boost issue - nothing happens before 4000 RPM.

[Vilhelm]

Well I got my new turbo installed. This late boost issue happened before I installed the new turbo though.

My turbo starts boosting, but nothing really happens until 4000 RPM. At 3500+ it boosts 0.5->1.4 bar but nothing really happens before it hits 4000 RPM, then it really kicks me back in my seat. I have cleaned my MAF (idle is a lot better). My O2 sensor was changed about a month ago.

What can be the problem?

Mods are in signature.

Thanks,
Vilhelm

[terrybullwon]

a remap might help

[Vilhelm]

It was mapped before the new turbo was installed (2 weeks ago), but the tuner said there was no need for a remap (I bought the turbo from him).

[alg]

It was mapped before the new turbo was installed (2 weeks ago), but the tuner said there was no need for a remap (I bought the turbo from him).

If you have fitted a different turbo it will need re mapping. It sounds like you have fitted a bigger turbo with a slower spool up. A remap will be needed to minimise this.

Was your previous turbo OEM ?


A quick 'google' indicates you have fitted a 'huge turbo which really only starts to kick in at 5000rpm'
You will need the car remapping to reduce the 'lag' but IMHO you will not get rid of it completely.
You will just have to 'enjoy' the wait to 5000rpm and hold on for the ride. And they say the RS2 has lag

But really contact Mihnea and Doug at MRC. They will at least give you some idea of the best way to optimise that set up

[Vilhelm]

Gave him a call now and he said there was no need for it. hmm.. Both are T3/T4 turbos. The new one can get 30 more HP though (480 compared to 450).

Also, it IS boosting, just that nothing happens. It's @ 1+ bar @ 3700 RPM, and it's still slow till it hits 4000. It's like their is an on/off switch with either full boost or no boost.

Don't think it's that fast up top as it should be. Too many damn problems with this car.

[Jamo]

I dont think there's anything wrong, it's just the fact you have got a large turbo with a big lag.

You've described the cars as per the early days ala Audiman before people bought garretts dual BB like the 2871R & 3071R

I would have gone for the 3076R for your target aims and it would have kept a good spool up time still.

[Vilhelm]

Same spoolup as my old one. My old one had a ****** exhaust blade. I see there is boost, just nothing happens.

[Vilhelm]

Could the timing belt have slipped a tooth or so?

[Jamo]

What exhaust cam have you got in the car? If it's an RS2 it could be incorrectly setup.

I'd still say this is the characteristics of your turbo but then you'd need to find another car with this turbo installed to see if it has the same characteristics.

[dkw_dude]

I have similar problems sometimes, and in my case I cured some of it by going over the hose clamps, some of them had loosened up. It seems to me that even very small air leaks can make the car slower.

[porkkis]

I think your new turbo is surging.

[4WheelDrifter]

It was mapped before the new turbo was installed (2 weeks ago), but the tuner said there was no need for a remap (I bought the turbo from him).

That still doesn't sound right to me.

[Vilhelm]

My mechanic (Jonus) is going to look at it tomorrow. I will let you guys know Thanks for all the suggestions.

[Vilhelm]

He suggested re-attaching the BOV. If it still had problems after doing so I should try another MAF (he told me that the surge damages the MAF).