Hi,

I got my car dyno tested yesterday. The results was good and bad.

The good part: I have lots of torque, 343Nm.

The bad part: When i pass 3500rpm, the torque drops fast, so i only get 150kW (200BHP?) peak. It seems like something is holding the engine back. I have an almost completly flat power curve between 4500 and 6500rpm. It only variate a couple of kW below and above 148kW (199BHP).

Could it be the wategate that don't allow the turbo to keep it's pressure. Or maybe the injectors or fule pump get overloaded? :confused:

Engine mods are:

V-tech tuning

Forge FMIC

K&N air filter in original air filter box

Cold air intake. 3" aluminium hose from the spoiler to the air filter box.

2,5" catback exhaust

GFB Hybrid dump

ECS Race N75 valve

Any help is welcome.

Great torque figures. Did you get any surging on the n75f?

Why the none standard N75? Is that correct for your turbo and allowing correct boost.

IMHO use a recirc valve not a dump as the turbo expects this.

Which engine is this a 1.8T?

Were the mods fitted after or before the map?

If all else fails I'd blame the map software.

What's "surging"? My technical english isn't the best. :(

The map was made after all changes, except the FMIC.

The engine is a 1.8T AUQ.

Surging is a feeling like you're going on and off the throttle, except that you aren't.

Is the stock airbox causing a restriction in airflow?

What about timing - is the ECU holding back becuase the timing is too high?

Why the none standard N75? Is that correct for your turbo and allowing correct boost.

IMHO use a recirc valve not a dump as the turbo expects this.

Which engine is this a 1.8T?

Were the mods fitted after or before the map?

If all else fails I'd blame the map software.

I agree recirc valve should be used,you should be getting a fault code and possible limp mode with an atmos dv.

Log block 115 with vag-com if you have it and you will be able to tell if the boost is meeting the requested levels set by the ecu. The torque on my current remap drops off at the latter end too, this is due to the levels set by the map.I think this is to conserve the turbo more but i want a more aggressive map so i think i will upgrade soon .

If you were to get a custom remap after fitting the Fmic you should see quite a decent increase in the bhp at the top end of the rev range due to the colder air going into the engine.

Why did you change to a Ecs race n75 out of interest?

Great torque figures. Did you get any surging on the n75f?

No surging (hey, i've learned somthing! ) as i can recall. The NCS valve was installed due to promice of a more controlled boost curve. No sudden fast drops on boost.

But it feels like surging above 4000rpm now. Maybe i should reinstall the original N75?

IMHO use a recirc valve not a dump as the turbo expects this.

The GFB dump is not a full atmos dv. Besides, there where no fault codes before the dyno run. I'll check the car again after work today. Maybe a code was saved during the run.

Is the stock airbox causing a restriction in airflow?

What about timing - is the ECU holding back becuase the timing is too high?

As far as i know, the stock air box is good for atleast 300bhp.

Log block 115 with vag-com if you have it and you will be able to tell if the boost is meeting the requested levels set by the ecu. The torque on my current remap drops off at the latter end too, this is due to the levels set by the map.I think this is to conserve the turbo more but i want a more aggressive map so i think i will upgrade soon .

I'm shure you don't loose torque from 3500rpm. My torque curve lokks like this:

343Nm @ 3500rpm

300Nm @ 4000rpm

295Nm @ 4200rpm

310Nm @ 4600rpm

280Nm @ 5000rpm

250Nm @ 5500rpm

240Nm @ 6000rpm

200Nm @ 6500rpm

If you were to get a custom remap after fitting the Fmic you should see quite a decent increase in the bhp at the top end of the rev range due to the colder air going into the engine.

A new map will be done during the summer. If i get this right, i'll go for 3" downpipe with 100 cell race cat and Forge intake hose (air filter to turbo) with remap when i've saved money enough for it.

I've also been told that it might be the air mass sensor. Anyone know wich block i should logg in vag-com to check it?

Easy way to check the air mass sensor is to just unplug it and see if the car runs better. If it does, that's your problem.

