ltft tuning clarification with predator
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Staging Lane
Joined: Feb 2007
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From: Moline, IL
ltft tuning clarification with predator i have seen 2 different opinions on tuning using the predator - 1 said to use the avg ltft to adjust settings to the fuel but another said to use the wot readings... I went out and checked ltft at norm driving conditions and also at wot - during normal driving it is an avg of -5 to -7% when at WOT its showing a +8%... i am using the diablo performance tune and have an slp lid and magnaflow catback on a 00 trans am ls1. if i were to adjust the inj slope up to zero and removed the same percent to PE table IE adj inj slope +6% and lower PE by 6% (as mentioned in another thread) wouldnt that make wot WAY too lean? If i were to use WOT readings i would be adding fuel which would make the norm rpm range even more rich... can anyone clarify this for me? also after about 20-30 mins of driving my front 2 02's are reading 835 and 810mv 
If in Predator terms injector slope refers to the injector flow rate, then changes to this setting will affect fueling from idle to WOT. You want no positive LTFT's anywhere as long as the STFT's are still fluctuating (closed-loop). Then, you dial in the PE % based on WOT AFR's seen with a WBO2. If you want to try to use the NBO2's (NOT RECOMMENDED) to tune WOT, .900mV is what you want to target with stock manifolds. If you're below that, you need more fuel. If you're above, you need less.
Remember, lower injector flow rates mean a richer AFR and higher PE settings mean a richer mixture.
So, I'd try lowering the injector setting 7% and leaving PE at 0%. Drive around a while and see where your fuel trims are. After enough miles of various driving conditions (light/moderate/heavy) throttle, check where your LTFT's are. If they are 0% or less than 0%, move on to PE. I would guess you would need to reduce PE. But, it might not be the same % as what you do to the injectors.
Remember, lower injector flow rates mean a richer AFR and higher PE settings mean a richer mixture.
So, I'd try lowering the injector setting 7% and leaving PE at 0%. Drive around a while and see where your fuel trims are. After enough miles of various driving conditions (light/moderate/heavy) throttle, check where your LTFT's are. If they are 0% or less than 0%, move on to PE. I would guess you would need to reduce PE. But, it might not be the same % as what you do to the injectors.
Last edited by SSpdDmon; Feb 28, 2007 at 10:26 PM.
Thread Starter
Staging Lane
Joined: Feb 2007
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From: Moline, IL
so basically the first step is to use the 8% positive ltft reading at WOT and nullify that by decreasing the inj% by that amount which will in turn richen the WOT and then see what the readings are after some driving and then fine tune using the PE ? I know that without dyno/ WBO2's its guess work i just want to dial it in fairly close and then fine tune it this summer at a dyno (and mainly make sure im not extremely rich or lean for the time being)
Thread Starter
Staging Lane
Joined: Feb 2007
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From: Moline, IL
btw thx sspddmon your post has been alot of help i adjusted the injectors down 7% and the ltft evened out around 0 under accel and at wot but 02 readings still seemed low (high 700's low 800's) so i richened the PE 1% at 2-4k and 2% at 4-7k my ltft stayed pretty steady still but 02's still showed low #'s also my idle ltfts went lower to around -11% at idle but are pretty close to 0 under a load not sure if this makes a difference but do you have any suggestions as far as getting the 02 readings closer? add a little more PE? again thank you for the help i have looked through alot of threads and none seem to be answering my exact questions - i am new to tuning so i appreciate any feedback
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From: CT
you need to adjust the injector slope based on your cruising/normal driving ltft readings - and you want to get them within +2 to -2 range.
If you're getting ltft readings of -7 at cruise, then you will need to adjust injector slope to +7%.
And modifiying the PE tables by 1% isn't going to do much. Do the injector slope change first then take another log and see where your ltft's are at and also the O2 voltage. Changing the injector slope will affect the WOT/PE as well.
After taking another log and seeing where you're at, then you can adjust the PE ranges - you want to be between .88x and .910. If you're lower than that, add to the PE ranges - I'd say +5%.
Do that and then drive around for a bit and take another log, I'll bet that'll have you right back in line.
If you're getting ltft readings of -7 at cruise, then you will need to adjust injector slope to +7%.
And modifiying the PE tables by 1% isn't going to do much. Do the injector slope change first then take another log and see where your ltft's are at and also the O2 voltage. Changing the injector slope will affect the WOT/PE as well.
After taking another log and seeing where you're at, then you can adjust the PE ranges - you want to be between .88x and .910. If you're lower than that, add to the PE ranges - I'd say +5%.
Do that and then drive around for a bit and take another log, I'll bet that'll have you right back in line.
