BMW 4.6 is poor acceleration and hesitation

[bcredliner]

Replace all coils? OP already replaced two and had the others checked. You could be right that the culprit is a coil or coils but what happened to read the codes before throwing more $$$$ at it?

[TerminatorX5]

i replaced only one coil out of 8 because i read the codes... throughout 20 posts, about 6 or 8 posts suggested to read the codes, but if for some reason OP can't go this route, then we can suggest throwing parts... in the course of last 10-20 threads i must have made that romanian guy super rich!!! if you are doing any kind of DIY on these cars, you must have the cable and the software to read the codes...

[nyum96]

Replace all coils. I had the same issues. I replaced one coil per the code, then the code jumped to another cylinder, then to another cylinder... BMW suggests to replace all at the same time and I understand why. What you here and see is fuel being cut to the cylinder because of no spark. Your running on less cylinders. The check engine light will flash at higher RPM's then would stay on. I replaced my spark plugs when I bought the vehicle and this happened. Weird but 6,000 miles later, still good. Look into the Bosch replacements coils. I hear you do not have to change all coils when one goes out but do with the Bremi's. I'm a believer. Code reader helps.

[upallnight]

Sound like your converter are busted up inside and choking the engine because it can't exhaust the gas fast enough. There was another guy that had the same issue.

Here's the link http://www.xoutpost.com/bmw-sav-foru...der-fixed.html

Before buying new converters, here's a video link on how to test the converters.

https://www.youtube.com/watch?v=9TlygJMxTps

[bcredliner]

Originally Posted by upallnight

Sound like your converter are busted up inside and choking the engine because it can't exhaust the gas fast enough. There was another guy that had the same issue.

Here's the link http://www.xoutpost.com/bmw-sav-foru...der-fixed.html

Before buying new converters, here's a video link on how to test the converters.

https://www.youtube.com/watch?v=9TlygJMxTps

It could be a cat, trace that rattling to the source, they rattle when they get bad

[Aman]

Originally Posted by TerminatorX5

replace all coils - at least as preventative... this is what i had with bad coil on cyl 5 (4.8 V8) - the car idled kind of ok... slight "murmur" instead of pure purr... driving was ok, as long as i did not push over 2500 RPMs... as i pushed over 2500 the car was "undercutting", as if in a hand combat, somebody hits you hard iin the area just below the chestplate, and that cuts off your breathing - the pedal would hit the floor, the RPMs will surge from 1200 to 2500 and instantly back to 800 and rebounce to 1200 while the car, instead of launching, would actually slow down (if it were rolling and i need to merge, it would not merge). straight outright scary... no engine light... until i drove on long uphill where i had to keep engine running at higher RPMs, the engine light flashed, and finally just stayed on... i had my laptop connected at all the times, and cyl 5 was acting up all along... the moment i stuck in a brand new Bosch coil, everything came to normal...

Go to fleabay, look for INPA... it is the factory software that will let you diagnose many aspects of the car...

Thanks. Am hopefully going to a bmw specialist garage in an hour or 2 to get codes read.
Did you have to replace all coils or only the one for cylinder 5?
Did you get the rattle too?
Best wishes

[Aman]

Originally Posted by nyum96

Replace all coils. I had the same issues. I replaced one coil per the code, then the code jumped to another cylinder, then to another cylinder... BMW suggests to replace all at the same time and I understand why. What you here and see is fuel being cut to the cylinder because of no spark. Your running on less cylinders. The check engine light will flash at higher RPM's then would stay on. I replaced my spark plugs when I bought the vehicle and this happened. Weird but 6,000 miles later, still good. Look into the Bosch replacements coils. I hear you do not have to change all coils when one goes out but do with the Bremi's. I'm a believer. Code reader helps.

Hi thanks for your reply.
Did you get a chance to see and hear the video I uploaded in this post?
Did you get the rattle / clicking noise with your car?
Did it go away after you replaced the coils?
Best wishes

[Aman]

Car is currently being looked over at specialist... Will update you all soon

[Aman]

I took car to a new garage
Car still has codes for misfire on cylinder 6 and 8 (originally was 5,6 and 8)
I know coils were definitely replaced by previous garage as I asked garage to leave covers off engine and I can see new coils on 5,6 and 8
Makes me wonder if original coils were fine after all (despite the first garage telling me they needed replacing)
To recap, plugs are all new
Today garage reset engine management light and at idle no faults came up (live test)
Need to bring car back for garage to investigate further

[pezho405]

Originally Posted by Aman

I took car to a new garage
Car still has codes for misfire on cylinder 6 and 8 (originally was 5,6 and 8)
I know coils were definitely replaced by previous garage as I asked garage to leave covers off engine and I can see new coils on 5,6 and 8
Makes me wonder if original coils were fine after all (despite the first garage telling me they needed replacing)
To recap, plugs are all new
Today garage reset engine management light and at idle no faults came up (live test)
Need to bring car back for garage to investigate further

You should try to swap coils to different places, then see if that cylinder begins to have a problem