missfire still ! worse when hot and full boost

[LCRglen]

right where to start i have a 03 lcr 210 , its had a missfire problem since i have owned it for 3 - 4 months the car starts fine from cold , it idles fine from cold , it idles fine right upto when it gets to normal operating temperature . It would start to get a lumpy / missfire at idle after either giving it 3-4 hard accelerations then left to idle or if its left idling untill the fans come on . when its driven whilst heating upto temperature its fine .when at temperature you can floor it 2-3 times and it behaves , however after this it then starts to missfire / judder under full boost .
right now the list of replaced parts and work done to try fix this problem
1. new maf
2 .new pipercross panel filter
3 . new coil packs
4 . new spark plugs
5 . new fuel filter
6 . new dumpvalve 007p
7. cleaned throttle body and reset with vag com
8 . n249 bypass
9 . checked all breather hoses and cleaned all , also replaced some and retighted clips
10 . redex fuel cleaner
11. insulating tape around coil pack wiring ( just incase)
12 . checked for exhaust leaks

also had vag com scans and i have NO error codes .also logged various blocks to which the lambda sensor says the engine is running lean .sooooooooo could my symtoms be a failing lambda ? would it fail for 4 months and produce no codes ? please help people i am at my wits end here

 

[Shaunyboy]

No, if its registerd lean, means that the engine is running lean, a dodgy lambda would flag up the light. Id be swaying towards temp sensor if its doing it when its hot. Have you checked the plugs see what there like as they can tell the story of how the enigne is running. Browny deposits indicate its running fine, black ish plugs dont spell danger either, heavily soiled plugs or plugs that are white means its running lean.

 

[LCRglen]

the plugs i took out were brownish with a red tinge , no deposits on them or damage , when you say temp sensor do you mean the coolant temp sensor ( green one) or the engine sensor or are they the same thing

 

[Shaunyboy]

Right, so have you detrmind which cylinders are down? It sounds like an ignition problem, and most of the sensors point to the ignition system. Does the guage say its at 90 when its warm?

 

[LCRglen]

yes the gauge sits dead on 90 just as it should , never wavers . the fault can be intermitant sometimes when driven hard , i am positive its a missfire of some discription rather than a boost problem because it happens at idle , when i fitted the fuel filter it seemed to dissapear for a few days then it came back

 

[Shaunyboy]

That could just be coinsidence, if its doing it on boost it could be the EGT sensor which i think reatards the timing when the turbo gets too hot to prevent damage, could be wrong but someone else may know more.

 

[LCRglen]

i doesnt do it when the engine is really hot under half throttle either if thats any help .

 

[Lodgey180]

hmmmm my first thought was some cam/crank sensor but that would show fault straight away..

 

[shauncupra]

No, if its registerd lean, means that the engine is running lean, a dodgy lambda would flag up the light. Id be swaying towards temp sensor if its doing it when its hot. Have you checked the plugs see what there like as they can tell the story of how the enigne is running. Browny deposits indicate its running fine, black ish plugs dont spell danger either, heavily soiled plugs or plugs that are white means its running lean.

I'd secound a faulty coolant sensor and for how much they cost its worth replacing for a green one,

mine had that same missfire when warm and smelt fuely because of the ecu thought is was still needing choke (hope that makes sence)

 

[LCRglen]

would a faulty coolant sensor give the lambda a lean reading i thought it would cause overfueling ?

 

[shauncupra]

would a faulty coolant sensor give the lambda a lean reading though would cause overfueling ?

I dont think so because lamda would be teling you its to rich on fuel(when engines warm) if it was the coolant sensor playing up .

but these engines can be strange and lots of the time the ecu says its found fault with something, but it ends up being something before or in line with that fault (if that makes sense)

if only the ecu could tell us exactly what part to replace

 

[ibizacupra]

what do the fuel trims say on 001 and 032 blocks?

 

[LCRglen]

right just bought a vag com cable and downloaded the free version i will scan it when i recieve the cable , can you log these blocks on the free version ? i still think in my head that it is one of three things .
1) a hole in the exhaust / blow in a gasket , i cant here anything though
2) faulty pre cat lambda sensor
3) a split hose that i have missed somewhere .i have checked and changed lots already .

 

[HallycupraR]

mine had a missfire a few weeks back changed coilpacks an all well, other day it did the same thing so got vag com on it an said summat like intermittent single from the tempature sensor on the exhaust, but while driving home the car ran fine when warmed up so clearned the fault an all if fine still might help u out to check that sensor

 

[Shaunyboy]

Could be a blocked cat?

 

[LCRglen]

is there anyway to check if the cat is blocked ?

 

[LCRglen]

took it to a exhaust place today and they put it on a exhaust gas analyser , they said that it all seems spot on anyway results were :
held at high revs for 10 secs
co: 0.01
COcorr :0.01
co2: 15.5
02 : 0.02
ppm vol hc : 0005
lambda :1.000


then at idle
co: 0.01
COcorr: 0.01
co2 : 15.4
02 : 0.10
ppm vol hc : 0001
lambda : 1.004
the guy said that the ( dont know what this means) lambda sensor were switching . so i am presuming i have cured my lean problem and now need to find this missfire , i did notice today that when it was left idling and got some real heat in the engine i let the fans come on then go off it was missfiring , i switched the engine off and restarted and the idle for about 10 seconds was sitting alot higher than before it then settlled . would the coolant sensor not flag a fault code ?

 

[HallycupraR]

When my coilpack went i could smell an eggy smell made me bit hungry to be honest as well

 

[LCRglen]

have fitted another coolant temp sensor ,to rule that out , also recieved me vag com and going to log blocks 001 and 032 as you requested bill in the next hour , also , is there a way of logging individual cylinder missfires to see which cylinder it is missfiring on

 

[Shaunyboy]

http://www.fabia.skodafriends.ro/m-blocks/010-019.pdf

So 15 & 16