Mysteriously Running Rich

[cjm41]

I brought my car in for rod bearings this week. I also had an Active Autowerke x-pipe installed while it was there since I continually had exhaust leak issues with my test pipes.

I picked the car up last night and it's running rich, like burn your eyeballs at a red light, change clothes three times a day rich. I just came back from dinner and I smell like I was racing go carts or mowing lawns.

Here's the weird thing... test pipes to x-pipe is, for the most part, the same amount of restriction, from an emissions perspective. Prior to this, the car might smell a bit at a red light, but it was barely noticeable, and not really a stinging burnt fuel smell like it is now. I also have black soot forming on the never before dirty tailpipes and i wiped a little off my bumper before.

Shop said the car needs a tune. I've got a BPM Stage 2 tune.

Any idea what could have changed from test pipes to x-pipe to turn my car from a luxury sports car to a track beater?

I've attached a picture of me after standing behind my car while it was running.

.

[nycplumber]

If you just had test pipes on your old OEM x pipe that means it still had the secondary cats. The AA X-pipe doesn't have any cats so of course its gonna smell different. So congrats on becoming a man and going catless

[cjm41]

Originally Posted by nycplumber

If you just had test pipes on your old OEM x pipe that means it still had the secondary cats. The AA X-pipe doesn't have any cats so of course its gonna smell different. So congrats on becoming a man and going catless

If that's the case, I've got an x-pipe with 80 miles on it for sale. It's useless as a DD. I can't walk into meetings smelling like I just came from my landscaping side gig.

Seriously, I cannot imagine the secondary cats filtering this much. I wish I was exaggerating about the burning my eyes thing.

For what it's worth I called AA today about this and they said going from test pipes and stock midpipe to their x-pipe shouldn't make a difference in smell, just sound.

[Timujin]

Lol dude you're gross.

[amrazM]

If there’s no cats in the x pipe the car will stink.

[cjm41]

I should mention I've owned cars with no cats before. This is worse than my built 306 in my 11 second mustang. Going to re-tune the car next week. If it still smells I may be willing to trade this new x-pipe for something with HFCs. I'll call AA tomorrow and pick their brain.

The shop told me it was running rich. I don't doubt for a second that these guys know their stuff and have probably installed 20+ of the same x-pipe on the same car.

I'd like to get to the bottom of the running rich thing before I try lose hundreds of dollars selling something I used to drive home from the shop and to the grocery store.

[Solo_M_Tech]

The exhaust leak ( at the header to xpipe connection) is making the car enrich the fuel mixture. The leak allows the faster exhaust velocity inside the pipe to create a pressure differential, allowing fresh air to rush into the pipe. The car thinks its running lean so it enriches the mixture.

Get the leak fixed. This is a common issue in cases where those gaskets are not replaced. I've installed that xpipe a dozen times and you can rotate the pipes into an incorrect position, and still bolt it on. The flange isnt flush and creates a leak.

[cjm41]

Originally Posted by Solo_M_Tech

The exhaust leak is making the car enrich the fuel mixture. The leak allows the faster exhaust velocity inside the pipe to create a pressure differential, allowing fresh air to rush into the pipe. The car thinks its running lean so it enriches the mixture.

Get the leak fixed.

There is no more leak. There has been for the last, who knows how many miles. Since i bought the car. I drove it 5k miles with an exhaust leak spending hundreds trying to run it down along the way.

As of yesterday I have a new x pipe and no exhaust leak. This is when the running rich problem first appeared.

[amrazM]

Interesting, reset the adaptations on the dme then do a drivecycle

[ALCOBENDAS]

I have many times that canceling the secondary catalysts brought much more smell so I did not cancel mine ... there are more people who canceled them and then went back to test pipes ..

[BPMSport]

People often think that they are running rich because of the smell. Our software does not run any richer than stock, and will be at lambda 1 under idling and part throttle conditions. Read the oxygen sensors or use a tailpipe sniffer and you will see that the mixture is likely spot on, and the smell of being Catless or having a modified exhaust setup is being confused with running rich.

If there is any unmetered air being introduced into the exhaust stream, the vehicle may respond by richening the mixture to compensate for this.

A shop indicting that you need a tune to solve this sounds very inexperienced. Instead of guessing, actually verify that you are infact running rich by looking at the mixture. Tuning to specifically solve something that shouldn't be happening in the first place would be band-aiding an existing problem that should be fixed with methods other the software. The software will not cause the mixture to be overly enriched unless there is a reason to call for it.

[cjm41]

Originally Posted by BPMSport

People often think that they are running rich because of the smell. Our software does not run any richer than stock, and will be at lambda 1 under idling and part throttle conditions. Read the oxygen sensors or use a tailpipe sniffer and you will see that the mixture is likely spot on, and the smell of being Catless or having a modified exhaust setup is being confused with running rich.

Thanks for the input. I guess it was really just cancelling the secondary cats. It's really surprising how bad it is.