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Originally Posted by ammuscleftw
btw thx sspddmon your post has been alot of help i adjusted the injectors down 7% and the ltft evened out around 0 under accel and at wot but 02 readings still seemed low (high 700's low 800's) so i richened the PE 1% at 2-4k and 2% at 4-7k my ltft stayed pretty steady still but 02's still showed low #'s also my idle ltfts went lower to around -11% at idle but are pretty close to 0 under a load not sure if this makes a difference but do you have any suggestions as far as getting the 02 readings closer? add a little more PE? again thank you for the help i have looked through alot of threads and none seem to be answering my exact questions - i am new to tuning so i appreciate any feedback
Idle fueling isn't too critical since the fuel trims are working to keep it in line. So, I wouldn't be discouraged if I saw LTFT's as low as -10% at idle. The key is while driving, you don't want more than +1~2% trims (again, as stated above). If you can increase the injector correction (ie pull it back to -5%) and still not see positive trims after a good bit of driving, then you should. If not, keep the injectors and finish PE.
Last edited by SSpdDmon; Mar 1, 2007 at 07:53 AM.
Thread Starter
Staging Lane
Joined: Feb 2007
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From: Moline, IL
awsome thanks. ill do that - and let you guys know what i find it seems to be getting closer to the numbers i want - idle seems to be off quite a bit though and getting better everywhere else any way to fix that or will it correct itself over time?
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It is correcting itself - that's why there's -10% FT's. If you could rotate the injector table instead of just shifting it up or down, you could make it better than -10%. But, I don't think the handheld will let you do that. Either way, I think you'll be fine. Did you try an injector slope only -5%? Maybe -7% was too aggressive/rich.
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From: CT
Power Enrichment - when you select a tune to install, choose "Modify tune" instead of Install and it's one of the adjustable parameters...
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06MonteSS / DiabLew Tune
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Power Enrichment (PE) is extra fueling added in for high load and WOT scenarios. This occurs in an open-loop format of fuel calculations where the PCM commands an AFR, but has no idea whether it's right or wrong. During closed-loop fueling, the PCM commands a 14.63:1 AFR, has feedback from the oxygen sensors, and can adjust fueling with the fuel trims. If fuel is added in certain driving scenarios, those positive fuel trims will be transfered to open-loop fueling calculations (ie when you go full throttle). That is why you want to focus on getting the fuel trims close to or below 0% before focusing on PE - to eliminate that extra variable. Also, it's NOT recommended to tune PE/WOT without a wideband oxygen sensor. Some try to use the narrowband sensors based on the raw voltage reported. But, this can be inaccurate and potentially damaging to the engine.
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Staging Lane
Joined: Feb 2007
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From: Moline, IL
ok for those of you reading this tread and to show my progress i had +8% ltft at wot from a predator tune and magnaflow catback and slp lid/bellow i adjusted the inj slope down 7% as was reccommended ... my ltft pretty much is pegged at 0 under a load and WOT and then after some driving the 02's seemed to be running lean according to the predator mv's approx 800ish sometimes high 700 i then added to the PE by +6% richer the car definately seems rich but all the numbers seem fairly close to what they are suggested using the predator i will be putting some miles on the car ( approx a few days to a week ) and let them settle in and tun slightly from there. before taking it to the track i will be getting a dyno to see the real numbers (AFR) I appreciate the help and if it were not for reading through this forum and the help so far from others on here my car apparently would have been running pretty lean and was showing + ltft under load and WOT which would have probably been bad news come summer time at the track! I think im on the right track and will keep trying to make things a little easier for those with the same questions and concerns i have had so far.. 
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Staging Lane
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ok after some driving and a few runs WOT looks good maybe a +1 on ltft and 900 and 925mv on the o2's but during normal driving my ltft's are around -4 to -8 ? if i correct that im gonna be lean on WOT again any suggestions?
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what do you have your injector slope and PE ranges set at??
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Originally Posted by ammuscleftw
ok after some driving and a few runs WOT looks good maybe a +1 on ltft and 900 and 925mv on the o2's but during normal driving my ltft's are around -4 to -8 ? if i correct that im gonna be lean on WOT again any suggestions?
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Staging Lane
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From: Moline, IL
just an update after driving some it seemed just a little too rich ( low idle and boggy) compared to the way it acted stock so i did what sspddmon said and backed it off a little and went -5% on inj and +5 on pe and all seems pretty close now still not positive ltft and is runnin strong i think now im ready for a wideband or a dyno thanks for the help!
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From: CT
yeah, I ran into that once myself - I had the injector slope too far negative, making it too rich, and this is what Mike from Diablo confirmed for me:
"SHIFTING: When you look at these logs, monitor engine load. Engine load is a major determining factor in shift settings. If the change in inj. slope is causing an excessive rich condition (and the car is losing power as a result) it will change the load and thus the tranny will react/shift differently."
I have mine at -5% now and PE at +3 and this thing runs like a raped-ape now!
"SHIFTING: When you look at these logs, monitor engine load. Engine load is a major determining factor in shift settings. If the change in inj. slope is causing an excessive rich condition (and the car is losing power as a result) it will change the load and thus the tranny will react/shift differently."
I have mine at -5% now and PE at +3 and this thing runs like a raped-ape now!
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06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS - LS3, 6-speed manual, short-throw performance shifter, NPP dual-mode performance exhaust, 1LE front splitter, ZL1 rockers, Z28 Rear Spoiler, all paint-matched Red Rock Metallic, BMR strut tower brace, Cold Air Inductions cold air intake, Apex Motorsports, Inc. catch-can, Custom DiabLew Tune
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