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Discussion Starter · #1 ·
When you had to exrend the connection for the O2's did you cut the harness or cut the sensor itself? Some one told me thatit does make a difference. I cut the sensor and then crimped exensions in. My gas mileage still sucks I ran some codes the other day and it said that both o2's were lean but I am burning rich? Today I ran my codes and no problems so I dont know what is going on I am still getting pispoor gas milege.
 

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I used plug in type extensions...
 

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DON'T CUT AND EXTEND THE HARNESS. I tried that with the pigtails on the sensors. If F'd my o2 readings all up. I'd read rich AND lean on both banks with them like that. Buy the harnesses and new sensors. Be prepared for crappy driveability for the few 3-4 min of driving. B/c the sensors are heated and now located farther back in the exhaust, they take longer to heat up. The computer has a set timer for cold starts from when it changes from open loop to closed. If you get a dyno tune, have the tuner change the timer.
 

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Just a thought...did you add a AFPR??? I was way rich after adding LTs....added a kirban and dialed the FP down....as it was pig rich and woofing gas bigtime...the Kirban helped....i dialed it down to like 28, ran it a tad, checked, dialed it up again....gas mileage came back around....you may need to fiddle with it some...mine would puke black smoke when you stood on it, a sure sign your rich....

o/2 position does come into play also....i been running em 3 yrs and alls cool...just need to dial that fuel down a tad and you may find your culprit???....Worked instantly for mine...

i cut my o/2s and extended and crimped connected as you did...worked fine for me....never pulled a code related to them, but they were fairly new sensors too...i cut them midway and spiced in there...
 

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The reason your car runs rich after a LT install is because you are placing the sensors much further down in the exhaust stream and they are running colder than they are supposed to. This gives the EEC false readings and it thinks the motor is lean and in turn it begins adding fuel. There is no way to cure this except with a pro tune. The EEC will compensate no matter what you do with the fuel pressure. Extending the harness will not hurt anything as long as you do it right and seal the connections.
 

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SSKiller said:
There is no way to cure this except with a pro tune. The EEC will compensate no matter what you do with the fuel pressure.
I'm not sure i agree with the Pro Tune thing??? My tune was the AFPR...and some plug reading....ending up at 38 lbs cured the issue he "appears" to be having....along with some EEC learn time..Most applications show the AFPR will cure his issues. The LTs and that almost go hand in hand...
I have dyno pulls that put my AF ratio right in the sweet spot...with the stock ECC to boot...

Not trying to be a ****...just don't get the theory, its not like your gonna get a chip for LTs?? What do you regard as a pro-tune??
 

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Well, by raising or lowering your FP you are essentially trying to "fool" the EEC and its adaptive strategies. Using the AFPR will usually solve your problems but many say its not the correct way of doing things. I personally think it works fine, I've just been around many tuners and done lots of tuning myself, and I hear it all the time "you dont want to fool the eec".. With the eec tuner or tweecer you can actually modify the amount of switching the 02's do and the HEGO BIAS to correct for having long tubes... but the old method of playing with FP works fine too...kind of a catch 22...
 

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Got it...well said to boot...Its a catch 22..

I have added tons of stuff to mine and be way lucky ECC wise...never had a lick of trouble, nor does it spit any codes opr act up....

bought a laptop over the winter to get a Tweecer, but 500.00, i can spend somewhere else, til it acts up....i wasnt aware you could do the HEGO/LT trick via the tweecer....
 

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Discussion Starter · #11 ·
SSkiller: So why doesnt everybodies fuel economy go down when they put long tubes on? SHoudl I not buy extenders and new sensors along with a AFPR first? Could I just take it to a place like Delk's Performance and get them to correct the problem? What is a catch 22?
 

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Charles9T4

I wanted to contribute a few things in your thread about LT's and your pcm's adaptive strategy.

I use a Tweecer to tune and have spent a good bit of time looking at datalogs to see what the pcm is doing when it comes to it's adaptive strategy.

The main goal of the pcm when using adaptive strategy (closed loop) is to give an a/f ratio of 14.7 to 1.

I've shared info with other Tweecer users who like myself, run LT's and this is what we have seen. The LT's can cool off some at idle, like at a long stoplight. If this happens the pcm will try to correct the a/f ratio. You can see this if you datalog.

I bring this up cause some folks have more trouble than others and don't ask why some do and some don't. I've not found anyone who knows the answer.

SSKiller has talked about things that fool the pcm.

If you can watch the pcm at work you will see that it does it's very best to correct some of the things we do to gain more power. Things like maf's with a cal the the pcm does not know about or fuel pressure that has been changed or the egr deleted, you know, stuff like that.

RIO 5.0 has told us about his good results with using some of these methods.

I've got to agree with him cause, lets face it, it's hard to argue with sucess!

You asked about catch 22 and I just gave you an example!!!

I'm not saying these things won't work and they might not even turn on the ce light or throw codes but if the pcm determines that something is not as it should be it's gonna go to work and start changing what we have done.

That is why after so many mods of parts and doing things that the pcm does not like you see people saying that a chip or tuning device has done wonders for their car in the drivability area.

Just wanted to share some things I've seen with my car.

Later
Grady
 
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