603 Rough idle
 

My newly purchased 300D (non turbo) sometimes has a very rough idle and I'm wondering if this has something to do with the actual idling rev's...is my car meant to idle at 500rpm?....this seems very low, and it does feel as if the car is on the verge of stalling.

If this is too low, how do you increase the idle rev's

Other than the idle, the cars seems to be going well apart from some noise from one of the lifters, which I assume I will have to live with.

Car is doing 36mpg (imperial), so I guess thats about 38-39mpg (US Gallons) on 80mph runs....is this a reasonable figure or should I be expecting more?

Many thanks

Try using synthetic oil next time you change oil if you not allready helps with lifter noise.
Also a can of Lubromoly Diesel Purge may help the rough idle follow can directions.
Your fuel milage sound unbelieveable are you sure>

Being a right hand drive car, I would assume that the electro adjustment knob would be on the other side on my car from yours.

Anyway, I'll describe based on my car. Located near the master brake cylinder, attatched to the firewall, there is a black colored knob with numbers printed in white. This is where I understand idol adjustments are made, at least on my US model 87 300D turbo.

GSXR has posted some info recently about this adjustment. Try the search and see what you may find.

Steve......... :)

I have looked for Luro-Moly Diesel Purge in the UK and it appears that Lubro Moly do not sell their products over here....shame!...are there alternative makes to Lubro Moly I could try?

Fuel consumption is correct, on my last trip I got 36.55mpg and trip before that 36.32mpg......figures were checked after a brimming the fuel tank after each fill.

Milage is about right.

Your electronic idle speed control is not working, idle should be 650-750 rpm and not change when you have the AC on or in gear with automatic (which I presume you don't have).

This is usually a broken wire at the three-wire connector at the back of the pump. They are at an bad angle and tend to fatigue. It could also be a major failure in the pump, in which case I'd leave it and live with it (you can set the mechanical idle up, but I don't know how!) until you need other IP work, it's very expensive on this pump.

You also very likely have collapsed engine mounts. Take a look at them and see how much space there is between the widest portion and the frame -- should be at least 25 mm, and you just be able to see the trapezoidal steel fitting on the bottom. If closer (they can actually touch) or if the steel portion has been pushed up into the mount, they have leaked out. The result is VERY rough idle and considerably more engine noise than you should have.

Peter

See if you can get Redline products.

Do you use imperial gallons or US gallons in the UK? Maybe the fuel mileage numbers should be adjusted for comparison to US numbers. But those are fabulous numbers in any case.

Sixto
95 S420
87 300SDL

Sixto:

Those would be Imperial gallons, 5 US quarts instead of 4 (because the Imperial Quart is 20 oz, not 16).

Multiply by 0.8 to get milage in US gallons, still pretty good.

I used to get a kick out of the Canadians telling me how cheap US gasoline was when I was living in Sault Ste. Marie, Ontario -- they were converting Imperial gallons to liters (4.2 L per gallon) rather than US gallons (3.7 L per gallon) -- I figured you would have to buy 50 gallons to pay for the bridge toll at the one time rate, 25 gal at the "buy a book of ten" rate to pay for the difference.

Peter

Peter,

The Imperial gallon is larger than the U.S. gallon. So, you can go further on an Imperial gallon. You therefore would multiply by 1.20 when you have the mileage in Imperial gallons and you wish to get the mileage in U.S. gallons.

With this conversion, his fuel economy really looks amazing.

Almost as amazing as magic, as it would be. The US gallon is smaller, so less miles per gallon (29 or thereabouts). You have the correct ratio, but upside down (you would need to divide by 1.2 rather than multiply).

The difference is confusing, as there are four Imperial quarts (and 8 Imperial pints) per gallon. The Pint, however, is defined as 20 oz. in Imperial measure, not 16 oz as in US measure (for reasons I probably don't want to know!). A pint in an English Pub is 20 oz, in the US it will be 16. The result is that the US gallon is somewhat smaller, as are our pints and quarts. Imperial quarts are larger than a liter, US quarts are smaller.

Peter

How in the hell...........
 

did I screw that up?

I think I need to retire from this engineering business. :rolleyes:

But a litre or liter is tha same size everywhere, just like a metre, a gramme or a degree C.
Apart from us "old farts" not being able to learn the new measurements, why does UK and USA continue to use these antiquated measurements which are different even from each other's measurements? The conversion cost is small due to the planned obsolescence of all items madethese days.

I just realised that I stuffed up on my Maths..........if I'm getting 36mpg (imperial), then this should equate to 31-32mpg (US Gallon)..... :p

Tony you should try living over here...bloody nightmare when it comes to using imperial and metric.

Since the mid 70's all school kids, me included, have been taught in metric which I naturally much prefer.

However, the UK still persists in using imperial for all manner of things, so we end up with people always quoting temperatures in Fahrenheit which means nothing to me, working in Pounds and Ounces....never ever understood this at all :eek: ....Kg's and gramms are way simpler.

Distances in terms of metres and Cm's much easier than inches, however, when it comes to bigger distances I'm still a Miles person...same when it comes to speed, although KM's are pretty easy to convert to.

I still like gallons when its comes to working out MPG and have to convert from Litres to gallons, however, when it comes to buying a quantity of fluid I prefer to work in Litres .....confused, you should be :eek:

I would rather they just bit the bullet once and for all and converted over to Metric, seeing as every school kid has been taught it for almost the last 30 years!

As for driving on the right, well there's a whole new subject :D

Drive on the "Right" side of the road, not the "wrong". :D

An Imperial gallon is 20% larger than a US gallon therefor take the Imperial milage in this case 36- 20% =28.8 mpg. its that simple .

Tony:

The US officially adopted the Metric system during Teddy Rooseveldt's second term, I believe (1912 or 1914? ). The ANSI and NTSC (otherwise known as SAE for society of Automotive Engineer) "inch" standards were promulgated later. Before that time, nearly all fasteners were hand made by blacksmiths, and you got what you got....

I am fairly certain I don't what to know the reasoning, I've had enough for today!

Peter