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Old 04-14-2010, 06:53 AM
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ls1 computer problem???

hi guys well i recently bought myself a trans am and it idles a little bit over 1000 rpm at engine start then it lowers down to about 600 and when you put it in drive and press on gas car pauses for a bit then pulls to the front and when braking to a stop cars rmp goes below 500 rpm so i checked it with the obd code reader and came out it needed the o2 sensor on bank 2 so i changed it and everything went back to normal then after a week or so problem came back again obd reads the same problem... so the thing is do i need a custom tune???

btw car has no catalytic converter, and has throttle body spacer, and k&n filter as performance mods...

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Old 04-14-2010, 08:13 AM
richard stewart 3rd's Avatar
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Hi,
That spacer may be causing a rich condition, thus setting the code.
With the O2 sensor ahead of the cats, they have no affect on the O2 sensor, some systems have o2 sensors after the cats, to check on the front ones.
Rich
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Old 04-14-2010, 08:37 AM
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so do i replace the front o2 sensor??? also would my car be needing a custom tune to delete codes and wake up the ls1???
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Old 04-15-2010, 01:23 AM
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so........................???????????????????
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Old 04-21-2010, 07:48 AM
richard stewart 3rd's Avatar
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Hi,
Did you get this problem straightened out? Replacing the o2 sensor doesn't work, you already did that. replacing the o2 sensor is the biggest mistake made by people, not to say the o2 sensors don't go bad, but the recommended mileage to change them is around a hundred thousand. You need to find the source of the problem, what's causing the check engine light to come on, & set a code? You'll need to have it scanned
& then go into the data screen & work from there.
Rich
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Old 05-02-2010, 03:15 PM
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i scanned the car and codes are: no activity on o2 sensor bank 2...

so car doesnt have cats no more will this be the problem???
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Old 05-03-2010, 11:38 AM
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More info on the vehicle would be helpful, like what year etc
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Chet
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Old 05-03-2010, 12:21 PM
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I know of a few cars that no longer have cats , so no its not a problem. Exhaust leaks can play with the O2 sensors as well. Also check the wiring to the O2 sensor . You may have not knowingly moved the wires and it got burnt on the exhaust. Try going to camaroz28.com for more help .
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Old 05-03-2010, 01:23 PM
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Quote:
Originally Posted by Jkingof956
hi guys well i recently bought myself a trans am and it idles a little bit over 1000 rpm at engine start then it lowers down to about 600 and when you put it in drive and press on gas car pauses for a bit then pulls to the front and when braking to a stop cars rmp goes below 500 rpm so i checked it with the obd code reader and came out it needed the o2 sensor on bank 2 so i changed it and everything went back to normal then after a week or so problem came back again obd reads the same problem... so the thing is do i need a custom tune???

btw car has no catalytic converter, and has throttle body spacer, and k&n filter as performance mods...
You got some not quite correct advice. The front O2s trim the mixture to stoichiometric so they directly affect the injection. The rear injectors are checking the quality of work the cats are doing. Since somebody removed the cats the rear sensors are always fed up.

Since the system has been monkeyed with who know what the real problems are. The codes tell you some sensor isn't see things as it is calibrated to see them. The problem might be a direct cause as indicated or can be something ahead of that sensor. You have to understand the system logic and lay out to figure out exactly what the code is telling you.

But I'm left to wonder about what you have. Dual cats is hardly a TBI more of a TPI configuration yet a TPI hardly needs a throttle body spacer. So what's really in this?