More on the surging thing. Is the rolling road an induction load or an old-fashioned water-wheel brake? I'm just remembering something from Dave Walker about an engine that looked ok on the induction dyno, but was unusable on the road. The problem was that the dyno could react to the surging faster than the car's EMS could and smoothed out the surges.

Easy way to check the air mass sensor is to just unplug it and see if the car runs better. If it does, that's your problem.

More on the surging thing. Is the rolling road an induction load or an old-fashioned water-wheel brake? I'm just remembering something from Dave Walker about an engine that looked ok on the induction dyno, but was unusable on the road. The problem was that the dyno could react to the surging faster than the car's EMS could and smoothed out the surges.

I think is a induction load. It'a a brand new brakebench.

Actualy, the surging, or something similar, is vissible on the dyno result. The bhp-curve gose upp and down between 198bhp and 203bhp five times from 4700 to 6500rpm.

I'll post the dyno result later today, so you can se the complete curve.

Block 002 is for maf, block 115 is for boost pressure.

Here's the dyno pull. Is it surging i see between 4700 and 6400rpm? Red line for power, and black for torque. The dip in torque at 4100rpm is also a mystery to me.

And here's a log of the boost pressure. I think it flickers a lot. The gray curve is for actual presure.

Your boost looks to be all over the place,nice spike though .

I would start by putting the n75f back on and work from there,with a bit of luck it may smooth things out.

Here is a log taken from mine to compare

Have you heard any hissing lately like an air leak?

Ok, i'll start with reinstalling the N75F.

No, no hissing detected, besides the turbo spool up. I get no fault codes detecting leaks either.

I'll plugg the dump to, so its a full recirculate valve.

Block 002 is for maf, block 115 is for boost pressure.

Thanks.

I've logged group 002 too, so i have the air mass sensors actual readings. But what use is it to me? I have no idea what the readings should be, of the actual redaings are wrong.

Your maf should peak at around 150-155 g/s for that sort of power.

Have you any idea how many miles the turbo has done?

According to vag-com, my maf peaks 169,14g/s

The turbo is the original k03s. The car has gone 54000km. I think that's about 34000miles.

According to vag-com, my maf peaks 169,14g/s

The turbo is the original k03s. The car has gone 54000km. I think that's about 34000miles.

Iirc thats sounds about right

Yeah, not bad then,i was comparing the figs i quoted compared to mine.I think mine must be knackered :eek:.

Did you put the f valve back on?

No, i haven't got around to do that yet. I'm not at home this weekend, so i have no tools avalible. Will do it tomorrow night or monday.

All right, now i've refitted the stock N75.

The result:

Slight boost drop at 3800rpm.

Still a bit out of control over the whole range, especially from 5300rpm.

Boost drop at 6200rpm. Down to 1400mbar then back up to 1800 mbar @ 6600rpm, then down again at 6700rpm. Rev limit is 6800rpm.

I,ve also lost the nice boost spike i had at 3200rpm. That should result in a 15-20Nm loss in torque.

I've plugged the GFB dump so it's a full recycle valve. Still, i get fault code 17608. Is that the DV? Maybe i should buy a Forge Closed Loop Diverter Valve instead?

I've compared curves from my engine with N75F, and N75 Race. Although i have a sligtly more controlled boost with the N75F, i gain up to 11bhp with the N75 Race.

I've got the numbers by logging group 120, and made an excel graph with torque and power.

To me, that indicates the N75 Race is not the problem, so i'll reinstall it tomorrow.

So, might the wastegate be the problem?

It still doesn't look good,i don't suppose you have done a block 118 run to see what the n75 is doing?

It still doesn't look good,i don't suppose you have done a block 118 run to see what the n75 is doing?

You maybe right about the wastegate after all but doesn't a weak spring cause it not to hit peak boost in the first place?

No, i haven't done a block 118. Will do it tomorrow for you.

What am i looking for? Boost pressure before throttle valve?

Weak spring where? In the diverter valve? That's why i'm thinking about a Forge DV instead.