single point back firing

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prisspringle · #1 Post by **prisspringle** » Thu Sep 17, 2009 10:30 am

hi guys,

well sods law would have it i've been saying how well the car has been on gas since i fitted it, its a single point emmegas kit that was fitted to another car but with the same engine, and it has started to backfire in the inlet pipes, the 1st time it did it a bit of rubber on the backfire protection valve came off, so i took it off and ran it without it had been fine without it when i drove back home,which was last week, sadly today it felt like it boged down while pulling out of a junction and backfired this time it broke the MAF, i bodged it so it is now constantly open and disconected the sensor so i'll only be able to run it on gas ironicly. when i started it up after this it ran a little rough then cleared it self up and now works again.

does rich or lean running create a better chance of it backfiring?

any ideas where to start looking?

chris

rossko · #2 Post by **rossko** » Thu Sep 17, 2009 12:54 pm

Running lean greatly increases the risk of pops in the manifold. As does any ignition issues (plugs, leads (if fitted), coil packs). There is also an obscure issue of 'ram air' effect depending on the cars air intake construction, this usually causes pops after slowing down for a roundabout.

umm, have you considered having the gas system set up? It could pay you back in economy anyway.

prisspringle · #3 Post by **prisspringle** » Thu Sep 17, 2009 5:00 pm

i was thinking lean would make it a bigger risk,i think i'm gonna have to invest in a AFR gauge or one that plugs into the feedback control unit. wheres the best place to get one from?

Oddly the economy is about the same as it was when running on petrol( 20mpg ave upto 25mpg on good runs)and that was running rich would be nice to maybe get more power as well.

chris

crossa · #4 Post by **crossa** » Sat Sep 19, 2009 8:58 pm

I had a Jeep Grand Cherokee with singal point system that kept back firing it blew holes in 2 air boxes it turned out to be a lazy 02 sensor which was making the system run lean I swapped that and it was fine.

gavbriggs · #5 Post by **gavbriggs** » Sun Sep 20, 2009 5:15 am

any leaks in the air intake system will also change the characteristics of the mixture. this was happening on my 4.0 range rover. the mixer ring wasnt connected to the air intake very well and leaked air in.

this made the mixture unpredictable and kept backfiring. i eventually permanently sealed the mixer to the intake with liwuid metal type epoxy stuff and i have suffered far less backfires.

i also run with a boy racer type filter on it too and this helps reduce backfires.

you will need to reset the gas system up for different cars even if they have the same engine!!!

prisspringle · #6 Post by **prisspringle** » Mon Sep 21, 2009 10:15 am

theres no air leaks i can find and the car seems to have behaved itself so far, i've got to order some new filters for the gas as i think the old one isn't helping. the car will be getting set up as soon as i can. still glad i swaped saving me a fortune!

chris

Brachunky · #7 Post by **Brachunky** » Sun Sep 27, 2009 9:35 pm

How critical is the condition of the cherrys air filter when on lpg?

Martin

gavbriggs · #8 Post by **gavbriggs** » Sun Sep 27, 2009 10:46 pm

dunno what 'cherrys air filter' is but the cars air filter/cleaner should be in good condition, both for petrol and lpg!!!

Brachunky · #9 Post by **Brachunky** » Sun Sep 27, 2009 10:59 pm

gavbriggs wrote:dunno what 'cherrys air filter' is but the cars air filter/cleaner should be in good condition, both for petrol and lpg!!!

Jeep Cherokee