[Joshboody]

Originally Posted by Tzu

Find Dzenno's therad about misfiring. He had a misfire in cyl 5 I beleive, which he spent many many $$$ trying to fix. The solution was to gap the plugs. Albiet, I'm sure his was exaggerated by the high power he was making.

No, Dz's issue was DME misfire detection which had to be turned off. Basically DME anticipates crank position, and apparently higher boost resulted in false misfire detection on cyl 5.

I don't believe gapping did anything in the end.

[335i E92]

Your're right, gapping the plugs didn't help him.

His problem was differnt to the rough idle in this thread though. His was a missfire under heavy load and very high boost, he tried closing the gap rather than opening it as i'm suggesting.

His thread is below, looks like he still hasn't found a a fix.

http://n54tech.com/forums/showthread.php?t=12811&page=5

[335i E92]

Originally Posted by Joshboody

No, Dz's issue was DME misfire detection which had to be turned off. Basically DME anticipates crank position, and apparently higher boost resulted in false misfire detection on cyl 5.

I don't believe gapping did anything in the end.

Is it possible to deactivate 'DME misfire detection' with a BT cable? Isn't this a fail safe parameter, any issues with turning it off?

[Joshboody]

Originally Posted by 335i E92

Is it possible to deactivate 'DME misfire detection' with a BT cable? Isn't this a fail safe parameter, any issues with turning it off?

I doubt this is your issue, unless you are heavily modded. The black #5 looks like it could be a leaky injector.

I noticed you reset adaptations by accelerator... I'm not familiar with this and it would be tough to know if it took. BT tool would be best approach.

[boom]

Originally Posted by 335i E92

I thought this and even had a full DME reset to BMW's latest software version, car still had a rough idle when finished.

Also the rough idle was immediately after changing the plugs, it would need to unbelievably unlucky that i suddenly gained a bad ECU circuit the second i changed the plugs?

It may be a crazy coincidence but when the dme goes bad, it just goes. No warning, no gradual decrees, etc. it just doesn't work right. It sounds like you've traced every mechanical cause to no avail. You might investigate the cost of a used ecu or a BMW performance kit that includes the new dme if youre msd80.

[raceyBMW]

Get the spark plug socket from N54tuning.com, its half the price of the OEM after shipping ($30), but has a magnet that actually works.

The one from ECS tuning works and is cheaper, but you have to take out the magnet as it won't fit otherwise without jamming the socket down and busting the magnet like you did. Also, not having the magnet means its a little harder to take the plugs in and out.

[Tzu]

Originally Posted by Joshboody

No, Dz's issue was DME misfire detection which had to be turned off. Basically DME anticipates crank position, and apparently higher boost resulted in false misfire detection on cyl 5.

I don't believe gapping did anything in the end.

Oh thats right. He did have some small success initially gapping them though... it's worth a try.

[bavaddict]

Originally Posted by taylors335

shoulda bought the SNAP-ON TOOLS socket !!!!

Originally Posted by geterdone

Your suppose to take the magnet out.

I don't see why I would have had to take the magnet out. It was there for a reason! Plus the brass washer was there to keep it in place and i really had to pull it out with pliers.

I think its either a faulty design OR I became a victim of 1 in a 1000000000's failure rate that this socket may have had.

And like few members have said: buy good quality tools! I suppose there is a reason why BMW socket is $60

[bavaddict]

Originally Posted by 335i E92

(Like your post mines a bit of an essay)

I replaced my plugs just over a year ago and immediately the car developed a rough idle.

On idle the car will misfire and shake / shiver every 5 seconds or so. When this happens and when the car is warm the rev’s will jump from the normal 600rpm to 750rpm and hold there until I restart the car. It as if the ECU raises the tick over as if to try to compensate for the misfires. Not once over the last year had my car thrown a code to indicate where the problem lies. My symptoms are all at idle, not once has it misfired under load.

Rough idles on the n54 are quite common and I have spent the last year trawling countless threads to try to find a solution.

From doing so much re-search my conclusion is that people experience these shakes & shivers on idle for many different reasons so there isn’t a one off single explanation or fix. Some found a fix with new injectors, other are saying new HPFP or coils.

Since I changed my plugs for the 1st time at 40k miles 12 months ago I immediately got this rough idle. To try to rectify the rough idle I’ve had the below changed, none of which solved the issue.

• X2 further sets of plugs
• X6 New Coils
• X6 Injectors
• X1 Low pressure fuel sensor
• A full engine out head off decarb and rebuild.
• Countless adaptation resets

The biggest clue that you and I have is that this happened IMMEDIATELY after changing the plugs. Because of this please don’t make the same mistake as I did by swapping everything out. I’m out of warranty now but luckily for me most of the above I managed to get under goodwill.

Yours and my problem is DEFINATLEY related to the plugs. Both rough idles have happened once swapping out the original plugs that had eroded away considerably.

Situation:

When you then change the heavily eroded original plugs for brand new ones the ECU struggles to adapt to the difference in plug gap. Even after resetting every single adaptation know to the n54 the ECU still can’t adjust itself enough to rectify the idle misfire.

Remedy:

When fitting new plugs re-gap them to something close to the eroded originals.

I’m booked in to my local Indy to get my plugs gapped out very slightly next week. After going though the mill of swapping everything out over the last year I’m going back to the part that caused the problem in the 1st place ‘THE PLUGS’.

I’ve read a few threads on here that have discussed this as a fix to this rough idle. I just wish I had spent more time in that area when trying to find a fix instead of swapping everything out

If I can help anyone else from going through the same torment as me then it will at least have been worth something.

