lt1/lt4
06-29-2009, 06:30 PM
#1
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Thread Starter
Join Date: Jun 2009
Location: florida
Posts: 11
lt1/lt4
i have a 95 z28 and i converted my lt1 to a lt4.. here are my mods so far. morso cai,pacesetter longtubes and ory,magna flow 3" out the back,lt4 intake and heads. hotcam. o2 sensor delete but needs bugs so light will go off.. air pump and smog delete, block off at the back of motor..
now this is my issuse, when got motor back in and running,worked out the kinks and try to get it tune on a dyno (mail in ok but not great) it could not link with my pcm... my year car is when they made the change from ob I to obII. ok now, i have a obI pcm with an obII connect under dash. what i think is there a bad ground somewhere that will not let it link.. i have check power source going to pcm and i have the 12v give or take.. is there so way to make a new ground to frame and tap into something to see if it a ground ??? or does anyone have any insight on why it will not link with software.. there just no comm.. back and forth??? oh my radio and seats and windows lost power also maybe they share to same comomn ground.. i have fuse bos taped for power... sorry so long but im just puzzled as of now!!!
now this is my issuse, when got motor back in and running,worked out the kinks and try to get it tune on a dyno (mail in ok but not great) it could not link with my pcm... my year car is when they made the change from ob I to obII. ok now, i have a obI pcm with an obII connect under dash. what i think is there a bad ground somewhere that will not let it link.. i have check power source going to pcm and i have the 12v give or take.. is there so way to make a new ground to frame and tap into something to see if it a ground ??? or does anyone have any insight on why it will not link with software.. there just no comm.. back and forth??? oh my radio and seats and windows lost power also maybe they share to same comomn ground.. i have fuse bos taped for power... sorry so long but im just puzzled as of now!!!
06-30-2009, 09:48 PM
#2
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,825
First, welcome to CamaroZ28.com. Always good to see another LT1 owner!!
Have you been able to connect with a scanner? Are you sure you had the OBD-I scanner correctly connected to the 16-pin ALDL connector? One of our members here, Shoebox, has the best site for LT1 info on the internet. Here's his method of connecting, if you don't have the correct 12-pin to 16-pin adapter plug:
http://shbox.com/1/xraycable.jpg
Are you trying to connect a software scanner (DataMaster, FreeScan, EFILive V4), or are you trying to connect tuning software like LT1_Edit or Tunercats? What type of port are you using on the computer the software is running on - serial or USB?
On some models, the 12V at the ALDL connector comes off the cigarette lighter fuse. Have you checked that?
Just curious - why did you do the "o2 sensor delete" (I assume you meant "sensors")? Are you running an open-loop tune? If so, why? The mods you list can easilly be supported with a good closed loop tune.
In any case, the best approach to resolving PCM related problems is to post on the "Computer Diagnostics and Programming" forum.
Have you been able to connect with a scanner? Are you sure you had the OBD-I scanner correctly connected to the 16-pin ALDL connector? One of our members here, Shoebox, has the best site for LT1 info on the internet. Here's his method of connecting, if you don't have the correct 12-pin to 16-pin adapter plug:
http://shbox.com/1/xraycable.jpg
Are you trying to connect a software scanner (DataMaster, FreeScan, EFILive V4), or are you trying to connect tuning software like LT1_Edit or Tunercats? What type of port are you using on the computer the software is running on - serial or USB?
On some models, the 12V at the ALDL connector comes off the cigarette lighter fuse. Have you checked that?
Just curious - why did you do the "o2 sensor delete" (I assume you meant "sensors")? Are you running an open-loop tune? If so, why? The mods you list can easilly be supported with a good closed loop tune.
In any case, the best approach to resolving PCM related problems is to post on the "Computer Diagnostics and Programming" forum.
07-01-2009, 05:21 PM
#3
Registered User
Thread Starter
Join Date: Jun 2009
Location: florida
Posts: 11
Just curious - why did you do the "o2 sensor delete" (I assume you meant "sensors")? Are you running an open-loop tune? If so, why? The mods you list can easilly be supported with a good closed loop tune.
i did a mail in tude from mad z28,then went to pcm for less..i was told that i didnt really needs the o2 becuz i deleted the air pump and smog..... should i run the o2??? i have blocks at back of motor where old tube was connected...i still have ceck engine due to the 02 being unpluged??? i also have sec. light on some of the time.. i have vats disabled thur tune.. and emmissions.. as far as opened or closed i think opened becuz car runs diff and sounds diff through start up and warmed up.. the guy at the dyno traied tunner cat software and could get nothing to happen...i think i want to invest in lt1 edit
i did a mail in tude from mad z28,then went to pcm for less..i was told that i didnt really needs the o2 becuz i deleted the air pump and smog..... should i run the o2??? i have blocks at back of motor where old tube was connected...i still have ceck engine due to the 02 being unpluged??? i also have sec. light on some of the time.. i have vats disabled thur tune.. and emmissions.. as far as opened or closed i think opened becuz car runs diff and sounds diff through start up and warmed up.. the guy at the dyno traied tunner cat software and could get nothing to happen...i think i want to invest in lt1 edit
07-01-2009, 10:00 PM
#4
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,825
The O2 sensors have NOTHING to do with whether the "air and smog" (assume you mean "AIR and EGR systems") have been deleted. The O2 sensors are there in order for the PCM to control the engine's A/F ratio.
In a setup like yours, removing the O2 sensors prevents the PCM from getting feedback on whether it is getting the A/F ratio correct. Helps the PCM adjust to aging components like injectors and other sensors, changing fuel pressure, etc.. Its entirely possible to run without the O2 sensors - I run an open-loop tune, but that's on a fairly beefy 800HP nitrous setup using highly leaded fuel that destroys O2 sensors - but not a good idea when you have a setup like yours. You will get better overall performance, and better fuel mileage operating in closed loop. Closed loop means the O2 sensors tell the PCM if the exhaust is indicating a lean or rich mixture, and the PCM adjusts the long term fuel corrections to maintain the desired stoichiometric A/F ratio at part load conditions. The PCM does not use the O2 sensor feedback at WOT, but it does use what it learned about the fueling at part load, to fuel the car at WOT.
In a setup like yours, removing the O2 sensors prevents the PCM from getting feedback on whether it is getting the A/F ratio correct. Helps the PCM adjust to aging components like injectors and other sensors, changing fuel pressure, etc.. Its entirely possible to run without the O2 sensors - I run an open-loop tune, but that's on a fairly beefy 800HP nitrous setup using highly leaded fuel that destroys O2 sensors - but not a good idea when you have a setup like yours. You will get better overall performance, and better fuel mileage operating in closed loop. Closed loop means the O2 sensors tell the PCM if the exhaust is indicating a lean or rich mixture, and the PCM adjusts the long term fuel corrections to maintain the desired stoichiometric A/F ratio at part load conditions. The PCM does not use the O2 sensor feedback at WOT, but it does use what it learned about the fueling at part load, to fuel the car at WOT.
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