Poor cold starter - computer diagnostics? Can mechanics think for themselves?

dunroving

OK, so the car I bought 3 weeks ago (2011 C3 Picasso) is a poor cold starter. It seemed fine the first week or so, then gradually got worse. It was only a bad starter in the morning (I live in a very cold, wet, windy part of Glasgow, and it sometimes sits for up to 3 days), but then one day it wouldn't start after being in the (indoor) works car park all day.


Symptoms: Rapid turnover (so not a flat battery), just no ignition (it coughs and splutters now and then). Last Monday, it wouldn't start at all, ended up calling AA and eventually it started just through continued trying. He thought it was possibly a fuel supply issue after being left standing, but didn't test anything, as I was talking it back to Arnold Clark anyway (bodywork repair) so I was happy to let them deal with it.


After running computer diagnostics, they said the spark plugs were corroded, and they replaced them, retested the next morning via computer diagnostics and said everything was A-OK.


Picked it up yesterday morning, guess what, rum-rum-rum-rum-rum-rum-rum-rum .... no catch. I called the bodywork manager out and said You try, or they'll think I am making it up. It took about 8 attempts total, and the last one, he just ran it for about 20 seconds before it actually started.


Took it straight down the hill to the AC service department and asked them to look again.


An hour later, they said it was starting every time (well, duh, that's the problem - COLD starting). Wanted me to leave it with them overnight so they can "see it having the problem". I brought it home, just because I couldn't afford to leave it there any longer (they had it 5 days).


So, here's my question(s): (a) can a computer diagnostic test tell you the spark plugs are the problem? (b) does anyone here with some car nous recognise the problem, and (c) can't car mechanics think for themselves any more? Surely poor cold start is a somewhat common problem with limited possible explanations ... in the old days, they just eliminated each problem one at a time, until they found the cause.


[AA man thought it might be the fuel pump as you don't really hear it priming when you turn the key to the first click in the ignition]

tberry6686

Diagnostic computer will not tell you anything about the spark plugs so that is BS. AC generally do not have mechanics, just parts fitters with the normal repair method of replacing parts until it works.

There are only a few things that can cause poor cold starting. I would start with checking the fuel pressure is ok. See if you can find a Haynes book for your car - great source of info. Never done any work on a citreon before so no idea where the valve is - looks like a schreader valve. Press in the centre of it and if you get fuel coming through then the problem is likely to be on the engine side.

Main causes of staring problems are - lack of fuel (fuel pump, fuel filter, fuse), lack of spark (Spark plugs, coils, HT leads, ecu,) Lack of air (filter, MAF), lack of compression, If you can check these and they are ok then take the car to a real mechanic not a dealer.

Try looking for a citreon forum - maybe a common issue for these cars.

atrixblue.-MFR-.

Who ever said spark plug corrosion was talking big BS. The citroen has a mahoosive coil pack covering them completely with rubber sleeved jackets that make a seal going into the spark plug ports in the head, so assuming it has its services at times intervals then I would inclined to say corrosion on a spark plug tip shouldn't be an issue on 4 yr old car.


I would be more inclined to be looking at the basics here too.


Spark and fuel. if you cant hear the pump priming ( by starting the car an leaving drivers door open to hear it they are rather quiet BTW) then it could be a failing fuel pump, IIRC theres a choice of 3 pumps on these French vehicles that have different head set ups on the in tank pumps.


Spark- coil pack, spark plugs. as the spark plugs have now been changed, then coil pack would be something else to look at.


failing that, your looking back at the common issues with citroen petrol engines the electronic sensors- CRANK sensor-MAF sensor-MAP sensor CAM sensors EVAP purge valve all tend to rise to issues with cold start problems when they are faulty.

dunroving

tberry6686 wrote: »

Diagnostic computer will not tell you anything about the spark plugs so that is BS. AC generally do not have mechanics, just parts fitters with the normal repair method of replacing parts until it works.

There are only a few things that can cause poor cold starting. I would start with checking the fuel pressure is ok. See if you can find a Haynes book for your car - great source of info. Never done any work on a citreon before so no idea where the valve is - looks like a schreader valve. Press in the centre of it and if you get fuel coming through then the problem is likely to be on the engine side.

Main causes of staring problems are - lack of fuel (fuel pump, fuel filter, fuse), lack of spark (Spark plugs, coils, HT leads, ecu,) Lack of air (filter, MAF), lack of compression, If you can check these and they are ok then take the car to a real mechanic not a dealer.

Try looking for a citreon forum - maybe a common issue for these cars.

atrixblue.-MFR-. wrote: »

Who ever said spark plug corrosion was talking big BS. The citroen has a mahoosive coil pack covering them completely with rubber sleeved jackets that make a seal going into the spark plug ports in the head, so assuming it has its services at times intervals then I would inclined to say corrosion on a spark plug tip shouldn't be an issue on 4 yr old car.


