Whole Left Bank Misfiring....
10-06-2010, 03:37 PM
#1
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Whole Left Bank Misfiring.... Ok well. My car his been misfiring for some time and stumbling a lot, can not figure it out. Anyways, as the car was idling today, I took off the spark plugs on the left bank and with a glove and flat head, held to 1 coil at a time, checked the firing/zap. It seems that the whole left bank is firing erratically. I then took off the main connector to all the coild for the left bank and it did not make a difference. Could it be the connector or am I going to have to follow the wiring all the way back to check for any breaks? I want to do this a simply as possible. Wondering if anyone else has experienced this problem. Any help would be nice. Thanks.
10-06-2010, 07:12 PM
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Is it getting fuel? Check the injector fuses 1 and 2. Under the hood. Idk about the spark. But in my opinion i think it would be like u said erratical. Being normal. Fuel air and spark. Ur gettin air most likely and spark u said. And its only on bank1? Ran into same problem on a lt1 hate those damn things. But thats what i found. Try the injector fuses under hood. See if 1 is blown.
10-06-2010, 07:17 PM
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or if u want to narrow down the connecter. get a ohm meter or dmm and test resistance at the plug connector onboth sides and note what u find. if the bank that u say is messed up then it should have a big difference in it than the other side which hopefully is running good. hope that helps ya
10-07-2010, 08:54 AM
#4
move the coil rail from driver to passenger side and see if the misfires follow...if they do go to the pick and pull and grab a set of coils for $30-40 (truck ones will work but won't match)
or strip your coil harness and look for problems...but it's easy just to pick up a rail of coils and keep yours for extras or sell them as coils/bracket with bad harness
or strip your coil harness and look for problems...but it's easy just to pick up a rail of coils and keep yours for extras or sell them as coils/bracket with bad harness
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10-09-2010, 10:35 AM
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. I will switch the coils to the driver side and see what happens. I will also check the fuses for injectors. Its odd too. If I start the car is runs fine then after a small warm up it will start misfiring. If you drive it, it misfires and as you apply power it will suddenly kick to life.... Weird. I dont have cats. Car has mods as follows; TSP 5.3L Heads, Cometic .040 gaskets, manley pushrods, ls7 lifters, PRC dual valve springs, Pacesetter Coated headers, True duals, Torqurer V2 CAM, etc. 425rwhp 400ft tq. Did the work myself =P. Hate electrical stuff though......
09-02-2014, 10:54 PM
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Bringing this thread from the dead. My car has this exact same issue.....to the T. I wish the OP would've posted his findings.
During a cold start the car runs normal and fires on all cylinders. Once the car gets to 170 it starts to misfire...as in it drops cylinders, but if i place the car in neutral (auto) or give it a little bit of gas the misfire will go away momentarily, but will come back once the idle stabilizes.
I have discovered that by disconnecting all 4 left bank injector plugs while its doing this misfire it will not change the way it runs in the slightest... so only the right bank is keeping it running.
Has anyone else had this issue? The car has had an engine swap in the past and is a 98 Formula with a 99 LS1.
Mods are longtubes, EGR/AIR delete (tuned out). Car ran fine for months and this started out of the blue. Any help is appreciated.
Edit: Didnt realize this thread was in the internal engine forum.
During a cold start the car runs normal and fires on all cylinders. Once the car gets to 170 it starts to misfire...as in it drops cylinders, but if i place the car in neutral (auto) or give it a little bit of gas the misfire will go away momentarily, but will come back once the idle stabilizes.
I have discovered that by disconnecting all 4 left bank injector plugs while its doing this misfire it will not change the way it runs in the slightest... so only the right bank is keeping it running.
Has anyone else had this issue? The car has had an engine swap in the past and is a 98 Formula with a 99 LS1.
Mods are longtubes, EGR/AIR delete (tuned out). Car ran fine for months and this started out of the blue. Any help is appreciated.
Edit: Didnt realize this thread was in the internal engine forum.
Last edited by MadFirehawk86; 09-02-2014 at 10:56 PM. Reason: Edit
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09-03-2014, 07:49 PM
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09-04-2014, 12:07 AM
#11
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Engine hasn't been opened up. I am thinking that it is fuel related. The right bank (passenger) fuel injectors have a very audible tick whereas the left bank's fuel injectors (the one that is giving me trouble) are not audible at all. That being said, I am pretty sure it is a fueling issue.
