Posted by Chris Richards on April 29, 2005 at 15:52:28 from 24.111.87.1
L-Jet Technical Question: (See previous post 3.5L Fuel System Controls) With identical injectors and fuel pressure regulator, which component (ECU, air meter, or both) determines the fuel quantity (not including feeback effect of O2 sensor)? Peter Florance posted previously that he has used different air meters with success.
Answer: ECU alone? Not necessarily. If the motor draws more air, both air meters send a larger signal, and paired with their matching ECU, should deliver the same calculated fuel.
Assuming ECU plug fits, any issues hooking up the '79 3.5L ECU to a 1980 harness connected to later US equipment such as O2 sensor, later warmup air valve, AC, etc.? I can probably use the 3.5L air meter.
So, the question is really whether the 2.8L ECU is calibrated specifically to the 2.8L air meter. The O2 sensor can add or subtract only about 10-15%. A 3.5L 218PS motor needs 20-25% more fuel, and has no O2 sensor online tuning.
Another option is to change tension on the air meter clock spring, but there is no way calibrate this with out online analysis. Chris.