Boosting by changing bias of ApacheSOLR has no effect I am trying to understand the content-biasing. Somehow it has no effect on our installation.

Stepping through the code learns me that the query-string did change: the modified boost values like &amp;bq=type:audio^1.0 show up, but have no effect on the search-results' sort-ordering or the $result["score"] value. the score remains exactly the same, no matter how high or low a bias is set.

Could it be cached somewhere on the solr server? (clear cache has no effect, code does not hint at caching it). Is this a known bug? Or an issue with the schema.xml? 

Update: 
Enabling debugQuery=on shows me an explain:

1.7849035 = (MATCH) fieldWeight(body:assen in 1952), product of:
  1.0 = tf(termFreq(body:assen)=1)
  4.0797796 = idf(docFreq=900, maxDocs=19600)
  0.4375 = fieldNorm(field=body, doc=1952)
","eskrkz/node/4622":"
1.1041226 = (MATCH) fieldWeight(body:assen in 1682), product of:
  1.7320508 = tf(termFreq(body:assen)=3)
  4.0797796 = idf(docFreq=900, maxDocs=19600)
  0.15625 = fieldNorm(field=body, doc=1682)
","eskrkz/node/8881":"


The field=body worries me. Why does it only search in body? Why not just any text? And why 

An example querystring:

&amp;fl=id%2Cnid%2Ctitle%2Ccomment_count%2Ctype%2Ccreated%2Cchanged%2Cscore%2Cpath%2Curl%2Cuid%2Cname&amp;rows=10&amp;facet=true&amp;facet.mincount=1&amp;facet.sort=true&amp;facet.field=type&amp;facet.limit=20&amp;qf=body%5E40&amp;qf=ts_vid_2_names%5E0.5&amp;qf=tags_h2_h3%5E3.0&amp;qf=taxonomy_names%5E0.5&amp;qf=ts_vid_3_names%5E0.5&amp;qf=title%5E5.0&amp;qf=ts_vid_1_names%5E8.0&amp;qf=tags_inline%5E1.0&amp;bq=type%3Aimage%5E0.1&amp;bq=type%3Aaudio%5E1.0&amp;bq=type%3Adoc%5E0.1&amp;bq=type%3Adossier%5E8.0&amp;bq=type%3Aarticle%5E13.0&amp;bq=type%3Apage%5E2.0&amp;bq=type%3Aprogram%5E8.0&amp;bq=type%3Asubsite%5E8.0&amp;bq=type%3Avideo%5E0.3&amp;start=0&amp;wt=json&amp;json.nl=map&amp;q=FOO"
Turns out the solrconfig.xml for Drupal was not properly installed on the SOLR server. Which made it unable to parse the querystring properl with DisMax.