megane f7r lumpy idle , stalling , missfire , overfuelling

[hairymel]

97 megane coupe 2.0 16v f7r

sudden onset problem

stalls when coming to rest and changing gear.

at startup will not idle without throttle.

will idle rough then revs will drop to 0

after 30/40 seconds will keep running but is very lumpy and revs fluctuate between 1000 and <500

missfire?lumpy running below 2.5 revs but clears at higher revs

seems to be running rich at idle

changed coil pack for s/h - no change

changed plugs - no change old plugs were all black and sooty

cleaned icv - no change

with stepper motor removed and valve manually activated the rough idle and missfire is still present

changed icv for s/h - no change

cleaned crank/flywheel sensor (tdc?) - no change

cleaned camshaft sensor - no change

injector cleaner - bit of improvement in lumpyness/drivability when warm

re terminated the 3 wires at front bottom of block - (all onto the stud earthing point as the torx bolt was not removable) no change

cleaned throttle body - idles a bit better but still really rough

blocked off egr valve - no change

i have also used several cans od wd40 on all the hoses/pipes but no joy

have ddt2000 and xr25 with vagcom lead but am struggling to understand them!

no faults registered - injectors seem to be firing with long duration at idle (9000ms?) and duration drops with revs (3-4000ms?)

temp sensors seem to be outputting ok values

map semsor seems to be doing something

lamda seems to be outputing a signal

any pointers would be most appreciated

thanks

mel

 

[Chris H]

I'd still look at the temp senders.

Unplug the coolant sensor (stat housing, should be green)

The fan may or may not come on (depends on loom etc) and see how it runs.

Also are you watching live data or data from a mulitmeter?

 

[Chris H]

Also it will be 9m's not 9000.

9 is still on the high side, cold start on an SFI will be up around 7 max and even then it would have to be a very cold start for that.

 

[hairymel]

Also it will be 9m's not 9000.

hi Chris

i have a black hole where my decimal points should live, thats why i put a ? :lol:

data is live from ddt2000/vagcom but my french is stored in the same place as decimals

i have tried pulling various sensors in a random fashion but as soon as it stops raining i will have a look

thanks

mel

 

[hairymel]

green sensor appears to be the dash temp guage sender

white sensor on thermostat housing disconect gives coolant temp sensor fault code and shows temp of -40c in ddt2000

car already warm

no difference in running, no fan

reconnected sensor and cleared the error

just dies without throttle for 20 secs after start then will stay running afterwards.

L'avance à l'allumage (ignition advance) fluctuates fairly quickly between 2 and 22 at idle but with higher revs settles around 35ish

when the idle is more stable the injectors show 4ish ms but as it falters it increases to a maximum of 9 or 10 ms

i'm much happier with spanners

thanks

mel

 

[hairymel]

also tps shows 19 with closed throttle and 220 ish at full throttle opening

 

[Chris H]

yeah forgetting the age of this, the later cars had all the functions in one sender.

The cts shouldn't default to -40, it should show fully warmed up engine. With it plugged in do you get live data off it? What time base? Is it increasing linearly or dropping out?

Ignition sounds fine, at idle though it should only fluctuate maybe every couple of seconds from a low like 2 to 22, it advances until knock is detected backs off then repeats. At higher speeds it obviously has a shorter window to alter so it stabilises out when being read.

Whats the lambda doing? 4 ish is correct, when it goes to 9 or 10 its doubling the injection duration which means it thinks its either just gone freezing cold (like -40) or the lambda is is saying its running lean.

 

[Chris H]

also tps shows 19 with closed throttle and 220 ish at full throttle opening

thats fine, the readings there vary scanner to scanner.

As long as it reads linearly when the throttle is opened its fine.

 

[hairymel]

data is in real time as far as i can see

temp looks as i wouyld expect with it rising fairly evenly from cold to mid 80's

advance cycles in <1sec

dump of lambda, advance, inj duration and rpm from startup below



started on throttle to prevent stall , then left to idle, then 3000 revs then back to idle

learning something new every day

thanks

mel

 

[Chris H]

lambda data looks funny, but that may be the time base its set to, which I can't see.

Does the speedo work ok?

 

[hairymel]

time base? no comprehende'

duration of capture was about 100 seconds

speedo works ok , not sure about trip comp as the stalk is non functional:roll:

i liked the lambda at 3k revs but i have no idea what im supposed to be seeing:lol:

pi$$ing down again this end of our sceptered isle so i will call it a day!

now that i have discovered data capture is there anything you think i should look at?

thanks for your help

mel

 

[Chris H]

if that entire capture is over 100 seconds then the lambda isn't switching properly.

It switches fine when the revs are raised, start it hold the revs up around 3k rpm for a few minutes and then let it drop to idle, see if the lambda switches.

Rain boohoo its snowing here :lol:

 

[hairymel]

its always grim up north:lol:

will post again after i have done as you suggest

have a hot toddy on me

thanks

mel

 

[Chunk]

Haven't read any of the thread but from the symptoms check your map sensor and associated pipework and wiring.