Bang...there goes my intake

**Uncle_Ken** · 26-03-2010, 03:24 PM

Bug@er... Two back fires in two days. Both after going down a hill off throttle then, accelerate,... then BANG. Pics on the weekend. Need a new section just after the concertina section. Ripped right thought the plastic.

UK

:

sd1800 · 26-03-2010, 04:10 PM

God Bless LPG

:

MAD · 26-03-2010, 04:13 PM

Assuming this is a mixer ring system...

Check your spark leads, dizzy cap and rotor button. Also check the converter balance line.
Common cause for this is weak spark. When on cruise/decel the mixture is lean, then when you accelerate the mixer takes a little time to respond with enough lpg creating a very lean mix, which burns very slowly (and is further exaggerated by weak spark), slow enough that next time the intake valve opens for a fresh charge it is still burning, this ignites the new stuff coming in and everything back to the mixer resulting in a nice big bang.

If you havent already, invest in some spring clips for the air box too.

POELWYK · 26-03-2010, 04:41 PM

ahh i get the atleast 2 times a week Fix is simple drive it on 91 or something better

**Uncle_Ken** · 26-03-2010, 05:08 PM

Quote:

Originally Posted by MAD

Assuming this is a mixer ring system...

Check your spark leads, dizzy cap and rotor button. Also check the converter balance line.
Common cause for this is weak spark. When on cruise/decel the mixture is lean, then when you accelerate the mixer takes a little time to respond with enough lpg creating a very lean mix, which burns very slowly (and is further exaggerated by weak spark), slow enough that next time the intake valve opens for a fresh charge it is still burning, this ignites the new stuff coming in and everything back to the mixer resulting in a nice big bang.

If you havent already, invest in some spring clips for the air box too.

Only had it tunned 4 weeks ago...
and
I have spring clips on the airbox lid.

UK

**Uncle_Ken** · 26-03-2010, 05:10 PM

Pics

and

Bang
Uk

GK · 26-03-2010, 05:26 PM

Quote:

Originally Posted by Uncle_Ken

Only had it tunned 4 weeks ago...
and
I have spring clips on the airbox lid.

UK

If it was only tuned four weeks ago, then I'd suggest the tuner tuned it too lean, hence the backfiring!

Worth a go I'd reckon for sure.

I have a section of that pipe you're after. You can have it for nicks if you like.

GK

**Uncle_Ken** · 26-03-2010, 05:50 PM

Quote:

Originally Posted by GK

If it was only tuned four weeks ago, then I'd suggest the tuner tuned it too lean, hence the backfiring!

Worth a go I'd reckon for sure.

I have a section of that pipe you're after. You can have it for nicks if you like.

GK

bit of a drive GK :(

my67xr · 26-03-2010, 06:27 PM

u can buy a rubber valve that u can fit into the airbox that will open if u have a backfire so it wont happen again, but i would have it retuned also.
ive even seen a few taxi's with rubber bath plugs pushed into a hole in the airbox with a chain to catch it if it blows out

TheInterceptor · 26-03-2010, 06:30 PM

Two backfires in two days?
I saw this bloke who backfired his au fairlane 3 times within 15 seconds :P

Anyway that musta been a pretty big bang to stuff it like it did with springs

**Uncle_Ken** · 26-03-2010, 07:38 PM

If only GK lived in Sydney... off to pick and pay less to look for parts..
interesting flap set up elf

UK

mik · 26-03-2010, 08:33 PM

Quote:

Originally Posted by elf100capri

u can buy a rubber valve that u can fit into the airbox that will open if u have a backfire so it wont happen again, but i would have it retuned also.
ive even seen a few taxi's with rubber bath plugs pushed into a hole in the airbox with a chain to catch it if it blows out

thats a great idea.

lofty · 26-03-2010, 10:15 PM

Is that a local product? I'm aware of the british one , but would rather buy a local one.

