What Affects Torque?

[metricspaces]

I did some VAGCOM logging in 4th gear a few weeks ago on my 1999 S3 (APY - 210bhp, 270 Nm). The max torque figure I got was 267.5 NM.

I did some more logging in VAGCOM tonight and the max torque I am getting is 248.5 NM (I did two runs, just to be sure).

The figures for my MAF are the same for both - a max of 165 g/s.

The car feels more sluggish than it did a few weeks ago. Doesn't feel as lively and responsive, if that makes sense. Especially at low revs.

What would cause my torque figures to drop down by 20 NM?

 

[S3KO4]

According to some wiser guys here, the max reading on the standard S3 (not mapped) MAF should be 180 g/s so if the car is 10 years old and the MAF hasn't been changed then it is liekly to be at fault,

to double check you could also take a log with your MAF disconeted, and if the reading is the same then you would probabily won't need to look much further..

hope this helps.

 

[metricspaces]

I've already replaced my MAF. Readings on the old MAF were 140ish.

When I logged a few weeks ago with the new MAF I got 165 g/s from the MAF and 267.5 NM of torque.

Now, a few weeks later, I'm still getting the 165 g/s from the MAF, but the torque has dropped down to 248.5 NM.

So based on that fact that I'm still getting the same figures from the MAF as a few weeks ago, when I was also getting 267.5 NM of torque, I would guess that it is not the MAF? Something else is causing the drop in torque?

 

[s4marsh]

forgive me if this is rubbish but could it be ambient air temps?same flow just less dense=less power?

 

[metricspaces]

Dunno, both runs (now and a few weeks ago) were done at night around the same time on the same road. It's probably marginally colder now. But no massive difference in air temperature.

Just wondering if there's anything I can log \ check?

 

[s4marsh]

are you using a different fuel? even atmospheric pressure could cause a small difference to actual boost pressure i think... i know nothing about vagcom logs

 

[<tuffty/>]

Intake air temps on an S3 can rise very quickly after a first run... Before I did the FMIC on mine, I was logging IAT's of up to 70 degrees in an ambient of 16 degrees.

This is likely to be the main reason your performance feels off. With a decent FMIC this effect is greatly reduced and you will get more consistent power delivery.

<tuffty/>

 

[MintyS3]

Perhaps you have a boost leak? Maybe log the requested and actual boost readings, see if this indicates anything.

 

[Westy]

Did you do all your runs on the same stretch of road? When I did VCDS logs a while ago I noticed different road conditions can cause quite major differences in the readings.

 

[metricspaces]

All runs were done on the same stretch of road. So I did two runs, one up the road and one back down. Each run was just putting it in 4th gear, starting at 1000 revs and bringing it up to the redline, then rolling down for a few mins, turning around and going again.

When I did the runs a few weeks ago I was getting in and around 267.5NM for the two runs.

Now, when I did the runs last night, I was only getting around 248.5 NM for the two runs.

I logged 115 for boost and I'm getting all the boost that is being requested - max boost being requested is around 1800mbar.