Technical Multijet diesel sluggish after starting, revs limited, repeated ECU fault? Try this.

[mattbacon]

If your Multijet Panda starts OK but goes into limp mode a few hundred yards down the road, recovers after a few minutes, and occasionally throws ECU fault lights, take a good look at your air filter. Here's why...

We have recently acquired a 2005 Panda with the 1.3 multi jet diesel. Lovely little car, most of the time except...

About one time in three, on a cold, damp morning, the car would start up fine, rev happily in the drive, and then about 30s to a minute into the journey suddenly lose all power. I'd then sit at the roadside out of the way, revving it or keeping my foot on the floor. To begin with, I couldn't more than 1000rpm, but over the next five minutes or so, the revs build unevenly towards 3000. At some point, after anything between a few and over five minutes, the engine "clears" with a puff of blue smoke, the revs spin up skywards, and the engine runs normally after that. Several times over the last month or so, the ECU light has come on after one of these episodes. Sometimes it clears after turning the ignition off. sometimes it doesn't. Diagnostics show different faults.

We've had a new EGR unit, new MAF sensor and new turbo boost sensor in response to the fault codes. And it was still doing the same thing.

Anyway, having seen pages of threads about similar behaviour, I phoned a nearby FIAT main dealer (in Cleckheaton) to ask if they'd had any kind of service bulletin, about this behaviour. The service manager said no, but he'd talk to his technicians and ask. Within ten minutes, he'd called me back, and told me that one of his team had had exactly the same fault in his sister's car, and couldn't get it running. After bringing it back from Birmingham to Cleckheaton, this guy had changed the air filter and MAF unit. Since we had had a new MAF fitted, I decided to look at the air filter.

EUREKA!

For about two thirds of its length, the air filter was absolutely sodden. It dripped as I lifted it out, and I could squeeze water out like wringing a sponge.

I can only think that once the engine start sucking air as it started pulling under load, that water was being pulled into the MAF and other sensors, triggering weird sensor readings, limp mode and occasional ECU faults. After a while, all the water that could be pulled from the filter had been, the sensor readings returned to normal, and the engine would rev freely again.

So, water going into the engine with the air can't be good. How does it get there?

If you look at the centre of the "gutter" below the windscreen, you can see that the rubber seal goes about half way across from the left. About where it ends is one screw, which goes through the firewall at the back of the engine compartment. It's the only thing that does go through the firewall -- the other nearby fixings terminate on the back of it. On the engine bay side is a plastic block which it screws into. I guess it's meant to be watertight. But mine wasn't.

Any water coming off the windscreen and gathering around this screw goes through into the engine bay and drips very precisely onto the joint of the air filter box. The air filter has a spongy rubber seal which sits in a gutter around the filter box on the bottom part, and the lid comes down on top of it to trap the sponge and make a seal. This spongy seal "wicks" all the water that falls onto the gutter into the filter, where slowly it soaks all of the paper "leaves" of the filter. The drain holes in the bottom of the air filter box are useless, because the water is absorbed by the filter before it ever get to run out of the bottom.

So what have I done?
1) Changed the soaking air filter for a clean, dry one.
2) Applied silicone sealant all around the screw, on both side of the firewall.
3) Cut a section of heavy aluminium disposable roasting tin to make a -\ section from the base and one side, and taped the base to the top of the air filter box so that the angled side sits over then rear join with its tabs and sockets, under the dripping screw, so any water that still comes through can't reach the joint, and drips down behind the filter box.

If this doesn't work, I'll be cross! It can't be right to have a dripping air filter, and the engine is clearly misbehaving while the filter is wet, so logic suggests the filter must be at least contributing to the problem...

Good luck!

bestest,
M.

 

[Most Easterly Pandas]

Very common issue of late, check the top of the air filter housing under the scuttle, there is a screw that works its way through the plastic air filter housing due to how tight it is in there, that normally wears a hole into is and then allows rain water to enter.

A very simple and easy fix, seal the hole with silicon sealer

A quick search on here and you'll get quite a few results about it

 

[Wee Smurf]

I've been telling everyone to do exactly that for a couple of years now.

 

[thetobby]

Any chance anyone you could post a picture of where this screw is located?

 

[Most Easterly Pandas]

Any chance anyone you could post a picture of where this screw is located?

As above, a quick search will bring you information over load

https://www.fiatforum.com/search.php

 

[blod65]

https://www.fiatforum.com/panda/152968-multijet-loss-power-after-cold-start-9.html

 

[mattbacon]

Well, it's good to know the problem's already solved. I'm not claiming it's original, but I Googled various symptoms which led to threads on here, which eventually pointed me in the right direction (toward the screw), but in my specific case, there's no hole in the air filter box. There are also a lot of threads about ECU lights showing for MAF sensor and EGR issues which make no mention of the water being sucked in. I was just trying to get all the words that I originally tried Googling to find this place into one post which described the symptoms I had and the cure, in case it helped anybody else... I probably didn't need to buy a new EGR valve, MAF sensor or turbo boost sensor, and maybe other people might not have to...

bestest,
M.

