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My car hasn't done vast amounts of miles (short of 60000), but already at 30-40000 I would say I noticed it's ability to accelerate has dropped. It is still OK for my use and the fuel efficiency is good (60+ US mpg, 70+ UK mpg). I am guessing reasons would overlap with some of these causes, but wanted to ask somebody more knowledgeable than me.

It is a standard turbodiesel (no common rail or variable vanes) with particle filter (DPF) and catalytic converter, manual transmission (and having read other posts here I think the clutch is fine). It is a 1422cc 3 cylinder engine with a balancing shaft, although I don't think that matters for the arguments.

Things I can think of are DPF (although it does not appear to give any new/unusal problems), air filters, worn bearings giving more resistance, perhaps the turbo is worn/less efficient (why?), but apart from that I am not sure what causes this.

I don't think losing the "new car effect" is uncommon or a problem as such, I am curious about the causes. Thank you!

Community
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nsandersen
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2 Answers2

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I've had this problem on every car I've ever owned over the past 35 years. With only 60k miles, it is highly unlikely to be any of the causes in the link you post.

What is most likely is deposit buildup throughout the fuel system, combustion chambers, exhaust system. Here is the method I use to restore acceleration to 100% capacity:

Start by changing the motor oil and filter with a top synthetic oil like Mobil 1. Substitute one quart of oil with automatic transmission fluid (ATF).

If the car has a PCV valve and EGR valve, make sure both have been replaced and the tubing cleaned with carburetor cleaner. Replace the air filter (and spark plugs, if applicable). Check the intake manifold and vacuum hoses for air leaks.

Add ATF to your gas tank at fill-up at a treat rate of 1 oz. per gallon. Drive the car immediately in stop-and-go traffic for 10 minutes, shut off engine for 10 minutes, then drive on the highway at 70 MPH for 10 minutes. Repeat this cycle multiple times, for at least an hour, and allow the mixture to penetrate at least two days.

When your tank drops to 10 gallons of gas, add two cans (30 oz.) of Cataclean. Immediately drive the car on the highway for 30-60 minutes, then "floor" the car at wide-open-throttle (WOT) from 50-80 MPH. Repeat the full throttle blasts at least six times, but up to 30 times if the cat. & sensors are very dirty. Be sure the cooling system and transmission are flushed and working properly beforehand. Turn the heater and fan on maximum, with windows open, when performing the WOT blasts. Repeat this cycle by driving the car in stop-and-go traffic, shutting engine off for 10 minutes, then driving on the highway (you can substitute highway speed with driving the car in first gear, 25-35 MPH, at high RPM to develop heat).

Cataclean evaporates out of the gas tank after about 24 hours, so be sure to run the car hard right away. The ATF never fully evaporates. The two products – ATF & Cataclean -- work together and will never damage any components of the car.

When the problems are resolved and you refill the tank, continue adding ATF at a treat rate of 4 oz. for every 10 gallons of gas. It will continue to clean deposits. Every fourth fill-up, add one can of Cataclean and drive at highway speeds.

Carguy
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There can be many reasons to your problem. It can be as simple as your turbo charger does not perform or ecu detecting a problem and limiting performance. You should take your car to a shop and get it checked. It won't help to mindlessly use cleaning additives or changing parts which may be in perfect condition.

The cars computer (ecu) records all sort of information about the performance of the engine and it's parts. Detail of the information changes from model to model. They can communicate with it at repair shop to determine exactly what is wrong. In some places they can even measure the performance of the car by running/tesing it on special measuring rigs.

The performance of your car should not get reduced by time as you explained unless something is wrong with it.

Evren Yurtesen
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