Diesel Car Delay in Acceleration

[zakmuh]

Hi,

What causes a delay in acceleration in a used cars?

In a brandnew or new car when you touch the accelerator pedal, the car just accelerates smoothly and quickly. Basically it has a very quick response. But when you do same in a diesel car, say a car with 150k mileage, there is a delay and response time is late. You feel like you have to press it all the way down to move that car?

Is this due to:
Clogged up air intake system - carbon build up in the intake manifold + throttle body and EGR valve clogged + blocked intercooler OR
Blocked injectors OR
faulty glow plug OR all of these combined?

Thanks in advance

[Mars]

None of the above. It's just newer technology that eradicates so much turbo lag.

[davetrombone]

Could be caused by numerous different issues, bad sensors (MAF is common), EGR valve not closing fully, leaking boost hose or intercooler, incorrectly installed timing belt etc..

[zakmuh]

Thanks for your replies.

I've driven a same car as mine with low mileage and it's pick up is very good and acceleration is smooth and nice. To start with, I'll try cleaning up everything you all have mentioned and the followings and see if that'd make a better difference:

Intake manifold
Throttle body + EGR
Intercooler system with MAP sensor

I'll keep you posted

[zakmuh]

A good video to watch

https://www.youtube.com/watch?v=3B-a8WJtd8w

[stevieturbo]

zakmuh said:

Hi,

But when you do same in a diesel car, say a car with 150k mileage,

So you're saying two absolutely identical cars, except one has 150k ? then clearly that car has a fault if it does not behave the same as the lower mileage car.

Otherwise, it's all gibberish.

[zakmuh]

Yeah...there are no fault codes.

Anyways as we speak, I'm changing and servicing almost all engine related parts, including the injectors. Lets see how it goes

[Grayedout]

Check the adjustment on the throttle cable. Almost every second hand car I've bought has required the throttle cable to be adjusted and tightened.

[GreenV8S]

zakmuh said:

I'm changing and servicing almost all engine related parts, including the injectors.

Do you have any reason to believe any of them are faulty?

[aka_kerrly]

Grayedout said:

Check the adjustment on the throttle cable. Almost every second hand car I've bought has required the throttle cable to be adjusted and tightened.

You've done well to have never bought a car with a drive by wire throttle. Most cars from the last two decades have them.

throttle lag & Drive by wire is a subject that really gets some people going

[InitialDave]

Are you definitely comparing the exact same model/generation for your "old vs new"?

What car is it, and what year?

[NMNeil]

You don't say what car it is, but I'll add the possibility of a plugged catalytic converter or DPF, if it's fitted.

[stevieturbo]

Grayedout said:

Check the adjustment on the throttle cable. Almost every second hand car I've bought has required the throttle cable to be adjusted and tightened.

Most diesels for the last 25 years have had no throttle cable.

[Jazzy Jag]

Go cheap, early.
Start by changing the fuel and air filters.

[zakmuh]

Hi All. I've got an update.

My car has better, much better performance now. Smooth and quick acceleration + improve fuel economy. So far I've done the followings but my work is not complete yet. Still on it...:

Cleaned EGR body and valve(+actuator inside) + throttle body + intake manifold, including swirl flap
Changed glow plugs
Cleaned MAP sensor (not MAF sensor) which is found in the hose coming out of the intercooler


I'll keep you updated as I go through my work...

Edited by zakmuh on Thursday 25th November 17:46