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Help needed on closed loop. Not o2s
PostPosted: Sat Apr 02, 2011 8:48 pm Reply with quote
96Formula6spd
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Posts: 195
Location: Greenville,SC




Hey posted this up in ls1tech. Anyways would anybody want to come check it out tomorrow. If so pm me.

Hey guys I am so close to getting my Firebird back running for the first time in 25 months. Anyways here is the run down. The car has a lt4 hotcam with 1.6 gm roller rockers out of the hotcam kit. I have a lt4 knock module. I also have a hotcam tune from Trifeca tuning. Anyways in start up the car runs like a champ in open loop. As soon as the car goes into closed loop it miss fires and will even stall out. I was working on it a couple weeks ago when I was home as I am 100 miles away at college and it had this problem so I ordered a new set of ac delco oxygen sensors. Even with the new oxygen sensors. I am stumped on it at the moment. So what could cause the car to run perfect in open loop then horrible in closed loop. I have checked for intake leaks and there is currently no exhaust except long tube headers. It would still act up when it had exhaust on it. Any Ideas as I would like to actually have a running car again.

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PostPosted: Sun Apr 03, 2011 1:49 am Reply with quote
97isuzu_4x4
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egr?

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Re: Help needed on closed loop. Not o2s
PostPosted: Sun Apr 03, 2011 2:05 am Reply with quote
roadconetuning
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Joined: 18 Sep 2006
Posts: 13368
Location: Upstate, SC




96Formula6spd wrote:
Hey posted this up in ls1tech. Anyways would anybody want to come check it out tomorrow. If so pm me.

Hey guys I am so close to getting my Firebird back running for the first time in 25 months. Anyways here is the run down. The car has a lt4 hotcam with 1.6 gm roller rockers out of the hotcam kit. I have a lt4 knock module. I also have a hotcam tune from Trifeca tuning. Anyways in start up the car runs like a champ in open loop. As soon as the car goes into closed loop it miss fires and will even stall out. I was working on it a couple weeks ago when I was home as I am 100 miles away at college and it had this problem so I ordered a new set of ac delco oxygen sensors. Even with the new oxygen sensors. I am stumped on it at the moment. So what could cause the car to run perfect in open loop then horrible in closed loop. I have checked for intake leaks and there is currently no exhaust except long tube headers. It would still act up when it had exhaust on it. Any Ideas as I would like to actually have a running car again.


Vince, who IS Trifecta, is on effin' point with the LNF guys and more than helpful... you should probably see what he says... I bounceed like 10 emails back and forth with him about tuning and never even bought anything from him...

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PostPosted: Sun Apr 03, 2011 7:35 am Reply with quote
Shon Herron
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Contact your tuner.
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PostPosted: Sun Apr 03, 2011 6:56 pm Reply with quote
96Formula6spd
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Joined: 18 Jun 2009
Posts: 195
Location: Greenville,SC




No egr. I am going to do my OBD1 conversion in two weeks as the car is in Greenville and I am in Columbia. Makes working on the car very hard.

_________________
1996 Pontiac Formula
5.7 LT1/T-56 Intake,Long Tube Headers,Exhaust,Hurst Short Throw,LT-4 Hotcam Kit,Spec Stage 3 Clutch
Down Since 2-21-09
2001 Miata Ls- Bone Stock DD for now.
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PostPosted: Sun Apr 03, 2011 11:46 pm Reply with quote
96Formula6spd
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Joined: 18 Jun 2009
Posts: 195
Location: Greenville,SC




Here are some videos.

This is open loop
http://www.youtube.com/watch?v=XXaKln1oXnk

Closed Loop
http://www.youtube.com/watch?v=j151FXwHHVY

_________________
1996 Pontiac Formula
5.7 LT1/T-56 Intake,Long Tube Headers,Exhaust,Hurst Short Throw,LT-4 Hotcam Kit,Spec Stage 3 Clutch
Down Since 2-21-09
2001 Miata Ls- Bone Stock DD for now.
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PostPosted: Mon Apr 04, 2011 7:43 am Reply with quote
Shon Herron
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Location: 29682




Closed loop fueling is not right, simple.
Contact tuner, he will want you to send a log file of it and then he will send back a new file to be loaded to try.
Or have him put it in OL all the time.....
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PostPosted: Mon Apr 04, 2011 7:59 am Reply with quote
ElecTech
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Joined: 03 Sep 2007
Posts: 425
Location: Charleston, SC




Shon Herron wrote:
Contact your tuner.


This ^

Also, if fueling TRUELY is good in open loop and it isn't in closed loop, 9 times out of ten it is an air leak up stream of the sensors.

I have seen the o2 plugs get crossed from left to right and cause the same issue. Also I have seen them mixed up front to rear. Be absolutely sure the sensors are plugged into the right spots.

Switching to an OBD1 PCM will not make this better because it is most likely not tuning related IF the open loop fueling is good.

My 2 cents.

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PostPosted: Mon Apr 04, 2011 10:45 am Reply with quote
minytrker
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Location: Texas




I know you said it still acted up with the exhaust on it, but it will never run right in CL with just open headers.
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PostPosted: Mon Apr 04, 2011 6:11 pm Reply with quote
96Formula6spd
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Joined: 18 Jun 2009
Posts: 195
Location: Greenville,SC




minytrker wrote:
I know you said it still acted up with the exhaust on it, but it will never run right in CL with just open headers.


Yeah I have herd that twice now. Going to contact the tuner when I get back to get the car. Hard to get home without a car. Been without one for a few months now.

_________________
1996 Pontiac Formula
5.7 LT1/T-56 Intake,Long Tube Headers,Exhaust,Hurst Short Throw,LT-4 Hotcam Kit,Spec Stage 3 Clutch
Down Since 2-21-09
2001 Miata Ls- Bone Stock DD for now.
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PostPosted: Sat Apr 16, 2011 10:07 pm Reply with quote
96Formula6spd
GM fanatic
Joined: 18 Jun 2009
Posts: 195
Location: Greenville,SC




Well swapped in the obd1 pcm and knock sensor. Car runs like a champ. So I am thinking the tune was off. Still going to talk to the tuner.

_________________
1996 Pontiac Formula
5.7 LT1/T-56 Intake,Long Tube Headers,Exhaust,Hurst Short Throw,LT-4 Hotcam Kit,Spec Stage 3 Clutch
Down Since 2-21-09
2001 Miata Ls- Bone Stock DD for now.
View user's profile Send private message AIM Address MSN Messenger
Help needed on closed loop. Not o2s
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