do efi 4age backfire?

[Dave W]

The throttle body has a vacuum pot that limits how quickly the throttle can return to the closed position. If it is defective or removed then the throttle plate closes tightly which causes a very high vacuum in the intake manifold, this draws all the fuel off the port walls of the intake. The raw fuel is then pump thru the cylinder into the exhaust manifold on the over run where there is sufficient oxygen in the exhaust system allowing the fuel burn i.e. back fire.
Dave W

[ash16valve]

Dave W Wrote:The throttle body has a vacuum pot that limits how quickly the throttle can return to the closed position. If it is defective or removed then the throttle plate closes tightly which causes a very high vacuum in the intake manifold, this draws all the fuel off the port walls of the intake. The raw fuel is then pump thru the cylinder into the exhaust manifold on the over run where there is sufficient oxygen in the exhaust system allowing the fuel burn i.e. back fire.
Dave W

Well explained

Mine does the same when i release my foot off the gas pedal or when changing gears on high and low revs....and its a stock S3 4age...
I always thought its back pressure from the exhaust

[kpretro84]

zenki Wrote:

kpretro84 Wrote:

zenki Wrote:Mine does it. Stock engine with straight pipe hks.

It usually pops when i suddenly let off the gas.

Tell me more about the engine

There isn't much to tell about the engine, it's just a stock 7ribs smallport.

what electronics? Map or AFM what ecu? Seems like your guys engine running correctly mines not?

[kpretro84]

Dave W Wrote:The throttle body has a vacuum pot that limits how quickly the throttle can return to the closed position. If it is defective or removed then the throttle plate closes tightly which causes a very high vacuum in the intake manifold, this draws all the fuel off the port walls of the intake. The raw fuel is then pump thru the cylinder into the exhaust manifold on the over run where there is sufficient oxygen in the exhaust system allowing the fuel burn i.e. back fire.
Dave W

hmmmmm Not sure what you mean. Vacuum pot? and whats S3 4age??????? is your guys timing set 10 degrees btdc? without TE1 and E1 jumped? i havnt jumped mine just 10 degrees btdc i think i should play around abit get it running at best

[kpretro84]

http://www.youtube.com/watch?v=nAmH7ITgBUY soooo jealous

[zenki]

kpretro84 Wrote:

zenki Wrote:

kpretro84 Wrote:

zenki Wrote:Mine does it. Stock engine with straight pipe hks.

It usually pops when i suddenly let off the gas.

Tell me more about the engine

There isn't much to tell about the engine, it's just a stock 7ribs smallport.

what electronics? Map or AFM what ecu? Seems like your guys engine running correctly mines not?

Map

[jondee86]

kpretro84 Wrote:Is your guys timing set 10 degrees btdc? without TE1 and E1 jumped? I
havnt jumped mine just 10 degrees btdc i think i should play around abit
get it running at best

Should be 10 deg BTDC jumped, or 15-16 deg BTDC not jumped. If it
does not change when you take the jumper out, then you are not doing it
right (conditions for entering diagnostic mode not met).

Cheers... jondee86

[ash16valve]

kpretro84 Wrote:

Dave W Wrote:The throttle body has a vacuum pot that limits how quickly the throttle can return to the closed position. If it is defective or removed then the throttle plate closes tightly which causes a very high vacuum in the intake manifold, this draws all the fuel off the port walls of the intake. The raw fuel is then pump thru the cylinder into the exhaust manifold on the over run where there is sufficient oxygen in the exhaust system allowing the fuel burn i.e. back fire.
Dave W

hmmmmm Not sure what you mean. Vacuum pot? and whats S3 4age??????? is your guys timing set 10 degrees btdc? without TE1 and E1 jumped? i havnt jumped mine just 10 degrees btdc i think i should play around abit get it running at best

Series 3 Twincam 16 valve

[kpretro84]

jondee86 Wrote:

kpretro84 Wrote:Is your guys timing set 10 degrees btdc? without TE1 and E1 jumped? I
havnt jumped mine just 10 degrees btdc i think i should play around abit
get it running at best

Should be 10 deg BTDC jumped, or 15-16 deg BTDC not jumped. If it
does not change when you take the jumper out, then you are not doing it
right (conditions for entering diagnostic mode not met).

Cheers... jondee86

thats the one its working now chucked it in dignostic mode 10 deg engine ran even better thank you all its now backfiring

[Ivan141]

where's the facepalm smiley when you need it