Very poor engine performance

[jhpratley]

Hi All

Recently had my Leon 1.5 150 on the dyno while getting it tuned, and stock numbers it was giving 117bhp when it is meant to be giving 150 brake - my cars done 108000 miles and the guys at the tuning place advised it could be something like a intake manifold being clogged up, does anyone on here have any ideas/experiences as to why it is performing so badly?

Thanks a lot

 

[black_sheep]

What was measured?

Diesel or Petrol?

For a start 150 is a PS, measurement so stock car is c.147 bhp. This is also a crank measurement - ie engine connected directly to dynamometer.

If the 117 bhp measurement is at the wheels, where parasitic draw of gearbox, drive train, binding brakes, friction etc then this is about right. Do they have any dyno runs for a similar vehicle logged? What do they achieve? - the 150 ps is fitted to loads of VAG cars.

There is also a big variation between dynos

If the tuning company gave an answer of intake manifold could be clogged up, I wouldn't be trusting them with my car!

Did they check any pre-existing DTC (fault codes) or check airbox/filter/MAF sensor?

 

[martin j.]

When was it last serviced? Air filter, plugs? Even fuel type can affect power, as does ambient air temps. Usually dynes can be calibrated optimistic -IMHO- this could be reading low though.

 

[jhpratley]

What was measured?

Diesel or Petrol?

For a start 150 is a PS, measurement so stock car is c.147 bhp. This is also a crank measurement - ie engine connected directly to dynamometer.

If the 117 bhp measurement is at the wheels, where parasitic draw of gearbox, drive train, binding brakes, friction etc then this is about right. Do they have any dyno runs for a similar vehicle logged? What do they achieve? - the 150 ps is fitted to loads of VAG cars.

There is also a big variation between dynos

If the tuning company gave an answer of intake manifold could be clogged up, I wouldn't be trusting them with my car!

Did they check any pre-existing DTC (fault codes) or check airbox/filter/MAF sensor?

Petrol, power to the wheels, and no they said theyd never had anything such high milage, and yes before they dynod they checked codes and airbox/filter are both brand new, not sure about maf.

When was it last serviced? Air filter, plugs? Even fuel type can affect power, as does ambient air temps. Usually dynes can be calibrated optimistic -IMHO- this could be reading low though.

last serviced 2 weeks ago fresh oil and filter, not sure about spark plugs

 

[rdraheim]

honestly 147 crank hp and 117 whp might be about right depending on dyno/conditions.

a quick search of VW 6-speed cars shows between 10-15% driveline loss (yours is 20%).

also, VW tends to be conservative with their ratings.

105000 miles could contribute to an additional 5-10% loss (slight compression loss, slightly dirty injectors, carbon building on intake valves ... etc) ... how tight are your piston rings measured via compression testing (real test) or oil consumption (makeshift test)?

 

[jhpratley]

Should've clarified, it is a DSG, but I have not had a compression test so might have a look into getting that done

 

[jhpratley]

honestly 147 crank hp and 117 whp might be about right depending on dyno/conditions.

a quick search of VW 6-speed cars shows between 10-15% driveline loss (yours is 20%).

also, VW tends to be conservative with their ratings.

105000 miles could contribute to an additional 5-10% loss (slight compression loss, slightly dirty injectors, carbon building on intake valves ... etc) ... how tight are your piston rings measured via compression testing (real test) or oil consumption (makeshift test)?

Just had a look at dyno sheet

Power at wheels stock was 102bhp - went to 117 at wheels after tune
Torque at wheels stock was 177Nm - went to 206 at wheels after tune

obviously way lower, much below even stock for both

 

[rdraheim]

Should've clarified, it is a DSG, but I have not had a compression test so might have a look into getting that done

Not an expert, but through online eyeball analysis ...

I would expect VWs rating to be conservative as VW AG wants all of their engines to perform at the specified PS anywhere on the planet (hot weather and/or high altitude being the toughest) ... I would expect a North American/European environment to yield about 5-10% above the specified PS output on pump fuel and fan cooling on the dyno.

I would expect 10% loss with a six-speed manual at a minimum (crank to wheel). I would naïvely expect greater loss via DSG (perhaps 5%).

I am happy to be corrected as I haven't dyno'd a car in a very long time.

20% loss with a DSG and 108k mi would be a decent result IMHO, which is where you're at.

 

[rdraheim]

Just had a look at dyno sheet

Power at wheels stock was 102bhp - went to 117 at wheels after tune
Torque at wheels stock was 177Nm - went to 206 at wheels after tune

obviously way lower, much below even stock for both

15% hp and Nm increase with an ECM tune?

I'd find 102 whp below the low end of my expectations, but I don't have a lot of experience with DSGs as I'm old school and like a 6-speed.

 

[jhpratley]

15% hp and Nm increase with an ECM tune?

I'd find 102 whp below the low end of my expectations, but I don't have a lot of experience with DSGs as I'm old school and like a 6-speed.

ECU remap and DSG tune, might have a look into compression hopefully nothing goes too expensive

 

[SuperV8]

Hi All

Recently had my Leon 1.5 150 on the dyno while getting it tuned, and stock numbers it was giving 117bhp when it is meant to be giving 150 brake - my cars done 108000 miles and the guys at the tuning place advised it could be something like a intake manifold being clogged up, does anyone on here have any ideas/experiences as to why it is performing so badly?

Thanks a lot

Carbon deposits due to direct injection slowly block up the inlet ports/valves would be my guess.

You can get something done called bead/walnut shell blasting - so they take of the inlet manifold, and blast walnut shells in the inlet port (with closed valves).

 

[mty12345]

What super V8 said above!!

All these direct injection engines suffer from carbon build up in the manifold and/or on the valves at high mileage.

 

[jhpratley]

Carbon deposits due to direct injection slowly block up the inlet ports/valves would be my guess.

You can get something done called bead/walnut shell blasting - so they take of the inlet manifold, and blast walnut shells in the inlet port (with closed valves).

So you think I get the blasting, then get it re re mapped as im assuming the increased airflow wouldnt be right for the old map

 

[mty12345]

Depends what sort of map it is. If it's just a generic stage one map then it will just adapt. If they we're custom mapping it then the map will probably need adjusting.