My '96 3 cyl has way too much black soot in exhaust pipe. I realize it's caused by a rich fuel mixture, but what can I do to lean it out? Will worn out O2 sensors cause that? I've cleaned the EGR ports and the diaphram seems to be working. The car runs pretty good, but my MPG are suffering. Sure would appreciate suggestions.
It should have the CEL on if you have a bad O2 sensor.
Have you checked your PCV valve?
How do the plugs look?
Air filter?
Any oil consumption?
Yep, changed out all the usual stuff and the light IS on. I was just wondering if an O2 sensor could cause a rich mixture. And, would the rear sensor need to be changed along with the manifold sensor? They're $71 a pop, and that a lot of Big Macs!!!
If it's multi-wire O2 Sensor(s) then yes they cost ...but if it;s single-wire, you can pick them up "new" off eBay for about $30. And yes, O2 Sensor(s) could cause you to run too Rich or too Lean depending on whether it's clogged or it's faulty. As suggested earlier ...have a look at your plugs for deposits ...maybe rich fuel mixture but could be oil beginning to get into the combustion chamber. If you haven't done so already, do a compression check.
Quote:
Originally Posted by igya
Yep, changed out all the usual stuff and the light IS on. I was just wondering if an O2 sensor could cause a rich mixture. And, would the rear sensor need to be changed along with the manifold sensor? They're $71 a pop, and that a lot of Big Macs!!!
If it's multi-wire O2 Sensor(s) then yes they cost ...but if it;s single-wire, you can pick them up "new" off eBay for about $30. And yes, O2 Sensor(s) could cause you to run too Rich or too Lean depending on whether it's clogged or it's faulty. As suggested earlier ...have a look at your plugs for deposits ...maybe rich fuel mixture but could be oil beginning to get into the combustion chamber. If you haven't done so already, do a compression check.
WOW, where do I go now? Did the OBI (O2 sensor) new sensors($75 ea.), Good compression(no charge), new exhaust system($178), tired brain($.25). Still black soot which, I'm absolutely positive, is fuel.
WOW, where do I go now? Did the OBI (O2 sensor) new sensors($75 ea.), Good compression(no charge), new exhaust system($178), tired brain($.25). Still black soot which, I'm absolutely positive, is fuel.
Was compression nearly equal in all cylinders or was #2 considerably lower? Have a look at front O2 Sensor (easy to access) if it's a single-wire going in, it's cheaper type. Before going further with guesses ...as "400Chevy" suggested ...read the codes to determine what problem(s) the check Engine light is indicating (eg. if you're fuel-injected, airflow sensor could also be faulty, telling computer your pulling in more Air than you actually are which then signal injector to flow more Fuel than necessary)
Was compression nearly equal in all cylinders or was #2 considerably lower? Have a look at front O2 Sensor (easy to access) if it's a single-wire going in, it's cheaper type. Before going further with guesses ...as "400Chevy" suggested ...read the codes to determine what problem(s) the check Engine light is indicating (eg. if you're fuel-injected, airflow sensor could also be faulty, telling computer your pulling in more Air than you actually are which then signal injector to flow more Fuel than necessary)
This 3cyl IS fuel injected. I've replaced sensors, and compression is good on all 3 (approx even 180). Plugs are too sooty. The light is off but still burning way too rich. I'm going to investigate the airflow sensor. That makes sense to me. Thanks again!
Forgot to ask ...does Check Engine Ligh come on when Ignition is first turned-on? ...sometimes bulb burns out and we think we have no Codes when in fact we may. (if bulb has burned out the codes should still be stored)
Forgot to ask ...does Check Engine Ligh come on when Ignition is first turned-on? ...sometimes bulb burns out and we think we have no Codes when in fact we may. (if bulb has burned out the codes should still be stored)
The light in on with the switch on, off when cranked. By the way, I appreciate you sticking with me on this. I'm a pretty fair mechanic, but I've only had this little bugger a few weeks and still learning about it. Other than this, I LOVE IT!!!
Rich Fuel Woes!!!
Linear Mode
