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smells rich, but BLM's high

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Old Aug 10, 2008 | 07:01 AM
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the blur's Avatar
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smells rich, but BLM's high

my LB9 TPI smells rich by the stench, but the BLM's seem to be stuck high, like 145 plus. no vacumm leaks that I can detect. sometimes the BLM's don't even move, like they seem fixed.

They should at least be jumping when the cells change.

the car is mostly stock.... stock prom.
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Old Aug 10, 2008 | 04:21 PM
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Re: smells rich, but BLM's high

Sounds like you may have a misfire in one or more of the cylinders.

If the mixture doesn't burn, the oxygen isn't consumed and the O2 sensor will read that O2, thereby telling the ECM that you're running lean. The BLM's will then climb. What's more, the ECM will try to compensate for the "lean condition" that it's seeing and start adding fuel making the rest of the cylinders run very rich, which is what you're smelling.

I believe your O2 sensor is on the driver side, so the problem is on either the 1, 3, 5, or 7 cylinder. Check your plugs and wires as a start.
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Old Aug 11, 2008 | 02:01 AM
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Car: 1989 IROC-Z
Engine: 350 TPI
Transmission: Th700R4
Axle/Gears: 3.27
Re: smells rich, but BLM's high

Check all your plugs, could even be problems at passengerside to..
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Old Aug 11, 2008 | 02:45 AM
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Re: smells rich, but BLM's high

Exhaust leak, bad O2?
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Old Aug 11, 2008 | 12:13 PM
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Re: smells rich, but BLM's high

Originally Posted by Theking
Check all your plugs, could even be problems at passengerside to..
Since the ECM only "sees" the driver side (where the O2 is located) and he's getting BLM's way off from 128, I'm more inclined to think it's on the drivers side.
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Old Aug 11, 2008 | 12:36 PM
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Re: smells rich, but BLM's high

I will check the passenger side RUNNER, and the drivers side plugs and wires.
I did the propane test, no vacuum leaks that I can detect.

I did notice that it jumps back to open loop once in a while. which may be the reason my BLM's seem "fixed".
If I pull 1 injector wire, it'll jump back to open loop after 2 seconds. So much for a new ac-delco O2 sensor.... should have keep the old o2 sensor.

My scanner shows the rich-lean flag mostly says lean. So the computer is responding as it thinks it should.....
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Old Aug 11, 2008 | 01:13 PM
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Re: smells rich, but BLM's high

Originally Posted by the blur
did notice that it jumps back to open loop once in a while. which may be the reason my BLM's seem "fixed".
A bad O2 or an intermittent connection (bad wire in the harness) can cause this. And yes, in open loop the BLM's will freeze at the last recorded number.
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Old Aug 15, 2008 | 03:14 PM
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From: West Central Ohio
Car: 86 vette
Engine: 383
Transmission: 700R4
Axle/Gears: 3.07
Re: smells rich, but BLM's high

What year and what chip are you running?
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Old Aug 15, 2008 | 03:21 PM
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Re: smells rich, but BLM's high

it's the stock 1989 prom.
stock fuel pressure regulator, although my guage shows 46 psi.

I keep hearing 43 is stock, but this is the original 20 year old regulator, and it has always been at 45-46 psi.
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Old Aug 17, 2008 | 08:33 AM
  #10  
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From: West Central Ohio
Car: 86 vette
Engine: 383
Transmission: 700R4
Axle/Gears: 3.07
Re: smells rich, but BLM's high

Your fuel pressure is a little high but that could be just the test gauge calibration being off.

Look for an exhaust leak or bad O2, if run rich long enough the O2 will "soot up" just like a spark plug. A longer hotter drive, not Idling will sometimes "clean them up". Your new O2 could "soot up" real quick at idle.

If you can program your chip, lower the max blm and intergrate to 130 or so, injector pulse width should be around 2 ms at idle. At this level the rich smell should be gone and idle smooth.
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