Seeking advice about potential car problems

[dvdlcs]

Hello.

 

I'm looking for some advice from the collective knowledge base about some problems that I am having with my car. I'm in Australia so will be mentioning kilometres and summer weather at this time of year.

 

The vehicle is a 2005 Nissan Pulsar (named Almera in Europe) that I bought in 2008 and has been a flawless performer until recently. It has an automatic gearbox.

 

Sometime in November or December last year there was a change in behaviour. Nothing dramatic, more subtle in an "I don't remember it doing that before" fashion from someone who has been driving it for a decade. Difficult to describe, but it seemed to become a little hesitant at times and possibly down on power, particularly on hot days. I did wonder if this was happening simply because the weather was warming up rather than any specific problem with the car.

 

I went to a number of places, starting with the Nissan Service Centre, but all they seemed to do was connect their diagnostics machine to the car and tell me that there was nothing wrong with it. One even told me that because the diagnostics had not shown any problems they didn't want to do any work on the car as I could/would end up paying for something that didn't need to be done. Which I suppose was refreshingly honest in a sense.

 

Last time I had the car 'diagnosed' as healthy was on New Years Eve.

 

On 5th of January I was driving on a dual carriageway at 80kph (50mph) when there was a sudden lurch as if the car had lost power for a few seconds before it recovered and the engine management light had come on. Hazards on, pull off the road and park in a place of safety. Consult the handbook to see what the implications of the warning light was.

 

Turns out I could drive the car, but at no more than 70kph, and proceed directly to your nearest Nissan dealer. That turned out to be a bit of an adventure as at seemingly random times the car would appear to drop out of gear (revs went high, loss of drive) for a second or two before re-engaging.

 

The Nissan Service Centre diagnosed the problem as the camshaft and crankshaft sensors having failed. These were replaced, although nobody could really tell me why they failed, and the car returned.

 

Since then I have been wondering if the sensor failures were an effect of a problem rather than the cause. Perhaps I am being hyper-sensitive, the thought of being stranded in the Australian summer doesn't appeal, but I am feeling every slight 'thing' that happens as I am driving.

 

Something in particular that I have noticed is that while the car starts off normally, later on in the journey once things have warmed up, or sooner on a hot day, there are noticeable changes in behaviour.

At the beginning of the journey, the idle speed when sitting at traffic lights, in a queue etc., is around 750rpm, which is what I would expect. However, as the journey progresses (and/or the day warms up) I notice that this speed is decreasing to around 600rpm and in at least one instance was only just above 500rpm, at which point I could feel the car shuddering as if it is thinking about stalling, though admittedly it never has.

I've mentioned this previously to the various car maintenance people that I've spoken to and have asked if the idle speed can be reset (this has been done at least once at service in the time I've had the car) but I keep getting the "diagnostics says there is nothing wrong" response.

 

This is definitely a change in behaviour and although the data seemingly says that there is nothing wrong, the gut is saying different.

 

I'm wondering what I need to do or say to these people in order for them to proceed past the diagnostics box results and actually look at something. Perhaps there is a "nuts and bolts" problem going on that an old-fashioned mechanic could diagnose and hopefully fix.

 

Has anyone had a similar experience or able to offer advice on how to proceed?

 

Or instead of spending my Saturdays running around garages looking for a fix, should I be going to a car yard on the basis that if I point at something on Saturday and say "I'll take that" I could possibly be driving something else in a weeks' time and the problem be resolved that way.

 

It isn't a new car, and hasn't been for some time, but it has been a faultless servant until now. Mileage is just past 160K km (100K miles), of which I've done 120K km. The car has been looked after (serviced every six months by Nissan and driven nicely) and is a known quantity so I'm reluctant to change it possibly for the sake of a simple fix, if only someone could be persuaded to look beyond the diagnostics for the problem.

 

Thank you for any forthcoming response.

Edited January 23, 2019 by dvdlcs

[Robert]

I am not an expert, so I'll refrain from commenting on what I think it might be.  However, I have found this to be a problem with all the diagnostic equipment in modern cars.  It often means that mechanics will no longer rely on their instincts and/or experience to find a problem.  Computer says yes, so there isn't a problem!

