Also poor 35i, but unusual outcome - nothing wrong?

[robbee]

Hi all,

So on Christmas Day, I was going to drive to my family reunion, only to have the misfire rough running and yellow engine warning light come up, sometime constant (while accelerating and up-hill), sometimes flashing (while coasting) and sometimes off while just idling. Drove around the block and it would hesitate more going up hill or accelerating harder, so had to abandon the car and take a cab.

So i’ve been following Maniacs thread on his poorly 35i, and other related threads to see if I could diagnose.

As I had just recently had the full BMW service (November), I did not expect it to be spark plugs. Bought the C310+ diagnostic scanner, which read a misfire in cylinder 3. So I swapped the coil pack and it did not follow to the new the cylinder. I then put in an old spark plug (which I asked to keep from the recent service), and as if by magic, the misfire was gone, along with the engine warning light. I was delighted, of course.

I was going to leave it at that (before ordering another BMW spark plug to replace the faulty one) when I thought I would try the faulty plug in cylinder 2, just to double check. Swapped them out and to my surprise, the car was still running perfectly, so spark plug was not faulty after all. Took a longer drive, and everything is running perfectly.

This leads me to think it was a poor connection, and that my jiggling around with the spark plugs and coils just corrected that. Alternatively, I know my battery is really on its last legs, and the scanner had picked up some other supply voltage faults (I’m guessing from when I connect and disconnect the battery to charge it, and driving with the ‘increased battery discharge‘ notice on the display. I’ve previously had other errors which seemed to be resolved following a battery charge, so the spark plugs may be another further consequence.

I just need to get INPA to work with tool32 so I can re-set and re-programme a higher capacity 80Ah 800CCA Hankook AGM battery (and double check its increased size will fit!

Will report back with any developments.

Robbee

[Kugaman1]

As per my previous post Robbee,
Check the dimensions of the 800amp battery I linked to and if the dimensions of the Hankook one are the same, it will definitely fit.
I do still maintain that there are only 3 or 4 companies that make car batteries for the uk market and brands like BMW just add their name to them and double the price!.