my67xr · 26-03-2010, 10:26 PM

im not sure where that one originated , it came on my ef ex-taxi

i have had the one u pictured too and fitted that to a mates courier ute, lpg/petrol that had blown up 3 airboxes at $198ea, and none since

u could always make your own too, its just a hinged flap with a bit of rubber behind it. when the engine is running the flap is getting sucked shut

are the sprintgas systems u are running made wholly in australia?
why not ask them if they do one

bodes-sh · 26-03-2010, 10:32 PM

i agree with GK, sounds like the tuner made the mixture too lean. the balance line is supposed to help the converter richen up under high vacuum conditions, ie high engine speed with little or no throttle because the engine tries to suck the converter diaphragm in leaning out the mixture. if this has been removed, blocked or moved for some reason it will affect it in the way you have found. did the car feel like it was shuddering just before the backfires? it will feel pretty rough if the motor is too lean.

GK · 26-03-2010, 11:50 PM

Quote:

Originally Posted by Uncle_Ken

If only GK lived in Sydney... off to pick and pay less to look for parts..
interesting flap set up elf

UK

I'll send it to you if you like? Australia Post is your friend! LOL!

GK

**Uncle_Ken** · 27-03-2010, 05:36 PM

Thanks for the offer GK. If I blow up another one I'll take you up.
Got on today for $10.

Question is do I use it? I am thinking of taping the blown one up and using it until I get he tune sorted or a flap spring installed. What do you think guys>

UK

GK · 27-03-2010, 08:27 PM

Quote:

Originally Posted by Uncle_Ken

Thanks for the offer GK. If I blow up another one I'll take you up.
Got on today for $10.

Question is do I use it? I am thinking of taping the blown one up and using it until I get he tune sorted or a flap spring installed. What do you think guys>

UK

I reckon that's a good idea until you sort the reasons for the backfiring. Go some epoxy glue and duct tape and you'll be right for a while I'd reckon.

Cheers,

GK

**Uncle_Ken** · 28-03-2010, 11:27 AM

Found an old stubby holder and cut to fit. Hope this holds until I get the car tunned.

Hole...

and the car

and

Now to take it for a test run

UK

GK · 29-03-2010, 12:00 PM

Awesome bush mechanical work there UK! LOL!

How did the test run go?

GK

Quote:

Originally Posted by Uncle_Ken

Found an old stubby holder and cut to fit. Hope this holds until I get the car tunned.

Hole...

and the car

and

Now to take it for a test run

UK

**Uncle_Ken** · 29-03-2010, 12:28 PM

Just call me Les Hiddins ...LOL

Drove it Sunday night and to work today.
No BANGS so far, car just driving like 'normal' today.
I kind of like the cover, looks like a footy injury from playing 1st grade....
UK

GK · 29-03-2010, 12:30 PM

Quote:

Originally Posted by Uncle_Ken

Just call me Les Hiddins ...LOL

Drove it Sunday night and to work today.
No BANGS so far, car just driving like 'normal' today.
I kind of like the cover, looks like a footy injury from playing 1st grade....
UK

You've at least increased the "thermal" properties of the piping! LOL!

GK

MAD · 29-03-2010, 12:41 PM

Do you have just the one hole there?
This was the protection used on my XF but there was 4 holes and they were approx 30mm.

**Uncle_Ken** · 29-03-2010, 12:48 PM

Quote:

Originally Posted by MAD

Do you have just the one hole there?
This was the protection used on my XF but there was 4 holes and they were approx 30mm.

yes just one hole on top, have spring on the box lid.
Got any pics of your 4 holes???
Uk

MAD · 29-03-2010, 01:10 PM

This is the only pic I've got...

The 4 holes were equally spaced around the pipe.

**Uncle_Ken** · 29-03-2010, 01:26 PM

Ok so on the same axis. Why 4 holes and why that size?

Uk

MAD · 29-03-2010, 01:39 PM

There is a lot of expanding gases that need to get out in a backfire.
I dont know if they were exactly 30mm but from memory about that size.

LANKY 1 · 29-03-2010, 10:07 PM

My ute used to backfire every now and then, not to that exent though, it hasn't done it for half a year since i got my zorst system put on! weird

**Uncle_Ken** · 03-04-2010, 05:46 PM

Got these today, going back to see Joe at Cresent on Tuesday afternoon, I'll see how these go
UK