[Gordy]

I've noticed that my Abbott Aero makes a lot of spitting noises and occasionally backfires. I'm not sure if this is due to my SS exhaust or if I have a problem with my mixture. Is there a simple test to check that I'm not running too rich? Can a common or garden garage check the mixture or does it have to be a place that knows Saabs and has the appropriate kit?

If Billj or Ylee reads this, can you listen to it on Saturday?

 

[billj]

Hi, Gordy. Yes, I can listen on Saturday, but I'm not sure listening will tell very much. I'm not very familiar with the Abbott exhaust system and I've been told it tends to pop a bit.

Any garage that can do an MOT should be able to check the mixture at idle and fast idle. My Aero was running lean a while ago due to a faulty temperature sensor. So much so that it failed an MOT due to emissions. The plugs looked a bit white, but to be honest, they look a bit white anyway and I've only just found out I've been running rich recently due to overdoing my fuel pressure modification. That was under load, however, and the idle and fast idle emissions were within spec. (just) for the MOT.

 

[mark e]

Hi Gordy,

Do you really mean backfiring? Or mild "popping" on overrun. IIRC you're running an Abbott SS system with cat bypass, in which case the popping is quite normal (mine does it). I understand it's caused in part by the fact that there's a longish un-muffled section of pipe that you different gas velocities in etc etc... or something like that

Sorry that's not a very good technical explanation, but it is normal on any car with that type of exhaust configuration.

However I've not heard any "spitting" so maybe there's a problem elsewhere...

 

[Gordy]

Mark,

It is during overrun that I notice it and there are 2 distinct noise. There is my 'spitting' which I'm guessing equates to your 'popping' and is there all the time, and the louder 'POP' which happens occasionally.