Lightening fast one day, slow on others...

[the1bandit]

Hi all,

Just wondering if anyone else if experiencing the same thing as me on their DS3 THP's..?

I have had a bit of fixing done over the 12 months (New coil pack and harness, Walnut Blast 7000 miles ago, Timing Chain last week). The car sometimes wants to pull forever - lots of torque and power. Other days it can be quite subdued and nothing much power wise.

Is this something mechanical that's not quite right..? Is it outside temperature..? Is there another fault waiting to come out - Friends of mine with fast(ish) car have power there when they want is (SLines/Focus ST)

Any info/help/advice appreciated!

Paul

[Dangerousfish]

Have you driven a vehicle with a turbo before?

[the1bandit]

Have you driven a vehicle with a turbo before?

Hi Dangerousfish

I have driven a few (Subaru, Renault 5) and more recently Sean Leon TFSI.

[Dangerousfish]

Hi Dangerousfish

I have driven a few (Subaru, Renault 5) and more recently Sean Leon TFSI.

Then my assumption that you weren't used to a a turbo is flawed

Without seeing what you mean in action it's going to be difficult for anyone to diagnose. I don't suppose you could get a comparison video of what you're referring to?

When you say it's subdued power wise what do you mean? Taking longer to go through the revs, decreased top speed, turbo not spooling until late in the rev range?

[the1bandit]

OK cheers Dangerousfish - I'm open minded!

I guess what I want is a bit more consistancy. As an example this morning I was happily changing into second, around 2000rpm putting the throttle down and it was pulling hard straightaway all the way until easy 5000rpm. Third continued nicely until about 80mph.

But, some days I can change into second at the same, I get a turbo kick but it's definitely not as strong. It can then take an age (what it seems like) to get to 5000rpm. Nothing like the pulls I should be experiencing.

Although, 4th always seems willing and I'm always impressed putting my foot down in forth

So, it seems like the late spooling you mention. Should I do a few runs with Torque pro..?

[Chris_Blue]

What fuel?

[BenS]

How is the idle on the car, especially on a cold start?
- Lumpy? HPFP could be on its way out.

How many miles you on?
- Anywhere from 30-50k will likely mean fouled spark plugs (although this may not be the case or the cause)

Also a dumb question but intake temperatures? Does this happen more on a hot day or when you've been driving for a long time?

Just trying to think of things which could give inconsistent performance.

Also worth noting that overboost only works in 3rd - 6th gear, so second won't give the same punch as the higher gears.

[the1bandit]

Thanks for the replies Chris and Ben

When I got the car at 21k miles I have put momentum in it. With the exception of half a tank last week when Tesco ran out and I needed it in the garage for the timing chain. It's full of momentum at the moment.

Idle is really nice (wasn't before the walnut blast a few thousand miles ago)

I'm currently at 29500 miles and just had a service (will need to check if they did the plugs or not...)

I get the whole cars go a bit quicker when given cold air. Sometimes I get screaming performance when nice and cold outside, but I have also had really good performance after 30 mins into a drive...

It isn't the end of the world and if I lived closer to SPTuning I would drop in to check it out - unfortunately I live 3 hours away!

Could it be the wastegate..? Can I get someone to look at that..?

[the1bandit]

Also worth noting that overboost only works in 3rd - 6th gear, so second won't give the same punch as the higher gears.

Hi Ben - I have been a lurker on the forum for a while but didn't know about overboost in 3-6. That's interesting...

[BenS]

Hi Ben - I have been a lurker on the forum for a while but didn't know about overboost in 3-6. That's interesting...

Active for like 20s on full throttle, ups boost to 1.3 bar I think

[V3nn3tj3]

I did a few runs with torque. Well odblink and this is not what i'm seeing. Max pressure was 0.67 bar. In all gears flat out uphill.

[BenS]

I did a few runs with torque. Well odblink and this is not what i'm seeing. Max pressure was 0.67 bar. In all gears flat out uphill.

Boost leak? Definitely does not sound right from what I've heard about THP pressures. Unless the OBD is reading consistently wrong. What does it read when not on boost, i.e. on idle?

[V3nn3tj3]

No boost leak as far as i'm aware. On idle it has a negative pressure but don't know how much. Should check.
I do get the nice dump valve sound .

[the1bandit]

Active for like 20s on full throttle, ups boost to 1.3 bar I think

Hi Ben

Do you have any further info on the overboost 20 second thing thats supposed to happen..? Useful to know

I think I will try to do a few runs with Torque app running - maybe a few 0-60 runs.

Thanks for the info guys

Paul

[BenS]

Looking up on it, it might only be on the Racing/Performance engines and possibly the newer Ultra Prestiges actually.

Also, with regards to the 0.67 bar boost, looks like that is normal too. I'm just so used to seeing people's remapped cars with much more boost