Hello everyone.

I am seeking some advice for a problem i have with my Grande punto T-jet (stock VL37 turbo).
My car has been chiptuned to around 140bhp, 250nm. Lately i feel like when i do a pull (put my foot down) that the car is holding back somehow. So as i have multiecuscan i connected the interface to the car and started a log to see what was going on (This log was made during a 30km trip with the a/c off, i added it to my post). Now when you take a look at the data you can see that the boost pressure hits the desired boost but after around 3200-3400rpm it drops off. My prime suspect after reading alot on the internet is the turbo actuator spring which could be too weak for the increased boost.

I am wondering whether i can check via multiecuscan if it’s the ecu opening the actuator after 3400rpm or if its the actuator spring that is letting me down. The only parameter I think shows this is the “turbo actuator command” parameter which is described in MES as “This is the duty cycle (in %) of the turbo actuator valve control.”. I did a 2nd gear pull with this (and a lot of other) parameter(s) selected. However I’m not sure how to interpret the data (I also added this file to my post).

Are there any people with knowledge of MES that can help me with this issue?
Greetings, Luuk

(I added the files within a zip. file as CSV files so they can be easily imported and viewed within MES)

I Luuk, what's the idea to Hide a .rar into a .zip file ? Can't open it ...

Bernie

Hi Iuuk, could finally open it with 7zip.

The large file doesn't contain the turbo actuator graph but the actual turbo boost pressure never falls below the desired pressure, which make me assume it is correctly regulated.

The smaller file is definitely too short to tell anything...

BRs, Bernie

Hi bernie,

Thanks for the reply, sorry about the .rar. I was messing about with winrar trying to create a .rar file but realised i could only upload a .zip so i had to convert it again which apparently created a .rar in a .zip.

The intake pressure keeps up with the desired pressure when i drive 'normally' what i mean with it dropping off is when i do a pull (see attached print screen) or do you mean that this is normal? my thoughts are that if the ecu wanted the boost to go down it would lower its desired boost value, but i could be wrong .

Ha, more understandable like this ;-)
The ECU keeps on asking for high boost since your foot is still on the floor, the delivered boost goes abruptly down because someone asked for: either the turbo reached its limit, but we'd more see a "plateau"or the wastegate has opened, which looks more like the curve we see. That should have been modified during the remapping but you already reach 1,6 bar of boost, which I believe is not that bad ...
And BTW, a "weak spring" would also show a plateau, not a drop.

BRs, Bernie

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Hi,

I have some more data gathered today with the turbo actuator data included in a 20min drive or so. Maybe this will shed some more light on things, but do you think it’s the wastegate opening then? and could this be fixed by buying a forge actuator with the appropriate spring?
(I added the file this time correctly I think, so without the .rar in the .zip )

edit: with fixed i mean hold boost longer

Hi Iuuk,

there is obviously something going wrong there, is it the result of wastegate opening too soon or does the turbo efficiency collapse ? very hard to tell :-(
We can clearly see that the actuator command is starting decreasing but the boost pressure keep going down eventhough the desired boost is still at max... Is this a result of the boost pressure going down (so the ECU tells to close the WG) ?, again hard to tell...
The only way I see would be to by-pass the actuator so it would keep the WG closed; you'll have to pinch the hose that connect the regulator valve to the actuator itself, doing so the high pressure from the turbo outlet will not reach the actuator chamber and the WG won't open...
But be EXTREMELY carefull when you'll run the road test: since the boost pressure won't be limited anymore, you may destroy your engine/turbo. If you do the same kind of run as in the pic, you should be able to check the difference, no need to make a 20sec pull ...
And don't blame me if you break Something ;-)

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Hi,

As it stands now i have 2 options either disconnect/clamp down the hose that goes to the wastegate actuator and figure out whether its the turbo itself that loses power. (possibly resulting in instant limb mode/engine damage) Or I could buy a new forge actuator and hope it will fix the problem. So risk of destroying the entire engine or losing €170,00 if it isn't the actuator :hm:

Anyway thanks for the reply

You have a problem.

