Originally Posted by ricks90billblass
this might sound to easy of a fix, but have you considered just moving the wires around in the 60 pin connector? all that you have to change are inj 3 on the HO 5.0 ECM to become inj 5 on the non HO ECM, and the 7 to 4. no need to cut the injector harness. as long as the cam is a non HO firing order its easy, than run the wires on the cap that way too.
..---HO firing order 1-3-7-2-6-5-4-8
Non HO firing order 1-5-4-2-6-3-7-8
That would fire the injectors but would wreak havoc on the HEGO balance for closed loop and result in a terrible idle and MPG. Cylinders 1 and 3 are on the same bank, then 7 and 2 are opposite banks, 6,5 same bank, then 4 and 8 opposite. The EEC will be expecting a report back from the HEGO's to tell it how close to the commanded AFR (lambse) it got so it can trim the fuel accordingly. So right after it fires the #1 injector it will fire the #5 next. Expecting the #3 it will think it was to lean and richen up the mixture, then it will see #4's fuel (same bank as 1 and 3) which is just a result traveling down the pipe right?
Imagine having a perfect combination and switching your HEGO's wiring. OR routing your headers side to side if possible, tube by tube. The EEC is about Math and that Math is garbage in, garbage out.
Let me provide the following:
SEQUENTIAL ELECTRONIC FUEL INJECTION (SEFI)
The A/F ratio control actuators consist of injectors whose fuel metering
function is affected by energizing and de-energizing the injector solenoids.
Each injector has a metering needle or pintle which opens or closes the
injector nozzle to release fuel.
A high pressure fuel pump delivers fuel to the injectors at approximately 42
Based upon the calculated air mass value, the software calculates the
injector pulsewidths required to give the desired A/F ratio.
The desired A/F ratio for all operating conditions is determined by the A/F
strategy and calibration.
The strategy is designed to handle any reasonable injector configuration and
Example configurations are:
1. 1 or 2 output CFI
2. 1 or 2 output bank EFI
3. 4, 6 or 8 output Sequential EFI
The strategy can run on 4, 6 or 8-cylinder engines. The calibration
parameters ENGCYL and NUMCYL control the engine type. The user must set both
parameters for the strategy to work correctly.
On SEFI applications, each cylinder has an injector located in the intake
port near the intake valve. The injectors are individually fired in an order
that matches the firing order of the engine. The injector output numbers
correspond to engine cylinder numbers. This allows for consistent
nomenclature for the module pinouts and the wiring harness. Under normal
engine running, each injection is timed to occur at an optimum point in the
intake event. Injector timing is determined by strategy and calibration.
Timed sequential fuel injection requires a signature PIP distributor. The
signature PIP allows the computer to identify cylinder #1. The PIP signal
for cylinder #1 has a unique duty cycle, that is smaller than the normal 50%
duty cycle. The computer recognizes the signature PIP to synchronize the
CLOSED LOOP MODE
During closed loop operation, the computer ramps the desired lambda values
(LAMBSE1, LAMBSE2) in a limit cycle manner about stoichiometry. Using the
EGO (Exhaust Gas Oxygen) sensor, the computer increases or decreases lambda
at a calculated rate of change. The rate at which lambda changes is
calibration dependent. For Stereo EGO operation, LAMBSE1 and LAMBSE2 vary
independently using EGO-1 and EGO-2 sensors. For Mono EGO operation, LAMBSE1
HEGO - HEATED EXHAUST GAS OXYGEN SENSOR (Analog Input)
The HEGO sensor is a modified (it is connected to a power and a ground wire)
EGO sensor and provides the same functions as the EGO. The modification
allows it to heat up more quickly than the unmodified EGO sensor
(approximately 18 seconds versus 80 seconds), thus providing an earlier
Closed Loop operation on a cold start. This modification also allows it to
operate at cooler locations in the exhaust system providing greater
flexibility in sensor packaging. Associated with this property is more
accurate sampling of the exhaust when the HEGO may be placed closer to the
There is a slightly longer transport delay between EGO switch and fuel
injection changes which may cause a longer "tracking" effect, but the bottom
line is the ability to elicit a more even and accurate sampling.
Additionally, the more stable sensor temperature of the HEGO is known to keep
contaminants away from the sensor, reducing degradation of the sensor over
50K miles. It also avoids the EGO cool-down during Idle which occurs with
the normal EGO.