Mk7 tdci cold start - rough idle & white smoke

[Peange]

Hello all. 

I'm having an issue with my 1.6 tdci Fiesta on a cold start. The idle is very rough and it plumes white smoke from the exhaust. Also the check oil light comes on while this is happening. After a bit the idle smooths out, the smoke clears and the oil light goes out. 

I replaced the glow plugs after watching a YouTube video describing the same problems and all looked good! Sadly the problem came back a couple days later. 

I'm wondering if something is burning out the glow plugs. I'm hoping it's as simple as the relay. 

First question - where is the glow plug relay? Second - do you have any other ideas on what could be causing my issues? 

Thanks! 

[zain611]

Did check for any error codes? Does the car look to be drinking a bit of oil? 

[Peange]

Haven't read any codes yet, still waiting on a reader arriving. It does drink a bit more than it used to. It got a change in January, I'll check the level tonight

[Peange]

No error codes at all

[Tdci-Peter]

On 5/15/2019 at 9:16 PM, Peange said:

I'm wondering if something is burning out the glow plugs. I'm hoping it's as simple as the relay. 

Have you checked the glowplug fuse. It will be a big fuse in the engine bay fuse box, usually 60A. I had a blown fuse back in 2012 on my car.

Glowplugs can be tested, a multimeter should read a short circuit from the terminal to the case, as the resistance is under 1 ohm on a good plug. Any higher reading would show a bad plug. They can also be powered up using jump leads from a car battery, but very, very great care is needed to avoid short circuits and burning fingers on the bright red hot end!!!

I managed to power up one from a couple of bench power supplies, and burnt a dip in my workbench while taking a photo!

A bit more in:

 

[Peange]

I haven't checked the fuse, no. I'll break out the multimeter and cross fingers that it's as simple as that. Did you get similar symptoms when yours went?

If I don't get luck there I'll pull the plugs again and see if any are gone. Thanks! 

[Tdci-Peter]

2 hours ago, Peange said:

Did you get similar symptoms when yours went?

It was Winter, and when starting below about 10C, the car started roughly, idled like it was on 2 or 3 cylinders, and gave a huge cloud of greyish smoke. I only changed 2 plugs, it started raining so I gave up on the other two, but one of the two I replaced was definitely duff, and that cured the problem.

Usually these common rail diesels are ok starting without plugs above about 15C, I sometimes can't be bothered to wait for the pre-heat and start straight away in warmer weather, with no problems. But the 1.6 is a bit more sensitive to plugs than the 1.8, so may be different.

So I am not 100% sure your symptoms stack up with glowplugs, especially if it does the same when starting with an engine temp above 15C or so. But white / light grey smoke smelling of diesel or badly burnt diesel is a key symptom of glowplug problems.

oil can build up in cylinders from, for example, leaking valve guide seals, but the smoke would be darkish, and smell worse, burnt oil is quite a noticeable stench. You would also see a drop in oil level.

The oil lamp being on could be just the engine does not get up to the steady rpm needed to pump up the oil pressure until it has warmed up a bit. So I think plugs remain suspect number one until proved otherwise.

You can also tell if the plugs are working by an appreciable drop in battery voltage. As soon as you turn on the ignition, the battery voltage should drop by one or two volts, then if you wait till the pre-heat has timed out without cranking, the voltage should start to steadily rise again back towards 12v. The plugs take a lot of current. That will check the fuse and relay, though it will not accurately check if one plug has failed out of the four,.

 

[Peange]

No luck with the fuse. It looks in good order. Tried turning the engine over without it installed and the smell was worse. It was too windy to see any smoke. 

The battery test is next on the list. I plan to get out at the weekend to try everything else you've suggested. Sadly the car isn't parked near my house; getting out to it can be a pain.  

Do you know where the relay is located? 

 

Thanks again for the help! 

[Tdci-Peter]

5 hours ago, Peange said:

Do you know where the relay is located? 

Most likely seems to be R2 in the engine fusebox. See:

https://www.autogenius.info/ford-fiesta-2008-07-21-2009-01-04-fuse-box-eu-version/

If it was worse without the fuse, then it looks like at least some of the plugs are working, which means the relay is probably ok.

[Peange]

10 minutes ago, Tdci-Peter said:

At least some of the plugs are working, which means the relay is probably ok.