 

Having said that, sensors do fail - particuarly the crankshaft sensors because they are in quite a hostile environment.  They are low down on the engine (obviously) and are subjected to quite severe heating and cooling cycles.  I had one go on my Vectra a few years ago.  However, they also diagnosed a problem with the camshaft sensor, and that turned out not to be the sensor, but because the garage had "forgotten" to renew the cam belt tension roller at the previous service.  Thankfully, the sensor caught the problem before the belt broke.

 

I can understand your concern about the Australian Summer though.  In a more temperate climate, I might be inclined to say wait and see what happens - because I know from experience that these sort of incidents tend to make one over sensitive ("Did that always feel like that?") but on the other hand, you really don't want to be stuck somewhere in 50° heat!  It's a tricky one - hopefully someone more experienced in automotive engineering will be along soon!

[dvdlcs]

Thank you for the response.

 

I've also fixed the mess that was post #1. I made two mistakes:

 

1. I wrote the text in Word and copy-pasted into the box. Normally I'll copy-paste from Word to a plain text editor to remove all the extra guff and then copy-paste from the text editor to the box. I didn't this time.

 

2. I posted from work. There the internet is behind a filter so some things work and some things don't. Unfortunately the editor didn't so after the post lost the line breaks (they were present in the preview) I couldn't fix the resultant mess.

[Tony_S]

We had a similar problem with our Renault Clio. The main symptom was a a very high tick over speed. We took it to a local garage and their diagnostic returned an unknown code engine management system fault. Disconnecting the battery for a few minutes seemed to clear the fault and when it returned every few months, disconnecting the battery cleared. It otherwise didn’t cut out or lose power though.Renault dealer said the replacement part was more than the car was worth. My wife put up with this but when the air con also failed she replaced the car. It had done well over 100000 miles so can’t complain.

Intermittent faults are very unsettling. Hope you get it sorted

[Nick Holliday]

Not any help, but I have had a vaguely similar experience with a VW Passat diesel that I've had from new. Right from the start, tick over was variable, often dropping to such low revs it felt like it would stop, but never quite doing so, and at speed there would be slight power loss on random occasions. Never bad enough to feel it needed urgent attention, nothing coming up on the dashboard display, and at each service, the computer diagnostics revealed nothing. Recently, however, the engine suddenly died whilst driving, mercifully at low speed, with the dashboard proclaiming doom and gloom. It restarted, fortunately, and a subsequent trip to the garage revealed that two of the four injectors had failed, or were close to doing so, and they were replaced. Since then, tick over has been much smoother, and the lumpiness on the move seems to have disappeared, and fuel consumption has noticeably improved. I am convinced that the injectors must not have been working properly since new, but not badly enough for the dreaded computer to register the problem until now, nine years on. I can't prove anything, but this seems to have been a case of a latent defect in manufacture eventually leading to failure.

[Titan]

Change the transmission oil and filter (if it has one). Old and/or dirty oil can cause the gearbox to misbehave, which could affect the engine behaviour., If it doesn't fix it you have not wasted much. Make sure that the correct oil for your transmission is used.

Edited January 23, 2019 by Titan

[DIW]

^^^ Yes, what Titan said.

 

You seem to have described a momentary drop out of transmission. Given the generally warmer climate enjoyed in Australia, plus the particularly warm summer currently being endured, your automatic box's transmission oil has had a rough time of it, and may well be giving up (viscosity-wise). That will certainly contribute to your symptoms! Whether the car's diagnostics can accurately inform of such event depends greatly on how well thought out is the reporting system for that model. If 'transmission oil viscosity warning' isn't among the listed reportable symptoms, then the likely result is that the unloading-reloading of the engine by the transmission will trigger some sensor(s) on the engine and thus cause the warning light to illuminate.

[kevinlms]

Ignition coils?

 

https://forums.whirlpool.net.au/archive/2523640

[dvdlcs]

Thank you for the various responses.

 

No burning smell, I am pleased to report.

 

A colleague who professes to know about cars offered to take a look yesterday. His thought was that there may be a leak in the vacuum system and that is why the idle speed varies. He also made the suggestion that I take it to a tuning shop and have them put it on a dyno - this would test the engine throughout the gears and speed ranges and would (should) show up any defects in the mechanicals. He apparently did that with a vehicle he owned in order to get to the bottom of a mystery glitch.

[billy_anorak59]

Hope you don’t mind me jumping on this thread, but I couldn’t find anything else more suitable.

