Found 12th May
My car has started to make a revving noise even when no gas is being added. This has happened when I was stationary in traffic and even yesterday when I switched the car off, the noise continued for 30 seconds. The car isn't revving, but the noise sounds very similar to that noise.

21 Comments

ECU could be faulty, O2 sensor, throttle sensor/cable.... Take it to a mechanic so they can check it over. There's too many things it could be for people to guess

get some EGR cleaner spray from Halfords £10! soon clear that issue.

I'm not a mechanic but I had similar experience with my car that's a few years old turned out the throttle sensor had to be replaced, best get it checked out asap if left could cause serious damage to engine... The joys of motoring!!..;)

AC Radiator fan? Sometimes really loud and can run for a while after the car shuts off!

Original Poster

swedishfireball

AC Radiator fan? Sometimes really loud and can run for a while after the … AC Radiator fan? Sometimes really loud and can run for a while after the car shuts off!



I never use AC.

Ok well that's a loose guess based on the info, a car sounding like it's revving but not actual engine noise could be a multitude of things. I would firstly google the year, model of the car and add your sympton or failing that get it into a garage to get it looked at asap.

david_wavid

\x09\x09\x09\x09\x09\x09My car has started to make a revving noise even … \x09\x09\x09\x09\x09\x09My car has started to make a revving noise even when no gas is being added. This has happened when I was stationary in traffic and even yesterday when I switched the car off, the noise continued for 30 seconds. The car isn't revving, but the noise sounds very similar to that noise.\x09\x09\x09\x09\x09


Should ask, are all your coolants and oil levels topped off? Is the engine temperature getting hot?
Edited by: "xfaxfa" 12th May

Was going to add, it was pretty hot yesterday and when stationary you can sometimes head radiator fans from the engine bay working to keep the car at temp. Also these fans can be pretty loud. Regardless get it checked out and good luck!

The only automated rotational noises when engine has physically stopped running would be fan noises. From combination of examples of this noise being present when "stationary in traffic" and after "switched the car off" it would suggest at least one possibility being the engine coolant (radiator) fan which could correctly run in both those circumstances.

Is it petrol or diesel? miss firing ?.

If miss firing the unburnt petrol could be igniting in the catalyst, Lots of things can cause that like faulty throttle/sensor.

It is typical of a faulty throttle tbh and would be number one suspect.

Your best bet would be to have an auto electrician diagnose the fault.




Edited by: ".MUFC." 12th May

Had this on my 99 civic. Was a faulty lambda/ o2 sensor

My car is doing something similar at the moment. The garage diagnosed a faulty crankshaft sensor, so I suspect your problem will be a faulty sensor of some kind too.

masai

Had this on my 99 civic. Was a faulty lambda/ o2 sensor



Yeah, That would be number two suspect, The o2 sensors give the ecu the incorrect reading so it injects more fuel to compensate, Too much fuel means unburnt fuel ends up in the catalyst where it ignites which in turn often melts the catalysts insides resulting in the need of a new catalyst as well.

I've known people to replace the catalyst only to find a few months down the line the cat has melted again due to some other fault.

90% of catalyst failures are due to other faults, So important to find the culprit, Often a faulty o2 sensor, Coil, HT lead or sparkplug.

Diesel doesn't ignite in the cat the same way as petrol does, They usually suffer more with oil contamination when excess oil is burned, Again that's usually because of some other fault.

Plus they natural have a lifespan, They in theory should last the lifetime of the vehicle.

swedishfireball

Was going to add, it was pretty hot yesterday and when stationary you can … Was going to add, it was pretty hot yesterday and when stationary you can sometimes head radiator fans from the engine bay working to keep the car at temp. Also these fans can be pretty loud. Regardless get it checked out and good luck!


^^This^^

Check temperature reading when next stuck in traffic (especially on a warm/hot day)
Sounds like the fan cooling the radiator maybe damaged blade or slipping belt - if it's not that then it will be an engine fault

AndyRoyd

The only automated rotational noises when engine has physically stopped … The only automated rotational noises when engine has physically stopped running would be fan noises. From combination of examples of this noise being present when "stationary in traffic" and after "switched the car off" it would suggest at least one possibility being the engine coolant (radiator) fan which could correctly run in both those circumstances.



Whilst that may well be the problem, There are certain conditions in which the engine will continue to run on for a brief period, Especially if diesel as glowplugs remain hot so could briefly run on if perhaps there was a leaky injector for example.

between us all we have named pretty much everything

fan noise, ECU could be faulty, O2 sensor, throttle sensor/cable, get … fan noise, ECU could be faulty, O2 sensor, throttle sensor/cable, get some EGR cleaner spray, throttle sensor, AC Radiator fan, are all your coolants and oil levels topped off? Is the engine temperature getting hot, miss firing, faulty throttle/sensor, faulty lambda/ o2 sensor, faulty crankshaft sensor, faulty o2 sensor, Coil, HT lead or sparkplug, damaged blade or slipping belt - if it's not that then it will be an engine fault, glowplugs remain hot, leaky injector



best take it to a professional i think
Edited by: "ding" 12th May

It's not a Vauxhall by any chance.

Its the fan. The only think that can make that noise when switched off is the fan. If you were start stopping in traffic on a hot day its perfectly normal. Check your coolant tho

Original Poster

robbarraclough18

It's not a Vauxhall by any chance.


Yes, the garage said there was no water in the radiator.

david_wavid

Yes, the garage said there was no water in the radiator.


Did you asked them to find out why there is no water in the radiator?, It's either leaking somewhere or the headgaskets gone.

Original Poster

shauneco

Did you asked them to find out why there is no water in the radiator?, … Did you asked them to find out why there is no water in the radiator?, It's either leaking somewhere or the headgaskets gone.



Now that you mention it, there was that creamy residue when taking one of the caps off. Time to quickly sell the car I think.
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