lambda problem

[Seight-v8]

hello All,

first first real try at tuning....my 4.6 v8.

but i notice that during pressing the light throttle...my lambda readings go to zero.

then when throttle is removed the lambda readings return....

during light throttle the engine is pulsing.....

ran a good log....and shows up everytime...

anyone got some ideas.

running v1.1.64 and latest vemstune...as cant run v.1.1.70 due to a fuel relay problem.

been through my settings...but its like a needle in a haystack for me.

cheers

scott

[Seight-v8]

looks like its only happening in vemstune, as my lcd is showing readings when vemstune goes to zero....

So maybe a fault with my vemstune somewhere.

scott

[mattias]

Upload a vemslog anywhere to get any assistance.

[Seight-v8]

hiya,

yes will try and get something sorted tomorrow, after work...when i've got some time....

think it's best i have a beer...and get rid of this headache ive had all day.

still learning just hurts more....

cheers

scott

[dnb]

Sounding like the lambda is dropping out of range.  My guess is that the lambda sensor thinks you're running a bit too lean, or you have a misfire somewhere.

Odd question, but what cam do you have?

[mattias]

Sounding like the lambda is dropping out of range.

Duh.. 

Assuming it's as simple as a really poor VE map this can all be fixed by just watching VE and lambda change together doing slow sweeps, increasing rpm and later load as you go. Either just enable strong EGO correction and watch what it's trying to do to correct the situation, it won't work very good if you mis-fire though..   

[Seight-v8]

hiya,

cam is a piper 285 and i have rhoads lifters fitted also....

I checked in megatune the spark and yes looks like its either a misfire or the spark  advance dropping to low, thats causing the low lambda readings.

Just now need to understand how to correct it.

I'm also sure my VE map is very low (lean) as some readings i changed from 40 to over 60 during a open loop tuning run i did.

But as i get to 900-1200 rpm this is when i get the problem, then engine just surges in a cycle.

Really am learning here, its just very hard to learn quickly enough.

scott

[messer]

VemsTune and new firmwares seems to have some problem showing lambda values outside the range 0.7 - 1.2, it simply does not.

Found one log that shows the problem, he may have others, but hopefully you see what I mean.

http://195.159.109.134/vemsuk/forum/index.php/topic,1208.msg12882.html#msg12882

[Seight-v8]

yep that looks like the same problem as mine.

Lambda readings are fine on my lcd....but not recorded in the log with a gap.....

cheers....make me feel better that its not me or my setup....spent over a day trying to work that out.

can sleep tonight now.....only had 1hrs sleep last night trying to find the answer to many of my problems.

scott