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Author
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Topic: EEC says i am running lean...
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james51381
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Member # 2813
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posted
 
 
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.
Posts: 122 | From: Newark | Registered: May 2003
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mtbaughs
Road Racer
Member # 4052
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posted
do you have a mass air meter calibrated for 24# injectors?
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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
I'd buy another left O2...This code is cuased by the left O2 not switching properly...Are you clearing the codes properly?...
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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james51381
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Member # 2813
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posted
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
Posts: 122 | From: Newark | Registered: May 2003
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mtbaughs
Road Racer
Member # 4052
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posted
Are the O2 wires extended at all?
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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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james51381
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Member # 2813
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posted
my old set were, but these sensors are brand new. I am running out of ideas here.
thanks
james
Posts: 122 | From: Newark | Registered: May 2003
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BlackNGold
CaliforniaFords.com
Moderator
Member # 655
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posted
Did you try switching the O2's yet?...Did you clear the codes and still get code 91?...
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-SLOWER TRAFFIC KEEP RIGHT-
Posts: 5132 | From: Bay Area, CA | Registered: Dec 2001
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dynolabs
New Member
Member # 4424
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posted
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.
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Dyno Labs, LLC
SCT Tuning
San Ramon, CA
(925)831-8240
info@dynolabs.net
Posts: 5 | From: San Ramon, CA | Registered: Apr 2004
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james51381
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Member # 2813
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posted
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
Posts: 122 | From: Newark | Registered: May 2003
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mtbaughs
Road Racer
Member # 4052
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posted
Is by chance the O2 ground wire (orange) at the back of the intake/heads not grounded? Are you running long tube headers?
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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RedBaron
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Member # 4361
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posted
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!!
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1988 4i coupe,
88 gt
85 ttop-
Posts: 830 | From: S.S.F. | Registered: Apr 2004
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RedBaron
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Member # 4361
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posted
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!!
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1988 4i coupe,
88 gt
85 ttop-
Posts: 830 | From: S.S.F. | Registered: Apr 2004
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james51381
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Member # 2813
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posted
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
Posts: 122 | From: Newark | Registered: May 2003
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mtbaughs
Road Racer
Member # 4052
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posted
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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R.I.P. Charlie Bruno Dec 2001
Posts: 2019 | From: Boise, Idaho | Registered: Jan 2004
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