Club G40 Forum
Technical => Engine and Transmission => Topic started by: Justin14100 on July 15, 2009, 05:38:08 pm
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Ok, well here goes describing this as well as i can!
The car runs well while driving to work and around (laps of town you know how it is lol) but every time I have done a long run in it - lets say 80 miles or more I get a strange problem.
What happens is the car will start to loose power, like a misfire but not juddery (made that word up) and if I slowly put my foot down the power stays the same till I get to full throttle and suddenly there will be the normal amount of power that full throttle gives. This is coupled with a nice dash of black smoke out the exhaust. So surely the fuel is getting there as its that not burning thats giving the black smoke. Air? Well that has to be getting there cause the charger, while putting the foot down the induction noise gets louder yet no acceleration till im flat!
So is it ignition? a dodgy chip? (has a 65mm pulley and jabba chip) and why does it only happen after a long run? Once it did stay there after 120 and I drove it to work the next day!
I am so confused and would be very grateful for any suggestions - sorry if I described it shite but its the best I could do lol!
Thanks!
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Don't worry about the shite description, I'll think about it and give you a shite answer lol.
Having thought about it it sounds like some sort of oil buildup in the induction side which takes a bit of time to make itself obvious. Plugs oil up then clear with lots of smoke ? How about a leaking charger seal ? Quick check inside pipework.
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Well I still have the boost return pipe and oil breather on so there will be some oil in the pipes, but there is quite a lot the metal 'o-ring' that sits in the plastic parts of the pipe to stop them from crushing from the jubilee clip where oiled enough to slide out!
I have been delaying the charger service and it was done a while ago.... so the chance is an oil seal is going in it?
Thanks!
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there will always be some oil in there from the breather. As long as it's not dripping out of the pipes then it's ok. I doubt a bit of oil in the pipes is anything to do with your problem. As you've already correctly said, black smoke is burning fuel not oil, oil gives blue smoke out of the exhaust. Perhaps it's the ignition coil breaking down under load after longer use?
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Well I was wondering about the coil, maybe after that amount of time its getting too hot or something? do they do that?
Needs new plugs, leads ect anyway I think... so if there is enough oil to drip from the pipes its defiantly charger service time?
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probably, although it could be coming from the breather. How many miles ago was the charger last done? and what size pulley is on it?
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I dont know if it was the last work done on it, but the only info i have was back in '02, got a 65mm pully on it so I presume its been longer than it should have been!
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yeah I'd say if you are running a 65mm pulley and you don't know how many miles ago it was done but know it's certainly not been done since 2002 then you should definitely get it serviced ASAP, whether you think it's leaking oil or not.
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Trying to get it booked in this week at jabba atm. need to find some £ lol!
any other ideas on what the problem is?
Thanks!
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there is a section in the haynes manuel on how to test your coil with a test meter i'd give that a try. you could also check the gaps on the spark plugs with a feeler guage and give them a clean as they will probably full of black sut.
If its not that could be the hall sensor on the dizzy playing up
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CO potentiometer? If this is faulty, it will retard the ignition timing causing a bit of a hold back like you describe before springing back into life. The CO pot is the sensor that clips into the boost pipe close to the throttle body.
They're about £45 IIRC.
But yeah, also:
Hall sender
Dizzy
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It should still accelerate with the ignition retarded though.
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Not a lot though if there's clouds of unburnt fuel/oil coming out of the exhaust. That would call for a major timing change. What could do that then go back to normal?
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(http://th06.deviantart.net/fs49/300W/f/2009/205/f/4/G40___03_by_Justin14100.jpg)
Too much oil?
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(http://th06.deviantart.net/fs49/300W/f/2009/205/f/4/G40___03_by_Justin14100.jpg)
Too much oil?
This is the boost pipe that runs past the washer bottle btw
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If you are mechaniclly minded and can get the use of a press and bearing puller you could attempt the service yourself, they arent hard to do and you need loctite and ptfe spray but thats it realy. if the charger shaft seal areas are worn you can get them metal sprayed and re-machined. i did it to mine and they did a great job, cost me about 250 but them it doesnt matter where the seals sit for future service. never had a problem with mine since.
