I own a classic STI (year 2000), recently had a V7? lump dropped in, and at the same time a brand new TD05 from Craig B. Car has been mapped by Duncan.

I have a very unusual problem.

If I attempt to boost from low RPM (wot from 2k for example) as the boost builds (from around 3,250) as soon as I get to around 4k rpm I get wastegate flutter - looking at the boost gauge, the flutter is from 1.2bar - 1.5bar boost. Its audible too, so its not a fault with the gauge. Additionally, if I boost in 4th gear, I get boost creep up to 1.6bar.. which eventually leads to boost cut.

What I have done to attempt a fix:

- Replaced MAP sensor.
- Loosened wastegate right off - Only boosted at 1-1.2 bar, and boosted really late - 4.5k RPM so I reverted back to Craig's markings.
- Replaced 2 port boost solenoid.
- Eliminated the BOV as being the cause by blanking off the BOV pipe completely.
- Performed full reset of ECU (battery disconnect) before making any and all changes mentioned above.

My thoughts - I could attempt to tighten up the wastegate even more, that may stop the flutter but will not help the boost creep. I have not tried this as I do not want to damage the engine.

Does anyone have any ideas on what could be the cause, or could point me in the right direction to get it fixed?

In summary:

Car boosts with wastegate flutter after approx. 4k rpm. It settles down by 5-5.5krpm. It also has boost creep in 4th / 5th gear.

Tried all above fixed, but struggling now!

Please help!!

 

When was it mapped? Have you fitted any more upgrades since the map?
Have you checked all the pipe work for splits?

 

It was mapped about a month ago, no upgrades have been done to the car since. Surge / flutter was never noticed as I drove the car sensibly until the map. When we were mapping, I only boosted when the car was moving and at speed, so it was never noticed.

All pipework was checked, one split was found in a vaccum hose (that lead to the boost gauge), I replaced this, but still have the flutter and surge!

 

Have a word with the mapper,I'm sure he will sort it out,might just need WG dutys tweaking?

 

Did I read right,you have done a dump valve delete?

 

^^^^ what ossett said if you've blocked off the bov that's why you're getting the flutter

 

3 post boost selonoid needed to control boost better and a map tweak should sort this out

 

^^^^^What Sarg said,and I believe the TD range of turbos don't like that!
The flutter is turbo stall.

3 port not needed,I'm still running a 2 port and it doesn't cause boost creep or overboost.
The 3 port gives better control tho so I do intend to fit one.

What I don't get is why after a week of been remapped then you would start messing with WG,fitting new BCS doing DV delete ect ect....
Why not just phone the mapper?

 

Td range can run with blocked BOV and it won't make a difference as it's happening on acceleration/boost so BOV would be closed anyhow

So unless the old BOV was leaking

 

What your getting is Conpressor surge. Not wastegate flutter and not anything to do with the bov.
This is because the compressor is flowing more than the engine can consume and is allowing boost to build and seep back through the blades, this is the noise you are hearing.
It's bad, can kill engines and turbos.
Why can you do?
Reduce the efficientcy of the compressor by fitting an anti surge housing.
Use a smaller compressor.
Or use boost controll to bring the boost in later.

 

On boost with your foot down? Won't make it flutter.
This sounds like true compressor surge, not a bit of pigeon when you back off after a pull.

 

Correct 👍😏

 

Yes I did remove the DV, only for testing on 1 run. It flutters and overboosts with or without. I initially thought the DV was the cause (faulty) but its narrowed it down to the Wastegate

 

This sounds like sound advice, I will get back to Duncan to see if he can do anything map-wise. If not then I will look at the anti-surge housing / boost control.

Thanks everyone for your replies!

 

It's a td05 running 1.5bar
I don't get why you would need to change the compressor housing?
Or use a boost controller ?
A simple tweak of the WGDC will sort boost creep and overboost.
Spending money on fitting extra parts just seems ott!

Is it defiantly a proper TD05 or a Chinese copy?

 

Putting an anti surge compressor housing on is the proper way to fix this problem.
Changing the boost controll settings in the ecu (the wastegate duty cycle as you say) is another way to fix it, but won't yeild the best power.
Boost creep could be too much pre load or too small a wastegate hole, further investigation required.
Chinese turbo or not it seems to be making the flow! Too much so in fact.

 

Which td05? 16, 18, 20?

 

Or big 16g too?
I would guess 20g, most likley to surge

 

20G wont @1.2 bar wont surge at any rpm,
At least, i never withnessed it. or heard of it.

 

looks like its surging at 1.5 bar though? the gauge is bouncing about a bit though by the sounds.

 

as has been said above, it's compressor surge and can be mapped out or mechanically removed.

Either way with a big turbo fitted you shouldn't really be doing WOT runs from 2000rpm as your just loading things up unnecessarily (mapper may have mentioned this when setting up the car).

See if you can get a trip back to the mapper to get it sorted before you start looking into the hardware sides of things would be my advice.

 

Yep, already contacted Duncan. I will be meeting him within the next couple of weeks to get it looked at.

I know I shouldn't WOT at 2k.. but the issue is still there regardless.

The turbo was purchased from Craig Bellworthy, so I have no doubt that he knows what he is doing..!

 

the surge would be more common with higher quality turbos so if it's been ported or anything you'll be more likely to get it. Cheapy ebay turbos are less likely to do it because they aren't as efficient quick tweak to the map should have it sorted - post back results when you get them!

 

Exactly my thoughts too, I see it as an engine problem not a turbo problem! the VE of the engine is not high enough!

 

yeh - technically that is more correct I suppose needs the heads porting and bigger displacement!

 

If you need Duncan I'd suggest calling him. I'm still waiting for a reply to my message sent 3 weeks ago when I had a problem. He used to be great at replying, but I think he must be just too busy now.

 

Lol I am not chasing power with this car. Just looking for a sensible 300bhp, its my daily driver!

I have another car that I am chasing power with!

 

What turbo do you have as a 16g is fine for your target but the 20g that could surge is overkill.

 

20g @ 300hp will be a slow dog to drive. Lag lag lag without the power.

 

For real