Car bogging after catless downpipe install

[M5_Raz]

Unfortunately looks like mine isn't covered. We'll see what the problem is on Tuesday. The pcv hoses looked fine to me.

[TinCanSailor]

Hoping ya come back with some simple easy to resolve news.

[M5Yams]

I was recently looking into the catless downpipe situation while still on a stock tune and saw a post somewhere that because of the catless downpipe the higher Temps extend farther down the pipe and reach the secondary o2 sensors, which in turn alert the car about the extreme heat and then the car pulls timing. this all occurs due to the car still believe there are cats there and needs to not overheat them and cause them to degrade. I think the answer to your problem is a tune or getting the secondary o2 sensors deactivated

[M5_Raz]

Originally Posted by M5Yams

I was recently looking into the catless downpipe situation while still on a stock tune and saw a post somewhere that because of the catless downpipe the higher Temps extend farther down the pipe and reach the secondary o2 sensors, which in turn alert the car about the extreme heat and then the car pulls timing. this all occurs due to the car still believe there are cats there and needs to not overheat them and cause them to degrade. I think the answer to your problem is a tune or getting the secondary o2 sensors deactivated

I would say I agree with the thought process. However, there's tons of people running catless on stock tune without a problem.

Hopefully I'll have an answer tomorrow.

[M5Yams]

Originally Posted by M5_Raz

I would say I agree with the thought process. However, there's tons of people running catless on stock tune without a problem.

Hopefully I'll have an answer tomorrow.

Exactly I will do some digging to see if I can find the thread again but I always saw the same with catless and stock tune

[M5Yams]

Here is the post!

https://f10.m5post.com/forums/showthread.php?t=935576

[M5_Raz]

Originally Posted by M5Yams

Here is the post!

https://f10.m5post.com/forums/showthread.php?t=935576

Thanks a lot for looking. I read through it and it doesn't sound like the same problem.

Mine still goes above 4.5k rpm, it just starts bogging and stuttering like it's cutting fuel. There's also no codes or any drivetrain malfunction, except for the increased emissions codes.

[M5_Raz]

UPDATE:
Hey all, it turns out that the crankshaft position sensor is the problem. They'll replace it and I can hopefully pick it up tomorrow.

Thanks again for the input and help.

[TinCanSailor]

Knowing how bad things can be I'd call that a win.

[M5_Raz]

Originally Posted by TinCanSailor

Know how bad things can be I'd call that a win.

For sure, it's not bad at all. Cant wait to have it back and healthy!

[TinCanSailor]

Originally Posted by M5_Raz

For sure, it's not bad at all. Cant wait to have it back and healthy!

I know that feeling. I've been separated from mine for about 2 months due to work. I'll be reunited in about two weeks though.

[M5_Raz]

Originally Posted by TinCanSailor

I know that feeling. I've been separated from mine for about 2 months due to work. I'll be reunited in about two weeks though.

Wow, that's a long time, bet you can't wait! It's why I could never live where it snows, I like to drive mine year round hahaha

[TinCanSailor]

Originally Posted by M5_Raz

Wow, that's a long time, bet you can't wait! It's why I could never live where it snows, I like to drive mine year round hahaha

I am definitely looking forward to a little throttle therapy and I thankful to live in Florida where i can ride on 2's or in my cage year round.

[M5_Raz]

Well, bad news. The sensor was replaced and the problem persisted.

Apparently there is a service bulletins for f90 m5's having this problem due to software. Nothing listed about f10 though.. they're saying it might be a faulty DME

[TinCanSailor]

A fellow on 6post recently mentioned a potential DME fault. I have read where folks have had dme issues when doing downpipes but it was due to the battery not being disconnected before unplugging the dme's and them reconnecting them with power on the line.

https://www.6post.com/forums/showthread.php?t=1798872

[M5_Raz]

Originally Posted by TinCanSailor

A fellow on 6post recently mentioned a potential DME fault. I have read where folks have had dme issues when doing downpipes but it was due to the battery not being disconnected before unplugging the dme's and them reconnecting them with power on the line.

https://www.6post.com/forums/showthread.php?t=1798872

The DMEs weren't touched with the battery connected. Just got a call from the shop saying that they have no idea what's going on.

I now have to take it to a dealer..

[TinCanSailor]

I wouldn't say anything about the other folks thinking it had a tune. The dealer will likely work with the aftermarket warranty company on billing if you have one.

[M5_Raz]

Originally Posted by TinCanSailor

I wouldn't say anything about the other folks thinking it had a tune. The dealer will likely work with the aftermarket warranty company on billing if you have one.

For sure, I told them it more than likely doesn't have one. But I don't have a warranty or anything. It's all coming out of pocket so they don't care that much in my case.

It's a mess though. They (dealer) called me today after a few hours and said they have no idea and need it for a week Now I'm stuck in a little 330i hahaha

[M5_Raz]

Final update:

Took it to the dealer who said they won't let the car leave without fixing it, which inspired confidence. However, a few days later, it was apparent that they had no clue about the problem. Advisor said the technician owns a gtr and the guy said you must run a tune with catless dp. I told him I don't care that his guy owns a Nissan and asked if he can fix it or not. He said they don't wanna look into it more since it has aftermarket parts. Charged me $215 and a total of a week of my time.

It's a bit far, but my last option was to take it to Steve Dinan's shop, Carbahn Autoworks. Wow, I haven't been this impressed with a business in a long time. Chris, the GM, told me they do things differently at their shop, no cutting corners. Booked an appointment very quickly and after a day of testing they found the problem! It was a loose connection to the DME, which under heavy acceleration was almost disconnecting and car was losing signal.

Glad to have it working perfectly again, can't recommend Carbahn Autoworks enough. Thank you everyone for helping out!

[Craze]

How did it have loose connection??

[x35250]

Originally Posted by Craze

How did it have loose connection??

The DME has several different connectors with locking plastic snaps. With two DMEs, you're looking at about 8 separate connections IIRC. The plugs sometimes look and feel like they are seated properly when they are not. It is very easy to put the connectors on loosely.

[M5_Raz]

Originally Posted by x35250

The DME has several different connectors with locking plastic snaps. With two DMEs, you're looking at about 8 separate connections IIRC. The plugs sometimes look and feel like they are seated properly when they are not. It is very easy to put the connectors on loosely.

Unfortunately yes. I had some problems with the Meistershaft 90mm downpipes. First set rattled badly so I contacted them and they sent a replacement. The second set rattled badly too so they had to be removed. After wrapping them with exhaust wrap, the rattling stopped.

So after 3 times of removing and putting everything together, it must've gotten loose.