Sudden Lumpyness / Missfire / Stalling Etc...

[MerlinGTI 3]

Hello

 

I have a 1.6 GTI 80 000 miles, only engine mods being K&N, Fast road cam, and stainless exhaust + Mani.

 

Its been getting a little harder to start over the last couple of months, only slightly but it used to start on the button. This morning no problems... drive to work ok.. I get in it after work and its lumpy as hell and kept stalling on idle. I limped to my mums house with it running and sounding like it was only running on 2 cylinders! rough as hell for a normally smooth(ish) car.

 

Taking the leads off whilst running makes a difference on all cylinders, although not so much on #4 (maybe just my imagination)

 

Im ording a set of plugs and leads now (any recomendations?)

 

Any other ideas? If you require any more info just ask

 

Thanks very much

[DamirGTI 342]

Hi !

 

Well id say , make the usual checks first starting from :

 

ignition - plugs , leads , dizzy cap , rotor , coil , ignition amp.

 

and then if that's all fine move to :

 

fueling - fuel filter , fuel pressure , injectors , mixture - AFM

 

or :

 

electrics - wiring , sensors , air leaks etc.

 

 

 

Try first with simple/cheap things like - new set of plugs/leads/dizzy cap/rotor , and if that doesn't helps move further with investigation

 

But as you say that you have fitted aftermarket cam exhaust K&N , is the fuel mixture and ignition timing adjusted properly to suit this engine mods you must enrichen the fuel mixture when fitting these aftermarket cams filters exhausts heads etc. and adjust ignition timing also ...

 

Have you check the plug color ?

[MerlinGTI 3]

Hi thanks for your reply.

 

I cant take the plugs out to check colour as all my tools are at work Im ording some now though.

 

The dizzy cap and rotor arm are new and in good shape. The fuel filter is new. The mods have been in place for ages and the car has run beautifuly up untill today. The plugs and leads are 'working' (but to what extent i dont know) due to the diffeence on all cylinders when they are popped off.

 

It just strikes me as weird that all has been well right up untill leaving work

 

It runs ok for a minute, rev it a bit (its hesitant) and it runs lumpy again.

 

Im so pissed off The girlfriends car is an old s*itter so we rely on my little baby

Edited October 3, 2007 by MerlinGTI

[DamirGTI 342]

So... , then check the ignition amp. and coil (try with some spare one , and when you are fitting the new ignition amp. apply the thermal transfer paste at the back surface of the amp. ..) also check the AFM (preform retracking if needed , make a search on the forum for AFM retracking , or if you wish i can send you this document via e-mail..)

Get the injectors flow tested and clean them on ultrasonic machine as needed . (i've had similar problems when one injector was broken/damaged)

 

And do the compression test .

 

Is this problem worse when the engine gets hot ? what i mean is it fine started from stone cold or it's the same hot or cold ?

 

Damir

[MerlinGTI 3]

Thanks again for your help.

 

Its same hot or cold

[damien 22 1 Cars]

So... , then check the ignition amp. and coil (try with some spare one , and when you are fitting the new ignition amp. apply the thermal transfer paste at the back surface of the amp. ..) also check the AFM (preform retracking if needed , make a search on the forum for AFM retracking , or if you wish i can send you this document via e-mail..)

Get the injectors flow tested and clean them on ultrasonic machine as needed . (i've had similar problems when one injector was broken/damaged)

 

And do the compression test .

 

Is this problem worse when the engine gets hot ? what i mean is it fine started from stone cold or it's the same hot or cold ?

 

Damir

hi, can you send me a copy of the "AFM retracking" please - thesonofthedevil@yahoo.com.

i would do a search for it but the search has been disabled at the moment.

 

thanks

[DamirGTI 342]

hi, can you send me a copy of the "AFM retracking" please - thesonofthedevil@yahoo.com.

i would do a search for it but the search has been disabled at the moment.

 

thanks

 

Hello !

 

Ok -> sending ......

 

Cheers !

Damir

[damien 22 1 Cars]

got it, big thanks.

 

will give it a try today

[kyepan 291]

any luck?

[damien 22 1 Cars]

still waiting on the 2nd hand AFM to be delivered for me to test it on

[Rob_the_Sparky 9]

Thanks again for your help.

 

Its same hot or cold

 

Working on the asumption that something has bust to cause this I'd try:

 

ECU temperature sensor, if it goes open circuit (breaks) then it will fuel as if it is -40C, e.g. super rich and will run like crap.

 

Rob

[kyepan 291]

Working on the asumption that something has bust to cause this I'd try:

 

ECU temperature sensor, if it goes open circuit (breaks) then it will fuel as if it is -40C, e.g. super rich and will run like crap.

 

Rob

any joy on this?

[MerlinGTI 3]

sorry for not getting back to you all, Ive moved and only just got the intraweb

 

I replaced the plugs and leads and the problem was sorted. There was a small amount of moisture/water in the plug recess's (sp?) which i think was the main cause as the plugs only looked half knackered

 

Thanks for all your help

[McPikie 0]

Anyone got the part number for the ECU temp sensor and where is it located?

 

Mine over fuels its cock off at idle