69427
The Artist formerly known as Turbo84
Had a problem today which shortened my track day. Towards the end of one of the sessions the engine would run like crap coming through the corners. I initially chalked it up to fuel spillage from hard braking (although it never spilled over before) and an overrich condition. However, when I looked at the WBO2 readout it indicated lean (13-22 A/F ratio) depending on the engine speed and throttle position. This sufficiently scared me enough that I backed out of the throttle and decided to pit early. On most of the drive back to the pits (about a mile) the A/F meter read 18-22. At idle in the pits it stayed in that region. My first thought was a plugged jet (but doesn't the idle circuit do most of the fueling at idle?), or possibly a broken plug or plugwire (and a cylinder just belching out uncombusted air), but the idle (exhaust sound) didn't seem to have any obvious sounds of a cylinder dropping out every 8 firings. The idle sound just sounded "anemic", for lack of a better description. The engine barely had enough power to get the car into the trailer.
If the issue was a fuel pump I would assume that the problem would only be at higher loads, and the idle quality and A/F ratio would be normal. But it wasn't, so I'm initially discounting the pump.
If there was a blockage issue in the secondary jets I would expect any WOT leanness to go away at part throttle, but it doesn't, so I believe the secondary fueling is working (although it is normally a bit rich, and that was the reason for running with the WBO2 sensor today to see how much adjustment I need to do to the jetting).
I didn't hear any unusual mechanical noises in the engine, so I don't think (at the moment) that I've broken anything major. So, unless something obvious jumps out at me I'm going to pull the plugs to see if anything looks suspicious (and probably replace them anyway. The electronic ignition gives me great plug life, and these plugs are several years old). and also take the primary side of the carb apart to see if there's any trash in there.
Any ideas or suggestions are welcomed.
If the issue was a fuel pump I would assume that the problem would only be at higher loads, and the idle quality and A/F ratio would be normal. But it wasn't, so I'm initially discounting the pump.
If there was a blockage issue in the secondary jets I would expect any WOT leanness to go away at part throttle, but it doesn't, so I believe the secondary fueling is working (although it is normally a bit rich, and that was the reason for running with the WBO2 sensor today to see how much adjustment I need to do to the jetting).
I didn't hear any unusual mechanical noises in the engine, so I don't think (at the moment) that I've broken anything major. So, unless something obvious jumps out at me I'm going to pull the plugs to see if anything looks suspicious (and probably replace them anyway. The electronic ignition gives me great plug life, and these plugs are several years old). and also take the primary side of the carb apart to see if there's any trash in there.
Any ideas or suggestions are welcomed.