Split BLM's driving me crazy!!!
Thread Starter
Junior Member
Joined: May 2000
Posts: 7
Likes: 0
From: Orlando, FL
Split BLM's driving me crazy!!!
Hi all, I dont have a third gen but my 93 w/speed density & batch fire is close enough right? 
The people on the LT1 Edit list were less than helpful to say the least so I'm hoping some of you can advise me.
Problem is my BLM's are split all the time and pretty badly too. There is almost always a difference of 5 between the two banks, some cells its even worse, up to 9 and 10 apart. 99% of the time its the left bank with the lower number, usually in the mid to low teens. The right bank is normally in the mid-lower 120 range.
The problem will get slightly better when I give it a little load but its still at least 3-4 off.
I've searched everywhere for an exhaust leak and havent found any. I just replaced the header gaskets (just in case) and no change. I've also switched the O2 sensors (left to right) and the problem is still the same...
That said are there any other reasons for split BLM's that I've overlooked?
The motor is stock internally with bolt ons. Basically I have a CAI, long tube headers, and 1.6 roller rockers.
Please help, im at my wits end here. I've been trying to fix this for months and I'm no closer than when I started...
BTW I have a Pocket Programer + Tunercat so I can make whatever tuning changes nessescary.
The people on the LT1 Edit list were less than helpful to say the least so I'm hoping some of you can advise me.Problem is my BLM's are split all the time and pretty badly too. There is almost always a difference of 5 between the two banks, some cells its even worse, up to 9 and 10 apart. 99% of the time its the left bank with the lower number, usually in the mid to low teens. The right bank is normally in the mid-lower 120 range.
The problem will get slightly better when I give it a little load but its still at least 3-4 off.
I've searched everywhere for an exhaust leak and havent found any. I just replaced the header gaskets (just in case) and no change. I've also switched the O2 sensors (left to right) and the problem is still the same...
That said are there any other reasons for split BLM's that I've overlooked?
The motor is stock internally with bolt ons. Basically I have a CAI, long tube headers, and 1.6 roller rockers.
Please help, im at my wits end here. I've been trying to fix this for months and I'm no closer than when I started...
BTW I have a Pocket Programer + Tunercat so I can make whatever tuning changes nessescary.
Thread Starter
Junior Member
Joined: May 2000
Posts: 7
Likes: 0
From: Orlando, FL
Courtesy of LJ on the LT1 Edit list.
o too much idle air through main plenum
o intake gasket leak
o fuel injector fault (dirty, stuck)
o major obstruction in fuel rail crossover
o Opti cap corrosion (weak spark on some cyl)
o high plug wire resistance (burnt, bad connection)
o weak or dead spark plug
o exhaust leak at cyl head or collector (including AIR
and EGR connections)
o O2 sensor dying
o O2 sensor wire harnesss fault (burnt, bad connection
The opti stuff is LT1 specific but 3rd gens have distrubutors too. The rest of it should apply to any engine so hopefully someone else can benifit from it as well.
o too much idle air through main plenum
o intake gasket leak
o fuel injector fault (dirty, stuck)
o major obstruction in fuel rail crossover
o Opti cap corrosion (weak spark on some cyl)
o high plug wire resistance (burnt, bad connection)
o weak or dead spark plug
o exhaust leak at cyl head or collector (including AIR
and EGR connections)
o O2 sensor dying
o O2 sensor wire harnesss fault (burnt, bad connection
The opti stuff is LT1 specific but 3rd gens have distrubutors too. The rest of it should apply to any engine so hopefully someone else can benifit from it as well.
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