Black soot
Has anyone experienced the following. From cold my 280 Auto will run really rough until warmed up and under acceleration there's no pull it almost seems to chug, if I look out the rear mirror there's black smoke or soot blowing out. once the truck has been started even if it cools down and it's started again later in the day the problem has gone, it only ever seems to reappear overnight or first start after say 24Hrs.
It's running too rich. Without having a look at mine I can not be too helpful but I'll give it a go. Not sure if I'm using the correct terms here but there is a cold start device that alters the fuel pressure to the metering unit. This alters the mixture when cold. As this device heats up (maybe electrically) it adjusts the mixture. I am NOT talking abouth the 7th injector which is there to supply extra fuel at start up only.
If there is nothing obvious I think it's sometimes best just take it to a bosch tuning specialist.
When I'm next under the bonnet of mine I will have a look and refresh my memory.
Russ
try posting the same message on the USA forum. If not speak to Nigel at spilsby road garage, you can obtain his number from Howard green. With all the above it could be valve guide seal leaking oil in chamber overnight.
he felt it wasn't the cold start unit as it always starts on the button,
It would. The 7th injector helps it start from cold. Then if it's running rich it would carryon running.
Suggest you need someone who knows bosch fuel injection. Te mechanical set up on the 280is pretty simple and is not MB specific. Still think it's the warm up regulator. This alters the pressure appied to the control plunger (attached to the air flow flap). When cold it allows the air flap to move more freely for a given air flow = more fuel for less air.
the last thing he did was replace the actuator
Best of luck,
Russ
Thanks guys. The truck is back with George Fraser, fingers crossed 5th time lucky.
JC.
I also had the same problem in the past. I presume you have the 280 E engine.The way it was cured was very simple. Change the fuel pressure regulator. This is a component which is bolted on the rear left side of the engine block. It has a bimetalic strip inside and gets the heat from the engine block. It converts temperature readings into electrical signal which is then transited through electrical cables to the engine management system and the feed pressure is thus regulated . This is particularly crucial when the engine is cold. The main culprit is rusty cable connections, so make sure you replace them. There is a kit available for this.
Sound advice: Use original Bosch parts, and Bosch specialists. They can get all the settings of your car through their service internet.
Good luck.
I'm having the same problem with the warm-up regulator on my 280ge. As I understand the system, the warm-up regulator enriches the mixture when the regulator is cold. The regulator is heated in two ways: a) the engine block, this prevents enriching after a warm start, and b) electrically, this is presumably set up to take about as long as it takes the combustion chambers to heat up. In my case a) works just fine but b) doesn't work at all. I have tested the heating coil of the regulator with an ohmeter and it reads within the correct range (20-25ohms). However when I checked with the engine running there appeared to be no voltage reaching the heating coil. Am I right in believing that there should be voltage reaching the heater when the fuel pump is running? If anyone knows better please let me know before I start tearing apart my loom looking for a non-existent electrical fault!
R
hiya, am having this same problem, was this ever resolved?
I have an entire spare engine, which part do I need to swap out? and what does it look like? any pictures or details would be gratefully received.
so far I have changed the leads, plugs, injectors, coil, had the cylinder head skimmed and the valves re-seated, compression test, and I was looking at air leaks and the cold start air valve, but this sounds like the same problem I have been having.
thanks
Hi All the cold start regulator is located to the rear and below the the oil filter..a two pin electric socket... two metal pipes with different sized threads and rubber pipes .it is bolted to the engine block with two 5mm allen key headed bolts...this is a known high failure item... the diaphragm inside leaks giving to much fuel on start up enrichment. the Bi- metal strip inside heats when the fuel pump is running and the capillary heat sensor closes the fuel as the block heats up....when working correctly the engine should rev to 1100/1200rpm on startup reducing to 700/800rpm when warm...starting when hot will cause the rpm to surge to 1200rpm for 5 seconds and settle at 700/800rpm...with the engine tuned properly you should be able to stand a glass of water on the rocker cover with little or no shimmy.......
I have been having a tinker with the truck this weekend, and after lots of fiddling about and refering to the forum, I disconnected the 7th injector.
I had started the engine several times during the day for various reasons, but it was still cold.
after disconnecting the 7th injector the engine immediately started to behave itself.
I am not suggesting this as a permanent fix, but it may be a good short term option for anyone with the warm up compensator problem. I was quoted £400 plus labour and vat to have it replaced.. (ouch)
I will leave it overnight, let it get really cold and give it another crack in the morning.
fingers crossed everyone.
