Nemo 1.4Hdi Undiagnosable Engine Problem - This Group is my final hope.

[Exgreenie]

Three garages have tried and failed to identify the problem - others are now finding excuses not to even try..

In short - there's random power fluctuation and response to the accelerator pedal plus random surges to ~3000 revs at tick-over. Diagnostics not showing any relevant problems..

The long story started almost a year ago.
After months of covid-caused very short trips (a couple of miles at most) only, we set off to go further, last December. At about 8 miles, the engine became intermittently slow to respond and lacked power. At lights, etc, the steady tickover periodically surged momentarily then dropped back. We pressed on and, at about 15 miles - everything became normal again and remained that for the whole trip (~150 miles) and back. Took it to our usual Citroen specialist garage - they put it on diagnostics, cleared some not-relevant entries but could find no fault. A couple of months of <2 mile journeys later, we set off on a longer trip. Guess what? Exactly the same again.

So, this time, after getting back with everything apparently fine, I took a longer trip every month. On the second one - it started misbehaving again. I booked it into the garage but, in the meanwhile, tried pouring a bottle of Redex diesel treatment into the tank. About a week later - everything seemed to have fixed itself and it drove beautifully. The garage gave the car the normal short service that was due and, again, didn't find any relevant entries.

A few weeks later of short trips - it played up immediately. Wouldn't go away, even after a 6 hour drive. Even after adding another bottle of Redex. Off to a different Citroen specialist garage, as I was a long way from home.

This time, they could, at least see that there was a problem. They suggested changing the fuel filter and did that - no change. So they said that they could only swap out other parts because they didn't know what was causing the problems.

I asked around and found another garage that was considered really good with common rail diesels. They had it for a couple of weeks. Took out an injector and had it tested, because it was "flat-lining". It passed as OK. They rang to ask me to collect it, as they couldn't identify the problem. They suggested a different company.

Who, when I described the above, basically gave excuses not to take it on and recommended someone else. Who made excuses...

The VIN is VF7**************[VIN obfuscated, can be read by forum staff]. Oh, yes, I have owned it from new. Had it serviced to better than the service schedule. It's done just over 100k, mostly on long motorway/dual carriageway trips ( grandchildren in Scotland, family in Cornwall and Norfolk). It's near Norwich at the moment.

Even when playing up, it's been giving almost 60mpg. I'd hate to scrap it, but that's the way it's looking. It would cost well over £150, just to get a main dealer to do diagnostics on it. I don't know whether their more comprehensive system would be worth that... it would if it identified the problem...

Any help or suggestions, much appreciated. You are my only hope...

[Dormouse]

Has anyone suggested an EGR fault? That is where i would start.

Also, have you read this article. It means that Ford specialists will be equally able to help as the 1.4 was a joint collaboration between PSA and Ford. Not that I am suggesting that the members of this forum are not more than capable, it is just that the quicker you get clues the better.

Do you have any fault codes to share?

[GiveMeABreak]

The Citroen Nemo is a Fiat Bipper Fiat Fiorino in disguise and uses mostly Fiat parts.

When Diagnosing these vehicles with the dealer-level diagnostic VCI and Diagbox software, a separate S1279 hardware module is required to read these vehicles correctly. This being the case, you may not have been getting the correct diagnostics previously. At least a dealer would have all the correct equipment and would be able to thoroughly test it.

With all due respect, a Ford dealership may not have the correct diagnostic equipment for the vehicle overall, but will end up charging similar prices and that's a waste of resources. Your issue is going to be getting the car to misbehave when at the dealership unless a fault code has been stored. In either case they should be able to check the memory for stored faults in the log.

[Dormouse]

Mark means the Peugeot Bipper. The Fiat Fiorino uses the same bodyshell and there is a mixture of engines available.

PS You need proper fault codes to help the diagnostics along. Some diagnostic equipment won't give you all the faults logged or the full codes.

[GiveMeABreak]

Yes, Peugeot Bipper Fiat Fiorino, Citroen Nemo - my bad, will correct my post above to avoid confusion, thanks Dormouse. 50 posts to catch up on tonight...

[Dormouse]

No probs. Proper fault codes are what is needed here to start the ball rolling in the right direction. Everything else is guesswork - albeit educated occasionally.

[Exgreenie]

Sorry if I didn't make myself clear - but three garages (two of them Citroen specialists) have said that there have been no relevant fault codes. I don't know what diagnostic kit that they have.
I'm reading from the above (and thanks, guys, for the helpful replies), that I really need to bite the bullet and take it to a main dealer, to have diagnostics done there.
Edit: would an egr problem cause those sudden brief increases in revs from tickover to around 3000 revs? The engine would be ticking over quite happily (apparently), feet clear of all the pedals and then just do a sudden rev up and then back down again.
Also, by sluggish to respond to the accelerator - like remaining on tickover for several seconds, as if the pedal hadn't been pressed at all. And then respond.

I can see that problems with an egr could result in lower power output. But I can't see how it could cause those power increase above idle blips. Or how Redex would help once but not twice...
Life was so much simpler with a Ford 100E....
But thanks again for taking the time to think about this and suggest things.

[Jay-Bruce]

I found Nemo!!

