Hesitant acceleration

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Lynnzer
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Joined: 09 Dec 2004, 19:55
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Hesitant acceleration

Post by Lynnzer »

My C5 X7 2014 model has had an issue ever since I bought it last year.
If you need to check the specs it is a diesel 2 ltr HDI 160BHP Automatic It has only 34,000 on the clock.
It runs well normally, ie when driving uninterupted. However, whenever I slow down to crawling speed, or stop then press the pedal to get moving again, there's a split second hesitancy in the engine kicking in. It's annoying.
I have had diagnostics run on it with no apparent cause as to why it's happening, but as sure as day follows night the problem persists.
If anyone can suggest a cure or give me an idea of what the cause may be I'd really appreciate it as the 12 month warranty is nearly up
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moizeau
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Re: Hesitant acceleration

Post by moizeau »

That sounds similar to my 136 auto, I put it down to the auto box. There's about a second of nothing before it responds. Bit of a pain to start with if wanting to nip past the car in front, now I have got used to it and hit the loud pedal slightly earlier than needed. Be interesting to see what other people with auto boxes (AM6) say.
Lynnzer
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Re: Hesitant acceleration

Post by Lynnzer »

moizeau wrote:
12 Jan 2022, 18:39
That sounds similar to my 136 auto, I put it down to the auto box. There's about a second of nothing before it responds. Bit of a pain to start with if wanting to nip past the car in front, now I have got used to it and hit the loud pedal slightly earlier than needed. Be interesting to see what other people with auto boxes (AM6) say.
You hit the nail on the head there my friend. A quick overtake when there's just about time to do it on a busy road is cut short when I hit the pedal and nothing happens. It's that split second delay that kicks in and makes me back off from overtaking, or indeed to do a quick pull out from a road junction into a line of traffic.
I had a gearbox software update done in September as part of normal servicing, but that had no effect. It's like turbo lag but longer.
aerodynamica
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Re: Hesitant acceleration

Post by aerodynamica »

I think mine is the same. It's not severe but there's a definite delay. I also thought it was the auto box but listening to the engine it seems more like there's a delay in throttle response. Not sure about you guys but I feel that if I press the throttle a bit slower it doesn't seem to delay. Although the overall response might actually be the same
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moizeau
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Re: Hesitant acceleration

Post by moizeau »

Have been thinking about this. I think it's a natural delay while the car changes down the gears. If you in a manual looking for a quick overtake you'd already be in the right gear....waiting. Sitting behind in the auto your probably in 5th of 6th, it needs to change down.
aerodynamica
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Re: Hesitant acceleration

Post by aerodynamica »

Well interestingly I had 4 new tyres fitted on Saturday. I was originally only ordering 2 for the front but I noticed that the tyres on the car were the wrong size - 225/50 R17 when they should be 225/55 R17. I recalled reading on here somewhere about how the tyre size can affect the auto box action. Well, with the right tyres now fitted I went for a spin (always do with new tyres in case they're not balanced properly) and it could be my imagination but I think the delay in throttle response is hugely improved and only seems to remain if I come to a long slow stop at a junction end down hill using engine braking. If I hit the go pedal there is a delay while it gets its act together but even this seems better now.

Have you got the standard tyre size on your car?

As an aside, the tyre place said my wheels were out of alignment. True that after replacing the L & R lower outer suspension bushings i noticed the steering wheel was no longer straight when going straight. But it was Kwik Fit and they used to be notorious for trying to sell you repairs and parts for things they were not always needed.... I declined to pay another £60 on top of the tyres etc but when I got home I used my Track Ace gizmo to check the front tracking and true enough it was more than 2 degrees toed - in. That explains why both front tyres had completely worn outer shoulders....

Anyway, I checked each track rod, left had at least two more threads than right so I adjusted this in that also corrected the steering straightness and a further adjustment to both sides bringing the tracking to zero degrees which I think is right for a 2.0 C5 with 17" wheels.. and another motorway blast shows that the steering is straight and the road feel is much better. It could be my further imagination but I feel the throttle response improved further still.. ? .. can't think why the tracking would affect it really but there might be some reason I can't imagine. Anyway, if your tyres are right then I am not sure what else to recommend for this.
Hell Razor5543
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Re: Hesitant acceleration

Post by Hell Razor5543 »

Years ago CitroJim had a problem with his XM (which had an automatic gearbox). Several forum members commented that the tyres looked wrong. Sure enough, when he checked, he found there was an issue with the tyres (I cannot remember what; wrong size of mismatch), and when he got the tyres sorted out the performance was then sorted out as well.