decosse Posted February 16, 2004 Report Share Posted February 16, 2004 94 Cadillac STS L37 Northstar I'm trying to diagnose a problem with high HC (1000 count) at idle - there is no problem at 2500 rpm, is only 1 count. So far, I have replaced the FPR, injector seals (seats & stems) & a leaky o-ring at the main fuel-rail connection (this may have been damaged during install of other components however); also have replaced both O2 sensors. Please see a picture of the O2 sensor responses from a GM TECH 2 engine analyzer tool. It looks to me like the front sensor is showing a much different scenario from the rear one, in that it is trying to trim but going to extremes, vs the rear which looks more in a controlling mode. (When you raise rpm to 2500 or so, both amplitudes & duty cycles appear more similar in a "controlling" region. Am I analyzing this correctly, in that there appears to be an issue with the front bank? I have switched all the injectors front to rear & it made no difference. I was hoping to move the problem from front to back & identify (or eliminate) an injector problem. The bank 1 fuel trim is adjusting to the lower counts - especially as the A/C kicks on, it will drop to 108 counts, while rear stays ~ 128 Any suggestions based on the data plots as to what else I should looking for? Any other data I should check to help pinpoint the trouble? Appreciate any assistance! Link to comment Share on other sites More sharing options...
This topic is now archived and is closed to further replies.