Stock GTI Boost Logs

[Slow_Polo]

Hi all,

I've just been doing some logging of my stock GTI with Torque Pro. I know VCDS or ME7 would be better, but I haven't bought VCDS yet (still using Lite) and haven't quite figured ME7 out either .

Im wondering if my boost reading is correct, or if have an issue bleeding my boost off towards high RPM. Heres a graph of two runs I did in 3rd gear.




I have read that the max of ~ 9psi is right for a stocker, along with the spike, but is it normal to drop off so much towards redline?

All my knowledge comes from turbo hondas, but they like the boost to hit the required pressure without a spike and sit there rock solid.

Cheers
Luke

[sambb]

The peak looks ok but I don't remember a drop off to 2 psi at redline being normal and the over/undershoot after the peak looks a bit ragged. If you look at Gavs build thread at about page 5 onwards he has included a standard tune dyno run you could compare to. But then again the required and actual boost traces do mimick one another quite closely. If the actual was well different to the required I think thats when you'd start to stress. But it seems that the MAP pressure is matching what the ECU/N75 is asking for.

[Slow_Polo]

Thanks Sam, but this is just a log of 2 different runs, not actual vs requested. Torque cant log requested boost.

Ill have a look at Gavs thread now.

[sambb]

oh ok. then its hard to know if the actual you are logging is following the boost request. I think your peak looks fine. The trail off down to 2psi is a bit steep though. i'll try to find gav's plots.

[sambb]

Gavin's cheapy but getting more expensive GTI ;)

[Slow_Polo]

Hmm, it looks like Gavs stock was spiking up to 12.5psi, leveling off at 10, then down to about 6psi at max rpm.

From what I've read 12.5 seems a bit high for stock? May the "stock" one click tune isn't quite stock?

Ill have to hook up my actual boost guage and see if it is reading the same as the logs.

[sambb]

assuming gav's is correct, your overall curve looks the same but scaled down everywhere. Could be a shagged wastegate actuator spring, boost leak, or N75 failed. You can check the condition of the wastegate actuator spring easy enough by simply unplugging the N75 boost control solenoid. The car should boost to and sit at 6-7psi. If it is less then thats your prob. Make sure you clear codes after that test though. If you can try someone elses N75 that would be quick and easy to check too. Beyond that I'd be looking for boost leaks..

[h100vw]

I know it's hard for most people, but you can't look at actual boost without requested. If the intake temps are through the roof because of no airflow over the intercooler for example. Also important to consider is the MAF output. Even though boost drops away, it doesn't mean there's less airflow. It does mean that the turbo can't keep up with the rate at which the engine is consuming air.
The comment about turbo Honda's really is just how the tuner likes to do things. VW tunes could be written the same, if required.
Really need to see a full set of logs, boost, fuelling and timing to accurately assess what's happening.
Gavin

[h100vw]

Hmm, it looks like Gavs stock was spiking up to 12.5psi, leveling off at 10, then down to about 6psi at max rpm.

From what I've read 12.5 seems a bit high for stock? May the "stock" one click tune isn't quite stock?

Ill have to hook up my actual boost guage and see if it is reading the same as the logs.

This was with a replacement turbo installed and possibly I had the actuator cranked a bit high, as I did remove and refit it. 10 PSI is probably the correct figure to reference.

[Slow_Polo]

Thanks guys.

I guess ill have to try to get ME7 logger working next weekend to log actual vs requested. Any tips anyone?

If that fails ill try unplugging the N75 and see what I get.