I would be more inclined to be looking at the basics here too.


Spark and fuel. if you cant hear the pump priming ( by starting the car an leaving drivers door open to hear it they are rather quiet BTW) then it could be a failing fuel pump, IIRC theres a choice of 3 pumps on these French vehicles that have different head set ups on the in tank pumps.


Spark- coil pack, spark plugs. as the spark plugs have now been changed, then coil pack would be something else to look at.


failing that, your looking back at the common issues with citroen petrol engines the electronic sensors- CRANK sensor-MAF sensor-MAP sensor CAM sensors EVAP purge valve all tend to rise to issues with cold start problems when they are faulty.

Thanks, both. Unfortunately, the car came with an Arnold Clark warranty so my first option is to take it there.


Several of the things you have suggested make sense to me, though I'd have thought (?) that some of them would be picked up by a computer diagnostic test - no?


I checked the Citroen forums (there's even one just for Picassos) but couldn't find anything that seemed to apply. Most of the cold start threads were for the diesel engines, not petrol.


If I were to turn the key to listen for the fuel pump turning on/priming, and it does turn on/prime, is that likely to flood the engine and affect starting next time (Monday morning)?


Next time I am due to use the car is Monday, to drive to work and then to the airport where it will stay until Thursday. Will let you know how I get on. The car clearly has an underlying issue so I will have to take it back to the mechanics at AC when I get back, so they can keep it overnight, try to start it, and try to diagnose the problem.


I just don't see how they wouldn't have had a cold start problem on the day I picked it up ...


Just to check, my start procedures typically are:


Depress clutch
Turn key in ignition to Position 1, and leave for about 5 seconds for fuel pump to prime.
Turn engine over to "start" (if it does)


I don't touch the accelerator until after the engine has started, generally.


Any issues with my technique? (although with modern cars it seems it shouldn't make that much difference, otherwise rental cars would be littering the roads).

Marktheshark

Find the Fuel pump solenoid cut off relay in the under engine fuse box or other fuse box and swap it over with the one next to it and see if it starts.
If it does buy a new relay they are about £10 parts store of £5 online
This relay is a source of many starting issues on French cars.

PS it might be the dual multifunction fuel relay on that model so there is only one, but that is the fault they throw up.

patman99

Just keep hassling AC. The car has been in your ownership less thaen 3 weeks, so they are responsible for getting it working properly.

marlot

Either reject the car, or demand a loaner whilst they get it fixed

reeac

Check the crankshaft position sensor - depending on position they can pick up road dirt which has a masking effect on the pick up of the signal and hence weaken the spark. Particularly affects cold starting when the battery voltage is lower. Been there , seen that.

atrixblue.-MFR-.

You don't need to prime the pump with turning ignition on 1 click and wait, they are high pressure pumps to keep pressure to the injector rail, it then returns through to tank from a separate return pipe on the injection manifold.


As for picking the codes for a failing sensor it would all depend on what equipment they use or used to diagnose, and the person interpreting that information at the screen, its common practice to for them to just go in a clear the DTC codes, even though the car is displaying a symptom they do it anyway like it the problem will sort itself with a reset, 95% of time it doesn't, but 5% of the time it could be a software glitch in the ECU this is a rare occurrence as out of many diagnosis ive performed over the years, I can count on 1 hand how many software glitches ive come across that with a DTC clear and reset cured the problem.


OH and mechanics get a bad name from the so called "technicians".
Technician= Someone reading a diagnostics screen and doesn't question the test and has generally been through a crash course of a days training to read the screen, tests electrical equipment with multimeters and generally swap out parts till the problem is solved and are generally lost without his trusty diagnosis machine.



Mechanic=The person getting greasy under the bonnet who is generally switched on to problems an engine can throw at them and will question what a machine tells him on the screen and will only use the machine as a guide on where to start looking the mechanic is usually technically savvy and will train himself or attend and extensive course and figure out what these diagnosis machines are really telling them, wont change a part out if its healthy or just needs a clean or if it can mechanically be repaired or remanufactured, and is not lost without a machine.


As dealerships usually take on the "technician" as they are paid generally on NMW or on apprenticeship scheme from college. dealerships usually have less than a handful of master mechanics at hand to trouble with routine diagnosis problems they don't usually look over vehicles such as problems like yours as they are tied up with other vehicles.

pendragon_arther

It's a long time since I worked on cars, 40 years, but one issue with problem starting on cold and damp mornings after ignition or fuel problems had been eliminated was moisture in the distributor and there used to be a special spray to cure this.

skivenov

His car won't have a distributor as such any more. The crank sensor gives a signal to the ecu which talks to the coil packs.

If you asked me to place a bet - Modern engine and a poor cold start is going to be the crank sensor more often than not.