I replaced all the plugs a month or so ago. Other reading online leads me to think that it could be the excess carbon build up (got a reamer kit on the way), relay issues or injectors. Thing is, the link is for Mercedes and I'm very far from an expert in this -> https://mercedessource.com/problems/electrical/frequent-glow-plug-failure

[zain611]

On my mk6 fiesta zetec s 1.6 diesel the next day I bought it I noticed it would start up rough, chug a bit of smoke and run lumpy until it was driven for a bit were it ran normal. Changed the glow plugs as I thought it might of been that which caused these symptoms. Changed all 4 glow plugs and the symptoms persists. In the end my dad suspected one of the injectors were leaking where it was leaking fuel into the piston which then caused the symptoms. Got all 4 injectors reconditioned and did some cleaning in the engine such as cleaning up the intake manifold. After that the car runs like new. 

The thing is you said there's increased oil consumption which I'm sure I didn't have. You could get a leak off test to see which injectors may be leaking (if they are) but Peter is more knowledgeable here than me. 

[Peange]

1 hour ago, zain611 said:

The thing is you said there's increased oil consumption which I'm sure I didn't have.

There's a chance the oil consuption is unrelated 🤞. I'd like to try all the cheap option first before I go chasing down an potentially expensive oil drinking issue.

1 hour ago, zain611 said:

You could get a leak off test to see which injectors may be leaking (if they are)

This doesn't look too hard to do. I'll give it a go!

[zain611]

Could give it a go. I didn't test it as my dad was adiment it was the injectors. Those symptoms I had came when the car was sitting for at least 2 hours before starting it again. It wouldn't happen say if I went to the shops and started the car soon after. 

[Tdci-Peter]

15 hours ago, Peange said:

Thing is, the link is for Mercedes

I have just had a quick look at the link, and there are a couple of differences on your 1.6TDCI. Pre-chambers are usually only found on an Indirect Injection Diesel, and the 1.6TDCI is direct injection without such pre-chambers.

The section headed "Overview" in this link is a good description of the difference: https://en.wikipedia.org/wiki/Indirect_injection

The glow plug relay on these Fords is just a simple on-off relay with no inbuilt timing function. Timing of the glowplugs is done by the ECU, which knows what the engine coolant temperature is. So unless the plugs are staying on all the time, or are never on, it is less likely to be the relay.

I think I would do the battery check, and a couple of other simple multimeter tests to check that power to the plugs is coming on and going off as expected, then disconnect the feed to each plug to do a continuity check on each. It is quite possible one of the new plugs was dodgy, and failed almost immediately. With almost all equipment, the first few months are the time of least reliability!

Like Zain says, if these tests on the plugs show no problems, Injectors are the next most likely culprit. Especially if the problem happens on a lukewarm start, as it did in Zain's case. I think engine temperature needs to be below 15C, probably below 5C for my engine, before it needs glowplugs to start cleanly.

 

[TomsFocus]

Does it clear if you give it a quick rev?  I don't mean bounce it off the limiter, just enough to spin the oil pump a bit quicker.  The reason I ask is because the cam-chain is tensioned by oil pressure.   If the cam timing is slightly off you won't be fully burning the diesel before it's blown out of the exhaust.

[Peange]

31 minutes ago, Tdci-Peter said:

the 1.6TDCI is direct injection without such pre-chambers

Whoops! Good thing the kit was only a tenner.

 

31 minutes ago, Tdci-Peter said:

it is less likely to be the relay

This is very good to know.

32 minutes ago, Tdci-Peter said:

It is quite possible one of the new plugs was dodgy

I'll give them a test next. If all's good there, I'll leak test the injectors.

 

13 minutes ago, TomsFocus said:

Does it clear if you give it a quick rev?

It definitely produces less smoke after a quick blast. I'll add this to the list of things to look out for. Cheers!

[Peange]

Sorry for the late update, had a house move get in the way. 

Finally performed a leak off test. Looked good to my untrained eye. All injectors flowed relatively evenly with minimal fuel flowing. 

Checked the oil level & it seems it hasn't noticeably eaten any since January. 

Off to test the glow plugs today. Hoping they come up faulty is a weird feeling! 

Cheers. 

[Static]

If it smooths out after a few minutes and your happy the fuel flow is even enough, you may have carbon build up on on or more of the injector ports which is not helping the cold start. Have you tried an injector cleaner? Maybe run a few over a few tanks of fuel. Ideally I'd say pull them out and clean but if we're doing cheep and non invasive, give it a go! This stuff isn't an injector cleaner but should help you out.

 

https://www.dipetane.com/