Perhaps someone could give me some guidance? Yesterday, whilst driving home, I came to a traffic calming ‘chicane’ :- This one:

 

 

(I drive through it at least once a day). Speed: about 15-20mph, absolutely nothing in front, nearest vehicle about 400yds behind. Just on the final approach to it – ‘Bong! Bong! Bong! -  and a large red triangle plus exclamation mark and ‘pre-sense’ appears on the dash.

 

Now I have had this from time to time before, (just a single ‘Bong’) but the difference this time was that the car really slapped on the brakes and took me to a virtual stop within a few yards, and all with no input from me. It scared the life out of me – if there had been a car right behind, there is no question I would have been tail-ended. I seems that the ‘pre-sense’ system had detected the traffic chicane as dangerous.

 

The thing is, if there had have been a vehicle close behind, and they had tail-ended me – who would have been to blame? I realise the car following would have had to have not been allowing sufficient braking distance in the eyes of the law, but in this case, no-one in their right minds would have expected this? Anyone watching would have thought it an incredibly bad piece of driving, but it was the car, not me. The autonomous safety system would have ended up causing an accident rather than preventing one.

 

I’m also now a bit more nervous that the car is trying to kill me – I was lucky that I was at a low speed, but what if it decides to do a similar trick on the motorway?

 

Unfortunately, I think I’ve just had my first taste of cars of the future: i.e. Actually taking control out of the drivers’ hands…

 

I’d be interested in any opinions out there? Anyone else had a similar experience?

 

 

[ejstubbs]

59 minutes ago, billy_anorak59 said:

Yesterday, whilst driving home, I came to a traffic calming ‘chicane’...

 

Speed: about 15-20mph, absolutely nothing in front...

 

Just on the final approach to it – ‘Bong! Bong! Bong! -  and a large red triangle plus exclamation mark and ‘pre-sense’ appears on the dash....

 

seems that the ‘pre-sense’ system had detected the traffic chicane as dangerous.

 

What make and model of car do you drive?  Many modern cars can - supposedly - detect lane markings and speed limit signs.  I'm thinking perhaps it detected the "give way" markings on the road and thought you weren't going to be able to do so if required.  Or perhaps it read the speed humps sign as a hump-backed bridge?

 

As for it apparently not having happened before, perhaps it could have been down to different lighting conditions (e.g. the clocks having just gone forward => lighter evenings).

 

59 minutes ago, billy_anorak59 said:

The thing is, if there had have been a vehicle close behind, and they had tail-ended me – who would have been to blame? I realise the car following would have had to have not been allowing sufficient braking distance in the eyes of the law, but in this case, no-one in their right minds would have expected this?

 

IMO it would still have been the driver of the vehicle that was too close behind that was primarily at fault.  If it came to a court case and if the other driver (or their insurance company) could prove that you had "brake tested" them then you might be held partly liable.  In this case, though, the cars ECU logs should show that the car itself made the decision to stop in a hurry, so unless you could be shown to have tampered with the system, or failed to maintain the car properly e.g. ignored any warning lights or ECU error codes, not had it serviced according to the manufacturer's schedule or the like, then I don't think you could be held in any way culpable.  (Whether the other party would then be able to sue the manufacturer instead of you, I don't know.)

 

There are other reasons why you might come to a stop unexpectedly quickly that a following driver wouldn't necessarily be aware of.  For example, if you suddenly realised that there was potentially dangerous obstacle that couldn't been seen until you were close to it (people have been known to spread tacks or, worse, caltrops on roads that they object to being used for some reason).  I once saw the whole exhaust drop off a car that was in front of me and slide quickly to a halt in the middle of the road in front of me.  Yes, that was likely down to poor maintenance on the part of that car's owner, but if I had been following too close and my car had been damaged by hitting the ex-exhaust then I would have been (or at least felt myself to be) partly at fault for not being able to avoid their debris.  That's why the onus is always on the following driver to keep a safe distance.

 

All that said, I wouldn't be happy driving a car that had shown itself capable of doing what yours did.  I'd be inclined to take it to a dealer to be checked anyway.  And if there is a means to switch off the system that did it, I'd probably do that in the mean time.

Edited April 3, 2019 by ejstubbs

[billy_anorak59]

Thanks for the reply - all food for thought, and I appreciate you taking the time to reply.

