Rav Posted June 10, 2023 Report Share Posted June 10, 2023 My 2000 986S is still running rough after the MAF and then a Oxygen sensor change. Today it got worse. I had to go into Swindon town and the parked the car up. When i returned the car wouldn't start. It turns over and over and only starts if i press the throttle a few times. I am sure that today when i tried to start the car, i heard a 'pop' before the endless turning over began. Its not the first time it has done this and previously after i get her started she runs well. This time she ran really ropey and almost cut out. I am starting to think that the best bet is to change the coil packs and the second O2 sensor just to be sure. Any ideas folks - Tesla is calling..... Quote Link to comment Share on other sites More sharing options...
Nobbie Posted June 10, 2023 Report Share Posted June 10, 2023 Wondering why the throttle would have any effect on starting🤔 Is it an e gas throttle? Doesn’t sound like a coil pack issue, these usually manifest in damp weather. Fuel pump maybe? Can you hear it priming when you turn on the ignition before a no start? Maybe a dodgy relay on the fuel pump? Seem to remember @Terryg had a dodgy pump which caused his car to run rough. Quote Link to comment Share on other sites More sharing options...
Rav Posted June 10, 2023 Author Report Share Posted June 10, 2023 (edited) Interesting- thanks Nobbie - Were are the relays? If they are up front, that might be what i heard click? I'm not sure that it is a e- throttle - its a 2000 MY car with only 2 O2 sensors. Edited June 10, 2023 by Rav Quote Link to comment Share on other sites More sharing options...
Nobbie Posted June 10, 2023 Report Share Posted June 10, 2023 17 minutes ago, Rav said: Interesting- thanks Nobbie - Were are the relays? If they are up front, that might be what i heard click? I'm not sure that it is a e- throttle - its a 2000 MY car with only 2 O2 sensors. I think they are on the drivers side under the dashboard above the fuse panel. Quote Link to comment Share on other sites More sharing options...
Rav Posted June 10, 2023 Author Report Share Posted June 10, 2023 Hum, I will investigate..... Quote Link to comment Share on other sites More sharing options...
edc Posted June 10, 2023 Report Share Posted June 10, 2023 1 hour ago, Rav said: Interesting- thanks Nobbie - Were are the relays? If they are up front, that might be what i heard click? I'm not sure that it is a e- throttle - its a 2000 MY car with only 2 O2 sensors. Only the 2.5 is a mechanical throttle. Quote Link to comment Share on other sites More sharing options...
edc Posted June 10, 2023 Report Share Posted June 10, 2023 In your situation it sounds like the pop was due to fuel going down then igniting. This would happen if the engine and exhaust were still got. It sounds like you have a hot start problem ie difficulty starting after a run. This is a classic symptom of crank position sensor. Quote Link to comment Share on other sites More sharing options...
the baron Posted June 10, 2023 Report Share Posted June 10, 2023 1 hour ago, edc said: In your situation it sounds like the pop was due to fuel going down then igniting. This would happen if the engine and exhaust were still got. It sounds like you have a hot start problem ie difficulty starting after a run. This is a classic symptom of crank position sensor. I would second that although when we ran the OBD reader it pulled up the oxygen sensor, it might be worth me popping over when I next pass your house, could be Monday if your around 1 Quote Link to comment Share on other sites More sharing options...
the baron Posted June 10, 2023 Report Share Posted June 10, 2023 Is it ok starting from cold? It could be the variocam solenoid, this is a big job so hopefully it’s not that, put systems are as you describe, if the car is left for 15-30 mins it will probably start straight up and run fine. 1 Quote Link to comment Share on other sites More sharing options...
Rav Posted June 11, 2023 Author Report Share Posted June 11, 2023 Thanks All. Car starts fine from cold. It is always an issue when starting hot or warm ish. i.e. the car has been used that day and then turned off and left for around 30 mins. I will whatsapp you @the baron and see if i can pop over tomorrow between meetings. Quote Link to comment Share on other sites More sharing options...
edc Posted June 11, 2023 Report Share Posted June 11, 2023 If it generally runs fine hot or cold and starts ok from cold then at least you have narrowed it down to a hot start issue. 1 Quote Link to comment Share on other sites More sharing options...
½cwt Posted June 11, 2023 Report Share Posted June 11, 2023 1 hour ago, edc said: If it generally runs fine hot or cold and starts ok from cold then at least you have narrowed it down to a hot start issue. Hot start issues, isn't that often the cam/crank position sensor? 1 Quote Link to comment Share on other sites More sharing options...
edc Posted June 11, 2023 Report Share Posted June 11, 2023 45 minutes ago, ½cwt said: Hot start issues, isn't that often the cam/crank position sensor? That's what I've posted earlier. Quote Link to comment Share on other sites More sharing options...
½cwt Posted June 11, 2023 Report Share Posted June 11, 2023 1 hour ago, edc said: That's what I've posted earlier. Sorry in a field in France and have had a few beers with @Patt... 1 Quote Link to comment Share on other sites More sharing options...
map Posted June 11, 2023 Report Share Posted June 11, 2023 I had the same symptoms and changed the Crank Position Sensor - that didn’t resolve it. The problem didn’t produce an error code either. After bit of digging I changed the Throttle Position Sensor (TPS) which is part of my accelerator pedal. This cured the problem. Depending on the car the TPS is either on the Throttle Body or the Throttle Pedal. In your case @Rav I’d change the CPS and if that doesn’t chase the problem away change the TPS 1 Quote Link to comment Share on other sites More sharing options...
