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Fuel very rich, Pegs O2 sensor

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BJICEVR4

Probationary Member
9
0
Dec 7, 2013
Salt Lake City, Utah
I have a Galant VR-4 that I have been through the ringer on. My current problem is that the O2 sensor is giving very rich readings. Off the charts. Over one volt. The injectors are stock, I have a higher volume pump, the fuel pressure is in spec. At idle the O2 sensor cycles up and down the way it should, but you touch the throttle and it pegs the O2 sensor. The car gets poor fuel mileage and does not run great. I have DSM Lync installed and was wondering if there is a fuel setting or O2 sensor setting that I need to adjust.

Thank you in advance
 
Do you have a bad o2 sensor I have link too but ive been using my wideband, I have yet to tune my car this year. I would start there first, is the sensor good? Do you have a wideband?
 
My O2 sensor cycles fine at Idle, and I dont know what wideband is. How else would I check my sensor?
 
A wide band is a sensor that can read an exact A/F ratio. A narrow band is what the stock o2 sensor is. If you have a gauge that doesn't show an exact A/F ration number, it's a narrow band sensor. The I'm gonna guess that the gauge you have just has a bunch of blinky lights and is divided into three measurements "Lean", "Stoich", & "Rich"?

Also, since you have DSMLink, post a log.
 
Ok I checked my O2 sensor, and it is working. My car will run too rich at 3-4k rpm. But in DSM link if i lower the global to about -17 to -25 top end works much better.
 
You really are not giving us any useful information. Why are you adjusting global fuel settings? You set the global fuel setting for your particular set of injectors.

These cars do run rich with a factory tune when under load. Really rich in fact. 9.5:1 A/F. But unless you have a wide band, you really do not know if you are running overly rich.
 
I'll try to be more helpful.
I have DSM lync 2.5 , When I look at the O2 sensor reading it is not cycling at all in capture mode. So I tested it manually and it is cycling between .3 to .6 volts @ idle ti the ECU. but the ECU is not showing any O2 sensor function. The global @ zero the car will idle fine, but as soon as i give it gas it will get to about 2500 rpm amd then stall, or fall on its face. It is from running extremely rich, and the turbo will not even engage. I recently replaced the head and found out that someone that I had "tune" my car had pulled out several vacuum lines, the factory boost controller and I then found that my O2 sensor wire was cut at the ECU. When I lower the global it will at lease run, because it is leaning it out a little. but at 3-4k rpm it still falls on its face, and there is no boost. I hope this sheds a little light. Does DSM Lync 2.5 have a way to shut off the o2?
 
Sounds like a boost leak to me.

I just recently had my j pipe blow of my 16g, still don't know how it happened... but anyways, the entire time I limped it back home with that boost leak (major one) anytime I went above about 3500 it would break up even just driving at about 20% throttle, or if I got around -3/-5 vacuum it would do the same before it would get near boost. My wideband cruising with that leak was reading around 10.5 @7-10% throttle, just maintaining speed.

Have you performed a blt on it? I used an safc to tune while I had a small slice in one coupler (back side, couldn't see it till I pulled it off) and my tune changed daily, on top of that the power sucked and it ran pig rich just like you describe.

Also, hello from slc!

Double also, if your o2 is already cut out, the easiest thing you can do is buy a wideband, which you should have anyways while you tune, and wire up the narrowband sim for link. You will have the one o2 wideband sensor wired in to get: a) accurate readings from, b) simulate the narrowband signal to the ecu. A lot of people do this when they put the wideband sensor in the o2 housing instead of having another bung downstream. Hope this helps!
 
I did have a leak in my intercooler piping. Fixed and works a ton better. Thank you!!!
 
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