The car is an Audi A4 - it's just over a year old.

Apparently there is a way to turn the system off, but it re-initialises when you next turn the ignition on... I have now rung up the dealers, and I've basically just been given a telephonic version of a shrug of the shoulders: -

Quote

"Mmm, it's a difficult one, and I see what your saying, but the car was behaving 'as designed' "

 

[ejstubbs]

Quote

 the car was behaving 'as designed'

 

Surely an Audi would be programmed to accelerate, so as to deter any other driver who might be impertinent enough to try to assert their right of way?

 

(Sorry.  I know not all Audi drivers are like that, and I'm sure you aren't.  I just couldn't resist.  Consider me as having issued a written warning to myself to play nicer in future.)

 

On a possibly more helpful note: if you join one of the Audi online forums then you might be able to find someone local to you who has a VCDS (the VAG group's diagnostic tool) and could check whether the car is showing any error codes.  I doubt the dealer can do that over the phone (though these days, what with connected cars and all that jazz, who knows?)

 

You can even buy a pretty cheap device that you plug in to the car's ODBII port that will display error codes and even allow you to clear (some) of them - e.g. this one.  Or a mobile phone app like Carista or Torque Pro can also do the job, given a bluetooth or wifi ODBII dongle.

Edited April 3, 2019 by ejstubbs

[billy_anorak59]

 

Ho-ho - you're yellow-carded. As soon as I typed in Audi, I knew something like that would be coming my way. I'm not a stereotype though, honest! (I use indicators and everything!)

 

[mark axlecounter]

I was a mechanic at a main dealer (10 years ago ) before I joined the railway so I can advise on why the diagnostic or the tech didn’t pick up the fault before. 

When the sensors communicate to the ecu they all have to work together. 

Right that is how the modern car runs but when a sensor is failing but still works to a fashion the ecu needs to have the fault for more than 6 seconds at a time before the ecu puts the eml   (engine management light) on if it fails for less than 6 seconds the ecu won’t identify there is a fault and thinks everything is ok. The ecu doesn’t feel the car how you do because you are a human and we have this ability to feel that something is not right. 

 

Mark

[Corbs]

On 23/01/2019 at 01:40, dvdlcs said:

Hello.

 

I'm looking for some advice from the collective knowledge base about some problems that I am having with my car. I'm in Australia so will be mentioning kilometres and summer weather at this time of year.

 

The vehicle is a 2005 Nissan Pulsar (named Almera in Europe) that I bought in 2008 and has been a flawless performer until recently. It has an automatic gearbox.

 

 

What engine? The QG15DE (1.5l) in the N16 Almera had a really bad problem with stretched timing chains.

[Derekl]

If the car is a year old is it not still in warranty? (Assuming VAG are 3 years as their competition). If so, surely you could be a little more assertive in requiring the dealer to find out if something is wrong.

[billy_anorak59]

Yes - vehicle is still in warranty, and the dealer did say "bring it in if you want to, but it's almost certain we won't find anything". So you can see where that's going.

I can be assertive when I want to, but I just get the feeling that this one would lead round and round in circles, and still not get me anywhere except inconvenience.

I guess I'll keep a watching brief on this, but if it happens again, I'll kick up a right stink.

Service coming up, I will get them to check then - many thanks for the observations on this.

[mark axlecounter]

Intermittent faults are a nightmare to find. 

If the ecu has no fault codes it could be mechanical or electrical but the way you are describing the fault it could be cam sensor what is faulty or it could be egr valve sticking. Without the car in front of me I don’t know. Get a Holden  Commodore  Or as we know them as VXR8. 

[Reorte]

1 hour ago, mark axlecounter said:

The ecu doesn’t feel the car how you do because you are a human and we have this ability to feel that something is not right.

 

That's an important part of it. If something doesn't feel right then it probably isn't. Most of us may not be great at putting our fingers on exactly what feels wrong but our subconsciousnesses are very good at recognising slight differences to what we're used to. It may not help the diagnosis of the problem but if something feels off it's a good sign that it's worth getting things checked out.

