O2 and LTFT readings
Thread Starter
TECH Apprentice
Joined: Aug 2002
Posts: 362
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From: Maple Grove MN
O2 and LTFT readings What do you guys make of these readings?
Bank One
LTFT: 16.4
O2: 790 - 885 (basically all over the place)
Bank Two
LTFT: 11.7 to 12.5
O2: 920 - 930
Bank 2 looks better than bank one obviously.
Bank 2 O2 readings look good.
They are both high on the LTFTs. If I was to bring the LTFTs down with the injector flow rate table will that cause the bank 2 O2 sensor to read too rich instead of where its at now? I would guess it would richen up the reading if its adding more fuel.
If it wont richen the O2 reading then how much downward do you adjust the IFRs and how do you do that? Multiply the whole table by ?????
I've heard that LTFTs from -5 to 0 are acceptable. If I made adjustments to bring LTFTs down 16.7 points that would put B1 at -0.3 and B2 at -5 which would make me happy but not if the 02s are reading extremely rich afterward.
Anybody know what I should do before <img border="0" alt="[shoot]" title="" src="graemlins/gr_guns.gif" /> at it?
Justin
Bank One
LTFT: 16.4
O2: 790 - 885 (basically all over the place)
Bank Two
LTFT: 11.7 to 12.5
O2: 920 - 930
Bank 2 looks better than bank one obviously.
Bank 2 O2 readings look good.
They are both high on the LTFTs. If I was to bring the LTFTs down with the injector flow rate table will that cause the bank 2 O2 sensor to read too rich instead of where its at now? I would guess it would richen up the reading if its adding more fuel.
If it wont richen the O2 reading then how much downward do you adjust the IFRs and how do you do that? Multiply the whole table by ?????
I've heard that LTFTs from -5 to 0 are acceptable. If I made adjustments to bring LTFTs down 16.7 points that would put B1 at -0.3 and B2 at -5 which would make me happy but not if the 02s are reading extremely rich afterward.
Anybody know what I should do before <img border="0" alt="[shoot]" title="" src="graemlins/gr_guns.gif" /> at it?
Justin
Launching!
Joined: Nov 2001
Posts: 219
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From: Westminster, CO
Re: O2 and LTFT readings You are going to need to tune for both WOT and non-WOT. To begin with tune you ltft to slighlty negative via the IFR table, don't worry about O2 readings. Then once you have consistent negatives monitor O2's. It is one of the PE tables you adjsut for WOT O2's, though all my information is at home so I can't say exactly what.
TECH Apprentice
Joined: Dec 2001
Posts: 357
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From: Whitby Ont Canada
Re: O2 and LTFT readings Bringing the figures down in the IFR table adds fuel at base which you need. With LTFTs numbers that high I would first monitor all 4-14 fuel cells (base load cells) and see if you are consistantly low at all cells or you may have to adjust at different amounts at particular levels if not. If the cells are consistant then multiply the entire table by 90% which is reducing the IFR figures in turn adding fuel and allow aprox 100 miles for the PCM turn relearn and log data again and see where you are.
<small>[ April 16, 2003, 05:34 PM: Message edited by: J&JsTA ]</small>
<small>[ April 16, 2003, 05:34 PM: Message edited by: J&JsTA ]</small>
On The Tree
Joined: Sep 2002
Posts: 109
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From: NOVA
Re: O2 and LTFT readings O that sounds like your problem, I think at WOT our O2's are worthless, log your o2's during part throttle and try to get them around .890 - 900 mV
some say Injector table, some say maf, some say other methods. Pick your poison, I will tell you how I do it next week, after I see if it works... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
I got some tips from a reputable tuner so we will see if they work.
For the PE tables, I think you need to use your buttometer or a dyno with A/F to figure it out.
<small>[ April 16, 2003, 10:15 PM: Message edited by: TreeGreenZ ]</small>
some say Injector table, some say maf, some say other methods. Pick your poison, I will tell you how I do it next week, after I see if it works... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
I got some tips from a reputable tuner so we will see if they work.
For the PE tables, I think you need to use your buttometer or a dyno with A/F to figure it out.