I’ll let you know the results next week.

Possibly the longest post I’ve ever written. Lol!!

Thanks!

I did read your thread and you mentioned that after adaptations were reset the issue went away (something you called LVS appearing in Gt1)? Is that not the case anymore?

I am assuming problem resurfaced for you...hopefully you can let us know what happened in your scenario!

EDIT: Sorry just realized you did post here that adaptation resets did'nt do a thing

[bavaddict]

Originally Posted by 335coupe2007

okay!! im so sorry for the misinformation then!! SORRY OP!! didnt mean to freak u out!!!! Im relieved myself because for the longest while, i thought i would need to get my plugs coded .PHEWWWW!!

No worries...perhaps what you may have heard is that, stealer(s) re-initialize the adaptation values (hence confusing them with "programming").

[bavaddict]

UPDATE: This weekend I had change to look at the brand new BMW Plugs and the BOSCH OEM's that I got. They look darn identical right down to gapping. I was thinking of ordering them from Tischer but it seems that it will be moot (based on the info i have thus far). What gives !!!!!!!

Secondly, I noticed something peculiar and I hope this is normal. Can anyone here confirm? I hope its not caused by the magnet pieces in the combustion chamber or the spark plug that fell off in the chasis My coolant temp needle moves after the car is off from last seen coolant temp to its current temperature (say after a run where coolant temp reaches 120 celsius and I shut it off). I might sound crazy so here are the steps:

1) After a normal driving/run, where coolant temperature reach is normal operating temp OR a bit below the normal operating temp (this does'nt matter as long as the coolant temp needle has moved few notches), shut off the car.

NOTE: In my case the coolant showed 110 deg Celsius before shutting off the engine.

2) Let the car cool off a bit. I let it sit for an hour while I was doing my shopping.

3) Now restart the car. What I noticed is that the needle climbs all the way up to 110 Deg celisus and then slowly drops down to 80-90 deg celsius mark.

4) I can reproduce this behavior all the time, however, I can't confirm if this was happening before since I never really paid attention.
NEXT: As one poster mentioned that my "low tech" method of resetting adaptation values may or may not work (based on the model year, production date etc), so I will be visiting my indy to see if they can do it via GT1 (after 335iE92 updates us if the gapping solution worked or not .... since he has tried resetting adaptions but to no avail).

[BlueLion]

I changed my spark plugs yesterday and drove the car yesterday and this morning with no issues. No reset, no gapping needed.

[mithiral67]

My temp sometime shows warm when i start it for a bit but settles down after a min or two. Pretty sure the temps on the car are based on averages over time and its just the computer doing its thing.

[335i E92]

Im booked in on Friday to try the plug gapping theory. When they did my head rebuild a couple of weeks ago they found the cylinder 6 was particularly coked up. I'm pretty sure that this is where my problem is. Even though I had my injectors replaced last year it's possible that I got the crappy ones again.

Anyway they've ordered a new injector to try if the plug gapping is a fail!!

One thing for sure is that on start up or idle a cylinder is failing to ingnite the fuel which produces the shakes on tick over and causing it to stubble in to life with a puff of black smoke from the unburnt fuel.

It's got to be plug gap or injector... The truth is out there!!

Will report back at the w'end

[R1000K3]

Originally Posted by 335i E92

When fitting new plugs re-gap them to something close to the eroded originals.

I’m booked in to my local Indy to get my plugs gapped out very slightly next week. After going though the mill of swapping everything out over the last year I’m going back to the part that caused the problem in the 1st place ‘THE PLUGS’.

I’ve read a few threads on here that have discussed this as a fix to this rough idle. I just wish I had spent more time in that area when trying to find a fix instead of swapping everything out

If I can help anyone else from going through the same torment as me then it will at least have been worth something.

I’ll let you know the results next week.

Possibly the longest post I’ve ever written. Lol!!

..... an interesting theory. But wouldn't it be easier and cheaper to switch plugs with a vehicle that has about the same mileage on the plugs instead of destroying a new set

Question; when the new plugs needs to be replaced, shall the upcoming set be opened according to this twice-eroded-gap, or to the original eroded gap ?

[zmt]

Just wanted to chime in here and say that I had the exact same issue w/ rough idle after changing plugs. I have yet to try resetting adaptations (only option is with cobb, any idea what values the "reset ECU" option actually resets?) but I'll give that a shot tonight and report my results.

[bavaddict]

Originally Posted by mithiral67

My temp sometime shows warm when i start it for a bit but settles down after a min or two. Pretty sure the temps on the car are based on averages over time and its just the computer doing its thing.

Thanks. But do you actually see the coolant needle moving from old temp mark to new (colder) temp mark?

Anyone else seeing this behaviour? Or I am just going paranoid?!

[bavaddict]

Bump...for an answer

[JO3]

I've seen that behavior too. I didn't really think much of it, since the needle eventually moved down to the accurate temp.

[bavaddict]

Originally Posted by JO3

I've seen that behavior too. I didn't really think much of it, since the needle eventually moved down to the accurate temp.

Cool thanks! Just wanted to make sure. Definitely didn't happen with my e36 and e46.

[Stein67]

Just a curiosity, but has anyone who replaced plugs, immediately got a rough idle simply put the old plugs back in to see if it promptly goes back to a steady idle?

[bavaddict]

I lost one plug (closest to the firewall) during removal, else I would have tried.

Perhaps someone else here who has all 6 can try?