Club G40 Forum
Technical => Engine and Transmission => Topic started by: DKnight on October 17, 2008, 01:22:25 pm
-
well my g40 over the last 6 months or so has started to run really rough on start up, so much so it sounds like a misfire, it only does it for about 2 minutes then it runs fine, no problems at all...
now i have checked the usual things, dizzy cap arm, leads plugs, are new from about a year ago
coil i ve checked and tested, ecu chip i have swapped still same
timing is correct too
when it is running rough there is a strong smell of fuel so i really do think it is a fueling issue, how can you check the injectors? maybe even a blocked line? filter swap maybe?
any ideas be great
cheers
Dan
-
hmm maybe it could be a sticky injector that starts working properly after a bit?
Easiest way to check is probably going to be to remove the fuel rail, point the injectors into a bowl and then get someone to try starting the engine. As that's happening watch for nice even spray patterns coming out of the injectors and that when they stop trying to start the car none of them leak fuel.
Alternatively, if you have some spare injectors put them in.
-
Blue temp sender?
Fuel leak?
-
blue temp sender i need to check yeah, isnt coming up with any faults tho
and no fuel smell or signs of leak
i will try the blue temp and hayeseys idea with the injectors
and report back :D
-
well there is a fuel smell isnt there, but we had a good look for leaks and couldn't see anything. no sign of fuel spraying out when you were trying to start it.
-
sounds exactly like my problem...i have tried every thing!!! filters/changed injectors/timing/new leads/plugs/dizzy/everything and i still have it...worse when cold lasts about 30 secs after start up from cold goes quickly if you drive...do you have a decat pipe on? mine started after i fitted a decat...could just be coincidence. car still drives mint after this has gone though. let me know im very very interested.
-
You could be onto something there Dan. Always wondered why ETKA list a different ECU for non-cat G40's!
-
Mine used to chug (the best way I can describe it) for about a minute when first starting in the morning but it didn't affect how it drove though, the funny thing is my old mk2 golf 1.3 used to do exactly the same thing.
I never found out what was causing it in either cars and I imagine when the g40 finally gets out of the garage again it'll do it then.
-
mine used to run very rich and there was a really strong fuel smell, that was the blue temp sender no good.
-
Mine does this as well, but I'm guessing it's because I need to take it for a long motorway drive. It's doing the trip to work (15 miles down the A1) every day but that's as far as I take it usually.
-
in this its likely to be something electrical in my opinion causing over fueling - like lambda, alternator, injectors, blue temp sender, chip etc. i suppose just swap all with those from a known good car and see if anything makes a difference
-
the only thing i havent changed is the alternator..i occasionally get the battery light on start up when cold but the battery is new and ive done the voltage check thing with a multi meter which was fine so im guessing its just a tired/aging alternator, never has any bother starting starts first time every time...can't see this problem being alternator related to be honest. ive changed everything else including vag lambda and i always seem to remember noticing this after i fitted the vag decat about 18 month back...any ideas? ive lived with it for ages now doing about 20k with the problem.... be interesting see what dk says...
-
Mine used to chug (the best way I can describe it) for about a minute when first starting in the morning but it didn't affect how it drove though, the funny thing is my old mk2 golf 1.3 used to do exactly the same thing.
I never found out what was causing it in either cars and I imagine when the g40 finally gets out of the garage again it'll do it then.
thats the best way i can decribe it 'chug' too
-
yeah it is a chug, and mine does have a decat yes!
if i rev the chug just ups its speed, until after a few minutes, it goes away
i will be swapping the decat for a cat soon so i will see how it goes!
good input from all here, i hope we sort it
-
The fact that my golf, which was a 1986 carb'd version with a mechanical fuel pump, did it makes me think that it's probably not one of the sensors.
-
yeah it is a chug, and mine does have a decat yes!
if i rev the chug just ups its speed, until after a few minutes, it goes away
i will be swapping the decat for a cat soon so i will see how it goes!
good input from all here, i hope we sort it
yep! exactly the same! try it and see..shame i weighed my cat pipe in ha ha
-
I've been running a VAG decat pipe on mine for about 3 years now and mine doesn't chug, either with standard ECU or a Jabba chipped, cup spec ECU. I do get a petrol smell on start-up sometimes though, but I think that comes from the rubber tube between the valve on the water cross-pipe up to the manifold, it's getting little cracks in it with age. Anyone know how much these are ?
-
what is a "cup spec" ecu?
