FUEL CUT REV LIMITER - WILL IT DO ANY DAMAGE?

scottieb · Post by **scottieb** » Thu Mar 29, 2007 9:49 am

Hello all,

I'm running a Rover V8, Meggasquirt (fuel only at the moment) and a Wideband O2 Sensor in one of the exhausts.

Last night I set up a hard cut rev limit using fuel cut. It works very well and sounds the business if you bounce it off the rev limiter during up changes. (not that that will happen very often.)

The thing that worries me a little bit is when this happens, you get some nice big flashes of flame out the exhaust. Will this do any harm to the engine or the O2 sensor (Bosch LSU4.2) in the long run? The sensor is mounted about a foot from the cylinder head.

Thanks in advance,

Regards,

Scott

Post by **Coops** » Thu Mar 29, 2007 10:12 am

aint the sensor a bit close to the head?
mines at the bottom of the down pipe and about 2-3 inches from the bend,

how do you get the flashes? as cutting the fuel should eliminate any excess, if it was spark cut that would have excess fuel in the system that would do the flames yeah?

ChrisJC · Post by **ChrisJC** » Thu Mar 29, 2007 12:52 pm

I had my lambda sensors about 2 inches from the head, in the primary pipes. Seemed OK.....

Totally agree with Tony RE flashes from the exhaust.

Chris.

ian.stewart · Post by **ian.stewart** » Thu Mar 29, 2007 1:32 pm

My Soft cut and hard cut back the timing off. and I do get flames sometimes but normally just a big black cloud out of the exhaust.

kiwicar · Post by **kiwicar** » Thu Mar 29, 2007 2:45 pm

Are you pulling oil up into the cylinders (past the rings) when the fuel cuts? If so this could be ignighting giving the flames.
Mike

bill shurvinton · Post by **bill shurvinton** » Thu Mar 29, 2007 2:53 pm

As there is some wall wetting, the fuel cut will leave some residual fuel in the inlets. too lean to burn in the cylinder it will head out the exhaust where it can burn.

When the you drop below the limit, again for one cycle or so until things stabilise the mixture will be too lean to burn in the chamber but may do in the exhaust. Should cause no issues to the sensor, so just enjoy the flames.

Post by **Coops** » Thu Mar 29, 2007 8:20 pm

mmm maybe i should do the fuel cut on my vems then

any one for a BBQ at the pod

kev_the_mole · Post by **kev_the_mole** » Thu Mar 29, 2007 10:22 pm

Oooooooooh

F L A M E S !

Someone will have to do me a map for a Chevy.

Post by **Coops** » Thu Mar 29, 2007 10:25 pm

i will have a play once engine is running for flames

must order the trigger wheel ready for the wasted spark set up.

kiwicar · Post by **kiwicar** » Sun Apr 01, 2007 6:47 am

I think you two may need one of these
http://www.axdo.net/

Mike

kev_the_mole · Post by **kev_the_mole** » Sun Apr 01, 2007 5:26 pm

Mike,

they are false F L A M E S

b'cos they have to be ignited by an extra plug or two.

The Church of F L A M E S specifically forbids its disciples to dabble in such debased practices.

Wot we need are real

F L A M E S ! ! !

kiwicar · Post by **kiwicar** » Sun Apr 01, 2007 6:18 pm

forgive me oh enlightened one I did not mean to offend.

Mike

kev_the_mole · Post by **kev_the_mole** » Sun Apr 01, 2007 8:18 pm

No problemo grasshopper.

Burn Baby Burn (as they say),

Ian

a.k.a. Brother Zippo of the Elucidated Brethren of the Fiery Conflagration

Ian Anderson · Post by **Ian Anderson** » Sun Apr 01, 2007 8:51 pm

These flames are great but some caution

With fuel burning in the Exhaust - is the flame burns back quickly it can blow the seam on the rear silencer. Happeed a few times on GT40 Kits but then mainly on the track and being over fed by Holly Carbs Big flame followed by bang and silencer opened up!

Ian

kev_the_mole · Post by **kev_the_mole** » Sun Apr 01, 2007 9:30 pm

Yep had it happen on the Healey before the teardown. My double pumper was overfuelling as usual with lots of pop.pop.pop on the overrun until big bang. It chucked out a great wad of red hot glass fibre packing.

Sounded much better afterwards

I think it was just clearing its throat.