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Ordered a new blue temp sensor today, will see if that helps.
Then new plugs and leads, will test the coil like it says in haynes manual too!
Any other ideas anyone?
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Id ascertain first what area you need to be looking at before spending loads of money on bits n bobs to test.
*Fuelling
*Ignition
*ECU Sensoring
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New theory - I know the G40 has injection mapping but am i right in saying that map only comes in at full throttle?
it fix's itself a max throttle so maybe there is a problem with something not sensing things right not at max throttle.
p.s started the charger work, and some other bits and bobs and there was a puddle of oil in the inlet manifold so was deffo needing a service!
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yes the full throttle switch in the throttle body activates the WOT map in the ecu.
get someone to slowly push down the throttle pedal and you can hear the click in the throttle body when the pedal is at WOT.
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I've recently bought my first G40 and mine is doing exactly the same thing! im the same, my charger has done probably done about 20k on a 65mm pulley since its last service.
I have the boost return off, but the flying saucer above air box is still attached, with one vacumn coming off it and goin to throttle body and another which has no pipe on it at all, then it has a large pipe on the top.
Mine too also blows out alot of oil out the throttle body, its making a right mes of all pipes and inside of engine bay around the area that it blasts.
I've changed plugs,leads,dizzy cap and rotar arm and it made no difference, it also seems to be an intermittant fault, also when it does do it whilst driving it will not idle smoothly either, kinda rythmic, dropping revs and picking up fast, but not hunting. sometimes it will just conk out all together.
So is it likely to be all the oil in the induction system causing this, as the seals in the charger are on their way out?
Thanks
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yeah - sounds like yr seals are weeping.
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Just re-built my charger, went well - need to put it in the car and see if it fix's the problem!
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Ok, charger re-built. Not fixed the problem.... so much for running the charger in when you have to kick it to full throttle to stop it slowing down and blowing out black smoke! Well pissed!
anyway, giving it a new blue temp sender tomorow, going to try steal a knock sender from another polo (1.3 genesis - is it the same and where it located? thanks!)
Oh, another thing it does is while its doing it if i clutch it and let it idle it revs itself, between 1 and 1.5k rpm for a few seconds - any idea what would cause that? doesnt do it any other time?
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hmmm - sound more like a dodgy head gasket/valve stem oil seals/piston rings gone - either that or your timing is miles out.
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If you are mechaniclly minded and can get the use of a press and bearing puller you could attempt the service yourself, they arent hard to do and you need loctite and ptfe spray but thats it realy. if the charger shaft seal areas are worn you can get them metal sprayed and re-machined. i did it to mine and they did a great job, cost me about 250 but them it doesnt matter where the seals sit for future service. never had a problem with mine since.
most charger services dont use a press or puller... it can both damage the casings and not get the beairng in straight. Heat the casing up and freeze the bearing and the plop in without any pressure.
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hmmm - sound more like a dodgy head gasket/valve stem oil seals/piston rings gone - either that or your timing is miles out.
Timing is fine, checked it when put the toothies on!
its not an oil burn, its very odd - and when you engage full throttle it runs perfectly, so now im under the assuption that one of the sensors on the engine is telling the ECU to dump the fuel in, cause im now sure the problem is over fueling!
Ah well, its so hard to get help over the net - if only I could show people what it does! Round town its OK, just motorways its rubbish!
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which did you checK the mechanical or ignition timing?
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which did you checK the mechanical or ignition timing?
mechanical, isnt the ignition set by the dizzy spinning anyway?
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yes ignition timing is set by the dizzy, and if way off can cause your car to run like a bag of nails and kick black smoke out!
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could be that, but it runs fine a lot till a few min a motorway driving, then it starts doing it, so surely the dizzy timing doesnt change?
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no it doesn't but if its set wrong, might be better with more/less fuel in it. Check it anyway.
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no it doesn't but if its set wrong, might be better with more/less fuel in it. Check it anyway.
is there timing marks? How do I check it?
Where is the knock sensor located? Thanks!
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you check it with a timing light and the marks on crank pulley.
Knock sensor is on the back of the block - is specific for g40 and is not an efficient knock sensor.