The aux air valve is quite expensive, VW only and I think they are over £60.
-
My first input on this one, I'd check that the throttle shut off valve switch is set-up probably(its the little microswitch on throttle body), it should be switched(pushed) when the throttle is closed, quite often a sticky accelerator cable or poorly adjusted idle screw can stop it closing probably. This is more noticable if the butterfly has been de-wegded.
-
My first input on this one, I'd check that the throttle shut off valve switch is set-up probably(its the little microswitch on throttle body), it should be switched(pushed) when the throttle is closed, quite often a sticky accelerator cable or poorly adjusted idle screw can stop it closing probably. This is more noticable if the butterfly has been de-wegded.
im interested in what your saying but im not 100% what to do to check this or cure it? my throttle butterfly is dewedged actually. cheers
-
ermmm i darent believe this but i went out side to try what you said G-spot and it didnt do it at all?
what i did: unclipped the throttle cable rubber support from the bracket on the manifold (not removing the little metal clip that keeps the cable under tension) so the accelrated cable was hanging untensioned and started the car...then i revved the car manually from in the bay...no chugging whatsoever?! Now the car has been sitting since i got in from work at about 5:45 so at the point i started the car is about 4 hours and its freezing outside which always makes it worse. I'll try it in the morning when it always does it and if it doesnt do it will be overjoyed! im not sure why it would do it and how the cable would effect it to be honest and why the cold would make it worse other than the cold makes the cable tighter and pulls more making something not close??
plus it always does it after sitting for a while 3+ hours as if something is slowly changing (previous thoughts were fuel flooding a cylinder from a leaking injector but swapping them proved otherwise)...cable tensing as time ticks by?
anyways fingers crossed!
-
its the idle switch in throttle - ther eis a like 2 switches, on and off if you like - one for idle and the other for full throttle. If the cable is too tight then it wont switch the 'off' switch
pete
-
so maybe its choking it with too much air? and fuel? thinking ite open than it is? make sense?
-
someone else noted havi the same problem a while back but i cant remember his name on the forums. had a red G which he sold to luke. sure it was him...said he had one in his garage which was doing the same.
-
sound like we fixed that one then, reason I suggested looking there is that I had similar issues after my last rebuild, even though everything went back the same, the switch wasn't quite closing out, it also meant that it was running rich on the overrun as the ECU didn't see the throttle as being fully closed.
-
well im otimistic but tomorrow morning will tell for sure then i can see as well and adjust cable accordingly.... fingers crossed. cheers for the help...dn knight said it didnt make a difference for him so im a little gutted about that...see how it goes though..
-
still no change this morning...gutted lol
-
:-[ :-[
-
tried another throttle? you sure switches are working?
-
no not yet but im gonna wait for dan knight to change his as its one of his plans. if all is well after then ill source one.
-
what is a "cup spec" ecu?
The aux air valve is quite expensive, VW only and I think they are over £60.
Thanks for air valve info, but it's the hose that's cracking. Is there a test for the air valve by the way ?Allegedly the "cup spec" ECU is an otherwise standard G40 ECU with a Jabba Chip in it, optimised for Cars used in the Polo cup. Maybe the guy that sold it to me was telling porkies, but it has got a Jabba chip in it and the rev limiter is higher than standard, and there is definitely more ignition advance in the map as it pinks like a b'stard on standard unleaded fuel and needs super unleaded to run properly. Car goes much better too.
Not sure if Polo cup entrants were supposed to mess with mapping, but this ECU definitely helps things along !
There used to be some sort of sealing sticker over the ECU joint (a seal to show if it's been tampered with)
-
jabbasport didn't even exist when the G40 Cup Car races happened, last g40 cup season was 1993 if I remember correctly and jabbasport didn't start till 1997. Although cup cars are even now still being used in other race series. Just sounds like a normal ECU with a jabbasport chip in it, I hope you didn't pay extra for it because it was supposedly from a Cup Car! I'm fairly sure the cup cars had to run stock ecus and were as you say. sealed.
Anyway, I'm not aware of any way of testing the air valve.
-
well ym car hasnt altered at all, i havent swapped anything, but it is a fuel smell out of back, so i was talkin to pete and he said maybe its a dicky injector, that maybe leaks, so when sat it leaks and there will be fuel there so fire up and it burns all that off as it runs rough, once cleared it then runs...
it seems a good idea...
how many people have serviced their injectors, the peopel that are having the same problem?
its something i cant say i have ever even thought about...
