narrow injector pulsewidth?
Thread Starter
On The Tree
Joined: May 2004
Posts: 133
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From: Dallas
narrow injector pulsewidth? My car's dumping excessive fuel even though my ltrims look good. Do I use the injector offset table? If not, which tables do I use? How do I narrow the injector pulsewidth? I know you're supposed to decrease the values a tad...any guidance is appreciated.
....your LTrims are fine yet your say the injectors are putting too much fuel in? I guess your reading the LTrims in AutoTap (or something like that) but how in the world are you seeing too much fuel (dyno)? What your saying does not make since unless your O2s are messed up and then you should have a code. Thread Starter
On The Tree
Joined: May 2004
Posts: 133
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From: Dallas
I've read a few threads that indicate that because ltrms are good, doesn't mean there's not a problem. I'm going through gas like water. Filling up every 3 days from simple daily driving, no WOT runs at all. I'm running rich as hell, and I can't figure out why. Even with a so-called "professional" tune on it, my car drains gas. I'm lucky to get 13 miles to the gallon if that. Lot's of people with the F1 cam that I've talked to don't suck through gas like I am. What do you guys do to conserve fuel consumption? My injectors are the stock 28 lbs that come on an 01. I changed the fuel filter...only thing left is to check the plugs and swap out the 02 sensors, but I believe they are fine.
TECH Resident
Joined: Jan 2002
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From: USA
This happens when some sensor is lying or the tune was mucked up.
Your LTFTs maybe be perfect but only to what the PCM is being told as to the AFR
If there was an exhaust issue as an example and your O2s were reporting false lean values, then the tune was really adjusting to a fault rather then curing the fault and and then tuning.
Or MAF or VE table was mucked up and so PCM thinks the engine was incorrectly lean and tune adjusted to make LTFTs close to zero but in fact your really way too rich.
Also incorrect analyzing of PCM scanner data makes it appear the LTFTs were about correct.
Your LTFTs maybe be perfect but only to what the PCM is being told as to the AFR
If there was an exhaust issue as an example and your O2s were reporting false lean values, then the tune was really adjusting to a fault rather then curing the fault and and then tuning.
Or MAF or VE table was mucked up and so PCM thinks the engine was incorrectly lean and tune adjusted to make LTFTs close to zero but in fact your really way too rich.
Also incorrect analyzing of PCM scanner data makes it appear the LTFTs were about correct.
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Thats not very rich at all (WELL within the computers ability to adjust). Negative numbers mean the computer is adding fuel (things its lean). Its possible that your O2s are lazy and not reading right (in which case you could be rich) but I don't think so.
Your saying you get 13mpg daily driving and have to fill up every 3 days? Personally I think you need to go to a Honda Insight
as your looking for WAY too much fuel economy. You have a V8 and your getting the typical "daily driver" fuel economy. You’re only going to get 20+ mph out on the highway where loads are low and the speed is constant. Is your car a manual or auto?
Your saying you get 13mpg daily driving and have to fill up every 3 days? Personally I think you need to go to a Honda Insight
as your looking for WAY too much fuel economy. You have a V8 and your getting the typical "daily driver" fuel economy. You’re only going to get 20+ mph out on the highway where loads are low and the speed is constant. Is your car a manual or auto? LS1 Tech Stories
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On The Tree
Joined: May 2004
Posts: 133
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From: Dallas
lmao @ honda...
Well I know my A4 with the F1 cam will decrease the mileage I used to get when my car had a stock cam...but this is a major decrease bro. I used to get 330 miles out of a tank on the highway...now I'm getting maybe 15 mpg on the highway with rpms around 2k consistantly.
Well I know my A4 with the F1 cam will decrease the mileage I used to get when my car had a stock cam...but this is a major decrease bro. I used to get 330 miles out of a tank on the highway...now I'm getting maybe 15 mpg on the highway with rpms around 2k consistantly.
hmmmm....then I would say check the O2s........when your driving watch the O2 voltage. It should jump all over the place really quick .1/.9/.5/.4/.8/.9/.1/.2/4/.2/etc.....if it does this then your O2s are good.