The forum's grownups will disavow you if you run any pollution control circumvention devices long term, but for the purposes of diagnosis, get a mechanic to install an EGR blank. Basically the Exhaust Gas Recirculation system is an emissions thing whereby under certain conditions the cars Electronic Control Unit will allow the engine to breath in some exhaust gas to burn the soot rather than straight air and fuel. This is done by means of an electronically controlled valve, I'm wondering if your valve is sticking open, choking the engine. I'm proposing you get a mechanic to blank off the exhaust gas to EGR valve pipework somewhere to see how the car runs.

I'd like to reiterate that the forum, rather than me personally, has a hard policy against supporting vehicles with pollution control systems inhibited.

If we eliminate the EGR system by blocking the exhaust gas, we can focus on other issues and reinstate the system when all is well. If blocking the exhaust gas to EGR valve pipe provides a miraculous cure, you need to get the EGR valve replaced.

[xantia_v6]

A random possibly is a blocked fuel tank breather which is causing a vacuum in the tank and fuel starvation on longer runs? Particularly if it happens when the tank is full.

[MattBLancs]

The random revving up it's self is curious - cannot think why EGR would cause that.

But I agree with Jay, try blanking the EGR in the short term to see if that's where to focus your efforts.

It's worth remembering that fault codes are only logged if a value reported by a sensor is sooo extreme as for the engine ECU to spot this is beyond what it would expect to see and so flags up as a fault. So in your case it would seem the poor running isn't down to a single sensor failing.

I think EGR clogging up is in with a good chance of being the issue, despite a relatively pampered life (serviced ahead if schedule etc) there's not much you can do to prevent it slowly filling itself and the intake with crud.

Matt

P.s. missed last post:
It it worth a run with the filler cap loose to eliminate the vacuum suggestion?

[Dormouse]

Sorry if I didn't make myself clear - but three garages (two of them Citroen specialists) have said that there have been no relevant fault codes. I don't know what diagnostic kit that they have.
I'm reading from the above (and thanks, guys, for the helpful replies), that I really need to bite the bullet and take it to a main dealer, to have diagnostics done there.
Edit: would an egr problem cause those sudden brief increases in revs from tickover to around 3000 revs? The engine would be ticking over quite happily (apparently), feet clear of all the pedals and then just do a sudden rev up and then back down again.
Also, by sluggish to respond to the accelerator - like remaining on tickover for several seconds, as if the pedal hadn't been pressed at all. And then respond.

I can see that problems with an egr could result in lower power output. But I can't see how it could cause those power increase above idle blips. Or how Redex would help once but not twice...
Life was so much simpler with a Ford 100E....
But thanks again for taking the time to think about this and suggest things.

There may be no need to go to a main dealer. Look up the list of members near you with Lexia and then contact them to see if they will give you a short session to read the codes - members will not normally offer any repairs or guarantees as they they are volunteering use of their Lexia readers to help fellow members.

[myglaren]

^ That may not work too well as the Nemo is largely a Fiat. Some members may have the adapter of course.

Lexia list is here though.
Map link at the end.

[Dormouse]

Sorry if I didn't make myself clear - but three garages (two of them Citroen specialists) have said that there have been no relevant fault codes. I don't know what diagnostic kit that they have.
I'm reading from the above (and thanks, guys, for the helpful replies), that I really need to bite the bullet and take it to a main dealer, to have diagnostics done there.
Edit: would an egr problem cause those sudden brief increases in revs from tickover to around 3000 revs? The engine would be ticking over quite happily (apparently), feet clear of all the pedals and then just do a sudden rev up and then back down again.
Also, by sluggish to respond to the accelerator - like remaining on tickover for several seconds, as if the pedal hadn't been pressed at all. And then respond.

I can see that problems with an egr could result in lower power output. But I can't see how it could cause those power increase above idle blips. Or how Redex would help once but not twice...
Life was so much simpler with a Ford 100E....
But thanks again for taking the time to think about this and suggest things.

As I remember it, 100E's were a pain the bum in the rain with their vacuum wiper motors.

EGR's can be a similar pain insomuch as they are not totally reliable once they start to malfunction and the symptoms can be inconsistent or masking something else. Sometimes they will clean up a bit but still act erratically. There are lots of blogs online about EGR's. Some good, some not. Getting any of the full fault codes will help.

[Dormouse]

A random possibly is a blocked fuel tank breather which is causing a vacuum in the tank and fuel starvation on longer runs? Particularly if it happens when the tank is full.

Interesting as one of the codes found was for the fuel system. But it has not been repeatable so far.

You could have swung a couple of cats in the space under the bonnet of a 100E and counted the number of parts on your fingers. Ain't like that now. There are scores of parts now with a bus connection to monitor them. Or not, as sometimes occurs.

[Jay-Bruce]

I always feel robbed when threads die like this, particularly ones where the forum doesn't have a definitive slam dunk diagnosis, and we need a bit more info to definitively conclude what the fault is/was. I get a certain amount of satisfaction and or closure from seeing the "thanks folks, the problem was XYZ, fixed that and the car's now running great" conclusions, but the OP's disappeared after two posts, likely never to be heard from again, so we're unlikely to get that here.