Nobbie Posted June 11, 2023 Report Share Posted June 11, 2023 2 hours ago, map said: I had the same symptoms and changed the Crank Position Sensor - that didn’t resolve it. The problem didn’t produce an error code either. After bit of digging I changed the Throttle Position Sensor (TPS) which is part of my accelerator pedal. This cured the problem. Depending on the car the TPS is either on the Throttle Body or the Throttle Pedal. In your case @Rav I’d change the CPS and if that doesn’t chase the problem away change the TPS That’s interesting as he said that pumping the accelerator seemed to have an effect. Quote Link to comment Share on other sites More sharing options...
Terryg Posted June 11, 2023 Report Share Posted June 11, 2023 I don't think my issue is relevant, I had a dodgy fuel gauge which led me to run out of fuel, this resulted in the pump sucking in the debris at the bottom of the tank. Good luck getting it sorted. Quote Link to comment Share on other sites More sharing options...
map Posted June 11, 2023 Report Share Posted June 11, 2023 3 hours ago, Nobbie said: That’s interesting as he said that pumping the accelerator seemed to have an effect. And this was what led me to look at the throttle control aspect. No-one I spoke to about this problem and symptoms pointed towards the TPS - I vaguely remember finding something in a very, very old post on a US forum that got me to look into the TPS in more detail. On older e-throttle cars the TPS is part of the Throttle Body. Later cars (mine is 2002MY) have the TPS within the accelerator pedal. I think the sensor gets worn and produces erroneous resistance figures which the ECU looks-up in the mapping tables that results in odd fuelling behaviours. I think the cooling down bit basically allows any residual resistance to be dissipated and so for a while the TPS is sending more accurate data until it “heats up” again. Italicised comments should be “fact checked” by an electronics engineer. Regardless I’d change the CPS before the TPS. The CPS seems to be a more common failure. Quote Link to comment Share on other sites More sharing options...
Rav Posted June 12, 2023 Author Report Share Posted June 12, 2023 A big thanks to @the baron who popped in this evening with his code reader. No codes present on my car at all. We did note a lumpy idle and the smell of fuel - over fuelling? I am not sure if it is connected - but the car seems to hum to itself. Its a humming noise, which i have been told is coming from the ECU - its quite load and can be embarrassing - could it be an air leak? Quote Link to comment Share on other sites More sharing options...
Everywhen Posted June 13, 2023 Report Share Posted June 13, 2023 20 hours ago, Rav said: I am not sure if it is connected - but the car seems to hum to itself. Its a humming noise, which i have been told is coming from the ECU - its quite load and can be embarrassing - could it be an air leak? The Throttle Body can make a "humming" sound. I've not heard the ECU hum, its in the rear boot, behind the liner. I can't think what could be inside it to actually make a sound? 1 Quote Link to comment Share on other sites More sharing options...
½cwt Posted June 13, 2023 Report Share Posted June 13, 2023 7 hours ago, Everywhen said: The Throttle Body can make a "humming" sound. I've not heard the ECU hum, its in the rear boot, behind the liner. I can't think what could be inside it to actually make a sound? The throttle body just behind the panel where it sits maybe? 🤔 Don't take this as gospel. a few wines have been taken, even on a school night... 🫢 1 Quote Link to comment Share on other sites More sharing options...
Menoporsche Posted June 14, 2023 Report Share Posted June 14, 2023 Surely humming is vibration, which can often be a motor working when it is not usually required. Fuel pump? Unless someone inadvertently switched the stereo on... Quote Link to comment Share on other sites More sharing options...
EXY Posted June 14, 2023 Report Share Posted June 14, 2023 1 hour ago, Menoporsche said: Surely humming is vibration, which can often be put down to not knowing the words. Fuel pump? Unless someone inadvertently switched the stereo on... I'll get me coat,,,,,, 1 Quote Link to comment Share on other sites More sharing options...
Everywhen Posted June 14, 2023 Report Share Posted June 14, 2023 12 hours ago, ½cwt said: The throttle body just behind the panel where it sits maybe? 🤔 Don't take this as gospel. a few wines have been taken, even on a school night... 🫢 TB is in on top of the engine, pretty much central. when I had my TB issue I could only hear the motor in it when the engine covers were off and I didn't start the engine, just first click of the key, then the TB made a humming sound. I posted a short video of it. Quote Link to comment Share on other sites More sharing options...
½cwt Posted June 14, 2023 Report Share Posted June 14, 2023 19 minutes ago, Everywhen said: TB is in on top of the engine, pretty much central. when I had my TB issue I could only hear the motor in it when the engine covers were off and I didn't start the engine, just first click of the key, then the TB made a humming sound. I posted a short video of it. My point was that the humming from the TB could be transmitting through the bulkhead to seem as if it were coming from the DME. A bit tenuous I know. Quote Link to comment Share on other sites More sharing options...
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