 

[Prontissimo]

There's more to it than that I'm afraid. It's mostly down to poor maintenance and idiot unsupervised service mechanics. On older cars the scuttle drains (two of them , moulded plastic inserts deep under windscreen in middle of car with very small/thin slits ) get blocked with dust/grit/leaves etc and allow the WHOLE under windscreen scuttle to fill with around 7 litres of water . When you brake ( particularly if you're at the bottom of a steep hill) a tsunami of water gushes over the air cleaner. Check my thread "bad air cleaner water ingress" . Unfortunately bad maintenance also allows the air cleaner to be assembled incorrectly so that the centre back tongue doesn't engage with it's socket . This allows the air cleaner box to distort/bow at the back so it doesn't seal properly. Another bad maintenance issue is over tightened front screws( x3) . When they strip the front seal on the air cleaner doesn't seal well and that's where the very low pressure sucking action of the turbo can encourage any water to be sucked directly into the turbo/engine/intercooler. My thread explains how to fix the problems . Theres nothing wrong with the air filter gasket ......it doesn't wick because it's closed cell foam . The issue is bad maintenance, distorted air cleaner box, and stripped threads. DONT WHATEVER YOU DO FIT A CONE FILTER INSTEAD! The air cleaner box is also designed as an umbrella to keep moisture/water from the injectors etc on top if the engine. If you remove the umbrella you're looking at corroded in injectors and compromised electrical connections. If you do the mods as outlined in my thread ......and in particular clean out the drains in the under windscreen scuttle area you shouldn't have a problem. The air cleaner and ducting is all tuned to suit the engine.....don't modify it.

 

[Sweetsixteen]

Interesting thread. I scrapped my Fiat awful air cleaner box entirely and fitted a cone filter straight onto the Maf. That was many thousands of miles ago and I've got better mileage and performance ever since with no side issues.

With the greatest respect to anyone who preaches differently, a lot of nonsense is talked about the scientific design of the air routing in the standard air box, and how necessary it is for correct performance - but much of this is unproven hogwash. Ask the tuning boys who regularly chuck the standard restrictive box for something better.

I've also got rid of the EGR electronically - without a blanking plate - and the whole vehicle is far more lively as a result, without throwing up any fault codes.

 

[Prontissimo]

I guess there may be positives and negatives which ever route one chooses over the air cleaner issue. My car's an incredibly nippy and torquey .......and economical device ......with the standard (properly configured) air cleaner. The multijet 1.3 is a VERY sophisticated engine......double overhead cam with 16 valves with lots of highly sophisticated electronic control and management systems in place. It's close to a sophisticated racing engine in its potential but by and large is investigated/serviced/maintained by pretty poor mechanics who look after them . They look at fault codes etc but have no real intimate understanding of the vehicles they are looking after. You get much more intelligent info about vehicles and their faults from sites like this because owners take the trouble to figure things out. You mention electronically disconnecting the EGR....how is that done ?

 

[Sweetsixteen]

You get much more intelligent info about vehicles and their faults from sites like this because owners take the trouble to figure things out. You mention electronically disconnecting the EGR....how is that done ?

Yep - this is a good forum, because there are loads of 'hands-on' types who pool their knowledge.

With my 1.3Multi I have inserted a 'shunt' between the MAF wiring and the EGR. It fools the ECU into thinking that the EGR is working - but I have disconnected the EGR so it stays shut. Quicker car, cleaner engine and improved economy. It cost peanuts to make.



The original idea wasn't mine, but I have modified it to suit this engine. Much easier than messing with blanking plates - have you tried to get to the EGR on the Multijet?

 

[ytareh]

More info how to please ? All MJs have an EGR including my early 2005 , right ? It's the DPF is only in some .

 

[Prontissimo]

Yep.....more info please. Are there any MOT emissions issues? Looks like a cool and simple mod.

 

[Prontissimo]

I've been reading about the EGR concept on the web. It's an incredible and complex bit of nonsense all designed to reduce NOX emissions. By diluting incoming air with exhaust the combustion temp is lowered and with it NOX emissions too.......but particulates go up and economy and power drops . Because the particulates go up they have to fit a particulate filter!!!!! And not only that, carbon particles ,of course , get into the inlet tract and combustion chamber causing more upper cylinder wear and dirtying up inlet tract and inlet valves , oil, etc.......turbo ducting and intercooler too ! It's a barmy bit of complexity . I wonder what alternative simpler technologies are being developed as an alternative to EGR?

 

[Sweetsixteen]

I wonder what alternative simpler technologies are being developed as an alternative to EGR?

VVT engines are designed so that inlet and exhaust overlaps on a variable basis, governed by the ECU, and this bit of wizardry allows a certain amount of exhaust gas 'recirculation' within the combustion chamber.
In theory, this does away with the need for a separate EGR. So the technology is already here.
Still makes for dirty combustion though.

 

[Sweetsixteen]

Yep.....more info please. Are there any MOT emissions issues? Looks like a cool and simple mod.

Just posted new thread - EGR DELETE ... THE EASY WAY

Hope that helps.

 

[Prontissimo]

Thought the overlap was to allow the velocity of the slug of exhausting charge to help draw in the incoming charge and to effectively purge the combustion chamber of exhaust as well as effectively sort of supercharging the cylinder filling ? I can imagine VVT might make an exhaust valve close early to stop "overlap" and trap some exhaust in combustion chamber and create EGR .......recycling! Anybody know about the science?