Misfire when cold

[SimmoCupra]

Right, Have just fitted a new MAF... Was driving it to GSF to get the new one and the Engine MiL light came up! (Engine warning light...) GREAT!

Cant get rid of it. OBD reader on its way!

 

[stewbie55]

Managed to get the bonnet up at the weekend while it was running rough. Disconnected the MAF and hey presto! it ran fine.

Going to try the dielectric grease trick first (just awaiting delivery). If this doesn't work then i'll fit a new MAF.

Snap! - I'm waiting for the grease I ordered too...

Only had 1 stutter since disconnecting (and re-connecting) the MAF the other day, so I'm guessing this cleaned the connector a bit. I also just received my Race Diagnostics gauge today so will log the MAF from start up in the morning. No error codes indicating a misfire either.

 

[Markyboyt]

Did you guys get this fault sorted?
I think mines doing a similar trick, intermittently from cold it will run rough at idle, idling at around 1250 RPM and I hear a noise underneath which I havent yet checked out but I think its just from the engine vibrating. If I try and drive its just totally flat, in gear it starts to rev then cuts to idle speed, I can give the throttle a blip then drop it into gear and drive away while its coming down and it drives ok. this lasts for maybe a minute if not driving.

To me a MAF would be a logical cause as it will rev ok out of gear (or clutch pressed) but once its in gear so is seeing load it just kills it

 

[SimmoCupra]

Nope, am now on my third MAF. Got a new unit from the stealers! Still crap.. Am going to change the coolant temp sensor tomorrow, and clean the throttle body. Havent got VAG COM to reset the throttle body. but its running soooo crap at the moment. would hardly make any difference.

Still howing the same. even though when the engine missfires. I can unplug the MAF and it restores normal running... Surely this isnt and accurate diagnosis of a failed MAF? As when unplugged the ecu will run on a different strategy. i.e throttle based instead of a torque / airflow based calibration. This unplugging the MAF may mask another problem I reckon I may have in a defective coolant temp sensor.

I'm thinking that the ECU when cold is see-ing some crazy temp i.e -40Dec or something and so is applying ignition advance and fueling to compensate, hence the missfire (as part of the calibration) when revving it goes out of "idle" mode..

Will do the changes and post back.....

Fingers crossed,, if this dont fix it. its going to be £80 and hour at the dealers to fix! great!!! either that or a cheap car going on ebay! What a shame!! Just getting narked!

 

[Markyboyt]

Nope, am now on my third MAF. Got a new unit from the stealers! Still crap.. Am going to change the coolant temp sensor tomorrow, and clean the throttle body. Havent got VAG COM to reset the throttle body. but its running soooo crap at the moment. would hardly make any difference.

Still howing the same. even though when the engine missfires. I can unplug the MAF and it restores normal running... Surely this isnt and accurate diagnosis of a failed MAF? As when unplugged the ecu will run on a different strategy. i.e throttle based instead of a torque / airflow based calibration. This unplugging the MAF may mask another problem I reckon I may have in a defective coolant temp sensor.

I'm thinking that the ECU when cold is see-ing some crazy temp i.e -40Dec or something and so is applying ignition advance and fueling to compensate, hence the missfire (as part of the calibration) when revving it goes out of "idle" mode..

Will do the changes and post back.....

Fingers crossed,, if this dont fix it. its going to be £80 and hour at the dealers to fix! great!!! either that or a cheap car going on ebay! What a shame!! Just getting narked!

god you've chucked a lot of parts at it then, might've worked out cheaper to go the dealer from the start lol

£80 an hours cheap, people pay over £100 + vat for me to look at their BM's, is hard to see why you pay so much extra but its because your not just paying for a techs wages

 

[SHADY-NINJA]

Sorry to butt in here.
i just too a short cliip of my own engine misfire on cold start. (its an AUQ engine code)
please ignore the picture quality but try to concentrate on the sound.

http://uk.youtube.com/watch?v=_fxYBHCdPMY

 

[SHADY-NINJA]

you can here the misfire clear off after about 18 seconds.
all this is followed by a smell of fuel.

