LTX8, s4/5 engine drops timing when warm
 

I'll start with my setup (to the best of my knowledge as I recently purchased the car a few months back). Located in Australia if that helps.

Series 3 SA22c
S5 13b-t, stock ports.
microtech mtx8 flashed to ltx8
stock s5 injectors
possibly S3 CAS as it has the S3 front cover on the engine
walbro fuel pump, swirl pot
rising rate fuel reg
XR6 gt35/40 0.50 A/R turbo
FMIC
dry cell battery

Here's what happens. When the car is cold, it idles smooth. You can see it in this video:
http://www.youtube.com/watch?v=RBUrp...eature=related

But then after about 10-15mins when it gets up to temp (sits at around 82-88deg C depending on ambient air temp, never seen it above 90deg) it starts running all bridgeportey like this:
http://www.youtube.com/watch?v=tSchP...eature=related

Unfortunately my hand controller has stopped working, but I have hooked up the microtech to a laptop and tried to find what changes when it starts idling like this.

It seems to be that when it's running correctly, it is reporting around 38-40deg of timing. When it's idling like a ported engine it's reporting between 5 and 15deg of timing erratically.

Any ideas as to what might be causing it? If it's a tuning issue then I can take it in for a dyno tune, but if it's more likely to be a faulty sensor or similar then I can do some further testing at home and that would be helpful to try first before taking it in for a tune. Having never dealt with an aftermarket EMS, i'm not really sure what kind of things can affect performance like this.

To me, it doesn't seem likely to be a ECU problem as it was running smooth when I bought the car, and in theory the tune shouldn't change with time since it should be 'locked' into memory until altered manually.

Happy to provide any further information, screenshots or manual dumps of the ecu map.

Thanks!

Sound like it needs adjustments in your wt map have a screen shot? I highly doubt a fautly sensor..

tuning check around the range of the problem might be too rich??? add or take some

cool, sounds like investigating the map is a good place to start. I'll try get some screenshots tonight and will update this thread.

take it to someone with more of a clue
any map that is giving 38 degrees of timing at idle is seriously fucked up,, or there is a huge error in setup of the timing calibration
the only time you see 38 degrees on a rotor is on stock maps,chipped maps and PFC's

-- and then only during decel

if talking true crank degrees ( noting most micro maps are datum 5 ( atdc ) and so will be smudged 5 degrees to account for that )

then stock rotors idle at 5 ATDC,, or 0 TDC
extendies tend to idle with a bit more 0-10 BTDC
( note micro may have 15 in the map ,, which can be a real 10 BTDC depending on the datum setup )

and bridgies may require a bit more again,, or if on a locked dizzy ,, may be set 22-25 BTDC

but NEVER 38,, even accounting for a +5 gain on micro maps to amount for the datum -5

ie,, 30 degrees in the micro maps ( or tmax= 30 )
,, if timed to -5 ( as the TDC/datum mark as per instructions ) would amount as 25 BTDC ( real ) crank degrees

,, also,, knowing micro's have a glitch when you play the static and timing trims
( they also shift the Tmax values ,, which should be locked,, but isnt )

suggests to me ,, that someone has played the timing maps in ignorance to the bug,, and set you up for an expensive fall ( fail )


the other possibility i see is that you may have timing in the Twat maps in the cold range,, and none at running temp
( way too much if it is pushing 10 to become 38 degrees )

so,, to me,, your map is rubbish ( or for a 4cyl ) and should start again

Nice post bro, don't have to be such a cock about things considering more than once in my original post I specifically said that if it sounds like a tuning issue then I'll take it to a tuning shop (in this case it will be rotormaster in Sydney, the previous owner had it tuned at SCR).

I just wanted to try get some feedback to see if it could possibly be a sensor playing up and feeding bad info to the ECU.

Off to the dyno it goes!

who is the cock mate? i did not have a crack and told you straight and why ,, -- but look at your reply

i could have said fuck all and let you toast your engine that idles with more advance than any rotor should naturally take

hrm, i did over react a bit. Just grated on me with the 'take it to someone with more of a clue' 'your map is rubbish' 'someone has been playing around ignorantly' etc.

sounds like dyno is the fix anyway, so i'll get it booked in.

Bump start is persistent on the facts and comes off strong but don't be offended its just a forum. Don't be intimidated if anything lets solve you problem, obviously those timing don't sound within reason.