-
have you also changed the chip?
-
chip is back to stock
-
well ym car hasnt altered at all, i havent swapped anything, but it is a fuel smell out of back, so i was talkin to pete and he said maybe its a dicky injector, that maybe leaks, so when sat it leaks and there will be fuel there so fire up and it burns all that off as it runs rough, once cleared it then runs...
it seems a good idea...
how many people have serviced their injectors, the peopel that are having the same problem?
its something i cant say i have ever even thought about...
spaniel got new injectors i think.
hmmm
-
i bought new injectors originaly and thought that maybe the issue was as mentioned above but put the old injectors back in to see but there was no difference whatsoever, so ruled that out...
-
bump...more thoughts on this please...dk and me have been pondering vacuum pipes/fuel pressure regs/that vaccuum thingy from the servo...although i put new vaccuum pipes on since and noticed nothing so im thinking more that hose with the yellow on it out of the servo.
we both seem to have the same issue:
chugging
overfuelling
missing on start up especially after being left a while like overnight more noticable when cold. goes after being revved/drove for 30 secs max. cars drive fine! boost well and idle spot on (well mine does, cant say for dk)
i tried unplugging a lead to try and relicate the missing but it wasnt quite the same. mine and dk's both chug around 2 k and it kind of 'rocks' the car like an american muscle car?! sounds great but its not!
input/opinions needed please.
I seem to remember someone on club polo had the same issue too when i raised it ages and ages ago! i think it may have been turbodaily? someone defo had the same issue and i want to find them!
-
hows about the isv, possibly air leak that when gets warm seals?
-
it has to be a direct fuel related issue as mine seriously over fuels, but like spankers says, its only for about 30seconds to a minute
if i then leave it parked up for say 3 hours, i come back and it starts right enough...
im gunna try a few things, but problem is i have a 1minute time window to test things lol
-
hmmmmmmmm fuel pressure reg?
-
What engine speeds are you getting on start-up and idle after thermostat opens? I had some of the symptoms you're getting only idle stayed very poor when warm. I got 1300rpm dropped to 1100 after 30 secs. Ran smoothly till temp. started to climb then dropped to 850ish. After that it was as rough as a badger's arse with idle rhythmically dropping (a sort of four from five effect) and smell of fuel. The following worked for me but I'm not sure why.
Fired up and when revs made initial drop to 1100rpm I disconnected the blue sender for about thirty secs. Re- connected and revs held at 1100 even when thermostat opened. Tweeked idle adjust to a nice steady 850. No fuel smell and steady idle. It's been OK since. Fires up 1100 and idles 850. No problems elsewhere in the rev range.
The blue sender had been changed to try to cure the problem, does the ECU hold an old memory which needs removing?
-
i tihnk thats a different issue, if you unplug ecu for a while it will reset it
its such a strange one this, only so many bits you can change
spaniel did you use the same regulator?
also dunno if linked, but my car struggles to start, on turn over it sometimes sounds like a flat battery, turns slightly stops, turns again fires all ok
i thought it might have been the starter...
im gunna get all my tools out and check bloody everything...
-
i think scotjohns issue is totally different too. i havent changed the fuel pressure regulator though or the throttle body...i did try another ecu though and that didnt work either...i feel like its more likely something sticking over time or something? like the fuel regulator but i have no idea what they look like inside? its more noticable when its cold. Warm mornings in the summer it would sometimes not do it? like something is sticking from the cold or something doesnt like the cold?....i then thought lambda..and bought a new vag one of those..but no difference. changed the blue temp sender too..but no difference....i havent changed the idle control valve either though. i like petes suggestion of it having a leak that alters when it seals as it expands though.. but then i dont have any idling issues other than the odd occasion i feel like the car skips like a burble you can feel when idling away but the car is never effected by it? and other than that occasionally, it idles spot on as it should and smoothly. i feel as tough the symptoms appeared after the de cat pipe was fitted but then that could be coincidence and seems unlikely as someone else has a decat and tried a standard chip without these problems...
-
Agreed the ECU can reset itself but other sources of info such as the blue temp sender dont come with spot on values and adjustment may be part of the game. The only real difference
from my problems is the miss-fire/ rough running at 2k and that does sound like fueling/ air leak probs which may be seperate( peteg40's temp air leak sounds like a good bet).
Only other thing I can think of thats not been mentioned is the knock sensor. If it's come loose could it start interfering with the timing? Critical torque setting seemingly.