[BPMSport]

Originally Posted by cjm41

Thanks for the input. I guess it was really just cancelling the secondary cats. It's really surprising how bad it is.

The secondary cats are still 200cel cats, and will drastically reduce the smell as compared to a Catless car.

They are akin to going with high flow cats over a Catless setup on a car with only one set of cats - a very large difference in smell and in reducing emissions. A completely Catless M3 will have a fairly strong smell.

[SAMM3Y]

Yep my car was catless for about a week.. now I have three different x pipes for my car..

Make sure you're sliding the choke from "turtle" to "rabbit" once the car's warmed up a little... lol

[BayE30]

I have the evolve Xpipe with HFC in secondary postition, and i still think the car smells pretty bad. Thats until i follow my buddies in their catless cars....catless s65 smells pretty bad.

[cjm41]

Alright so I called AA to price out their HFCs. They ain't cheap, that's for sure.

- They agreed that my description of how strong the smell is and the carbon buildup is not simply from deleting the secondary cats. That I should expect to smell more, but to the extent I describe.

- The shop that installed the x-pipe (reputable, forum members, authorized AA dealer) told me the car seemed to be running rich, almost immediately after starting it.

Anyway- AA said it's possible re-tuning would help, but that it's not that it's a problem related to any tune itself, but that something may be amiss and re-tuning could solve the problem.

Especially since BPM commented here I wanted to make that clear. I purchased the car with the BPM tune so I'm not a BPM customer, myself, I do not have the software or the cable. I have no reason to believe this is related to any specific tune, but it couldn't hurt to wipe a 5 year old tune and start fresh to at least rule it out.

If a new tune and new plugs don't clear the issue up (or at least bring the smell and soot within tolerable threshold) I will consider purchasing the AA cats which will fit my new x-pipe, this way I can swap them out for meets/cruises or track days.

[yidgyi]

Whats your AFRs? I'm straight piped and sure I smell gas but not to the extent you're talking about and I'm running Gintani's extreme burble tune. Double check for leaks.

I doubt its the donut gasket at the headers / test pipe area because those usually throw a bunch of misfire codes if something is missing. Like you said, the shop installed the x pipe so they probably forgot to tighten something up. They recommended a tune off the bat to fix a smell problem? lol.

[cjm41]

Originally Posted by yidgyi

Whats your AFRs? I'm straight piped and sure I smell gas but not to the extent you're talking about and I'm running Gintani's extreme burble tune. Double check for leaks.

I doubt its the donut gasket at the headers / test pipe area because those usually throw a bunch of misfire codes if something is missing. Like you said, the shop installed the x pipe so they probably forgot to tighten something up. They recommended a tune off the bat to fix a smell problem? lol.

They indicated that it was running rich. They did recommend a tune. I let them know I had one at that point. They may have been unaware and just defaulted to no cats at all, needs a tune for that.

I'm super sensitive to exhaust leaks. There are none. I'm positive. No codes being thrown either.

[yidgyi]

Originally Posted by cjm41

They indicated that it was running rich. They did recommend a tune. I let them know I had one at that point. They may have been unaware and just defaulted to no cats at all, needs a tune for that.

I'm super sensitive to exhaust leaks. There are none. I'm positive. No codes being thrown either.

Sorry, I got nothing then. Is your nose super sensitive? I know a couple people who are super nose sensitive and know I'm outside their house by my exhaust fumes. Could just be you being more sensitive then others. To me, I smell fuel at stop lights or if I'm outside my car when idling. Inside I don't usually smell anything.

Did the shop tell you how they indicated its running rich?

[Powashiftin]

I'm fully catless and I don't think the smell is that strong. I have the bimmerworld x pipe FYI.

[Scharbag]

I think part of it is that the S65 in general is a gas guzzling pig. Akin to a 1976 Ford with a 460 and a 2 barrel. Come to think of it, my 1976 ford may have actually been better on gas than my M3...

All that fuel has to go out of the exhaust... Likely why they E92 has more catalytic converter volume than any other car I have ever seen!!!

I know the smell when I had test-pipes was very noticeable compared to stock. Could only imagine it with zero cats...

[cjm41]

Originally Posted by yidgyi

Sorry, I got nothing then. Is your nose super sensitive? I know a couple people who are super nose sensitive and know I'm outside their house by my exhaust fumes. Could just be you being more sensitive then others. To me, I smell fuel at stop lights or if I'm outside my car when idling. Inside I don't usually smell anything.

Did the shop tell you how they indicated its running rich?

My nose and ears are super sensitive. But this seems to be more than me just being a b*tch about some smell.

I was at the shop when they started it for the first time. After about a minute they said it was running rich, to which I immediately agreed as the smell was pretty intense.

Although I'm not getting any popping, my downshifts are a little sloppy sounding like maybe it's a bit muffled. I'll occasionally get a pop on downshift but it's happening under me, not put the tailpipe.

Here's a quick shot of me coming to a red light. Downshifting into first you can hear it's not super clean. Don't know if something that mild is indicative of running rich.