HELP! Car would not shut off and started small fire

[johnnylud3]

I’ll get to it. Car is 89 535i. I pulled into my Driveway, turned the ignition off, pulled the key out and the car kept running but didn’t sound normal while it was still running. Lights were still on while it was running. I tried putting the key back and and then out....made no difference. I saw some flames under the hood and started panicking. Grabbed my fire extinguisher and by that time the car shut off and I gave it a shot to put out any fire (wasn’t really too bad pretty much melted the plastic where air intake is). What the hell could cause this? Still not sure what the source of fire was but it was around the front of the engine on exhaust side. This happened once before but shut off quickly and no fire.

-relatively new Ignition barrel as key was getting stuck
before
-turbocharged
-megasquirt pnp
-fuel pump has dedicated wiring from battery and relay off of existing fuel pump wiring
-electric fan also with direct power and tapped into fuse box to get switched power

[moroza]

My first thought was "hm, there's not much wiring in that area" but then I read all the mods. Yikes, sounds like a lot of hacked wiring, so it could be anything... The ECU and lights both getting power when they shouldn't suggests that the main IGN wire from the tumbler switch (not the same as the key barrel) is hot when it shouldn't be. Got wiring diagrams? Got multimeter and know how to use it? Got patience? 'Cuz you'll need all three.

[CarterH]

That mods list is a little concerning. What was the sound like when it was still running? Maybe the starter motor jammed on somehow.

[johnnylud3]

Wiring not bad the megasquirt is pnp into the factory harness. Really just fan and pump.

I have to read more about this but I have heard that the spinning electric fan can cause reverse current back to ignition to keep things live. It is hooked up to a separate relay which makes it more unlikely but you never know!

Ya it kind of did sound like starter was spinning.

[katit2]

I would first examine area carefully to find what IS burning. And then go from there.

[fo3]

Option 1: it's dieseling due to high heat (turbo) and either the turbo seals are leaking oil so the intake is full of it, or the injectors are leaking
Option 2: you damaged the ignition switch when installing the key barrel, now there's a short in it or it's not grounding to kill alternator (just a thought as right now I'm looking at another forum talking about kill switches and their wiring diagrams that have covered that). Seem more likely than what you said about electric fans causing reverse current. Even if you didn't damage it when installing the barrel, the old lock may have been sticking because of damage.

E: you say the dash lights were on: that points to option #2. But then again there was a fire, that points to option #1 with leaks and high heat.

[johnnylud3]

I will inspect filter cone on the intake of turbo and the charge pipe after for signs of leaking....the cone is almost touching the plastic piece that disintegrated that covers back of headlights. I must admit I did abruptly shut the car off so as to not upset the neighbors because it was late and the car is a tad loud.

How long would dieseling last though? This went on for a minute or so.

Dash was on, I recall the rpms kept moving as they engine continued to run. My mind wasn’t that clear at the time though as I thought the car was about to go up in flames if it didn’t shut off .

Funny this other forum member advised awhile back I have fire extinguisher handy and sure enough here we are........

[johnnylud3]

So turbo does not leak a dripple of oil. This is where i am.......

I think the car (probably ignition related) was continuing to run and had starter motor engaged which is why idle seemed high and it sounded horrible while it continued running for almost a minute. Could it have been the electric fan?.....doesn’t seem probable, but it did melt near where that piece of plastic lit on fire and i believe the melting stopped the fan and maybe stopped the electric current that was keeping ignition on.

The fire I am attributing to something electrical. I did have the boost controller wired up right where the plastic melted. The controller itself survived but the wiring seemed to have sustained the most damage compared to everything else. And was melted along almost the entire length.

At this point I am putting mechanical fan back. Mechanical boost controller back. Checking all grounds and probably just replacing the ignition switch. And.....maybe having a kill switch to the battery installed for future.

[Hofmeister]

Pictures are worth a 1000 words. im sure we can help more with some.

[shogun]

Read this thread, could be the unfused RxD data link. On the E32 forum an E32 started fire, he switched the engine off, jumped out of the car, airbag came and then the engine started again on it's own and as it was a manual gear and 1st gear was still selected it slowly crashed into another car, no key in ignition.
https://www.bimmerforums.com/forum/s...2-fire-warning!
same applies for the E34

quote: RIP Factory 5spd 735
I lost my 735i this morning. I was driving to Wegmans to pick up some bread, noticed a brake circuit OBC error and thought nothing of it. 5 minutes later, I noticed a burning smell and saw smoke start coming through my vents. I immediately got out and tried to get my dash apart, but couldn’t get it in time. Not three seconds after I duck out of the car, airbag explodes. By the time my knee panel was off, the fire was already everywhere, fire extinguisher couldn’t keep the fire down. I left the vehicle and called 911. By the time they showed up, car had started all on its own and lurched into somebody else’s car (still in 1st gear, no key in the ignition.). I frantically started pulling relays out of the fuse box till it stopped moving. But this point, fire department showed up and hoses the car

