Ihave duel exhaust new ford injectors 730 8d
I have 2 o2 sensors one on each side and a
switch so I can go to ether side I can read ether
side with my scanner right side the B Learn is 118
left side is 138, both sensors are in
the same approx place on each side
what do you think, o2's are AC delcos

 

could be the difference in resistance for the switch. Any break in the wire is never a good thing.

might also have to do with the difference in header shape between the two sides.....

just guesses though

-jason

 

Thanks, anyone else have any more thoughts on it

 

did you pull the plugs and compare the left bank to the right? That should let you know whether its a sensor glitch or a leak (vacum for lean, injector for rich).
If all 8 plugs look the same, I would say take the average of the two blms.

 

Exhaust leak on the side that is registering higher (leaner) BLM values.

 

I would see if the readings are the same when in open loop.
Compare to see if they read the same.
Much of what I've heard on the subject points to air distribution problems from the IAC.
Try increasing the TB opening to reduce the amount of IAC influence (or vice-versa) to see if you can reduce the problem.
Change throttle following settings too to make the reaction more or less.
HTH

 

I would check all the plugs as suggested earlier. Variances in the injectors can easily affect things. Just one injector running overly rich or overly lean on either side could cause this.

I wish our ECM would allow "trimming" the individual injectors like the newer PCMs do. For cars running alternative intakes such as a Miniram, the ability to trim individual injectors would be a god-send due to the "inbalance" betwen the front and back ports.

 

Ghecked open loop o2 readings 200mv difference between
both sides at idle, 450mv lean 650mv richer

 

Ahhhhh yes...... the split BLM's of death!

Much has been discussed on this subject....

There are two ways to go about solving that problem. Either adjust the fuel to the amount of air entering each cylinder (which, as Glenn said, would require individual injector trim capability, something our dinosaur ECM's don't have). Or, adjust the amount of air entering each cylinder so that it's uniform across all eight (that way, each cylinder makes use of the default amount of fuel that the ECM is throwing in).

I went the air adjustment route.

https://www.thirdgen.org/forums/diy-...ight=blm+split

 

can the 730 ecm have the same problems with the IAC
I have 8d map 52mm throttlebody bored to 52mm got it off a 85 vette
it's not after market

 

It can. What happens is that often times factory manifolds have built-in idle air passages that the IAC should be dumping air into. These passages are separate from the main plenum and are there to ensure equal air flow at idle speeds. However, when the throttle blades are opened to the point where the IAC closes, then the idle air passages are bypassed and you start getting air distribution problems that lead to the uneven BLMs.

 

I also have a wet plate nos system with a plate behind the throttle body
would that aggravate the problem, thanks for all your help

 

Does your upper plenum have a hole that interfaces with the IAC port on the throttle body? If it does, and your NOS plate bypasses that hole (i.e. allows air from the throttlebody IAC passage to go directly into the main plenum), then yes, it could aggravate the problem.