This is topic EEC says i am running lean... in forum Tech Talk at Northern California Ford Owners .
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Posted by james51381 (Member # 2813) on
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I keep getting code 91 (running lean). The o2 sensors are brand new. I have a 306 with 9.4 compression. Crane 2030 cam, Holley heads ported to flow 260 and 190. Holley intake. For fuel I have a 255lph, 24lbs injectors, and regulator.
At 40 psi, the comp will still give me the code 91. Is this right? I dont want to run too rich and wash out my rings or bearings.
Posted by mtbaughs (Member # 4052) on
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do you have a mass air meter calibrated for 24# injectors?
Posted by Black94 5.0 (Member # 655) on
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I'd buy another left O2...This code is cuased by the left O2 not switching properly...Are you clearing the codes properly?...
Posted by james51381 (Member # 2813) on
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The 02 sensors or no more than 2 days old. I will try switching them though. The MAF is calibrated for the 24# too.
james
Posted by mtbaughs (Member # 4052) on
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Are the O2 wires extended at all?
Posted by james51381 (Member # 2813) on
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my old set were, but these sensors are brand new. I am running out of ideas here.
thanks
james
Posted by Black94 5.0 (Member # 655) on
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Did you try switching the O2's yet?...Did you clear the codes and still get code 91?...
Posted by dynolabs (Member # 4424) on
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I've seen something like this that drove us nuts. This was until we replaced the actual 02 sensor connector plugs. They had gotten stretched and unreliable after long tube headers were installed. Verify the voltages on your 02's with a data scanner. Normally the voltages should be oscillating somewhere between 65mv's to 800-900mv's.
Posted by james51381 (Member # 2813) on
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I had the wiring harness out, and I checked the ohms between all of the wires, and they were fine. I swapped the 02 sensors, and same thing.
james
Posted by mtbaughs (Member # 4052) on
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Is by chance the O2 ground wire (orange) at the back of the intake/heads not grounded? Are you running long tube headers?
Posted by Gt88 (Member # 4361) on
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Do you have a way to monitor the switching voltage of the 02 sensors? That will tell you right there if the sensor is at fault.
Did you swap in the intake recently? Mess around with the vacuum hose on the brake booster? The 02 sensor may be telling you the truth!!
Posted by Gt88 (Member # 4361) on
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Do you have a way to monitor the switching voltage of the 02 sensors? That will tell you right there if the sensor is at fault.
Did you swap in the intake recently? Mess around with the vacuum hose on the brake booster? The 02 sensor may be telling you the truth!!
Posted by james51381 (Member # 2813) on
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I thought the 02 sensors were grounded with the Black and Light green wire with the computer at the battery? It does have a new intake, There is a orange ground there, but the intake is aluminum which isnt the greatest ground. I will ground it somewhere else, but on the Chassis or the Block. I also checked the voltage coming from the ignition switch under the dash and it is getting 12v. So Code 91 is my left (pass.) 02 is lean? I do have a small exhaus leakt at the Head.
Thanks for the replys and help
james
Posted by mtbaughs (Member # 4052) on
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Yeah the orange lead stock is grounded to the back of the head. I've seen many people ground this to the intake without any problems so I would bet thats not it.
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