Hi,

I sadly don't have a dyno graph of the tune. But regarding your comment, shouldn't the vl37 be able to keep up till about 4200-4400rpm instead of suddenly dropping al its boost after about 3200-3400rpm.

I've edited my response.. because i was watching the wrong lines)

I'd say check the exhaust manifold and the turbine housing... it looks like you have one or more cracks.
Takes a few hours to check, ca be done in an afternoon.

Don't buy the stronger actuator, won't help.
You can use a hand luggage scale.. to measure the actuator force, should be around 5.5-6kg to start mooving(i've measured mine recently..but still have to do some more tests to see if there's an actual difference between vl36 and vl37 actuators)

Hmm i'll check that tommorow, thanks for the scale tip

Looks and sounds similar to the issues I was having. As Aurick says, check for cracks. My manifold was cracked and the hot side of the the turbo housing was cracked in several places to such an extent it was probably loosing pressure straight to the downpipe.

I replaced turbo for rebuilt VL36 and updated manifold 55214797 from A500 that supposedly is much less likely to crack.

Cheers

Ben

Hi ben,
I took off the protective cover today, and had a look at the intake manifold and the turbo as far as i could see (couldn't get the heatshield off) there were no obvious cracks. i'll stil have to ask my brother who's a mechanic to check for cracks when the car is on a hoist.

So if there are no cracks i could buy the forge actuator and hope it will fix it. Or I’m contemplating just saying F*it and buy a new turbo like a TD04. TD04's are actually pretty inexpensive compared to vl36/vl38's. I'm wondering however what parts i would need, can you fit the turbo with just different flanges on or is it necessary to upgrade to a different downpipe? (not seeking massive power numbers)

Luuk

My manifold was cracked on the underside and the turbine housing crack would only be seen if removing downpipe..

You'll need all heat shields off and ideally manifold and turbo removed from head to check.

TD04 needs custom manifold or flange and downpipe. Also requires water and oil lines and 380cc injectors plus map for sure.

Cheers

Ben

Hmm i'll have to check it out from bellow the car then. About the td04 do you know if it's possible to use the standard downpipe but modiffy it to fit the td04?

I think protoxide sell the flanges to convert downpipe.

Cheers

Thnx mate

Also do a boost leak test (google/youtube, MCM did a video on it... just fixed a massive boost leak on my t-jet)

Again.. you have a problem, the actuator isn't going to fix a crack or a split hose.... it will just make the turbo work harder to try and keep the same boost... (which it won't be able to)... the turbo will spin faster, will heat up the air more, will wear out faster ..etc etc

In order to check you need to take off the dust/mud shield, the downpipe, and look inside the turbo...
This is where they crack
Hairline cracks are expected and..pretty normal/common, but i have seen ones with big chunks missing/ wide 1-2mm gaps, these won't work.
the Manifold usually cracks underneath, opposite the turbo... might be able to see that from underneath.. or at least you can take a few hundred photos.
You can see here how it cracks.

The stock actuator is fine.. you can see the boost rises fine.. if it was bad the boost would not climb at all.
Less probably:
You might want to check the boost solenoid isn't actually mechanically broken =>stuck opened .... you could do a few graphs with the boost source connected through the solenoid..and a few with it connected directly to the wastegate actuator.... if the graphs are similar you know you need to check it more carefully with a 9v battery on the solenoid terminals blowing through the boost line seeing if the air gets diverted correctly.

aurick86 said:

The stock actuator is fine.. you can see the boost rises fine.. if it was bad the boost would not climb at all.
Less probably:
You might want to check the boost solenoid isn't actually mechanically broken =>stuck opened .... .

Click to expand...

The boost pressure would NOT climb as it does with a defective actuator OR solenoid !
As suggested earlier, disconnect the hose that goes to the actuator and do a SHORT run / plot the graph. If the fault comes from the ECU command,You will see / feel immediately the difference and if you stay gentle with the right foot, ECU will not even go in limp mode. If the faults comes from the turbo (cracks etc), then you shouldn't notice much difference , proceed by slight increases ....

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)