<small>[ April 16, 2003, 10:15 PM: Message edited by: TreeGreenZ ]</small>
Thread Starter
TECH Apprentice
Joined: Aug 2002
Posts: 362
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From: Maple Grove MN
Re: O2 and LTFT readings TreeGreenZ: Let me know how your tuning goes. My part throttle O2s seem more worthless than anything. They range anywhere from 30 to where they're suppose to be. Part throttle over 50% throttle position they have the same range that I listed for WOT. I will try the IFR table but it will be a while cuz the weather here is going to suck for at least a week. Last year when I tried to fix those LTFTs with the MAF table my car was acting all weird so I put it back to where it was. It acted the same way it did when I jetted my nitrous with a 100 N20 jet and a 150 fuel jet. So that wasnt the answer. I also barely ever see any knock. On my last 15 minute logging session I got one knock occurance of 2.99 but thats most likely cuz I run straight 100 octane unleaded. Cant be too careful when your tune is out of whack.
I will go to the dyno and get a wideband AF and adjust on the dyno but dyno time is by the hour so I dont want everything to be screwed up when I go there. You guys say the PCM needs time to learn adjustments anyways. So I'd like to get the LTFTs to be more normal before I go. Paying a tuner 750 bucks scares me too even though that would be the best thing. Too bad I already spent 750 on custom tuning plus however much LS1edit was (too much). I also dont know where a place is in MN if it came to that point. Somebody told me of a place that does it but I cant remember the name. Doug something motorsports. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
I will go to the dyno and get a wideband AF and adjust on the dyno but dyno time is by the hour so I dont want everything to be screwed up when I go there. You guys say the PCM needs time to learn adjustments anyways. So I'd like to get the LTFTs to be more normal before I go. Paying a tuner 750 bucks scares me too even though that would be the best thing. Too bad I already spent 750 on custom tuning plus however much LS1edit was (too much). I also dont know where a place is in MN if it came to that point. Somebody told me of a place that does it but I cant remember the name. Doug something motorsports. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
TECH Resident
Joined: Jan 2002
Posts: 754
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From: USA
Re: O2 and LTFT readings You did not mention what your injector pulse width or duty cycle is.
You have a SC and only 42 lb injectors. Being over 17% too lean will force PCM into overspeed and its a norm for piston 7 to do a meltdown.
I have seen 3 C5s in the last month with that piston deformed due to a SC and improper fuel supply.
Determine if you have any flow left in the injector and/or can fuel pressure be raised first before commanding PCM to increase pulse width for if the injector is maxed out commanding longer pulse width will not solve the problem
You have a SC and only 42 lb injectors. Being over 17% too lean will force PCM into overspeed and its a norm for piston 7 to do a meltdown.
I have seen 3 C5s in the last month with that piston deformed due to a SC and improper fuel supply.
Determine if you have any flow left in the injector and/or can fuel pressure be raised first before commanding PCM to increase pulse width for if the injector is maxed out commanding longer pulse width will not solve the problem
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Thread Starter
TECH Apprentice
Joined: Aug 2002
Posts: 362
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From: Maple Grove MN
Re: O2 and LTFT readings I know my fuel injectors are far from maxed out. Dont know what the duty cycle is but I could probably figure it out. There are a lot of people making a lot more power than me with 42lb injectors. For 8psi ATI recommended 38lb injectors so I think I have some room left. Somebody was actually selling C5 procharger kits for 8psi with 38lb injectors included. Fuel pressure is at about 62psi and never moves.
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Verdad Gallardo Thread Starter
TECH Apprentice
Joined: Aug 2002
Posts: 362
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From: Maple Grove MN
Re: O2 and LTFT readings I multiplied the IFR table by 95% to start with and that gave me these results at WOT.
Bank 1: 12.5 LTFT
Bank 2: 5.5 LTFT
So that brought it down some. I then reprogrammed and did a total of 85% of the original and came up with this.
14.1 for bank 1
2.3 for bank 2
There must be something going on with bank 1 because that makes no sense. I'm going to get under the car and check that all the ypipe bolts are tight and check for anything else weird. Going from 95% to 85% I expected bank 2 to be around -5 but it only moved just slightly. Why is that?
Bank 1: 12.5 LTFT
Bank 2: 5.5 LTFT
So that brought it down some. I then reprogrammed and did a total of 85% of the original and came up with this.
14.1 for bank 1
2.3 for bank 2
There must be something going on with bank 1 because that makes no sense. I'm going to get under the car and check that all the ypipe bolts are tight and check for anything else weird. Going from 95% to 85% I expected bank 2 to be around -5 but it only moved just slightly. Why is that?
