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Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec

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7 months 2 weeks ago #63082 by Mechanic 350
Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec was created by Mechanic 350
So this is my personal vehicle.  Placed the scantool on it, and I'm constantly getting fuel numbers in the negative all the time.  so I need some direction as to which way to go.  My miles per gallon could improve a little bit.  so the question is, how do I get my numbers as close to zero as possible?  Because as I was studying, the #1 job of the LTFT is to keep the STFT close to zero.  and that's not happening.  please advise.

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7 months 2 weeks ago #63083 by juergen.scholl
Replied by juergen.scholl on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
Your description suggests you 're basically dealin g with negative SHORT TERM fuel trim numbers. Nevertheless it will be helpful to clarify what long term and total fuel trim is doing. Also the trim trend with varying rpm and load conditions.

Things to look at would be fuel pressure, improper air metering, evap purge solenoid.....to beginn with.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.

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7 months 1 week ago - 7 months 1 week ago #63143 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
Hey Juergen, my exact condition is this.  I have a Lean Command in response to a rich condition. So can I remove the 02 sensor, clean it with a wire wheel and cleaning it with spray, put it back and then take it for a drive and see to see what the fuel trims report.  What say you?
Last edit: 7 months 1 week ago by Mechanic 350.

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7 months 1 week ago #63160 by Noah
Replied by Noah on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec

Mechanic 350 wrote: So this is my personal vehicle.  Placed the scantool on it, and I'm constantly getting fuel numbers in the negative all the time.  so I need some direction as to which way to go.  My miles per gallon could improve a little bit.  so the question is, how do I get my numbers as close to zero as possible?  Because as I was studying, the #1 job of the LTFT is to keep the STFT close to zero.  and that's not happening.  please advise.

As Jurgen suggested, what exactly are the LTFT & STFT  values across the operating range of the engine?
If we're talking +/- 10% total correction, there's probably not a whole lot to do. 
"Ground cannot be checked with a 10mm socket"

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7 months 1 week ago #63161 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
yes, long and short term are definitely under 10%. so i just will probably clean the 02 with a wire wheel just to be anal about it. thanks Noah.

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6 months 3 days ago #63502 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
My fuel trims, short and long, are all negative reading during idle and during 2000 rpm range. The lean command, (PCM) is constantly taking fuel away. I'm going to hook up my verus and T pin the black wire as my signal wire and see what the scope shows me. besides that Noah, I don't have any direction. Remember, I'm not a mechanic. Just an experienced DIYER. What say you buddy?

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6 months 3 days ago #63504 by Noah
Replied by Noah on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
You still haven't given us any actual fuel trim values other than "negative", so it's hard to say.
If I was going to pull a random ticket out of my bag of Honda tricks, I'd say a valve adjustment probably wouldn't be a complete waste of time.
They need to be adjusted periodically anyway, and if you've never done it, it's probably never been done.
Misadjusted valves can result in low vacuum, which will be interpreted as load by the computer resulting in more fuel than needed, and in some cases, negative fuel trim. You could see this reflected in higher than normal MAP voltage at warm low idle. If memory serves, I think 1v or less is the spec....
"Ground cannot be checked with a 10mm socket"
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6 months 3 days ago #63505 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
I haven’t adjusted the valves yet. But because you suggested it, I’ll do that first. The thing is I can’t report to you any positive numbers because they’re aren’t any. The idle is in the 600 to 700 rpm range.
Do you know how to do a screen grab on a verus? I’m still trying to learn this tool. Then I can send you the screen capture. So you see what I see.

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6 months 3 days ago #63511 by Noah
Replied by Noah on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
Press the S button, it should bring up a drop down menu on the screen where you can choose to take a screenshot.
Also, you can save a test drive and share the
.vsm file, then anyone with Shop Stream Connect can open and view the file as if it were on their own scan tool
"Ground cannot be checked with a 10mm socket"
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6 months 3 days ago #63512 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
ok I'll do that.

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6 months 2 days ago #63517 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
I figured out how to take the captured photos. Now, where can i find the screened shot photos along with the .vsm file. I think i saw 7,000 plus frames while I was test driving the vehicle. I don't have shop stream connect. by the way, I couldn't find 02 SENSOR voltage pid. it's crazy. I know I must be overlooking something.

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6 months 2 days ago - 6 months 1 day ago #63519 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
I have 12 captured images

Last edit: 6 months 1 day ago by Chad.

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6 months 2 days ago #63520 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
sorry for this whatever it is in the post. if you can delete it, please. but these are the photos.

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6 months 1 day ago #63525 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
I made 2 files and they're in data manager in shop stream. don't know how to retrieve it. there you could see different rpm ranges that I performed during the drives. thanks for your help Noah.

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6 months 1 day ago #63527 by Chad
Replied by Chad on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec

sorry for this whatever it is in the post. if you can delete it, please. but these are the photos.
 
There was a problem with inserting files. The problem has been fixed, now.
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"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right. :-)
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6 months 1 day ago #63529 by Noah
Replied by Noah on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
Unfortunately I can't make out a single picture. I don't think it's anything you did, just how the forum uploads them. When you do it again, include engine rpm, loop status (so we know if the trims are actually doing anything), MAP voltage and temperature so we can tell how the fuel trims react to changes in engine speed and load.
Also, you will not find a PID for bank one sensor one oxygen sensor as it does not have one.
The wideband air fuel ratio sensor pid will be displayed in milliamps. The pid will be something like AFSENS 1
"Ground cannot be checked with a 10mm socket"

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6 months 1 day ago #63530 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
I took a video and saved to my verus. I don't know if it's available in shop stream for you to view. next video I'll include what you have told me:
1. engine rpm
2. Loop Status
3. Map voltage
4. Temperature Pid

any suggestion as to how I can upload the video from my Verus I took yesterday to the forum?

What I definitely noticed yesterday during the test drive, was that STFT did not drop below 800ihs to 1 volt. It never switched.

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6 months 1 day ago #63532 by Chad
Replied by Chad on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec


any suggestion as to how I can upload the video from my Verus I took yesterday to the forum?


 
www.scannerdanner.com/forum/off-topic-se...-a-member.html#63531
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right. :-)

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6 months 1 day ago #63534 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
hey I have 3 files in shop stream for you to look at. the're in the documents library under the following headings:
11-16-23 civic
11-16-23 civic 2
11-17-23 civic 3

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6 months 23 hours ago #63535 by Mechanic 350
Replied by Mechanic 350 on topic Fuel Trims constantly in the negative - 2008 Honda Civic LX 1.8L Non-Vtec
if you have your Chats again with other mechanics, I would like to attend. please let me know. thanks

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