lambda gauge shows 10:1 afr missfiring
Turbo Mini Forums

lambda gauge shows 10:1 afr under full load, boost 12 to 13 psi missfiring only on full monte! takes about 10 seconds to develope

timing standard turbo dizzy set 6 deg BTDC
afr spot on 12.5 to 13:1 on part & 3/4 throttle
i know it needs a rolling road sesion

the other older thrown togeather 1275 engine was the same


YOUR thoughts please gents

surely that suggests it sover fueling badly as its takeing time to foul the plugs.

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yes carl i would agree

its a standard BDD needle

the misfire did it with the old engine with diffrent needle

this engine is totall diffrent the only original parts left is the pressure reg and carb which i got new!

i know afr needs to be corrected but.... wondering if standard dizzy is a shade too advanced

will put this to bed this week as going megajolt.

missfires will usually show a lean reading on a wideband, due to excess oxygen going thru the engine.....

But it can be mis-leading...

How are the AFR's before the missfire ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

stevie, perfect 12.5 to 13:1

12.5:1 is only perfect for full power

not part throttle.


You need a setup

Alex

AlexF

Its very odd that its so rich even with the standard needle.........

Have you checked fuel pressure Ben?

Jim had the same thing with his last engine I recall - an un-modified BDD needle... It shouldn't have worked, but it did...

If the thing is changing - especially gradually - under full load, then you need a sligthly heavier spring. And a re-tune after fitting the heavier spring.

Everyones different, but I wouldnt trust a turbo car at 12.5:1
IMO thats bordering on meltdown.

I always play safer and aim for mid-11's Any power difference, just isnt worth the risk IMO.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

could be your coil which i had a problem with also my float needle in the carb was leaking when on boost which resulted in the car running rich and holing back and misfiring.

always looking for them bigger bunches of bannanas

''timing standard turbo dizzy set 6 deg BTDC ''

why ? my 276 cam has the dizzy at 16btdc at 1500rpm no vac,6 deg is only for std cam(thats my theory)

Metro turbo weekend driver,Mini turbo in the making again!

fuel pressure ok tom

i believe the mixture screw requires leaning some more, will see what the lambda gauge shows then

the spring dave there are 2 in

one standard and one uprated

alex your right also is steviturbo

carl maybe right but surley the engine would burn an afr of 10:1 on boost WOT ???
a few more modds and off to peter baldwins for a shake down

i would still check your float valve, mine was fine untill i up the boost then the fuel would piss past the valve causing fuel to come up the main jet hole..

i checked mine taking of the dashpot, fit a inline prssure gauge then winding the regulator to at least 12 psi this is when the fuel stated pissing past the valve,

new valve fitted problem solved.

aslo this was masking my coil problem as well.

changed that she ran sweet as a nut.

not saying this is your problem.

but worth a look at before you go to rolling road.

always looking for them bigger bunches of bannanas

thanks hoggy will check that out buddy