C63TSgt

If you have been following my last thread on slicks you know I've bought quite a lot of stuff and was ready to hit the quarter. Well, 2 times in a row, Wednesday and today I went out to Sacramento raceway and did some runs. I threw all kinds of codes Wednesday with a huge misfire in cylinder one that set off a light and had me coast from the 1/8h every run. I changed the plug and coil pack on cylinder one and went back today. This time I got lots of runs in on the V4 93 map with no misfire CEL, however I felt hugely down on power and my best run with all my mods in the list and 1/4 tank 93 and 4 gallons 100 was 12.5@109 with a 1.8 60ft. The da wasn't great at +1500 but something still isn't right. I checked my codes and found what I'm posting below. The car is not under warranty and I'm a mechanic so I won't be visiting the dealer and doing any work myself. Curious about the O2 sensor readings I got as well as what you all take away from my codes. Please let me know what you think.

mr747

I'm sure merc63 will be able to help you out

Looks like to me your oxy sensors might be shot

When you were at the track the first time were you running the race fuel??
Maybe that has killed your oxy sensors

C63TSgt

I was, I think that may have been it as well, but it was supposedly the ss100 that was safe for those things. Considering doing the intake manifold gaskets I hear so much about, as well as the pcv valve while the manifold is off. Unless it's for sure just the O2 sensors. I mean the pcv is easy with the manifold off and the gaskets and bolts are cheap, I just hate to hear O2 sensors because $$$$$$. Any of those three things would cause me the same CEL and be down on power. I'll suck it up, whatever it is. Thank you very much for your reply.

Merc63

Time for a new O2 sensor on bank one.

How did the plugs look??

Don't run the car hard till you fix this.

There is other sources for O2s beside the dealer, call around.

jptaylor

As for the intake, I pulled mine Wednesday to add a catch can and change the intake gaskets....so glad I went this route-intake was FULL, COVERED, NASTY with oil and sludge.....I've never seen a manifold this filthy.....I will say that a catch can should be a must on the m156....anyway, cleaned it for 2+ hours and reinstalled with catch can and even though I thought it was fine before it feels totally different now....interested to hear how your manifold looks in the inside

C63TSgt

thanks Merc63!

Would that be two sensors? One before cat and one after? The rear one is cheap at around $25, that 5 wire forward one is another story, but gotta do what you gotta do. Both for bank one on the passenger side I'm assuming. Man I love this forum.

The plugs looked nice and tan, maybe a little extra stuff on the #1 but nothing severe, I replaced it and the coil anyway. Very cheap for some peace of mind. Will be taking it easy until the sensors come in, I'll order a front and rear tonight.

Merc63

Just the front sensor. The rear just monitors for the cats.

I'd try replacing just bank one, since the other side seems fine.

Don't run fuel with lead it will kill them.

If you have headers they usually die after headers are installed.

Merc63

These O2 sensor issues should almost be a sticky. They seem to come up every few days now.

C63TSgt

Will order one in the morning. I think I was scared about the camshaft code and misfire. I'm still saving for headers, I'll make sure that an extra set of sensors is in that budget as well. I used the search function to no avail/rock solid answer, and only posted after "googling" to death, a sticky would be awesome. Definitely not leaded fuel, just the Cali legal ss100. Not sure how we are supposed to use the 100 octane map if every time we do it destroys the O2. I have a 100 octane for headers and one without so I assumed the without headers would have been safe. We all know what assuming gets you...thanks so much again and I will update as soon as I have verified the results.

mr747

Just change all of them while your there trust me you will feel better about it and also buy an extra set for just in case next time

I've been though 2 sets in 6 months
Especially if your always racing and stuff it's a pain waiting for them to come and stuff

c63buckeye

year and how many miles and how have you drive in? i,e. DD, 1/4 mile, road course, etc.?


thanks.

Wobble64

The part number for the front O2 sensors is A 0035427018, that is actually a Bosch 17016. They are available for between 90 and 290$ per piece, depending on where you buy - quite the range!


Why do they fail often with headers? And how often? I had my LTHs for a bit over 4000 miles and indeed, one of the front O2 sensors failed a couple weeks ago. Mercedes replaced under warranty.

Merc63

You're lucky they are even replacing it with headers on. I think it's from oil and fuel getting into them easier without the cat to burn the crap off.

I've had mine for 25000km no issues.

Wobble64

That can't be it. The O2 Sensor sits in front of the first catalyst.......

C63TSgt

Scored one on amazon 17016 5 wire for $90 on Prime so free 2 day shipping, can't believe how widely spaced the pricing is. Completely insane. So I'll do the install on Thursday or Friday and report back. Having access to a lift and every tool imaginable for free is a great perk.

Merc63

Oil, moisture, Unburned fuel are all harmful to the O2 sensors.

They have to be mounted at an angle as to drain moisture from them. It can crack the material in them.

Wobble64

That makes sense. On my LTH setup all 4 sensors are installed on the sides of the exhaust, pointing up at an angle (i.e. the tip inside the exhaust tube points down). Obviously only a certain angle is achievable due to space constraints, but they are on the upper half of the tube pointing up at an angle.
This picture shows the front ones (one of which failed recently):

Merc63

I thought you said your O2 is in front of the cat? It's not in those pics. That's mhp v2 headers same as mine, primary O2 is in front of that cat.

Typically after the header install the o2s will die if they have a good chunk of miles on them.

Wobble64

That is right. 2 O2 sensors are between the 4-in1 merge and the race cats, and the 2 secondary O2 sensors are at the beginning of the X-Pipe.
What I meant to say a couple posts higher up is that also in the case of the stock exhaust system, the primary O2 sensors are before the 2 primary cats. In both cases (headers or stock), the first O2 sensor gets exhaust gas directly from the motor, not gases already cleaned by a catalyst - hence that should not be the reason for why headers are harder on O2 sensors.

Wobble64

Just found a better picture showing the 4 O2 sensors in a header setup

WESLEY KAY

Yeah my primary O2 sensors are before the high flow cat on the MBH Headers. Installing the headers this weekend. I hope all goes well!

Op: thanks again for the wheel help. Good luck with the O2 sensor! Amazon has the best prices from what I have seen.

WESLEY KAY

Op, and if you ever need O2 extensions, especially if you get headers and the secondary O2 sensors come up short, eBay has the extensions. I picked these up for cheap. I'll let you know If they actually work...lol.

C63TSgt

Was reading your thread on those and wondering if you found them or not. Hoping those work for you, as headers is next on my list. Hoping also the extra wire doesn't change the resistance range and throw off the o2. Why not just have the secondary o2's turned off by your tuner?

WESLEY KAY

I have to have them on to pass emissions here in VA. They all have to be in a "ready" state. I turned them off on my last vehicle and immediately failed because they were in a "not ready" state. I don't know if there is a way to eliminate the rear O2 sensors completely and not have them in a "not ready" status on the emissions test. Damn emissions!! lol

pNutz

This just recently happened to my car as well. When I pulled my plugs, the entire driver side were fouled out. Purchased a new upstream O2 for bank 2 (Driver side) and replaced all the plugs. Car is running fine now. Here are some pics of what the plugs look liked.