Car running too lean??

ITR01

New Member
Hey guys, I just wanted to preface my car so you guys have a full understanding on my issue. I have an 01 integra with 50k miles and well maintained with me being the only owner. my car only has all bolt ons, but has a test pipe with an o2 spacer so I am throwing no codes. A year and a half ago I got it tuned and wideband/afr gauge installed, however the tuner did not know how to properly tune my car so I called it quits and just put back the stock ecu and have been running that for about a year now. Last month my afr gauge started messing up like jumping the numbers on the gauge like crazy then either stayed at 10.0 or stayed at --- throughout my drive. Every other drive it would work again then go back to displaying ---. At that point I just thought the AEM o2 sensor got messed up so I thought nothing of it. I have been both driving city and highway but nothing out of the ordinary when I would usually get about 25 mpg since I got the car. However, I noticed that my gas milage has increased dramatically to 40 mpg for the past month, around the same time I noticed my AFR gauge got messed up. I did a full tune up about two years ago and since then only added around 5k miles. I do not want to go back to my tuner for I feel like they will just screw me even more and not know what to do. I figured I see what you guys have to say. Thank you so much for all your help and any assistance would be appreciated.
 

Muckman

Not a M0derator
First off I think that its amazing you have an 01 with only 50k miles. I have a '00 with 75k and I've barely driven it 500 miles in the past 5 years. So you must drive it even less than I do. I have a couple questions and points about your issue.

1.) Your wideband can only affect your fuel economy if it wired into the Ecu. Is it? And did the wideband replace the primary O2 sensor? The wideband could only provide feedback as the primary O2 sensor if the 0-1v wire was fed into the Ecu where as you would have tuned with the 5v wire feeding signal into the Ecu. Unless you are familar with what I am talking about Im doubting that the wideband has any affect on the tune of the stock ecu.

2.) If your wideband is reading accurate AFR then you would have major driveability issues with full rich and full lean readings. Lets just say the readings are NOT accurate bc the sensor is bad or the wiring was corroded, the wideband controller is still signaling the Ecu that the AFR is full lean or rich making the Ecu trim the fuel to the min or max short term fuel trim. This is only +/- 5%, not enough to cause drive issues but enough to cause a CEL. Neither is the case here.

Its hard to theorize without an accurate AFR reading. Why dont you work on fixing the wideband first. Then lets find a new tuner.
 

ITR01

New Member
Hello Muckman, thanks for getting back to me and thanks, I'm really driving to baby this car!

The wideband has not become my primary o2. I still have the primary o2 on the test pipe with an o2 spacer. we welded another hole on the test pipe for the sideband though, so there are two sensors on that one pipe.

To my knowledge, my wideband is not wired to my stock ecu. My tuner brought the wire out externally and put in a splice connector onto the tuned ecu harness so he would not ruin the stock ecu. So that wire that connects into the ecu is just loose and is just reading info for AFR (to my knowledge about the AEM gauge).

yea that's what i was thinking, if my air were true my car would be running very poorly

I will look into fixing the wideband and finding a new tuner...

Had my car not had the air gauge installed etc, and it was bone stock... what would you think would be the cause of my all of a sudden high gas milage? Would running this lean hurt my engine? Any remedies?

Thank you!
 

Muckman

Not a M0derator
The change of seasonal fuel blends is a likely culprit. That and engines generally get better mpg in spring and fall. Its hard to speculate without solid AFR data and it sounds like you may not be able to trust yours if its reading full rich or full lean. There is a calibration step you can do that you might want to look up.
 


ITR01

New Member
I will definitely look into that.

the past weekend that I have been driving, it no longer jumps lean and rich, the AFR gauge now just sits at "---" that being said, if it were running super lean it still would give me a number, right? or does "---" mean that it's so lean there no number for it? But at that point like you said my car would be running noticeably different and terrible?

Also, I am trying to look at the wiring of the AFR gauge. Is the only wire that feeds input into the ecu that with external wire i was talking about in an earlier post? Or is there other wires that would connect it to ecu? I see one wire plugged into a fuse slot etc but i think that is just to power the gauge. Since that external wire I had mentioned earlier is not connected to an ECU, no AFR gauges input into my ecu?

Thank you so much.
 

Muckman

Not a M0derator
"---" means its off the scale rich OR lean. The only way to tell is to look at the analog led to see which end of the spectrum its resting at. But if it was running that lean it should have drivebility issues. Because you don't have driveability issues it makes me doubt your wideband reading.

All widebands will have a single output wire. This signal can be either 0-1v or 0-5v which can be selected on the back of the gauge. This feeds the Ecu either a narrow band or wide band signal depending on what your Ecu expects. This signal into the Ecu is only needed if you use close loop feedback OR datalog it. Otherwise the wideband can be independent.

The wideband should have its own switched 12v power and ground separate from the Ecu (and sometimes a light wire). That holds true for every aftermarket gauge.
 

ITR01

New Member
may I ask what you mean by drivability issues? like examples of what I would be experiencing?

also so if the 0-1v/0-5v isn't plugged into anything and just free, that means the wideband is independent?
 


Muckman

Not a M0derator
hah If you have to ask then you aren't experiencing it.

Running slightly lean under light load can cause misfires. Very lean under moderate load will cause bucking and inability to accelerate. There can also be "dead spots" where full throttle feels like half throttle etc. Running lean under heavy load is the #2 cause of piston failure behind detonation.

Without the signal wire from the wideband there is no way your Ecu is making adjustments for the readings which is why I suspect the wideband is faulty. Wideband is reporting extreme readings but driveability does not support those extreme conditions.
 
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