DeLorean backfire...is that possible

[uhhair]

So when I went to start up my D the other day I immediately heard a loud bang from the back. I shut the car off and looked around but didn't see anything out of the ordinary. I started the car up again and it ran fine, save for it seems to be hunting more than was. Is it possible this could have been a backfire? Is this even possible with our cars? If so, does it mean I need to investigate another problem that would lead to this?

[louielouie2000]

Bill Robertson would correct you & say that your car had a "muffler explosion," which is unburned fuel igniting in the exhaust system. A true backfire is when unburned fuel ignites in the intake manifold, or in a carburetor (obviously the great majority of DeLoreans don't have carbs). Whatever you want to call the phenomena, I've definitely heard DeLoreans do it.

[stevedmc]

One of Bill Robertson's church's school buses developed a bad miss, and no one told him about it until a muffler explosion blew the crimped seam wide open.

[David T]

A backfire is possible with any internal combustion engine. Causes include:
tight, or burnt valves
bad ignition wires
Bad distributer cap, rotor, spark plugs
timing way off
fuel leaking into the intake (stuck float valve in a carb for instance)
Decel valves not working correctly
David Teitelbaum

[uhhair]

So is this something I should be concerned about the first time or just wait and see if it does it again?

[BABIS]

A backfire is possible with any internal combustion engine. Causes include:
tight, or burnt valves
bad ignition wires
Bad distributer cap, rotor, spark plugs
timing way off
fuel leaking into the intake (stuck float valve in a carb for instance)
Decel valves not working correctly
David Teitelbaum

...or maybe a free flow exhaust ;)

[Bitsyncmaster]

If it was a muffler explosion. Your ignition was not working when you were cranking the engine or you are leaking fuel into the exhaust when the engine is off.

Did it take a lot of cranking?

Do you have a hot start problem?

[Citizen]

A backfire is possible with any internal combustion engine. Causes include:
tight, or burnt valves
bad ignition wires
Bad distributer cap, rotor, spark plugs
timing way off
fuel leaking into the intake (stuck float valve in a carb for instance)
Decel valves not working correctly
David Teitelbaum

I've heard of and concur with all these reasons for backfires, except that last one! :shock:

[Nicholas R]

I've heard of and concur with all these reasons for backfires, except that last one! :shock:

Dave Teitelbaum is a very common cause of backfires :biggrin:

[stevedmc]

Dave Teitelbaum is a very common cause of backfires :biggrin:

I've been the source of backfires as well. When I was in high school we used to light our farts with matches.

[uhhair]

I do not have a hot start problem and it occurred almost just as the car was starting. I don't have to crank my car long, maybe 1-2 sec before she turns over.

[Bitsyncmaster]

I do not have a hot start problem and it occurred almost just as the car was starting. I don't have to crank my car long, maybe 1-2 sec before she turns over.


You may have a leaking injector. If I were you, I would pull the injectors, put them in jars and give the fuel system a prime.

[SS Spoiler]

Took the delorean to bible study one evening and a loud bang occured when starting. Nothing I did would get it going. After AAA golding it home I still had no luck. So I called my ace in the hole Bruce Benson to help. We dinked around for hours until Bruce notice it had popped off one of the pipes that feeds my single turbo. Hooked it back on and Varooom! Simple fix. Still don't know why it happened, just glad it was easy to fix.

Paul Cerny

[mluder]

Here's a good one.

I too had a funny bang under normal driving one day. Afterwards the car idled rough and and had power limitations under acceleration.
Further inspection found that two of my injectors had blown out of their cylindars.

Put them back and it's been fine since. I replaced the rubbers and clips anyway just in case.

Cheers
Steve

[dmc6960]

I had a really loud backfire during the car show at DCS '02. A year prior I had purchased a new high-performance Bosch coil and new ballast resistor from John Hervey. Hey, what could go wrong right? Well the car would barely run on it. Checked connections countless times, it just wouldn't work. At the car show, I had asked him if he had any problem with those coils. The answer was no. Well I had a problem, could I borrow a different one to see if it works? After a little pressure I convinced him to do so, and proceeded to hook it up. Engine again, would barely run. So just for the hell of it I hit the throttle all the way... BAM!!! I returned the borrowed coil with the information that it still doesn't work.

Another year later after my next tuneup I decided to give it one more try. I had previously been running a capacitance-discharge ignition setup (you know, one of those magical make-you-car run 200% better things?). The car ran at 100% on that setup with the stock coil, and of course 5% with the replacement. Now that I was back to a standard plug and wire set the coil went in one last time. Engine did run a little better than before, but still crappy. I'd give it a 15% max.

Thats why to this day I never recommend deviating from the stock ignition setup.

[stevedmc]

Bill Rice and Steve Robertson are running HEI no problem, as are many uncombined members of this forum.

Perhaps you wired the coil up backwards? That's a surprisingly common mistake many owners make when upgrading to high winding coils.

Also we notice that nowhere in your post do you mention widening the plug gap.

[thirdmanj]

Took the delorean to bible study one evening and a loud bang occured when starting....

Maybe it was a sign?

[stevedmc]

Maybe it was a sign?

I believe your response counts as a religious post. BAN HIM#!@~!

[SS Spoiler]

Sign of what?

[thirdmanj]

I believe your response counts as a religious post. BAN HIM#!@~!

Hey HEY! The man said "bible study" ok? :lol:

[thirdmanj]

Sign of what?

I dunno, stop sign? Yield sign maybe?

[stevedmc]

Sign of what?


http://www.youtube.com/watch?v=DNPjeIamsck

[thirdmanj]

http://www.youtube.com/watch?v=DNPjeIamsck

As good an explanation as any...