Smoky start in cold weather. What next?

Technical questions and answers about the Mazda Bongo

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teenmal
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Re: Smoky start in cold weather. What next?

Post by teenmal » Sun Apr 23, 2017 4:26 pm

g8dhe wrote:The ECU commands the relay, if the engine temperature is not sufficiently high for the rev's being asked for then the relay will operate to keep the glowplugs hot. So if you start and sit on the drive after a couple of minutes the glowplugs will turn off, if you then accelerate the ECU may turn the plugs back on again to make sure the fuel will ignite in the shorter time available.

Hi Geoff its actually the opposite , accelerating to approx or above 1500RPM will turn the heaters off.
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sotal
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Re: Smoky start in cold weather. What next?

Post by sotal » Sun Apr 23, 2017 4:28 pm

Given that I don't know the age of the glow plugs, and that they are relatively inexpensive. It might be worth replacing them anyway.

Does anyone know the correct type to get for a 1999 facelift diesel?

Thanks.
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Re: Smoky start in cold weather. What next?

Post by teenmal » Sun Apr 23, 2017 5:02 pm

sotal wrote:Given that I don't know the age of the glow plugs, and that they are relatively inexpensive. It might be worth replacing them anyway.

Does anyone know the correct type to get for a 1999 facelift diesel?

Thanks.
If you are referring to the length of the plugs ,owing to the fact that these old bangers have probably been through the mill at some part of their life it would be advisable to measure the actual glow plugs that are fitted to your vehicle, otherwise you might need to fit spacers etc.
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Re: Smoky start in cold weather. What next?

Post by Northern Bongolow » Sun Apr 23, 2017 7:16 pm

you could have either long or short plugs fitted as there are 2 lengths fitted to bongos.
refer to your pic on page 2 and compare them to the plugs you can buy. the best out there are njk ones, but these only seem to come in short plugs, the longer ones seem to be in less popular makes. the difference in the length is all outside the engine/head, so a long plug sticks out of the head (taller), this can be a problem if you have long plugs fitted then fit short replacements as the connecting live bar can short out and burn the little link pipes on the injectors, so fit the correct ones that dont touch anything else and short out the glowplug lecky system.
you can fit the more reliable njk short ones to a long plug system by extending the top of the glow plug, there plenty on here about it.
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Re: Smoky start in cold weather. What next?

Post by mikeonb4c » Sun Apr 23, 2017 9:59 pm

NJK or NGK Ady? I'd thought it was the latter? Sorry if I'm being dumb or pedantic :oops:
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Re: Smoky start in cold weather. What next?

Post by sotal » Sun Apr 23, 2017 10:07 pm

mikeonb4c wrote:NJK or NGK Ady? I'd thought it was the latter? Sorry if I'm being dumb or pedantic :oops:
Maybe it's the northern accent? :lol: :lol:
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Re: Smoky start in cold weather. What next?

Post by Bongolia » Mon Apr 24, 2017 1:31 pm

Might better to tag Ian on the correct P/No against your chassis number.
I would also be checking the resistance of the coolant temp sensor a wrong reading here would influence the ECU.
I would suspect that the relay would remain on if it is the only control relay as it is 12V all the time when on I would think there is only the one.
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Re: Smoky start in cold weather. What next?

Post by mikeonb4c » Mon Apr 24, 2017 4:45 pm

sotal wrote:
mikeonb4c wrote:NJK or NGK Ady? I'd thought it was the latter? Sorry if I'm being dumb or pedantic :oops:
Maybe it's the northern accent? :lol: :lol:
Don't know 'bout that, but I'd trust him with my Bongo \:D/ 8)
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Re: Smoky start in cold weather. What next?

Post by sotal » Tue Apr 25, 2017 9:58 pm

For the last few days, I've been starting in the morning by turning cycling the glow plugs twice until the relay clicks then starting. Smoke has been minimal and lumpyness has been for at most about 1 second.

However this morning was colder again. The Bongo was covered in snow this morning. I did the glow plugs twice, then fired the engine straight up. It ran lumpy for about 10 seconds or so during which time it chuffed out a big white cloud of smoke. I didn't touch the revs and it settled itself out but the smoke screen was a bit embarrassing! This is what it was like for most of winter!

So I think that I can conclude that cycling the glow plugs twice does improve things a little bit, but does not cure it. It almost seems like there is a tipping point with the temperature, when it goes past a certain point it goes terrible!
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Re: Smoky start in cold weather. What next?

Post by Bongolia » Wed Apr 26, 2017 1:08 am

I reckon what needs looking into further is if during those very cold starts that the plugs are holding on after the engine is running as it has been said it is designed to do.
If that was not happening then it would be understandable that you would have smoke and poor running until the combustion chamber had warmed up.
The trigger it would seem is what temperature the ECU sees the engine to be at. This would be taken from the CTS, a primary sensor. It may be worth checking its resistance at that low ambient temperature and comparing that with its spec.
First though you would need to prove the plugs where being switched off to soon with a volt meter. If they were not then you could discount that and focus your attentions elsewhere.
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Re: Smoky start in cold weather. What next?

Post by rita » Wed Apr 26, 2017 7:32 am

sotal , if you want to check the operation of the glow plugs you could make up a test lamp and connect it to the glow plug rail and have the holder/bulb in the cab with you. Then you can watch when the feed to the plugs are On and Off as you drive about your daily business.


Good Luck.
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Re: Smoky start in cold weather. What next?

Post by Bongolia » Wed Apr 26, 2017 8:18 am

rita wrote:sotal , if you want to check the operation of the glow plugs you could make up a test lamp and connect it to the glow plug rail and have the holder/bulb in the cab with you. Then you can watch when the feed to the plugs are On and Off as you drive about your daily business.


Good Luck.
Nice one.
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