PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Open Loop

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Old Aug 4, 2005 | 07:28 AM
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Default Open Loop

Is running in open loop bad? What does it do and how much HP do you lose? What are the ups and downs of it?

I keep getting a P1133 code for no reason with stock manafolds and I was thinking of just deleting the code from the pcm, and I have been told this will cause it to constanly run in open loop.
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Old Aug 4, 2005 | 08:01 AM
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If you tune OL for the right mixture, you can make just as much or more power as CL.

That being said, the stock OL table is a safe rich tune.

This should get you started
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Old Aug 4, 2005 | 08:37 AM
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Power is found at WOT and WOT is always open
loop anyway.

Problem lies with the car's attempt to learn fine
mixture adjustment, based on the lame O2s. This
tends to overenrich the closed loop operation
-and- carry over as an adder to WOT enrichment
(which is too high anyway, from factory). The code
won't set until bad learning has already happened.

Low throttle, open loop will make your butt stank
is the main issue. If the O2s are whacked because
you already changed the exhaust to long tubes
and "off road" plumbing, then the baby seals are
doomed, I say doomed anyway so fuggedaboudit.
But if it's stock hardware then the O2s ought not
to be messed up, and replacing them might get
you back some drivability.

If you want to truly run open loop then you want
to disable not only codes, but fuel trim learning
and suppress closed loop operation (attempt) to
keep the tune you put, from being massaged as
you drive.
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Old Aug 4, 2005 | 12:12 PM
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So since it is in open loop when at WOT open loop will burn more gas and no power loss will be noticed. Is this true even if you leave it in the stock open loop setting?
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Old Aug 4, 2005 | 12:31 PM
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Open Loop in itself doens't necesarily mean you will burn more gas. OL is mearly a state of running with no feed back and or adjusments to fueling being made by the NB O2 sensors.

Now, if you decide to run OL and run the stock OL table, yes you will burn more fuel than running CL. The stock OL table is a safe rich tune.

If you set your OL and VE tables up correctly, you should see little to no difference in fuel consumption.
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Old Aug 4, 2005 | 04:29 PM
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will the stock OL table harm the perfomance, and roughly how much more fuel consumtion could the stock OL table cause.

This is driving me crazy... Going through too many bank 2 sensor 1 sensors. I will put in a new O2 and be fine for a month or so then I get P1153 and it is not a fluke because I will reset the pcm and it will go of for 2-3 days and then another P1153 until I put in a new O2 then it will be ok for another month or so... Thats the cycle I am going though with stock manafolds. Only thing I can think is a leak somewere, but I cannot find anything. I have not tried the Bosch 13111 sensor yet. do you think that could fix it if say I have a leak somewhere that I cannot notice.

I am just about to give up and reprogram the pcm to ignore it. I was quoted $200 for that. If I also decide to do that I have been told that it will cause OL and to adjust the OL stock table it is like $450. Thats why I am asking about how it would be to stay in stock OL table since that is alot of $$ to keep the ses light off.
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Old Aug 4, 2005 | 04:43 PM
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For that kind of money, you just get yourself a copy of EFILive/Flashscan.

Yes the stock OL table will slightly degrade your performance, and I don't know how your fuel consumption will be other than increased.

If you keep blowing O2 sensors with a stock exhaust, you should probably try and fix it. Are you sure you manifolds are torqued properly? Are you sure the manifold gaskets are good? Are you sure you don't have a leaky injector that's spraying raw fuel all over the O2 sensor?

have you compared the B1S1 to B2S1 to see if they have an equal amount of exhaust dust on them? Are they the same color?

I'd hate to see you pay someone out the nose for a tune if the problem can be fixed.
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Old Aug 4, 2005 | 06:19 PM
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No fuel or dust on it. What could be causing them to go bad? It seems like they are ok for a couple week then fail. Could a leak burn them up? I dont see how cause if there is a leak then they should be cooler.

Do you think this would be a good case for the Bosch 13111 sensor? Could it fix it if say I have a leak somewere that I cannot find? That would sure beat looking and looking for leaks.
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Old Aug 4, 2005 | 06:28 PM
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one other thing I thought of (before you have to throw some more money at it lol). Check to see if you heater wire is supplying a constant feed to the B2S1.
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Old Aug 4, 2005 | 06:29 PM
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Originally Posted by The Knightrider
No fuel or dust on it. What could be causing them to go bad? It seems like they are ok for a couple week then fail. Could a leak burn them up? I dont see how cause if there is a leak then they should be cooler.

Do you think this would be a good case for the Bosch 13111 sensor? Could it fix it if say I have a leak somewere that I cannot find? That would sure beat looking and looking for leaks.
The Bosch 13111 sensors took care of my codes from coming back. They do work for some.

Bill
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Old Aug 4, 2005 | 06:31 PM
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[QUOTE=TAQuickness]Yes the stock OL table will slightly degrade your performance, and I don't know how your fuel consumption will be other than increased.
[QUOTE]

What table is the OL Table (B3605??? or what)?

Bill
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Old Aug 4, 2005 | 07:16 PM
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b3605
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Old Aug 4, 2005 | 07:22 PM
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Originally Posted by TAQuickness
b3605
I thought so. Mine is stock. If I went to OLSD all the time how should I set this table?

Bill
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Old Aug 4, 2005 | 07:29 PM
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do you have a copy of the VEAutotune Doc? I have my table set per the doc and have been running this way for a month now. my fuel economy rivals a stock vehicle.
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Old Aug 5, 2005 | 08:21 AM
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Originally Posted by TAQuickness
one other thing I thought of (before you have to throw some more money at it lol). Check to see if you heater wire is supplying a constant feed to the B2S1.
I had to run out before I could finish this post...

If you have a test light or a multi-meter, you can probe the brown (labeled on the connector as "C") wire. When the key is in the run position, this wire should have 12vdc and should not switch off while the key is in the run position.

It might be a good idea to get an o2 extention, then tap into this wire and run a light inside your car. Take a nice long drive and verify the light doesn't go out.
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Old Aug 5, 2005 | 03:24 PM
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Originally Posted by TAQuickness
do you have a copy of the VEAutotune Doc? I have my table set per the doc and have been running this way for a month now. my fuel economy rivals a stock vehicle.
I have a copy and just setup my table to look like that. I had mine at 1.13 for the whole table when I was tuning the VE table.

Thanks,
Bill
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