Bogie
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Old 10-14-2010, 10:11 AM
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ok its been a while i havent log in so i took the car to a tuner and he told me car might be running rich cause of the cats delete car did not get tune cause its getting modded i took the car to the track and ran a best of 13.8 at 98mph letting go before finish line. so far i found out something wrong which was a clogged pcv valve i changed it and car has gained alot of throttle response and power, but still i have the check engine soon light on i also got the throttle body spacer, bellow, lid, and a ram air mod, ported throttle body, ported MAF sensor with no cats as performance mods everything else is stock even exhaust with only a flowmaster muffler car is ways stronger all i did is changed the pcv valve made alot difference. also noticed the radiator that it has it doesnt belong there it has the coolant hose eliminated from the radiator so no coolant is going to the engine i guess am about this will this be the problem??? thanks in advance Jerry...
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Old 10-14-2010, 02:06 PM
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bump...
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Old 10-14-2010, 05:31 PM
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Exactly which O2 sensor is the one in question?
Bank 1 sensor 1
Bank 2 sensor 1
Bank 1 sensor 2 or
Bank 2 sensor 2 ?
Did you look at live data to see if it is registering?
What do the fuel trims look like?
Upstream sensors control fuel trim( up to 25 % of final mix ratio)
Downstream sensors only check cat health. Hollow cats wont be a terrible deal as most sensors have heaters built in on the newer stuff.(mid 90s and up).
If the O2 sensor is not registering on the data stream or is fixed ( Substitute value by PCM for missing signal)then you should check the wiring for the sensor as it is probably shorted out on the exhaust or ripped in half or is a replacement that is not wired correctley to its connector

Also... bank 1 is the side of the engine with the number 1 cylinder FYI
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Old 10-15-2010, 09:51 AM
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Quote:
Originally Posted by latech
Exactly which O2 sensor is the one in question?
Bank 1 sensor 1
Bank 2 sensor 1
Bank 1 sensor 2 or
Bank 2 sensor 2 ?
Did you look at live data to see if it is registering?
What do the fuel trims look like?
Upstream sensors control fuel trim( up to 25 % of final mix ratio)
Downstream sensors only check cat health. Hollow cats wont be a terrible deal as most sensors have heaters built in on the newer stuff.(mid 90s and up).
If the O2 sensor is not registering on the data stream or is fixed ( Substitute value by PCM for missing signal)then you should check the wiring for the sensor as it is probably shorted out on the exhaust or ripped in half or is a replacement that is not wired correctley to its connector

Also... bank 1 is the side of the engine with the number 1 cylinder FYI
i checked every o2 sensor and they seem to be in pretty good working condition what i think it could be is that the radiator is not an ls1 trans am camaro radiator so car has a line elminated the one that goes from the throttle body to radiator in hot weather engine just lacks power and its a totaly different car during night time so no coolant is going to engine from radiator to throttle body i noticed this cause i wanted to do a throttle body bypass but i cant do it cause the radiator is not for the ls1 could this be the problem??? am hoping i can drop my times at much as possible with this lil problem since i already fixed the clogged pcv valve after car ran a 13.84 at 98mph letting go before finish line
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Old 10-15-2010, 03:50 PM
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ttt bump
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Old 10-15-2010, 03:50 PM
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Stop making guesses....You aren't listening to what the people here are telling you. The removal of the cats WILL NOT make the car run rich or lean. The only thing it will do is cause the check engine light to come on when the system runs a catalyst efficiency test. IF the car is before 1996 then this doesn't matter because OBDI does not check catalyst efficiency.

The reason that you have no activity on the O2 sensor is because your system is too rich or too lean for the computer to compensate. The O2 sensors don't send a signal if the fuel mixture is too far off. They will stay maxed out lean or maxed out rich. Or it could be a wiring problem.

CUSTOM TUNING!?! You have 2 bolt on parts (wasted money) and no cats there is no reason that the computer shouldn't be able to handle these "mods".

You need to look at the datastream....find the 02 sensors on the screen and see what they have for voltage. If it is close to 0 mv (millivolts) then your system is too lean) if it is close to 999 mv then it is too rich.

Causes of a lean condition could include...
-stuck closed injector
-vacuum leak (probably under that P.O.S. spacer)

Causes of a rich condition could include....
-stuck open or leaky injector
-fuel in the oil
-too much fuel pressure
-restricted air intake (clogged filter)

Take it to someone who is certified to be working on this stuff. And remember that there is no certification that includes the word "tuner"
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