Rich but reads Lean

[DSM_23]

Ok my mods are in my profile, but me and my other DSM friends have been trying to figure out whats the deal with my car. Everything points to the car to be running rich. Heavy black smoke under boost, Worthless LED gauge pegged on rich sometimes, 660 injectors etc. But everytime I do a log on my logger, it shows O2 readings of around .80, .78 with 30-43 counts of knock . There is NO studdering through the powerband but it definitly doesnt feel as fast as it should be with my mods. Im getting about 5 degrees of timing at full throttle which I know is killing my power. I just cant figure out whats the deal. I am thinking maybe the 02 sensor is dirty, but I havent pulled it to check. What else should I do or look for to fix this problem?

justin

 

[andymoraitis]

Is your CEL working and are you getting any trouble codes? If not, you may want to look into pulling the O2 and looking at it. Black depostis will indicate that it's going south on you. For replacements, go to http://www.sparkplugs.com and plug in your info for the model year. You'll get an amazing price and the unit will be a Denso leaded so you can run race gas without frying it.

Let us know what you find, but I strongly believe you're on the right track.

Andy

 

[DSM_23]

Alrite thanks for the quick reply, I'll probably pull the sensor out soon, and clean it out. Does anyone have any other advice? Any advice is very helpful

 

[andymoraitis]

Cleaning it isn't going to help you. If you see black buildup, it's on it's way out. If it's an original unit, it should have been replaced a long time ago (depending on mileage). Do a visual inspection and replace it if necessary.

Keep me posted,

Andy

 

[DSM_23]

It was replaced in a recall session about 3 yrs ago, and since then I have upgraded parts alot. Would the 02 going bad cause the logger to display lean under WOT? And why do I seem to get 43 counts of knock and the car runs perfectly smooth? My LED gauge sometimes pegs on rich for a while, and sometimes it pegs on lean at other times. I know the guage is worthless but still it displays the readout it receives. Plus my LFT on my logger is 139 and it doesnt seem like it should be that lean with my setup, considering my afc at idle is pulled only -10.

 

[andymoraitis]

Justin,

If it's recently been replaced, then I would still look at it. O2's can fail just like anything else. I think the second thing you should go after is the knock sensor. Feel around the base of it for any goo or sticky substance. If you find that the knock sensor is slimed, it's toast and your 43 counts of knock isn't real but the knock sensor will read it as such. If this has never been replaced, it's another promising area to check. As far as the AFC goes, I don't use one but I'll se if I can get someone in here to lend a hand.

Andy

 

[GVR4592]

Heavy black smoke could be the turbo spewing oil into the exhaust. I wouldn't pay attention to narrowband O2 or A/F gauges.

 

[DSM_23]

The turbo is brand new less than 1k on it, we just pulled the o2 sensor and I will upload some pics in a little bit. We also checked the knock sensor and there was zero sign of slim or stuff coming out of it.

 

[GVR4592]

Just becasue the turbo is brand new doesn't mean it's still working properly. I went through 3 PTE turbo's in about 6000 miles.

 

[DSM_23]

Heres some pics

 

[DSM_23]

I highly doubt its the turbo, it never smokes oil, its fuel, people behind me have said it and plus its just common sense with the setup im running.

 

[Newlogics]

First, look at the knock pattern on the logger. If you see a spike around 2500-3200, and then very gradually reducing itself, then welcome to phantom knock world. With 5* of advance a WOT, you are probably dumping all kinds of unburnt/half burnt fuel out of the pipe. While leaking knock sensor can be a cause for phantom knock, I found that it's rather rare. In most cases (at least the ones I've dealt with), that bad of a phantom knock is caused by thick and nasty carbon crown and other deposites on valves, piston tops and head surface. A tooth off on timing will also bring in a lot of non-predetonation-related knock.

Again, with knock at 43, trying to determine your true AFR is next to impossible due to retarded timing. Take care of knock first, then figure out if you're rich or lean.

 

[chuckdog_5]

 

[DSM_23]

Yes I am seeing a spike right when boost hits, The motor was just redone at polk performance a few months ago, with ported head new valves etc, I dont have a wideband, and I'm not sure which direction to go in here. How does my o2 sensor look based on the pics?

 

[HighPSI TSi Guy]

what compression? are you chipped for the 660s? or are you on stock ECU? what do you have your base timing set to?

 

[DSM_23]

Compression is 160-165psi, ECU is stock, not chipped for 660s, base timing should be correct it was set at polk and has ran fine since.

 

[FORMONTOYA]

I had a leak between the turbo and o2 hsg. Setup said it was a non gasket connection, however i had a slight leak that would suck in air before the o2 sensor making it think that it was running lean and then dumping in a ton of fuel to compensate, but never quite getting in line.

