Fuel consumption

I had a Challenger towing out 2500kg van, best thing I did was get rid of it and get into the D-Max.

It just had no more get up and go left towing that weight.

Good car but also got sick of nearly running out of fuel every time I had the van on the back - had a range of 250-300k. As a result I now have a long range tank that give me 500+ k towing.

Is the auto trying to hold too high a gear which would be unduly loading the engine and perhaps then trying to overfuel the engine?

Is the aircleaner element clean and allowing sufficient airflow into the engine under load as the turbo WILL be spinning faster and trying to maintain a balance of injected fuel and intake air.
The airflow meter may be dirty, usually positioned as air leaves the airbox, this will then be out of whack with the ECU especially when additional fuel is being asked for.

Did the service agent not change the element and it is dirty/restrictive to airflow?This is mentioned because some folk say "I just had it serviced". Not all service is performed fully or correctly.

Is there any wasp nest inside the air intake tract which would reduce total flow when most required.

Under correct operation there should never be black smoke emitted except perhaps on acceleration. The ECU should be able to balance turbo boost/airflow and fuel at any normal operating parameter so as to give a fairly clean exhaust. ie, a hot haze but not smoke.

Is the fuel being used of sufficient quality, although supposed to be much the same, sometimes there is a difference in cetane value etc.

The Throttle Position Sensor may be worn and not indicating correct position to the ECU, it then may be confused as to what to do at higher throttle opening than what is used for normal use.
Boost sensor may be gummed up and require cleaning or replacement. Situated close to intake throttle body.
If you have access to a Scan gauge or similar it should indicate turbo boost and that may be lower than needed. Split hose to turbo vane actuator or turbo can't perform well.

Maybe a quick check of the entire brake system on the van would be a good idea.

Bob.

Robert
Black smoke from a diesel is a sign of unburnt fuel, so anything that can cause a lack of combustion of the fuel that is being fed into the engine can be the cause
These are any of, or any combination of the following;
Any restriction in the air intake system, including air filter(s), wasps or rodents nests, hoses 'sucking in' etc.
Any loss of boost pressure including turbo issues, faulty waste gate or variable vane mechanism, leaking intercooler or hoses,
Any build up of deposits in the inlet manifold usually caused by the mixture of exhaust gas (via the EGR) and engine oil (normally from either the PCV system) (Mitsubishi's are renowned for these issues)
Lack of engine compression (leaking rings or valves)
Tappet clearances, especially if they are too tight.
Faulty Injectors (poor spray pattern or quality).
If you have confirmed that there is no issues with the air filter/inlet air track and intercooler system, then I would suggest that action be taken to clean out the inlet manifold either by the removal and clean method, or one of the propriety spray in systems that are available.
The fitment of a 'catch can' system into the PCV system can greatly reduce the formation of these deposits in the inlet manifold whilst still maintaining full compliance with the law.
Hope this helps.
Regards
Athol

Robert,

You don't say whether your vehicle is petrol or diesel. Given the presence of black smoke under load, I will assume it is a turbo diesel....

You also haven't mentioned how many kilometers the vehicle has done. If it over 200,000 then I have a suggestion. Have the mechanic (or do it yourself if you know how) remove the air intake ducting between the EGR valve and the intake manifold. I can almost GUARANTEE that the pipe will be chock-a-block full of carbon/tar build up.

I had a 100 series Landcruiser diesel (1HD-FTE motor) and I did this when it had about 210,000klm on the clock.....the amount of crud in there was astounding and it took me a couple of hours to chip it out and wash the remainder in a petrol bath.

A similar thing happened last December with the Toyota Hiace I drive for work. This van has a 10,000klm service every 3rd Friday (just to give you an idea of how much I drive it). It has given very little trouble and I just had the 717,000klm service done 2 days ago.

However, last December it was running like a dog.....black smoke and dead spots through the rev range. Mechanic tried all sorts of electronic "fixes" (ie: MAF sensor, throttle control module etc) and finally decided to follow my advice regarding the intake from the EGR onwards. The opening should have been around 50mm diameter, but he wouldn't have been able to get a 10 cent piece through the hole that was there!!! Clean all that C R A P out and she ran perfectly again.

Best thing to do is disable/block the EGR set-up, but it's illegal.

Having said all that, you may just find that you're asking too much of that particular vehicle. Many vehicles, rated to tow a particular load, really do struggle when a load approaching that limit is added to the towbar. I like to build in a healthy margin. When I had the Landcruiser 100 series (tow rating of 3,500kg), I only towed a 1200kg camper trailer....and felt that was enough of a load. When I decided to buy a 3500kg caravan, I decided to upgrade to the Chev Silverado which has a towing capacity of 8 tonnes (or only 5 tonnes if a conventional towbar)...the 8 tonnes relates to a gooseneck or 5th wheeler.

Roachie

This may not help ...... but it might

..... injector cleaning products are not recommeded on diesel engines ...... while they are effective on petrol motors, they are less effective on diesels and are considered too aggressive and may erode the faces and the mating parts of the injectors. ... particularly in common rail motors.

What oil, are you using, Incorrect or downgrade oils can have a variety of long term bad effects on diesels ...... top spec correct spec oils can have long term helpfull effects.

The top spec oils are Shell rimular, Mobil Devlac and Caltex dello .... in a grade and oil spec appropriate for your vehicle.

Do you change your oil and filter at the recommended interval.

Do you drive you vehicle round town a lot between trips ....... those trips you do ..... are they long or short .... more or less than 6 hours highway driving each day.

Pretty much all diesels clog up if babied around town. .....The oil does not get hot and stay hot, so the detergents and dispersants don't get the opportunity to do their job ..... carbon and slugge accumulate where it should not .... the PCV and EGR circuits clog, soot gets behind the rings and stops them sealing, the interiors of the injectors get clogged and don't open and close as fast as they should, the faces of the injectors and the combustion chambers get full of carbon and the mufflers get clogged with soot

Getting a diesel out on the highway for a good hard flog, with some good, correct, fresh oil in the sump can do em a lot of good.

Keeping them hot and running at high RPM allows the engine to clean its self and burn off accumulated carbon from being babied.

When I first got my current diesel ...... it took 2 or 3 days solid 100/110kmh highway work before it stopped getting better.

even now, if its been running around town it comes back from a 4 hour highway run driving a lot better

Cheers

I'd strongly look at erg valve being clogged up as per roachie's comment. You can get what is in effect a pre-cleaner whihc removes the vapours beofre gases go back into engine.

Flashlube have a unit been advertised in wa 4wd mag over here and fairly certain others as well.

Ebay also has them as well. I would be interested how it goes with a legal status as far as engine modification goes as i know manufacturers and blue shirts don;t like things being meddled with.

reminds me another thing to get spanner monkey to check out with next service

I agree with RMD, I had a 2011 and now a 2014 Challenger (I tow approx 2 ton) and they always have been serviced and in between filter and oil, I have also chipped mine up and top end power is great. BUT are you towing in top gear??? as this a NO NO lock in 4 gear when towing and when I start to climb hills etc I change back to 3rd. I have found this car never wanting for power yes it's my first 4wd but I am more than happy, I towed for 45,000ks in the 2011 and not one hitch and now in the 2014 I have already got 20,000 towing my average is 13.8 L per 100 and that's for both Challengers. As for smoke blowing yes but only when you accelerating up hill but it only lasts a few seconds, not like some who never service their car.