an aftermarket camshaft of any consequence. Hell you can make a stock car smell gas like by just removing the cats and high flow cats don't filter for ****.
If you want a real educated guess post up more information like the cam specs and the tune.
05-29-2015 | 01:47 PM
#33
To tune at idle with your narrowbands for a big cam, lean out the car with VCM to get them reading as close to 0 mV as you can (assuming they are even working - don't know, can't see a log or the tune to know what's been done). Or you can just listen and lean it out with the VCM until it achieves a lean stumble.
Either way, my LTFTs are disabled - you don't need them. In fact, with the OP's cam, he should be idling in open loop and can set it closed loop for driving around. I also have mine set this way.
05-29-2015 | 06:44 PM
#34
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Thanks.
05-29-2015 | 07:37 PM
#39
I know alot of tuners that solely use OL and OLSD on nearly every car. There is more than one way to tune a car. I was talking to the op.
The ltfts can be problematic indeed but i have been tuning for a bit and have only needed open loop on very few vehicles honestly. 2bar 21psi 900 hp monsters (positive displacement sc) and still closed loop with stock sensors and stock CL tables. May not be ideal on quite a few turbo rigs, but that is why there are so many tuners.
The short terms can only compensate so much. In a perfect situation a car runs like a top all the time. Nothing is perfect.
Everyone tunes differently. My tuning is likely no better than any others, but i am fairly successful in the tunes i do.
The ltfts can be problematic indeed but i have been tuning for a bit and have only needed open loop on very few vehicles honestly. 2bar 21psi 900 hp monsters (positive displacement sc) and still closed loop with stock sensors and stock CL tables. May not be ideal on quite a few turbo rigs, but that is why there are so many tuners.
The short terms can only compensate so much. In a perfect situation a car runs like a top all the time. Nothing is perfect.
Everyone tunes differently. My tuning is likely no better than any others, but i am fairly successful in the tunes i do.