 

[SimmoCupra]

Well after weeks of crap driving and missifre the same as your vid.. I replaced the MAF with a dealer MAF, New Coolant temp sensor.. And cleaned the throttle body..

This had no effect! and was still crap.. although didnt drive it..

So after much thinking, I reckoned that the ECU being, adaptive would have learned that it was driving with a crap MAF unit and compensated as soon as I plugged it in.

I did an ECU reset, disconnected the battery for 30 mins (followed the desciption found by searching) And it worked... Car is much better and drives smooth! Cant believe it!!!!

So, Shady, Unplug your MAF when its missfiring. if it cures it then get a new one. Do an ECU reset and it should be better!..

Fingers crossed.

 

[Markyboyt]

managed to get my MAF unplugged while car was misfiring tonight and it cleared instantly but was still clear when I plugged it back on, but round the corner I had the loss of power, so I reckon a new MAF might be finding its way onto the car soon.

Does anybody know the workings on the electrics of the leon? (Seat techs or anything) basically when I unplugged my MAF and plugged it back on, got in the car and the traction control light was lit in yellow, a quick ignition off and restart and it was off, but I can't see the link, i was expecting the engine warning light if anything. I know traction control systems link in with the engine ECU for reducing power output in wheel spin etc, but can't see the link here.
I did a week or so ago have the traction control light come on while I was driving, I switched the ignition off (while I was still driving lol) and restarted and it was gone.

 

[drinkwell]

I have this on my car and have spent a lot of money to cure but to no avail...Audi said it was the remap
my car goes like a rocket but its just cold/overnight start up so I ain't worried

 

[Markyboyt]

I have this on my car and have spent a lot of money to cure but to no avail...Audi said it was the remap
my car goes like a rocket but its just cold/overnight start up so I ain't worried

Has it always done it since the remap? chances are its not the remap but if your car isn't standard engine wise then I wouldn't imagine they would be too keen to pursue it, its a lot easier to say its down to the remap, get rid of you and get a service or something in that they can make time and bonus on.

 

[cupratune]

Ive been having the issue again but it's very strange for me........parked up right hand side higher than left car starts fine........park it at work on slight incline and get the idle issue etc.......I'm wondering if it could be related to the sai as once this has gone off the car is fine.....now with this when your rocking and rolling down the road do you get the usual hesitation around 2k revs in 1st/2nd gear?

 

[fcuknafe]

Im having simular intermitant problems when engines warm and its started again. takes ages to start and its misfire'n if rev'd and idles at 1500rpm. ive just had a brand new Bosch MAF and still no fault codes and still the same problem. it happens like 1 in 5 drives but go's once i drive off ... strange

 

[lee_woollett]

mines always done this and i've fitted a new MAF with no luck. It only seems to be when cold and with the Secondary air pump whirring away. Once that has finished doing its job, the car runs fine. Try leaving the car on tick over until the SAI has finished it's job and then try pulling away.

 

[SHADY-NINJA]

check your breather hose mate.
it might be split.

 

[TRUMPY]

mines always done this and i've fitted a new MAF with no luck. It only seems to be when cold and with the Secondary air pump whirring away. Once that has finished doing its job, the car runs fine. Try leaving the car on tick over until the SAI has finished it's job and then try pulling away.

i am with you on that one mate , wait for the SAI to go off then see what its like.

 

[cupratune]

Thought i read it somewhere

http://uk-mkivs.net/forums/t/141240.aspx

Quote

The air pump unit in question, does only need slight 'seperation' as displayed in the pics earlier in the thread and it causes a loud noise. I remember another user on here with a 1.8T Seat Leon Cupra said that it was more than just a noise problem on his car, it caused real problems cold starting, with the car lurching and stuttering.

 

[fcuknafe]

Sorry to bring the thread back up but i had simular problems when the engine was warm . I changed the Temp sensor which i mate did on his passat 20v t who had same problems and its been 2days and ive had no signs of the problem? it maybe the issue worth a try because mine work'd and it was £5 fix