Club G40 Forum
Technical => Engine and Transmission => Topic started by: pinky on March 07, 2008, 12:51:12 pm
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Hey Guys,
Just following on my thread from CP really I thought it would be better to post it here. I had problems with my G idleing all over the place, poor fuel consumption and it keeps bucking at low speeds (which must look funny from the outside but it's really annoying in traffic)
Following andys and yoofs advice I changed the blue temp sender and the lamba probe which has helped but its still doing the same things. I really need to give it a good service but before I do that is there anything I shoudl specifically look at? Its fine on boost and pulls hard throughout the gears, when I slow down for traffic lights or sitting in traffic it will cut out or nearly cut out or just die completely. I have noticed the battery light will flash when its idleing badly so it maybe a electrical problem but this would be a stab in the dark. Im not sure if it is because my rear seats are stripped out but the fuel pump is really quite loud but im not sure if this is normal?
Any help appreciated! it would be nice to having it running properly before the summer fingers crossed
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Is the ignition timing set correctly?
Have you stuck a meter on the battery to see what the voltage is with the engine running?
What's the CO pot resistance set to?
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following andy - it could be alternator thats duff from the battery light and poor idle - you need to measure voltage across the battery
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I am not sure about the ignition timing, I haven't checked the battery but I can do that this weekend. I think Marshall set the CO pot resistance slightly higher to even it out a bit but I maybe wrong another thing I will have a look at.
Thanks for the suggestions guys
EDIT : Another thing it doesn't do it in the morning till it warms up but I imagine if the alternator isn't charging correctly it will be pulling power from the battery so that might explain but I will check with the multimeter
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It's hard to say what's going on - the battery light might just be coming on because the car's on the verge of stalling, so the alternator is dropping in and out.
The fact that it's okay when cold might be because the auxiliary air valve (what people call the ISV) is open, giving higher idle speed. The ECU controls idle by varying the ignition timing, so if the base timing is out (or you've got a spastic map in the car) the car might not idle.
It's also worth checking the closed throttle switch on the throttle body is working properly.
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[quote pid=203 author=Andy date=1204901541]It's hard to say what's going on - the battery light might just be coming on because the car's on the verge of stalling, so the alternator is dropping in and out.
The fact that it's okay when cold might be because the auxiliary air valve (what people call the ISV) is open, giving higher idle speed. The ECU controls idle by varying the ignition timing, so if the base timing is out (or you've got a spastic map in the car) the car might not idle.
It's also worth checking the closed throttle switch on the throttle body is working properly.[/quote]
Yeah it does idle slightly higher in the morning then will drop under 1000 when it has warmed up
I shall get the ignition timing looked at how do I check the closed throttle switch is working correctly?
Thanks for the advice!
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Sounds like a weak alternator not pumping out enough juice. If the battery voltage drop benith 12.7v the ECU drops into a failsafe mode.
Test the battery voltage across the battery poles with all ancileries turned on to drain current. Even with everything trned on the voltage should be well above 12.7v. £120 will buy you an genuine VAG alternator which will resolve the issues for a long time if voltage drop appears to be the issue.
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Sorry for the late response, Just got the multimeter out and it read 13.3v (average) with nothing on and 12.4v (average)with everything on. The idle got alot worse when I turned everything on which I presume like you said steve put it in failsafe mode? Is the usual voltage alot higher than 12.7v ?
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sounds like a knackered alternator
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Ok cheers for the replys, I shall give it a go
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Another thing I forgot to mention is the car will sometimes cut out when I roll up to a set of traffic lights or just die when sitting in traffic when the idle is considerably bad would this be because of a lack of power?
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[quote pid=772 author=pinky date=1207743891]Another thing I forgot to mention is the car will sometimes cut out when I roll up to a set of traffic lights or just die when sitting in traffic when the idle is considerably bad would this be because of a lack of power?[/quote]
Classic traits of low voltage from the alternator, combined with the low voltage readings I think it is safe to say you have to dig deep and buy a new unit.
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Cheers Steve just wanted to make sure
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exact same thing as mines doing :(
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Its a royal pain in the a$$ but I should have a alternator arriving tomorrow and will hopefully be fitting it Saturday
Have you checked yours with a multimeter jon?
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Mine's been doing stuff like this for ages and is having a new alternator fitted also.
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[quote pid=948 author=Jeefer date=1208505253]Mine's been doing stuff like this for ages and is having a new alternator fitted also.[/quote]
Do you what voltage yours is with everything on out of interest?
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is the lambda probe genuine cus sometimes they dont match the car disconect it then take it for a drive see what happens if all that stop u no wat wrong
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mine does this now i have a brand new battery and alternator on lol oh the joys of owning a G40
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[quote pid=1041 author=lance date=1208959366]mine does this now i have a brand new battery and alternator on lol oh the joys of owning a G40[/quote]
What was your voltage before and after?
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Have you cleaned the idle valve? Remove it and soak it in carb cleaner for a while. Sorted mine out when it was stalling all the time coming to a stop at traffic lights.
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Just like to jump on this one too. Right mine is doing a similar thing but not stalling. When started from cold or semi cold runs sweet as then when hot and traveling low revs it jumps about. As if its missing. Gun it and its fine or sit at high ish revs and runs nice. when i slow down in traffic it runs still but sometimes hunts (I'd say dirty idle valve) but this can't be the problem when moving. As it seems to get worse after a high speed drive in other words engine is hotter i thought poss plugs or leads breaking down with the heat. Changed these today as well as rotor arm and dizzy cap. Guess what yep still doing it.
I'm now becoming puzzled by it. I wouldn't have thought it was a dodgy alternator. If that was the case surely it would be worse when cold started, Engine not charged all night, Low speed driving not charging much, but give the car a run and alternator would have charged the battery somewhat. therefore surely when returning to slower speeds the battery would have aditional charge and run better. Just my logical thinking.
Someone must have sorted this problem before as it does sound quite common.
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[quote pid=945 author=pinky date=1208471843]Its a royal pain in the a$$ but I should have a alternator arriving tomorrow and will hopefully be fitting it Saturday
Have you checked yours with a multimeter jon?[/quote]
I brought a new battery and brought another alternator from a cp member and fitted that. Still doing it!