Code 2742 - harrop m3

[Bakerboy]

Hi

My e92 m3 is supercharged on a harrop charger.

I am getting the odd misfire when changing gear at high rpm that only really comes about after prolonged high rpm driving (on track).

I get the code of 2742 which is bank 1 heater circuit on the o2 sensor, it doesn’t come up frequently though. I clear it and it might not come back for a few hundred miles.

Wondering if anyone has had similar issue and how they overcome it?

Car has had new plugs, new primary o2 sensors, new charger belt, new exhaust gasket where midpipe joins the headers.

One of the gaskets seemed problematic to seal so used a little grey sealant in installing which seems to have done the trick in sealing.

Just to reiterate car can be faultless but this misfire happens some of the time.

I also noticed what felt like a little clutch slip on my last track day which was a little disconcerting but might not be related. I thought the dct was more than up to the job of handling these sort of power levels, I guess I need to just keep an eye on this as it seemed ok on the drive home after.

Thanks

[Mvy]

When was the last time you changed coils? My harrop smoothed out a ton once I changed out old ones for new. I was not getting misfires, but Coils would be my first stop if they had not been replaced recently.

[Bakerboy]

Never changed them, car done 30k

Worth considering though. You would get a misfire code surely on a specific cylinder?

Car is going into specialist for rod bearings week after next and I will ask him to run a few checks to try and work it out.

Any help in meantime is appreciated though

[Bakerboy]

Originally Posted by M3Post

Without high flow cats the exhaust gas temps can creep up in super charged applications due to back pressure. For this reason, I run a plug that's one heat range cooler than stock = NGK Racing Iridium R2556B-9 - with hi-flow 200cpsi cats.

If O2 sensors, Coil Packs are both good, then fuel injectors and higher octane gas are worth checking. Consider running test pipes to rule out and test for back pressure issues.

Check to see if the misfire is isolated to just one cylinder.

Yes, the DCT clutch can slip on cold days with the Harrop - or at least mine did. I went with the SSP Spec R clutch pack. The weak traction link is usually tires but I ran drag radials for a while. So if high grip rear tires and cold day then DCT can slip.

In summary:

1) Check for coil pack codes
2) Increase octane
3) Run with test pipes
4) Consider cooler heat range plugs

Yeah I have test pipes already.

Plugs are stock ones atm

No coil pack codes atall, only 2742

Very odd

Thanks for the pointers!

[Bakerboy]

so for the clutch slip

I hear there is adaption reset, has anyone tried this?

Also can a low fluid level cause slip?

it slips for a second or so in 3rd 4th gear.

[Mvy]

Originally Posted by Bakerboy

Never changed them, car done 30k

Worth considering though. You would get a misfire code surely on a specific cylinder?

Car is going into specialist for rod bearings week after next and I will ask him to run a few checks to try and work it out.

Any help in meantime is appreciated though

Coils seem to deteriorate performance wise and not throw codes every time. In my case i had no codes but once I changed them out my smoothness and sharpness in acceleration improved. It was just an idea since you are getting misfires sometimes spark can be a contributing factor.

[Bakerboy]

Originally Posted by M3Post

Bakerboy, yes there is such a thing as clutch adaptation reset but DCT software adaptations are employed as fine tuning for clutch engagement as the DCT clutch packs wear down, at least as far as I understand their purpose. Search the forums, and no doubt you'll find reims of information. I would advise against clearing the DCT clutch adaptations just incase the engagement point or clutch slipping in 3rd to 4th becomes worse. My DCT did the same thing too. Low fluid level does a bunch of bad things like make the DCT run hot, judder and causes shift delays. A DCT fluid level check at normal operating temp wouldn't hurt.

Try the following: Set DCT shift program to 5 level with traction control off, or in M Dynamic mode, and see if the DCT clutch slip is mitigated by the higher DCT pump (fluid) pressure setting. The software uses less slip with the higher shift severity maps.

Thanks for your reply.

I always drive in level 5 and Mdm mode. I did back it off to 4 when doing the trackday as thought I would give the transmission a break plus smooth it out but maybe wasn’t the best idea after all. As soon as it felt like it was slipping I turned it back up again.

Clutch looks a very pricey job

The clutch seems to momentarily slip then is fine to the redline, almost as if not all pressure has been applied to clutch for a second or so. Is this what you had?

How easy is it to check fluid level? should I change fluid? I’m guessing it’s a wet clutch?

Sorry for all the questions but better to hear it first hand from harrop owner.

Thanks

[Bakerboy]

Originally Posted by Mvy

Coils seem to deteriorate performance wise and not throw codes every time. In my case i had no codes but once I changed them out my smoothness and sharpness in acceleration improved. It was just an idea since you are getting misfires sometimes spark can be a contributing factor.

Thanks for the heads up buddy, I will defo ask A Reeve when he does bearings if he can do some checks.

How much is a full set of coils roughly?

[Mvy]

Originally Posted by Bakerboy

Thanks for the heads up buddy, I will defo ask A Reeve when he does bearings if he can do some checks.

How much is a full set of coils roughly?

At FCP euro, to buy a coil and spark plug replacement kit costs $625. Thats for all 8 and OEM. If you want BMW brand, which I would avoid as we know the OEM is the same part thanks to Theodores post, its an extra $300.

BMW Ignition Service Kit - 12137841754KT

While you are in there you might want to replace the spark tubes as well to keep everything sealed for another $80. BMW Spark Plug Tube - Genuine BMW 11127835170

[m3boost]

change o2 sensor precat bank 1 & 2

[Bakerboy]

Already done as explained in first post

[Bakerboy]

I don’t seem to get the code 2742 anymore, which is very strange I know.

The hesitation is still there if going hell for leather through multiple gears on occasions but I barely get the space to really pull many gears before having to brake on the road.

I had my rod bearings done last month and at same time a clutch readaption which didn’t really help proceedings as noticed slip still.

However what I have noticed is it only does it in the really cold weather and can stop it happening by doing the following.

Once car is up to operating temperature I used to just hit the m button and go for it and this is normally when slip is most noticeable. If i do a few half throttle pulls to almost get the box up to a higher temp then give it everything it doesn’t slip atall. I really think it’s a temperature thing.

I am also in the process of dropping the gear box fluid and adding a new suction filter to see if this helps. The oil that came out was pretty spotless and a clear gold colour, the magnet in the dct pan had a small film or grey metallic sludge on it but nothing alarming. The car is still in the air in my garage with the fluid about to go back in.

Will keep you posted

[Bakerboy]

Got the car off the the axle stands last night and took it out for a drive, so far so good no slip, no warning lights etc. Gear seemed slick as always.

Gave her a clean today and will probably keep her garaged for a while now.

One thing I did notice was small metal deposits in oil dribbling out of pipes that you have to remove at side of box to get the pressure filter changed! Not sure if this is normal practice to see.

[jvictormp]

Did you figure it out?

[Bmwdoubles_]

Originally Posted by Mvy

At FCP euro, to buy a coil and spark plug replacement kit costs $625. Thats for all 8 and OEM. If you want BMW brand, which I would avoid as we know the OEM is the same part thanks to Theodores post, its an extra $300.

BMW Ignition Service Kit - 12137841754KT

While you are in there you might want to replace the spark tubes as well to keep everything sealed for another $80. BMW Spark Plug Tube - Genuine BMW 11127835170

You can replace the tubes without pulling the valve cover?

[nycplumber]

Originally Posted by Bmwdoubles_

You can replace the tubes without pulling the valve cover?

No