Jump to content
Oneball

E39 540i Misfire Rough Running

Recommended Posts

Yes, I reset them eveytime I do something. 

 

The adaption values have returned to what they were before after everything I've done except putting the X5 injectors in and in that case they just leaned it off a couple of points more than it once was doing previously. 

 

I think its running slightly rich but can't think of a reason. I've not excluded. 

Share this post


Link to post
Share on other sites

I've reread your whole post and it seems to me that you've checked everything!

The only thing I can think of is if it's a 9/97-9/98 M62 with 5.2.1 is the ignition coil power relay in the E-box.

Share this post


Link to post
Share on other sites

Thanks

 

Ive swapped the relays with the Ines from the Alpina and it made no difference. Worth a try!

 

May get new coils but the ones from the Alpina made no difference. 

 

 

Share this post


Link to post
Share on other sites

No. It's got the twin prong NGK ones in. Might try taking one out and seeing what the spark looks like. 

 

Adaptions are leaning it off. Lambda sensors are sooty but the plugs are really clean and never wet. 

Share this post


Link to post
Share on other sites
2 hours ago, Oneball said:

No. It's got the twin prong NGK ones in. Might try taking one out and seeing what the spark looks like. 

 

Adaptions are leaning it off. Lambda sensors are sooty but the plugs are really clean and never wet. 

 

My old e34 540i hated those plugs!! I spent a small fortune on the splitfire plugs when they first came out and when i fitted them the car ran like a bag of nails!!! Fitted oem and then ran spot on.....never used them since.

Share this post


Link to post
Share on other sites
14 minutes ago, 530d titansport said:

 

My old e34 540i hated those plugs!! I spent a small fortune on the splitfire plugs when they first came out and when i fitted them the car ran like a bag of nails!!! Fitted oem and then ran spot on.....never used them since.

The ones I put in are the OEM ones. That's what BMW recommends for the M62

Share this post


Link to post
Share on other sites

I got oem from sytner for my e34 520i at massive expense!!! (£84 for 6), the car ran like a bag of s**t it was completely dead until around 3500-4000 rpm I really thought it was a coincidence that something was terribly wrong and overlooked the spark plugs completely as they were brand spanking from the dealer, even did a compression test on the engine, anyway in the end I decided to try the old(12000 mile) spark plugs back in and surprise surprise, it ran like a smooth 6 pot again.... anyway after much shouting on the phone they decided to take the car in any try the spark plugs for themselves at the workshop and when I had the car back they said that they put the new plugs in but reduced the gap by 0.2 mm and it was perfect!!! Also have you checked all of the spark plug boots? (Coil to plug) cracks etc and also there are 2 types with different resistance, 1.8 ohm and 1ohm I believe don't know if it makes a difference but check they are all the same if you know what I mean

Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

Different plugs in it and the coils from the Alpina and no change, so think I can rule those out.

Share this post


Link to post
Share on other sites

Swapped the TPS from the DSC with the one on the throttle body and no change.

 

There's a little bit of a tappet tick on bank one so took the cam cover off and none of the lifters are squishy and none seem to be jammed so pretty sure I can rule that out too.

 

Every time I think about it my first reaction is that there's a vacuum leak but I've replaced what was needed to fix the vacuum leaks that were present and done vacuum tests and the garage did a smoke test all of which said no leak, just can't figure it out.

Share this post


Link to post
Share on other sites

So I've fixed the small exhaust leak in the joint between the centre box and the cat on the right hand side and it's made a massive difference. Can't really understand why a tiny leak behind the cats and o2 sensors would make it run rough but it's a lot better, there is a little leak in the manifold to downpipe joint too, maybe I'll sort that and it'll be 100%

Share this post


Link to post
Share on other sites

 My old 540i had been de-catted and the pipes that were put in instead rotted out on that joint on both sides. When I repaired it, the engine seemed a lot smoother and more responsive (not to mention quieter!). Also, when I had a stainless system fitted to my 535i the exhaust guy, who really seemed to know his stuff, told me that using the correct diameter pipe in the centre of the system was critical as using too big or too small would affect the back pressure and cost the engine a lot of torque.  I would say the manifold joint leak could actually cause an incorrect mixture on that bank to as it is before the o2 sensors so would definately be worth getting that done, access isn't going to great though!

 

 It's good to hear it's running better by the way! B)

  

 

Edited by NWJW

Share this post


Link to post
Share on other sites

Result!

 

Get a full S/S system in from someone who knows what they're doing and move on. Cats on these beasts break up and can block outflow significantly. E39 exhausts are built to last and it's likely that you're still running the original pipes she left the factory with. Custom built S/S normally about half the price of a full OEM system (around £2k), but that assumes that it's built to the right spec, as NWJW suggests tolerances appear to be quite fine. So there's a decision to made there.

 

Glad you've found a solution.

Share this post


Link to post
Share on other sites

Cats were replaced at BMW about 5 years ago, I've got the bill in the history file for mucho dinero!! However it's BMW's joint that was leaking as they had cut the joint to the centre box longer on one side than the other so the split in the sleeve wasn't over the pipe, I've cut them symmetrically and put new sleeves and clamps.

 

The manifold leak is only audible when it's cold, as it heats up it goes away which is why I had discounted it but yes I'd agree with you that a leak before the o2 sensors would mess up the mixture. Will do it and see what happens.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×