7 months later: Baby CSi is happy!

[LappingLuke]

And so am I!!

After I bought my 93 850Ci in late January my fiancee and I suffered the 1000 mile drive home through Midwest Winter with failed EML, failed fuel pump(s) and one more mystery failure that is the subject of this thread. Full story of the stressful drive home if you're curious (LINK). Car kept dying, having no power, getting dusted by 18 wheelers in the mountains of TN on the interstate running 3rd gear 4k rpm....

But I'm here to tell you my car is now HAPPY and so am I!

Big thanks to all the guru's here who have given me helpful advice especially dragon850 who hooked me up with refurbed DK's, fuel pumps and a diagnostic computer which where all desperately needed to restore this car to working order. Obviously DK's and fuel pumps are a piece of cake to replace, so what was causing my issue? Long story short, it felt like a little baby misfire at idle, there was a clatter sound from the clutch at idle, car got dreadful MPG 13-14 on the highway according to the MID, felt pretty slow all the time and from time to time it felt like I'd lose a whole bank of cylinders while slowly letting off the gas pedal...


Last weekend I tested fuel pressure and all came back fine so I spent tons of time staring at INPA trying to decipher what it was saying to me. it was reporting one bank was consuming 38% more air than the other which was matched by a 38% longer injection time. My friend who is a Mustang guy but has done quite a bit of engine calibration (even though I think he's a bit of a goon and take everything with a grain of salt) suggested that the DME must be increasing the MAF transfer function and reporting higher mass rate due to adding fuel for a lean condition and this was the change of mindset I needed. I isolated Bank 1 by disabling bank 2 and it ran like crap! Misfiring all over the place. So double checked the other bank alone, it was fine. Pulled the plugs and found 5 of them badly fouled and 1 of them was clean and new....

After just throwing new plugs in didn't do the trick, I inspected/tested the ignition system with my calibrated eyeballs, multimeter and hooked an old plug to the #2 wire to see the spark was actually there and it was so it wasn't ignition problems. Frustrated, I hooked the wire back to the plug in the engine and pulled the injector connector off #2 and things did not get worse.... I thought you gotta be kidding me. After fussing with the connector for a bit it finally clicked back on and suddenly things got 100x better! The clatter at idle went away and the subtle shake cleared up. Apparently someone before me also struggled to get that connector on and wasn't fully clicked on.

I went for a cruise around the block and it felt like a completely new car! I drove it to work yesterday and didn't have to downshift from 6th to make passes on the highway. I could nail the rev match downshifts every time. It felt fast! My MID fuel economy on the highway at 80mph was 18.4 when usually it would say 14.5 max if I babied it. Literally just a glorious success all around. Granted, I cemented myself among the world's worst mechanics by taking 7 months to figure this all out, but I did get a notoriously complex and somewhat finicky car 1000 miles home and got to the bottom of the problem eventually which is more than a lot of people can say I guess. In the end some of you will have already figured out, with #2 not firing consistently (or at all I suspect) it was dumping oxygen down the exhaust tricking the DME into thinking there was more air getting in. To correct, it added tons of fuel, fouling my plugs and running those 5 on a very rich mix, killing my MPG and power, making it run substantially different from bank 2 causing the clutch to rattle as uneven pulses were hitting the crank.

So I know that was a lot of words but I'm just super stoked and I loved this car even when it was acting up. Now it's working correctly I'm over the moon and I just wanted to share and to say thanks to the forum again.


Luke

[dragon850]

Awesome news!
Congrats on getting her sorted finally!!

[TedBobo]

Congrats! Didn’t know “8er” was a 6spd…definitely a keeper.

[LappingLuke]

Thanks guys! Another note, on a "closed course with professional driver" yesterday the car was still pulling hard at 115mph in 5th gear....or so I am told

[CD05001CIA]

Thanks guys! Another note, on a "closed course with professional driver" yesterday the car was still pulling hard at 115mph in 5th gear....or so I am told

HEY ! ! ! All right, all right, all right. Got the windows to roll up finally. Waaah hooo...

https://www.youtube.com/watch?v=ghpDCT5VIok


https://www.youtube.com/watch?v=VpvrRB79koU


https://www.youtube.com/watch?v=XMTfHbc788Y


https://www.youtube.com/watch?v=vdHBsWXaHN8 .
Don't you make me spill my coffee, Grasshopper.

[Hyper]

Well, dang.
Was hoping you were going to send it back to California.
Just for the record, I didn't do it.

[LappingLuke]

LOL I think I did mention early on that I was considering just letting the car go in the acute phase of frustration but I am glad I hung in here with it. The East coast needs a lot more cool BMWs!

[chicosito]

Congratulations on getting the issue resolved! This car is definitely a beautiful beast and was also sad for it to leave the Bay Area.