#####   
 ##  ##  
 ##  ##  
 ##  ##  
 ##  ##  
         

         
 ####### 
 ##  ##  
    ##   
   ##    
  ##  ## 
 ####### 
         

         
   ##    
 ######  
   ##    
   ##    
   ##    
    ###  
         

    #    
 ######  
   ##    
   ##    
   ##    
   ## #  
    ##   
         

         
         
 # ###   
 ##   #  
 #       
 #       
 #       
         

IMPORTANT: enter the case-INsensitive alphabetic (no numbers) code AND WRITE SOME SHORT summary of changes (below) if you are saving changes. (not required for previewing changes). Wiki-spamming is not tolerated, will be removed, so it does NOT even show up in history. Spammers go away now.


Visit Preferences to set your user name
Summary of change:
'''Ignition Missing''' A rare problem with simple trigger causing mysterious stumbling has been noticed by several people, myself including. This time I found a car where this was easily reproducible. * Volvo 16 valve engine, essentially stock hardware with a larger turbo. It uses the stock distributor ignition and coil, with a simple trigger on the front damper, two teeth and a Honeywell GT1 Hall sensor. * The trigger seems a bit broken, this might be why it shows the problem. The individual power gauge is very useful. It seems there is a 5 (!) degree discrepancy if I calculate correctly (worst to best is 400 us while cruising steady at 2200 rpm). This is going to be fixed later on of course. In retrospect I should have tried lowering the ignition advance to find out if that helps, but it is perfectly fine exactly below and above the problematic rpm so it seems unlikely. Importantly the car ran fine with 1.0.73 and the owner looked me up to do some fine-tuning and upgrade to the latest software, in this case 1.1.92, so we did and off we went to do some tuning. Immediately we noticed how the engine started to stumble at an exact rpm, not only that, we could see the tachometer drop a little as this happened, and because the tachometer took it's signal directly from the negative on the ignition we could figure out that there was simply no spark fired at that moment. A slight lean reading from the lambda was also a clear sign. Why it was so simple to reproduce is because of how the car is driven, it is sufficiently strong to be driven in 5th gear at 1700 rpm, around 60-80 km/h, which is common for normal city driving at cruise speed. Download [http://www.vems.hu/files/MembersPage/MattiasSandgren/vemscfg/nervous-lambda-1700rpm-fw1.1.92.vemslog vemslog] file of the problem. The interesting part is only at the first few minutes of the datalog. * At 1:35 is a steady cruise at 1700 rpm and just below. * At 2:40 is a faster acceleration Next week I will return to the car, this time we can fix the trigger wheel and set it up correctly and see if the problem persists. Any ideas on what to do/not to do?
Optional: Add document to category:
Wiki formatting: * is Bullet list ** Bullet list subentry ... '''Bold''', ---- is horizontal ruler, <code> preformatted text... </code> See wiki editing HELP for tables and other formatting tips and tricks.