Idle 451 Cdi

[CKpt 0]

Well, long story short... December 2012 I've traded my always faithful 2005 450 cdi with 98000Km on the clock for a 2012 451 cdi (DPF equipped), and although I really like the car, it has been at the dealer more times in one year than the 450 in the whole time I've owned it. The only good thing here is the extended warranty till 2016...I know you guys don't have this engine but you are more than acquainted with the "old" unit.Compared to my 450, this 451 does two annoying things that everyone says it's normal:- A whining sound coming from passenger side (back) - Perhaps fuel pump? More audible on cold - it seems to be the fuel pump. Dealer says it's more audible because it's a cabrio . - The idle isn't as steady - When compared to the 450 the needle fluctuates a lot more, seems to improve a little bit after the engine warms up.Does someone have any clues to what may be causing these issues?Thanks

[MikeT 744]

The excuse about it being whiny because it is a cabriolet is nonsense! The fuel pump or some other moving part is failing!

[dmoonen 54]

I find the noise a weird factor. Usually an unsteady idle on a diesel is caused by bad injectors or a problem with the injector pump/high pressure pump. The HP pump shouldn't really make a noise, its more of a hum. Maybe get a stethoscope and try to pin down the area where the noise is actually coming from before digging in :)I have a couple different ideas but I think start off with using a stethoscope and pin down where the noise is coming from. Could vary well be the noise and the idle problem are two separate problems.

Edited May 14, 2014 by dmoonen

[Huronlad 186]

Does the 451 cdi have some form of "Secondary Air Injection" like the gasser?

[CKpt 0]

Thanks for all the answers.

Unfortunately I still haven't found a similar car (cabrio - 54hp) to compare noises but in comparison with my 450, where I could only hear the pump priming on startup, in this I can hear it all the time.

It's not very audible in this video, but it's the "ueeeee, ueeeee" noise.

Edit: After doing some research on youtube trying to find the noise it seems to be the alternator?

Edited May 14, 2014 by CKpt

[Lito 2]

tee hee... that movie looks like it's about to become the next horror classic :)I could not hear the noise in the video, but I have to say that my 451 does not seem to have any noise like the one you explained I can easily detect, other than the loud 10 to 30 second air pump charging the exhaust system when I first start the engine from cold.As for the idle, I have an Ultra Gauge and according to it, once the engine is warm, say at a red light, the idle moves by around 10 to 40 rpm (just above 900), which I guess it is somewhat normal; however, I would not be able to distinguish the wondering of the idle purely by ear, so it maybe just "computer noise" or something of the sort.

[CKpt 0]

tee hee... that movie looks like it's about to become the next horror classic :)I could not hear the noise in the video, but I have to say that my 451 does not seem to have any noise like the one you explained I can easily detect, other than the loud 10 to 30 second air pump charging the exhaust system when I first start the engine from cold.As for the idle, I have an Ultra Gauge and according to it, once the engine is warm, say at a red light, the idle moves by around 10 to 40 rpm (just above 900), which I guess it is somewhat normal; however, I would not be able to distinguish the wondering of the idle purely by ear, so it maybe just "computer noise" or something of the sort.

Yeah, I'm not a good movie producer lol but it's easier to hear if you turn the volume up and use headphones, It's a whiny background noise. I'll try to do a sequel tomorrow and also use the Torque app to check the difference in the revs.Very, very similar to these:Noise

Weirdly, like the example above - "noise 2" the noise seems to have some effect on the lights.Fuel filter has been changed at every yearly service (10.000 and 20.000km). Edited May 14, 2014 by CKpt

[CKpt 0]

Anyone has/had a similar issue with the old 450's?

Edited May 17, 2014 by CKpt

[tolsen 630]

The 54hp Cdi has a noisy electric feed pump. I've seen owners complain about this before. Last time was recently on OnSmart forum.

[Colsmart 0]

I have the same 451 Cdi as I am in Europe (Scotland), though my Passion Fortwo has a plastic clear roof.I find idling is very steady once warmed up, and when stopping at lights or at a junction. No problems at all, the needle is steady at idle.As for noises at startup and shutdown, yes there is a noisy sequence in the engine bay, as the engine is primed to start, pump noises, quiet whining, relays clicking, etc, but it does not take any longer than the glowplugs to heat up and its light to go out on the dash display. This only takes seconds and then turn the key to start, the engine noise then drowns out all other noises. The engine noise then settles down when hot and running. If that whinning noise continues after startup, then I do no hear it because of the engine noise, so it must be quiet. Oh, my car has only done 23,000 miles in three and a half years.The shutdown sequence is much longer, as when you switch off the engine, there are relays clicking and quite a bit of machinery still running back there for maybe another 30 seconds, again quiet whinning, a final click and silence.I do not hear any whining at all when driving, slow, fast, or on idle. On idle when hot, I only hear the 'typical diesel noise' from the engine that you get as normal, other than that, nothing.SOUND INSULATION....If you find that you have to live with certain noises (assuming that there are not fault noises), then we do have to agree that the diesel engine is a bit noisier than the petrol, though it does have the fuel advantage, getting around 70 to 80 MPG, then you can cut down on the noise with sound insulation.I did this mod that only cost £30 (UK), and made a big difference. Also did a similar mod to my previous 450 petrol Fortwo.....http://clubsmartcar.com/index.php?showtopic=28132

Edited May 18, 2014 by Colsmart

[CKpt 0]

Thank you all. It seems to be quite normal then...Col, I'm already thinking about soundproofing the car, I'll give it a go once I take half of it apart to install the electric mirrors. I'm thinking on doing the door panels and the boot panels.

[Colsmart 0]

....Col, I'm already thinking about soundproofing the car, I'll give it a go once I take half of it apart to install the electric mirrors. I'm thinking on doing the door panels and the boot panels.

I always found the engine noise just behind the seats, more intrusive than road noise (be it petrol or diesel), hence my 'insulation around the engine bay' mod only.If you are concerned with road noise, it would be better to insulate the cabin from the wheel noise, ie, insulate the front bulkhead and front floor area for front wheels, and also behind the boot panels for the rear wheels.If doing the door panels, you may have to consider a thinner 'stick on sound insulation pads' type of insulation material, to avoid hitting the moving glass.Remember also this all adds weight to the car, so is it worth it to do the cabin?And with you having a convertible, is doing a lot of cabin insulation a waste of time, if you have your roof off a lot?Anyway, all the best with your insulation mods