[johnnylud3]

Here are a few pictures. The electric fan was direct wired from battery terminal as shown below and got 12v source from fuse #12. It melted but I think the entire fire was a result of the plastic piece catching. The rest of what was singed was anything high up probably from the flames hitting bottom of hood and the fan blowing it. The red line I had highlighted is the path the EBC wire took which was sitting near the plastic that went up. I am still not clear what happened here and not knowing makes me a little nervous. On the bright side looks like a little rubbing compound got rid of all of the yellowing. Almost like it never happened .

[moroza]

What makes me doubt the starter theory is that starter RPM is usually lower than engine idle.

If it's running for even 30 real seconds and at high idle, I highly doubt it's dieseling. A dieseling engine is in an unstable state, where it's either a chug-sputter-cough affair at ~300RPM that lasts perhaps 10 seconds, or a positive feedback loop where it's burning enough oil to rapidly increase RPMs, which causes even more oil to get sucked in and burned, and the engine soon grenades from spinning too fast. Also, dieseling for any length of time on oil would produce a lot of nasty blue smoke... got anything like that?

EDIT: er, wait... the latter condition happens to actual diesel engines with no throttle plate. Yours obviously has one, which just might allow a somewhat stable high idle to continue for a while, I don't know. Anyway, any blue smoke out the tailpipe?

Read this thread, could be the unfused RxD data link. On the E32 forum an E32 started fire, he switched the engine off, jumped out of the car, airbag came and then the engine started again on it's own and as it was a manual gear and 1st gear was still selected it slowly crashed into another car, no key in ignition.
https://www.bimmerforums.com/forum/s...2-fire-warning!
same applies for the E34

quote: RIP Factory 5spd 735
I lost my 735i this morning. I was driving to Wegmans to pick up some bread, noticed a brake circuit OBC error and thought nothing of it. 5 minutes later, I noticed a burning smell and saw smoke start coming through my vents. I immediately got out and tried to get my dash apart, but couldn’t get it in time. Not three seconds after I duck out of the car, airbag explodes. By the time my knee panel was off, the fire was already everywhere, fire extinguisher couldn’t keep the fire down. I left the vehicle and called 911. By the time they showed up, car had started all on its own and lurched into somebody else’s car (still in 1st gear, no key in the ignition.). I frantically started pulling relays out of the fuse box till it stopped moving. But this point, fire department showed up and hoses the car

I had data link meltdown too, but nothing like that. Easiest preventative measure is to unscrew the diagnostic cap.

[The Chauffeur]

I had data link meltdown too, but nothing like that. Easiest preventative measure is to unscrew the diagnostic cap.

Would that be a trouble-free solution? And also, what about using a spare cap with the internal board and pins removed? I mean, just to not let the port get dust and grime from the engine bay.

[johnnylud3]

I’ll have to comb over some of this wiring and I will be removing that cap for sure!

I have a video camera on my house and have part of it on tape. No blue smoke. Wondering if noise was starter motor engaged while the engine was continuing running? It sounded no bueno and I have it timed at running for exactly 57 seconds with no key. Right when it finally stopped there was a big flash from center grill area. Could have just been from the flame and electric fan abruptly stopping.

[moroza]

Would that be a trouble-free solution? And also, what about using a spare cap with the internal board and pins removed? I mean, just to not let the port get dust and grime from the engine bay.

Apart from dust, yes. I deleted my 544's diagnostic circuit entirely and everything works fine. That system is near-useless these days anyway. Modifying the cap would be a better solution, agreed. The issue is that one of those pins is hot straight from the battery with no fuse, and the cap contains a bridge that connects the hot pin with the diagnostic circuit, which has no fuse downstream either and goes all throughout the car. See here.

[The Chauffeur]

Apart from dust, yes. I deleted my 544's diagnostic circuit entirely and everything works fine. That system is near-useless these days anyway. Modifying the cap would be a better solution, agreed. The issue is that one of those pins is hot straight from the battery with no fuse, and the cap contains a bridge that connects the hot pin with the diagnostic circuit, which has no fuse downstream either and goes all throughout the car. See here.

Great info, thanks! Looks like I'm gonna be de-pinning my cap...

By reading the threads, I never quite finished to understand what's the purpose of the cap being all circuity and all (aside from more money for the stealer), and also if the new ones are "fixed"... Nevertheless, I'll get rid of the pins ASAP!