Probably need new engine--now what

[az3579]

Whatever the case--Shell 93 octane V-Power is all that's going in from now on. A friend tried to convince me that 87 octane gas is "just fine"--no more.

Your friend most definitely gave you some very very bad... and very expensive... advice. Your car isn't designed to run on 87, and as a result was probably suffering from detonation, which could definitely destroy your engine. One must use whatever the manufacturer says to use for this reason.

Also, even if you were using 93, you shouldn't use crap quality gas. Use only Top Tier gas brands to reduce the likelihood of having gas-related problems.
http://www.toptiergas.com/

[BMWCurves]

Don't our cars have perfectly good knock sensors to help prevent early detonation? I feel like that's a pretty poor oversight if not and would assume you would have seen or heard of more BMWs having this issue given how many cars were sold.

[slater]

Don't our cars have perfectly good knock sensors to help prevent early detonation? I feel like that's a pretty poor oversight if not and would assume you would have seen or heard of more BMWs having this issue given how many cars were sold.

they do have knock sensors, however they are not designed to be run on less than 91 octane for prolonged periods of time. it says right in the manual, also i believe on the backside of the gas fill door, too?

whatever the reason, the manufacturer states to use 91 or bad things will happen. not worth the risk.

OP - are you having the replacement engine done at another shop? please tell me you're NOT paying $6000 to have this done!

[BMWM3186]

I highly doubt the low octane would have done it in, but then again maybe it could. Also the gas travels through a fuel filter to filter dirty gas. Anyways my f150 has some sort of timing issue and has always had very audible pre-detonation, and it has not blown up yet. In addition, I know many people who run 87 in their cars that require 91. None have suffered consequences from it. I believe cars should retard the timing, giving you worse gas mileage and less power to avoid pre-detonation. I myself run 93 just because it does not bother me that much to spend the extra few dollars at the pump.

[usinjin]

I had never heard it pinging on 87 octane--of course, just because I didn't hear it doesn't mean it wasn't happening. I feel like it probably was a mix of poor engine care/maintainace/gas. I only hope the engine I'm putting in was treated better.

And hah, no, definitely not paying $6k..a place is doing parts + labor for ~$2700.

[az3579]

And hah, no, definitely not paying $6k..a place is doing parts + labor for ~$2700.

Win! That's a good price.

[slater]

And hah, no, definitely not paying $6k..a place is doing parts + labor for ~$2700.

excellent - that is a good price. i hope it turns out well for you!

[Dave1027]

Even if it was detonating or pre-igniting, neither of those will bend or burn valves. Prolonged pre-ignition can if left too long burn a hole right through the piston top. But for that to happen you would have been hearing a constant knocking for a long time.

Under normal circumstances the knock sensor will sense the knocking and tell the ecu to retard the timing which will stop the knocking. The problem you'd then have is reduced performance. Still, not a engine killer.

I still think the head needs to come off to learn the real cause of this mystery.

[az3579]

Even if it was detonating or pre-igniting, neither of those will bend or burn valves. Prolonged pre-ignition can if left too long burn a hole right through the piston top. But for that to happen you would have been hearing a constant knocking for a long time.

Under normal circumstances the knock sensor will sense the knocking and tell the ecu to retard the timing which will stop the knocking. The problem you'd then have is reduced performance. Still, not a engine killer.

I still think the head needs to come off to learn the real cause of this mystery.

I am curious as to what really did the engine in.

[usinjin]

I am curious as to what really did the engine in.

Me too, very much so--I hope to still have access to the old engine, if so I'll definitely see if I can't get the head pulled and report back with some pictures.