Car bother

Or the timing belt! They had a habit of snapping at the best of times.

A perfect illustration of the importance of live data over fault codes.

 

I'm told that mine has a timing chain rather than a belt. So I shouldn't need to worry about that.

Oil was flushed and changed about 6 months ago, when the turbo was replaced. At that time they also steam cleaned the entire induction side. There was concerned (raised by the mechanic) that the oil vomit from the turbo failure could snot up the egr, as well as the O2 sensor, but he said I'd know within days if that happened.

It did a couple of misfires today, but for the most part, it runs like new.

 

Car is in the garage. Not because of the engine woes, just routine. It's getting a suspension bit done that has simply worn.

I did get the codes read while it's there. Mechanic said a number of codes were logged, and in his experience (he is an exceptional mechanic, his experience counts for a lot with engine matters), they all point to excess carbon build up. Ie no components have actually failed, it's just "full of snot".

He recommended 'terraclean'. But it's expensive. He said £200 plus vat. A web search seems to suggest that's above the going rate. He did say that a good fuel treatment will help a bit, for a while, but would not be a long term solution.

My thoughts is that in this weather, my car is never reaching normal operating temp. The temp gauge never gets past about quarter the way across, whereas in summer it sits smack bang in the middle. This gets me thinking it can not burn at max efficiency, so it will snot up again fairly quickly at this time of year.

The mechanic thinks it is unlikely to just drop dead. Most likely just reduced performance. I can live with that for now.

Any thoughts? I could bite the bullet and have this terraclean process done sooner rather than later, or I could buy some Forte turbo diesel treatment and give it a good ragging.

One thing that worries me a bit with the terraclean option is, what if it's only carbon deposits that's sealing ageing joints in the manifolds etc.

 

That's the least of my worries - I've had diesel cars bend valves when bits of crud in the inlet manifold dislodge and get stuck under the valve seats. Now I'm not saying that it will happen but I am saying that it is possible. However, the Terraclean injector clean service is safe enough as it deals with the fuel side but will not clean the carbon build up in the inlet/EGR.
Just one thing, carbon build up is not really intermittent. Having said that he has seen the car, I haven't. Did it play up whilst he was looking at the live data?

 

The mechanic said it cleans the inlet side including the egr.

He didn't do much being reading and interpreting the codes because thats all I asked him to do today. The primary job was to replace a worn lower arm.

Mechanic said to use a good fuel treatment and give her a good thrashing for now. He also asked me questions about my driving style and then gave me a polite telling off when I said I always drive in the highest gear I can get away with. In my car, in top gear at 60mph, she only revs at 2000rpm. Apparently with a modern diesel you have to use the rev range occasionally.

Codes were:
Intake air temperature, faulty signal.

Air mass sensor, incorrect function.

Fuel system pressure, incorrect pressure.

Glow plugs, glow plug failure.

The last one I believe, because it once felt like it had started on 3 cylinders and then the fourth fired up when I revved it.

First two remind me of my first Volvo that always reported a failed MAF sensor until I fixed an ignition fault. If the o2 signal massively contradicts the MAF, then the MAF gets blamed when it's actually done it's job right, but the burn was inefficient for other reasons, leading to more oxygen in the exhaust than there should have been.

The EGR one is in my opinion probably key. As I understand it, a misbehaving EGR will seriously mess with the mix.

I have no idea about the fuel pressure one.

 

Depending on the set up the air mass meter frequently houses the intake air temp sensor too.

Perished fuel hose allowing air into the system. Faulty sender. Failing pump. Failing injector.

Easily diagnosed with a multi-meter.

That is easily clarified by checking the hydrocarbons.

You had and EGR fault code as well? What was that?

This one is the most likely cause of the intermittent issue you have. A choked inlet will not cause intermittent misfires, an airmass fault could be intermittent but would not produce a misfire.

Get the codes reread after it has messed about again. As with all faults check the wiring using voltage drop tests if possible before you start chucking money at parts.

 

That is the one that I would not like to use. The fuel system clean is good, better than Forte (from the two times that we used the local agent) but bear in mind that the laquering of injectors can mask wear issues. Cleaning to such a high level can expose wear issues.

 

Sorry, I thought I'd typed the egr one. Must have just thought it instead.

It said EGR, incorrect operation.

 

Ok, EGR and air mass faults usually tie in together - could be either. Is the EGR electrically operated or vacuum operated?

 

If I get another year out of this car, I'll be happy. I don't envisage keeping it much longer than that so I'm reluctant to spend more money on it than I really need to.

I think after reading the codes, the garage reset everything, because she drives like new. The mechanic did say he thought it would play up again though if left untreated, but recommended I choose a reputable fuel additive/treatment for now if I don't go for the terraclean.

Car starts every time (so far), so I'm reluctant to spend more dosh just now.

 

Then my gut feeling is that the MAF will also be VDO. Probably 5 wire meaning that the air temp sender is part of it. As the code was not "EGR circuit A" or similar it kinda points to a MAF fault (ie it has deduced an EGR fault based on the lack of change in the MAF reading). Not gospel but an educated guess without the car. Remove the EGR and check for blockage to rule that side of it out first though.