As I have said the left bank only drops when the engine reaches operating temp so I am assuming that it runs good in open loop and drops the left bank once it switches over to closed loop. Once it starts its misfire, if I give it gas it will smooth out for a few seconds and then drop the left bank once again shortly after the idle stabilizes.
This is a very rare issue it seems....there are only two threads that I have found with people that have had this issue (this one and another one on another forum) and the OP didnt post his/her findings....
As I have said the left bank only drops when the engine reaches operating temp so I am assuming that it runs good in open loop and drops the left bank once it switches over to closed loop. Once it starts its misfire, if I give it gas it will smooth out for a few seconds and then drop the left bank once again shortly after the idle stabilizes.
This is a very rare issue it seems....there are only two threads that I have found with people that have had this issue (this one and another one on another forum) and the OP didnt post his/her findings....
09-15-2014, 12:24 PM
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The o2 sensors are the culprit. I switched the o2 sensors around and the problem went to the right bank...so that o2 sensor is toast. Just ordered some Densos....should fix my issue.
08-13-2020, 09:22 AM
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Old post but Engine hasn't been opened up. I am thinking that it is fuel related. The right bank (passenger) fuel injectors have a very audible tick whereas the left bank's fuel injectors (the one that is giving me trouble) are not audible at all. That being said, I am pretty sure it is a fueling issue.
As I have said the left bank only drops when the engine reaches operating temp so I am assuming that it runs good in open loop and drops the left bank once it switches over to closed loop. Once it starts its misfire, if I give it gas it will smooth out for a few seconds and then drop the left bank once again shortly after the idle stabilizes.
This is a very rare issue it seems....there are only two threads that I have found with people that have had this issue (this one and another one on another forum) and the OP didnt post his/her findings....
As I have said the left bank only drops when the engine reaches operating temp so I am assuming that it runs good in open loop and drops the left bank once it switches over to closed loop. Once it starts its misfire, if I give it gas it will smooth out for a few seconds and then drop the left bank once again shortly after the idle stabilizes.
This is a very rare issue it seems....there are only two threads that I have found with people that have had this issue (this one and another one on another forum) and the OP didnt post his/her findings....
just long tube headers and no cats
once it goes into closed loop it idles horribly sounds cammed
Like the OP stated can't tell if it was noticable before/after the tune
But had the front O2 sensors replaced AFTER tuning
(Never went into a closed loop)
Deleted the rear sensors and adjusted timing in the tune
Said it was running lean so they added more fuel?
My mechanic is saying the 1357 (left) bank is missing
Gonna be looking into maybe fuel rails (or fuses)
Hopefully something simple
08-13-2020, 10:57 AM
#16
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Originally Posted by Zach Harriz
Sorry about reviving the old post... But I'm having this exact issue in my 2007 LS2
just long tube headers and no cats
once it goes into closed loop it idles horribly sounds cammed
Like the OP stated can't tell if it was noticable before/after the tune
But had the front O2 sensors replaced AFTER tuning
(Never went into a closed loop)
Deleted the rear sensors and adjusted timing in the tune
Said it was running lean so they added more fuel?
My mechanic is saying the 1357 (left) bank is missing
Gonna be looking into maybe fuel rails (or fuses)
Hopefully something simple
just long tube headers and no cats
once it goes into closed loop it idles horribly sounds cammed
Like the OP stated can't tell if it was noticable before/after the tune
But had the front O2 sensors replaced AFTER tuning
(Never went into a closed loop)
Deleted the rear sensors and adjusted timing in the tune
Said it was running lean so they added more fuel?
My mechanic is saying the 1357 (left) bank is missing
Gonna be looking into maybe fuel rails (or fuses)
Hopefully something simple
There is also a reference ground at the back of each head. Might be worth verifying that ground is intact.
08-14-2020, 03:36 AM
#17
TECH Senior Member
Do you have a waveform/log of the O2 voltages?
Said it was running lean so they added more fuel?
Can you smell unburnt fuel in the exhaust?
My mechanic is saying the 1357 (left) bank is missing
Can you detect a dropped temperature in the header primary pipes?