[friscopete]

I had a problem when I bought a used 2002  Golf .a nice car ,oldish low milage but soon cropped up with a problem .Middle of a cold snowy spell and the water temp  wouldnt reach normal temp for ages .The fans also started running and didnt stop when the ignition was switched off .So flat battery as well one day .I worked round the the fans problem by disconnecting them as I just used the car locally and until I got it fixed so no real issue of overheating on a winters day .I took it back ,bad sensor blah blah ,fixed but still did it ,this was a major VW centre all official .Tis the thermostat I said .If the water doesnt get hot the thermo is jammed open .,basic mechanics ......blank look  etc .After a couple of tries and keeping the car for week they still hadnt solved it ..back I goes.......' "Try fitting a fugging thermosat .$@£$^%^&*(*

This time they tried fitting the  fuggin thermosat which seems  these days to have a huge number of sensors  and pipes attached .All solved .The company was very good ,gave  me several full tanks of gas and a Lexus for a week so no real moan issues.This was the  main city  VW dealer and they consulted VW service about it and still no-one had heard of the basic thermostat rules .The thermo didnt show as faulty so it wasnt the thermo ...gawd.

[mark axlecounter]

That’s the problem with the job now. I was trained at Land Rover with old school trainers but now the old hands have gone and the new ones are more like computer mad.  

[polybear]

Computer diagnostics are only ever as good as the bloke that wrote the program.  And whilst he may be a whizz at programming, how much does he know about fixing cars?

[mark axlecounter]

We had the apprentice going mad because the car was pre tech 1. 

It was when I was at vantage bury (Vauxhall main dealer) we gave the apprentice a D reg nova to work on (poor idling) So he brought the car onto the ramp and went straight to the diagnostic cage where tech 1 and tech2 are.

(Tech 1 is the first diagnostic for Vauxhall 1990 onwards to 1998  tech 2 is after1998)

so he grabs tech 1 goes to the nova and spend 30 minutes looking for the plug. In the end I took it off him and carried out checks (the old way ) 

fixed it found out it was the carb setup wrong. 

Old school mechanic 1 new tech 0

[ejstubbs]

12 hours ago, polybear said:

Computer diagnostics are only ever as good as the bloke that wrote the program.  And whilst he may be a whizz at programming, how much does he know about fixing cars?

 

I fear you may have a somewhat simplistic view as to how these things are built.  The knowledge and skill of the guy who writes the code obviously has some bearing on the quality of the resulting product, but he/she will not have been responsible for drawing up the requirements that the code is written to satisfy so won't need to know all that much about fixing cars.  The code itself will almost certainly have been checked in code reviews performed by at least one other set of eyes, and it will have been subjected to several rounds of unit, integration and system testing, with any bugs that are found* being fixed as part of the testing cycle.

 

If the functionality that results is inadequate, that is most likely to be due to a deficiency in the initial specification, which should have been the responsibility of the engineers who designed the overall system.  In an automotive context that will include things like the sensors that the vehicle is equipped with, their detailed capabilities, and how the information they generate can be tracked, analysed and combined in order to form an adequately useful picture of what's going on.  At a very fundamental level, if no sensor has been specified to detect a particular fault then there may be little that the coder can do about it.  While the vast majority of engineers would love to design and build the very best system possible, outside of esoteric domains such as Formula One they all have to work within the constraints if cost, time and quality.  As the old saying goes: "Good, cheap, quick: pick two".  (Which also happens to be a fundamental mantra for project management, as it happens, and is probably applicable to many more aspects of life than a lot of  people would realise.)

 

I doubt that many dealer technicians these days will ever see a customer vehicle that has carburettors.  More's the pity, in some ways.  Whenever I feel temped by a nice shiny new motorbike I always end up reminding myself that my current (24-year-old) bike is a far better bike than I will ever be a rider - but at least I can fix it myself.  And there is something rather nice about a cluster of four carburettors nestling on top of a v-four...

 

* Finding and fixing bugs is an art area of expertise all of its own - and not one that I've ever professed to have any particular skills in.  People who are good at it talk of mysterious things like Heisenbugs, mandelbugs, schroedinbugs and Higgs-bugsons.  I'm told that one technique is to make random changes to the delivered code, with the expectation that they will evidence as a roughly equivalent number of bugs when the code is tested.  You then run the code through your test harness and look at the number of bugs that are reported.  Some will be actual bugs, others will be ones introduced by the random changes you made.  The proportion of the bugs caused by random changes vs the number of random changes that were made gives you an indication of how many real bugs are still left to be found.  Apparently.