Technical Engine noise at 2000 rpm

[ee00ffk]

Noticed over the last few days a light smell of exhaust in the cabin (cant smell it, when im just circulating cabin air).

I'm sure its all related, when my car hits 2000 rpm I hear this whizzing sound, stops around 2500. Then comes back again as i shift gears and it hits 2000rpm again.

Then earlier today, i see the EML come on. Called RAC as i don't have a diagnostic reader - came out with a fault code of P0101.

Looking in the threads, appears to be a MAF issue, although wondering if this causing the whizzing sound i hear at 2000rpm..

I was thinking, replace MAF and clean (or replace) EGR, maybe even add blanking plate.

any ideas where i can pruchase the above two - goggling keeps getting me eBay results.


wondering if anyone has any pointers before i go ahead on the above.

Fiat 500 Sport - 1.3 Multijet Diesel..

 

[alexGS]

I believe a MAF fault code is registered when the measured airflow doesn't correspond to the estimated airflow (calculated by the ECU from engine speed, boost pressure, and accelerator pedal position). One reason for the discrepancy could be an airflow leak, perhaps from the turbo pipe or (if an intercooler is fitted) the intercooler pipes. The MAF has 'seen' the air come in, but there is less boost pressure than expected by the engine ECU, yet the boost pressure is varying under ECU control, so the ECU doesn't register other faults with EGR or waste gate control - instead it suspects the MAF.

This would tally with the whizzing sound you hear, which is probably the turbocharger pressure leaking away. And of course, the exhaust smell. If the pipe is really split or hanging off, there will be an amazing gurgling noise (or perhaps not THAT amazing, as the MultiJet's turbo is very small!)

I would not replace the MAF yet, as a faulty MAF will not cause unusual sounds or smells.

I think you are right to clean the EGR - always a good idea - though a problem there will usually trigger an EGR fault code. I would consider performing a DPF regen - has there been any history of problems with the DPF?

As always, I have to recommend MultiECUScan and ELM327 cable if you are going to go further with fixing it yourself - it will be money well spent in the big scheme of things.

Obviously this advice is fairly general in nature as I have not had that exact fault you have with a 500 MultiJet - but hopefully it will prove fruitful to check and tighten the air intake pipe connections (the larger, 'boost' pipes, I mean). Due to the fault code, you'll be looking downstream of the MAF. Sometimes, slight oil leakage (deposits of oily dirt) will lead you to the culprit.

It's always possible that it is actually a much more serious fault with the turbo itself, but it always pays to check the straightforward and cheap possibilities first. A loose pipe is an easy fix.

Best of luck

-Alex

 

[ee00ffk]

Hi Alex,

Thanks for the reply. I'm gonna remove the cover off the top of the engine hopefully later today and have a look at the pipes and see if there is anything loose or hanging. Cant say I've heard gurgling sound though.

Picked up an aftermarket EGR from EuroCP, incase the one i pull out is shot... will let you know how i get on... im hoping its that.. No issues with DPF. The car does a round trip of 40 miles everyday dual carriage and motorway..

any ideas on where i can get a decent ELM327 cable? there seems to be a wide selection on ebay from cheap to expensive, any brands you'd recommend?

 

[alexGS]

I don't have any particular 'brand' to recommend - few products of this type have proper brands anyway - the Chinese factories can put on any brand you request

I bought one with an orange and blue sticker. I found it worked OK for engine and gearbox ECUs, but couldn't connect to body computers. The solution was to remove a resistor from the circuit board, as explained at MultiECUScan.net under "Faulty ELM327 interfaces demystified" (I think that was the title).

There is one supplier that I do recommend - gendan.co.uk - I bought their set of coloured adapters (red, green, yellow) and have found them very useful. Purple is included now too; but that is for certain Alfa Spider convertible top ECUs which are a rare encounter. For the 500, you mainly need the yellow adapter. Gendan sell the ELM327 interfaces, too.

-Alex