Hi Jed... effectively what you have done is stopped the enrichment through the seventh injector by disconnecting it. if you have the fuel line off the injector fuel should flow as you start the engine.. if it continues to flow afer 5 minutes of running either the electrical connections to the cold start module are broken or the unit has failed internally..(a common fault) most likely the latter..they are fiddlely to change because access is better from underneath so a pit or a lift will help..the unit is GBP 69 + vat from MB (12 months ago)..the major problem if this system is not working as it should the excess petrol floods the cylinder walls and washes the lubricant into the sump diluting the viscosity of the engine oil which can lead to main and big end bearing failure... as you have it now it will be harder to start and idle from cold because there is no accelerator pump as on most carburettors......
well even running from cold the 7th injector being unplugged has made the world of difference.
much smoother, was a little sluggish at start, but much better than it was.
no clouds of soot and smoke, all in all a good short term fix.
I popped into the merc garage at lunchtime to check on the price of a new warm up regulator. ugh.. £496.25 + VAT and they have only sold 3 in the last 12 months to the whole of the UK.
was it a pattern part you got? or an original and where from? I will scour the internet for a replacement and ring the usual suppliers to see how much I can get one for, but I am amazed it is so expensive as it presumably is the same part as on the 2.8 car engine and not G specific.
thanks
Jed
hi I bought the last one from a Bosch stockist..it is common to all the Mercedes m110 series engines. I have one here which needs taking apart and a new bi metal strip fitted...most of them are easy to repair..the bits are available from any Bosch or Bosch Jetronic / CIS Jetronic fuel systems repair shop.
well I did it the hard way and swapped out the warm up regulator from my old and rusty g to the swb I drive daily.
I needed to borrow a 5mm T handle allen key, to get the WUR off, as you just cant apply enough torque with a normal allen, 12 and 14mm spanners to undo the two fuel lines, and a hell of a lot of swearing, patience, and bloodied knuckles and arms.
access to the WUR is a complete pig, once you reach in to undo any of the parts you then cant see what you are doing, so then you are mostly working by feel. I managed to get the 14mm line off by reaching under the intake from the side of the engine and using a medium size spanner to turn it 1/6 of a turn at a time, at least this way you can see what you are doing down the back.
reconnecting it all is also a nightmare, as the same 14mm line is so short and bolted to the block that I had to use quite a bit of brute force to get it threaded back on. ugh.
still having done all that the truck started first time, revved up to about 1400 exactly as it should, this was still accompanied with a cloud of steam/smoke and soot from the exhaust, but I hope it was just boiling off the old crud that is still in the exhaust, will let you know how that gets on in a couple of days.
so with the warm up sorted I took her out for a spin and got her nice and warmed up, she felt like she wasnt accelerating as fast as she had done before, and once she was all warmed up the idle revs dropped to the point that when I stop in traffic it would run lumpy and almost stall, the lumpiness carried on when pulling away until I had got to more than about 1500 revs.
any thoughts? I just fixed one problem and seem to have another. doh
jed
Hi now you need to set the idle and air mixture.....the idle is a large white slot headed screw just behind the distributor..... very small adjustments clock wise and anti clockwise.... but before you set the idle set the fuel / air mixture which is done using a 3mm allan key inserted against spring pressure in a small hole just alongside the air intake duct on top of the fuel management assembly..again minute rotation clock and anti clockwise until the engine runs without hunting or vibrating and with no sputter from the exhaust tail pipe...the steam is normal and will take five to ten minutes to clear depending on the weather........it is possible that you have so much soot/carbon in the cylinder head your max rpm is affected...a half hour run at 60mph will get the engine hot and most likely clear the problem...change the engine oil before you atempt this as it must be below viscosity and diluted with petrol.....when all is set correctly the engine should start from cold and run at 1200 idle... reducing to 800 after five minutes...when started hot it should rev to to 1200.. for ten seconds and drop to 800...when tuned correctly you should be able to stand glass of water on the rocker cover with little or no ripples...... if lack of revs persists change the fuel filter located under the G' just in front of the fuel tank..... the seventh injector must be working in order to obtain the correct rpm's
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Thanks Russ, I'm having a nightmare with the truck. I took it to George Fraser for a major service and three weeks later this problem still exists, he felt it wasn't the cold start unit as it always starts on the button, the last thing he did was replace the actuator but now from cold as well as all the black smoke the braided pipe leading to the unit leaks petrol but again only the first time the truck is used once warmed up the leak disappears. I'm pulling my hair out now starting to feel like it's never going to be sorted.
Anybody somebody help Please.... :(