Thread Starter
On The Tree
Joined: May 2004
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From: Dallas
Yeah, I'll do that next. I remember when I was logging that's what they did. I just adjusted my IFR table to give it less gas and the car is running smoother. So hopefully that's it. I gave it a new tune just now because I went and filled up to find out what mpg I was getting...a whopping 11.45 mpg. ouch.
Negative trims mean the "natural" tune is
that-% rich, but the PCM has subtracted
enough to put it to (what it thinks is) dead
even.
Changing the IFR is something that the PCM
may "learn back out" for city (closed loop)
driving. You should take a look at the trims
in a couple of days; you may see some have
crept up by about the percentage that you
changed the IFR.
If you truly want to change the closed loop
mixture, you could mess with the target AFR
setting. But the O2 sensor gets to be a poor
quality feedback very far from 14.7:1. Still
you could put it to, say, 15:1 and pick up
some economy perhaps. You might have to
fiddle with the O2 sensor trip threshold (?)
to pick something that represents a leaner
level, though looking at the curves the bottom
corner is pretty abrupt and not that far from
14.7.
If you were to screw with this then you would
also want to adjust all of your open loop targets
and PE, which are relative to the central "ideal"
value. Could get messy. But, peak economy is
to be found about 15.4:1
http://community.webshots.com/photo/...75387375MYoTiA
The Lean Cruise functionality would help on
the highway. Setting tight / low part throttle
shiftpoints in the part throttle settings will
take the fun out and put the economy back
in, around town.
15MPG highway is pretty bad. I see low 20s
there, never have a tank w/o some highway
in it so don't know about pure city MPG.
that-% rich, but the PCM has subtracted
enough to put it to (what it thinks is) dead
even.
Changing the IFR is something that the PCM
may "learn back out" for city (closed loop)
driving. You should take a look at the trims
in a couple of days; you may see some have
crept up by about the percentage that you
changed the IFR.
If you truly want to change the closed loop
mixture, you could mess with the target AFR
setting. But the O2 sensor gets to be a poor
quality feedback very far from 14.7:1. Still
you could put it to, say, 15:1 and pick up
some economy perhaps. You might have to
fiddle with the O2 sensor trip threshold (?)
to pick something that represents a leaner
level, though looking at the curves the bottom
corner is pretty abrupt and not that far from
14.7.
If you were to screw with this then you would
also want to adjust all of your open loop targets
and PE, which are relative to the central "ideal"
value. Could get messy. But, peak economy is
to be found about 15.4:1
http://community.webshots.com/photo/...75387375MYoTiA
The Lean Cruise functionality would help on
the highway. Setting tight / low part throttle
shiftpoints in the part throttle settings will
take the fun out and put the economy back
in, around town.
15MPG highway is pretty bad. I see low 20s
there, never have a tank w/o some highway
in it so don't know about pure city MPG.
Thread Starter
On The Tree
Joined: May 2004
Posts: 133
Likes: 0
From: Dallas
hey thanks for the info Jim. In a couple of days I'll recheck it. I'll know immediately though if the car starts sucking down gas again. This morning I threw a damn PO102 code. Gonna clean the MAF and check everything out. It's like ever since I rebuilt the motor...everything is going out...wtf?
9 Second Club
Joined: Nov 2001
Posts: 1,445
Likes: 0
From: Bay Area, CA
Originally Posted by 2001CamaroGuy
Thats not very rich at all (WELL within the computers ability to adjust). Negative numbers mean the computer is adding fuel (things its lean). Its possible that your O2s are lazy and not reading right (in which case you could be rich) but I don't think so.
Your saying you get 13mpg daily driving and have to fill up every 3 days? Personally I think you need to go to a Honda Insight as your looking for WAY too much fuel economy. You have a V8 and your getting the typical "daily driver" fuel economy. You’re only going to get 20+ mph out on the highway where loads are low and the speed is constant. Is your car a manual or auto?
Your saying you get 13mpg daily driving and have to fill up every 3 days? Personally I think you need to go to a Honda Insight
as your looking for WAY too much fuel economy. You have a V8 and your getting the typical "daily driver" fuel economy. You’re only going to get 20+ mph out on the highway where loads are low and the speed is constant. Is your car a manual or auto?other way around its taking fuel away.
Ltrims are perfect for part throttle cruise.
ask your tuner to raise the the WOT PE turn on TPS maybe?
