Radiator busted, now misfires on cylinders 5 & 4
 

Hello gents,

I need your help to see if I finally managed to kill the engine or just have other issues with it.

While driving in town, the radiator developed a crack and the engine overheated. I drove it about 4 miles in total, going about 10 miles/hour and stopping to cool down every half mile or so until I got home (probably damaged the engine doing this - see codes below).

Anyway, I parked the car for about 3 weeks and I just installed a new radiator yesterday, refilled and bled the coolant, and got the cabin heater working too.

Took it for a spin just now and several lights came on: SES, DSC triangle, Brake [Red], ABS - And of course the car is limping.

The codes it is throwing are in various subsystems:

[DME]
242 - Misfire cylinder 5, misfiring with cylinder cutout (Misfire CARB_A)
241 - Misfire cylinder 4, misfiring with cylinder cutout (Misfire CARB_A)

090 - Exhaust temperature before catalyst bank 1, signal line, short circuit to negative. (Shadow memory)
091 - Exhaust temperature before catalyst bank 2, signal line, short circuit to negative (Shadow memory)
093 - Exhaust temperature after catalyst bank 2, signal line, short circuit to negative (Shadow memory)

[DSC]
15 - Recirculation pump error

[IKE]
189 - Electronic braking force distribution

[ZKE]
167 - Mirror, potentiometer horizontal or cable, passenger's door
128 - Servo-valve or wire, open circuit
112 - Servo-valve or wire, open circuit (shadow)

I am going to run a smoke test, and play "whack-a-mole" with the coils. Will report back.

Yea, you should have called a tow truck immediately. I don't understand why people try to limp home a car with an aluminum engine while it's overheating, no way it'll survive.

Usually results in a warped head or a cracked block. As soon as it overheats, shut it down and park it. Especially with our idiot temp gauge. As soon as it shows you are over heating. you're already overheated. Call for a tow. It's much cheaper and far less hassle than fixing the above.

Interesting...271K miles on ? original radiator...That is good.
But should have done a preventive cooling overhaul.

you need an accurate coolant temperature reading, at all times
 

One of the first things I did when I got my '01 X5 in May '21, was to replace the mechanical fan with a 3000 cfm aftermarket electric fan, which I configured to automatically switch on at a specified temperature, using a thermostatic switch. It worked great like that, but I wanted more control (always), so I installed a motor speed controller that allows me full control (the thermostatic switch is still in effect, or I can go full manual, via another switch. I tend to turn the fan off at highway speeds, limit its' speed to 75 or 90% in cold weather or at stoplights (reducing the noise).

But, knowing how fragile aluminum engines are (I'm from the days of robust, all-cast iron Chevy V8's), I didn't want to trust a thermostatic switch to turn on the fan, or the weird in-dash temperature gauge that BMW uses, to tell me when to do so, if the T-switch failed. So, I use a dash-mounted 8" Android tablet to run the Torque Pro app, so I can see the ACTUAL coolant temperature (and other parameters, of my choice) at all times. I could've used an Android radio and a Resler adapter to do the same, but I couldn't see buying a new radio and adapter, when my radio was also new, and I had a spare tablet.

The previous owner refreshed the cooling system about 1000 miles before I got the X5, and I've only put another 2k miles on it since, so I'm pretty sure that it's good for awhile. But, I'm constantly underhood checking on things, so I'm keeping an eye on it, too.

I am the original owner but I can't recall exactly if I replaced it, and if I did, I probably just bought something aftermarket locally because I can't find a record of an online order on my email. Also, I just looked all over the failed radiator and could not find a BMW marking on it. So, let's say 135k miles. ;-)

Ok. I swapped coils #1 and #5 and installed a new air filter. Cleared the codes (but forgot to clear adaptations). The mysfires on cylinder #5 and #4 returned, along with a new DME failure:

F6 - Secondary air system flow rate too low, bank #2.

Ok, gonna do the smoke test now.

Go old school. Pull the plugs and see if 4 and 5 look any different than the others. Also, is it overheating now? If you warped/cracked something, it should be blowing exhaust gasses into the cooling system - especially something bad enough to throw all those codes.

Thank you, great idea! I just checked them all. Not a ton of difference between them all. #4 did have a bit of oil on it. Photos below.

No, not overheating at all. If I don't accelerate quickly and just drive it like I am going for my Sunday morning drive, it behaves ok. It starts throwing the codes and complaining after I step on it.

I did the smoke test (using a cigar), and did not see any smoke escaping anywhere.

However, I do see that the system does not hold pressure very long (whatever pressure I can manage to apply with my small handpump), is that normal? I assume not as it is supposed to build a vacuum?

The balloon I used to connect myn hand pump's outlet hose to the "Rubber boot with resonator" deflates in about 2 minutes. So, not a quick leak, but definitely not holding. Note that, for this test, I did cap off the small outlet that's on the "tube elbow" that connects to the throttle housing assembly.

I will try the smoke test again when it gets dark as it is easier for me to see the smoke at night.