Car losing acceleration

jasonb

Hi there,

I drive a 2002 2ltr 406 Diesel.

I've noticed over the last few months that sometimes the car will slow down, even if I'm accelerating. It normally happens when I'm on on the motorway. So, for example, yesterday I was coming from Cork, doing about 120kph to 130kph, around 2800rpm in 5th gear.

Sometimes, once the motorway started going up a hill ( even a gentle one ) the car would start to slow down, and even if I accelerated fully, it would still slow down. At one stage I went from 130kph to approx. 90kph before it got going again. It normally speeds up once I start going downhill.

Now, normally I'd think that my car just doesn't have the power to get up the hill, though I'd a thought a 2ltr Diesel should be able to handle it. But I've only started to notice this in the last few months, never before ( I bought this car new ). Also, sometimes it has no problems with hills. And finally, sometimes I can almost feel the engine 'kick' back in again, sometimes when I'm going downhill, but sometimes when I'm still going uphill.

So, any ideas? Is it just that my car doesn't have the power to take a gentle hill in 5th at 130kph? Or is there something wrong that's causing me to lose acceleration?

Thanks!

J.

CarMuppet

jasonb wrote: »

Hi there,

I drive a 2002 2ltr 406 Diesel.

I've noticed over the last few months that sometimes the car will slow down, even if I'm accelerating. It normally happens when I'm on on the motorway. So, for example, yesterday I was coming from Cork, doing about 120kph to 130kph, around 2800rpm in 5th gear.

Sometimes, once the motorway started going up a hill ( even a gentle one ) the car would start to slow down, and even if I accelerated fully, it would still slow down. At one stage I went from 130kph to approx. 90kph before it got going again. It normally speeds up once I start going downhill.

Now, normally I'd think that my car just doesn't have the power to get up the hill, though I'd a thought a 2ltr Diesel should be able to handle it. But I've only started to notice this in the last few months, never before ( I bought this car new ). Also, sometimes it has no problems with hills. And finally, sometimes I can almost feel the engine 'kick' back in again, sometimes when I'm going downhill, but sometimes when I'm still going uphill.

So, any ideas? Is it just that my car doesn't have the power to take a gentle hill in 5th at 130kph? Or is there something wrong that's causing me to lose acceleration?

Thanks!

J.

Well Jason the fact you've written a post about your car probably means there is something amiss with it recently....

It's hard/difficult to diagnose a problem without seeing/hearing/smelling a car but at a guess I'd say it would be one of three things (assuming it's a turbo diesel):

1 - Air MAF sensor - dirty - needs to be cleaned/replaced.
2 - Wastegate leaky or sticking.
3 - Turbo charger problem - air leak, bearing problem, oil starvation etc.


- How many miles are up on your car?
- Any work doen on the car recently?
- Does it idle ok?
- Does it surge when coming to a stop, for example, up to a red light?
- Is it running 'hotter' than ususal
- Will it pull up a hill at say 30mph in gear without vibration? Do you notice any shuddering from the clutch when taking off from a standstill?


Anyone else?

Row

CarMuppet...you have it well covered there...:)
I suppose if you got fault codes read as this should pick up a low turbo boost
pressure fault...egr valve problems etc.
As above it could be the early stages of a slipping clutch.

jasonb

Thanks for your replies! Please excuse my ignorance of my own car, and hence not knowing the answers to some of your questions!

Firstly, I should have said that the car recently ( a couple of weeks ago ) got its 140k miles service ( including new timing belt etc. ) so I'm guessing some of your suggestions ( filters etc. ) should have been covered by that? Also, I've had this problems a few months now, so it wasn't the service that caused the issue.

It's a Peugeot 406 Rapier, with is a 2ltr, 110bhp HDI engine. It seems to idle ok, I haven't noticed it running hot , surging ( apart from maybe when the power seems to 'kick' back in and I start to speed up again ), and I haven't noticed it shuddering.

Did I miss anything?

J.

BESman

I had a similar problem. Back box was clogged with dirt and debris, replaced it and acceleration returned to normal. So maybe get your exhaust and back box checked, simple job.

jasonb

Thanks a lot, I'll give that a go!

J.

raymon

The clutch on your car is gone ... probably