Fuel injection and additives
 

I searched the e70 forums and cant find anything in regards to to my issue so I wanted to start this thread. I have a 2007 e70 with 95k and I get this rough idle, rough shifting so I replaced the spark plugs, air filter, cleaned the MAF, and I still get a rough idle and rough shifting. So on separate fillups I put a bottle of Seafoam, Redline and BG k44 in and every time I put these additives in it ran perfect, like new! but once I refilled the tank without the additives it goes back to it would slowly go back to its rough shifting, rough idle. To clarify, the rough idle isnt that bad but the shifting does get much worse over time. Yes, I did the tranny reset and throttle reset but that only helps temporarily. I am thinking my fuel injectors are he issue. I use premium unleaded, Costco or ARCO or Chevron fuel, but I always use premium unleaded. No codes. Any ideas? :dunno: Thanks!

When was the last time you replaced the fuel filter? That could definitely be a contributing factor of the rough idle.

Thanks for that suggestion. I thought that as well until I found out that it appears 2007-2008 (4.8) e70's don't have fuel filters. I searched realoem and couldn't believe there was no fuel filter listed, so I went under the car and did a visual search and still couldn't find a fuel filter. I never heard of a newer model car not having a fuel filter, my E53 and Z3 have one and it looks like only 2009 3.5d and higher model year E70's have fuel filters. If anyone knows if I'm missing something, let me know.

Yes, it has a fuel filter. It is in the fuel tank, and is part of the fuel delivery unit (pump/level sensor). It isn't straightforward to change it, and I suspect it is expensive. I don't think it is a planned maintenance item.

It is possible that there is a problem with the fuel filter, but the most common problem is that it gets clogged. When that happens, you are likely to have issues with reduced power (lack of fuel) rather than at idle (when it hardly needs any fuel).

Using some of those products you list can damage a fuel system.

If you want to just use a good cleaner, put a bottle of Techron in it. Get it from Chevron, or from BMW (who rebrand it in a BMW bottle). Other cleaners that use harsh solvents are not recommended, as they can dissolve things.

do you have a code reader and scanner?

WHY NOT INVEST IN THIS?

You've got DIY skills...you've spent money on some tools...buy something that lets you look at engine operating parameters. (like a $30 cable and hacked EDIBAS/INPA BMW software) If you can see what the engine is doing, in terms of timing, fuel trims, etc, etc.

MUCH better that this empiric guesswork.

Go for it- take that step into the modern DIY era and you will be AMAZED.

;)

Try a full clean tank of a quality fuel like Shell 93 and put a full bottle of Techron in. I've used this in all my vehicles for years now and you'll be amazed the difference.

If after running through a full tank, you might need to use a second bottle if things were really dirty. It's amazing how dirty fuel injectors can really get.

Same stuff that your BMW dealer sells and will put in your car...

http://i138.photobucket.com/albums/q...%20Cleaner.jpg
http://i138.photobucket.com/albums/q...20Injector.jpg

Thanks for the replies.
ARD, funny you mention the EDIBAS/INPA BMW software, I just ordered the cable and I installed the software yesterday, now I got to learn how to use it, good thing there is a website (bmwcoders) to help with that.
JCL, I have read a lot on all the various engine/fuel additives, and there is good and bad reviews about all the different snake oils. I have used them for years on 3 bmw's with no adverse effects. Funny how they make my car run better/smoother until it is out of the system. Hard to believe that BMW has that delicate of a system where it wont allow us to add fuel additives without ruining the fuel system. If that were the case, I'm sure we would hear a lot of complaints.
I haven't yet tried Techron, I will try it and let you guys know how it works out.

If your vehicle is running better when you have a low tech additive in the tank, I suggest it isn't the cleaning effect at all, but rather the change in fuel properties by combining whatever base the additive has with your fuel.

Many of them use naptha, kerosene, or solvents a base. It is those solvents that damage components in your fuel system. The products you are using don't appear to be cleaning, as the cleaning effects would still be there.

Techron is a cleaner of a different class. It is what is added to good quality gasoline as a cleaner by the fuel distributor, but more concentrated. You can't compare it to the snake oil products.

On the topic of a fuel treatment that is safe for BMWs.

I've been adding 10oz of Lucas Upper Cylinder Lube/Injector Cleaner/lube at EVERY fill for almost 5 yrs and over 80k miles. No issues with almost 190k on the X.

OE cats, injectors, fuel pump and pressure regulator working flawlessly.

So, I wanted to give an update. Being the additive junkie that I am: I have tried Seafoam, Redline, STP, BG 44k, Techron and Lucas Oil Upper Cylinder Fuel Treatment... and the winner is........Lucas Oil! Techron is a close 2nd. I put in the Techron first and 90% of my issues went away, then I put in Lucas Oil----I couldn't believe the results, no rough idle and smooth shifting, but of course the Techron could have done most of the work cleaning the injectors and the Lucas Oil was the icing on the cake. But from what I have read, these 2 additives treat different things and have slightly different chemicals properties. Others may have varied results but this worked for me. Seafoam and Redline only helped my issue temporarily and IMHO, a waste of money. This weekend I am changing the transmission "Lifetime Fluid" and filter in hopes of perfect shifting (if there is such a thing). That said, I am a fan of Lucas Oil Fuel Treatment. Hope this helps others.