Jim

 

[andymoraitis]

Justin,

The O2 sensor looks fine (but looks can be deceiving) and it should read whitish when functioning correctly. I think Jim may be on to something as a pre-O2 exhaust leak will cause the ECU to dump tons of fuel. Make sure all of the gaskets are sealing correctly. Since Polk is a reputable shop, you may want to find out if they found carbon deposits on your piston tops when they did the head work and if they cleaned everything off.

A great way to tell if you have a pre-O2 leak is to unhook the BOV vacuum line to the manifold and suck through a can of Seafoam while revving the motor up to about 3K. Pull the heat shields in advance and if you have leaks, the Seafoam will pour white smoke out of them. It's the method I used to track down my O2/downpipe exhaust leak.

Also, you may want to re-check the correction factor on the AFC as you could either be that lean or way too rich. Each one can contribute to knock.

Keep us posted.

Andy

 

[spyderturbo007]

Would the 02 going bad cause the logger to display lean under WOT?

Yes, most definately.

I have never seen a bad O2 sensor cause a vehicle to run rich, always lean. When the O2 wears / dies the voltage begins to approach 0.0V. The lower the O2 voltage, the leaner the mix and the more fuel the ECU adds to try and compensate.

 

[DSM_23]

Ok, well today Im going to go buy an o2 sensor and pop it in and make a run or two. I have a hunch its o2 related still, but after I put one in, it will eliminate that factor based on what I find. I do have a manifold stud with no bolt on it, so if this doesnt fix it I'll look into that. But why does the o2 "seem" to be working at times, and whenever I do a log it seems like its working and the voltage is around .78ish? Could it just be weak and on its way out, because the car hasnt really been tuned much since the 660's were put on so I maybe figured that by driving around so rich for a few months may have killed it early. Also why does the LED guage peg on rich, while if I hook up the logger, the o2 voltage will be stuck at .00 volts. The only way I can get the o2 voltage to cycle on the logger sometimes is if I adjust the correction on the afc. Thanks for all these replies guys.

justin

 

[FORMONTOYA]

When mine was leaking it would read around .02-.06 at idle and would not go above about .75-.8 on the top end.

Jim

 

[Newlogics]

Not to argue here, but exhaust section between turbo and CAT would normaly be above atmospheric pressure, since cat is a restriction, so how could it possibly suck ambient air in?

 

[Mike Marnik]

When you shake the o2 sensor does it rattle?? if it does its definatly bad. Also my car ran rich when my o2 went out and the a/f gauge would jump around or not even work some times. Also what is you high fuel trim set at. I was having problems with the ecu pulling out alot of fuel while i was trying to add fuel and never could get any where so i reset the ecu and my knock came down from 43 to 12 ish im still trying to get that worked out.

 

[FORMONTOYA]

Not to argue here, but exhaust section between turbo and CAT would normaly be above atmospheric pressure, since cat is a restriction, so how could it possibly suck ambient air in?

A leak before the O2 hsg has rushing exhaust gas that would create an area of low pressure outside the exhaust at the leak. That would pull air in from outside and spike the O2 sensor with oxygen (lean), thereby causing a drop in voltage.

Jim

 

[RiceKiller_TSi]

Ok my mods are in my profile, but me and my other DSM friends have been trying to figure out whats the deal with my car. Everything points to the car to be running rich. Heavy black smoke under boost, Worthless LED gauge pegged on rich sometimes, 660 injectors etc. But everytime I do a log on my logger, it shows O2 readings of around .80, .78 with 30-43 counts of knock . There is NO studdering through the powerband but it definitly doesnt feel as fast as it should be with my mods. Im getting about 5 degrees of timing at full throttle which I know is killing my power. I just cant figure out whats the deal. I am thinking maybe the 02 sensor is dirty, but I havent pulled it to check. What else should I do or look for to fix this problem?

justin

What you're going through I have battled for three months now.
I replaced the knock sensor, no effect.
I replaced the o2 sensor, no effect.
I replaced the plugs and wires, no effect.
I tuned and retuned till I nearly wore out my maft knobs... no effect.

When I got rid of my 43 count "phanton" knock, (which happened to be REAL knock) all my other problems vanished with it. What I did was simply clean out the head and pistons with 2 cans of MCCC (Mopar Combustion Chamber Cleaner).
It was a very simple solution to a nightmare problem. I havent had phantom knock since doing this.

Grab yourself a few cans and use one full can on the head (Let the engine vacuum suck this stuff up). And on the pistons I evenly divided a can directly into the spark plug wells and let it sit up overnight then changed the oil. Problem solved.