D-Jet lean theories Options

[Morrie]

Hi Guys,

When I did a recent tune up on my car's EFI I noticed a few interesting things. Most importantly, the car is running strong, but lean. Here are my observations and findings.

Engine is a 1976 2056 running D-Jet and a 123 Distributor.

Spark plugs were clean, but a little more white than the golden brown I would like to see. Not severely burnt, no signs of oil consumption.

Idle mixture knob on ECU is full CCW to idle. Still surges a little like it is running slightly lean still.

AAR tests good. Correct PN. Closes securely within 5 minutes.
All new vacuum lines, all lines have clamps.
CHT sensor checked. Passes resistance mesurement checks both warm and cold.
MPS holds vacuum for 15minutes (Decided that was good enough and terminated test).
Checked and adjusted FPR. Now set at 29psi and holds steady. Holds pressure well after shutdown. (check valve) No drop or change in pressure when engine is revved, or during starting.
Vacuum line routing checked and re-checked against 1976 requirements. Note that this means that the crankcase is vented to the air cleaner without a PCV valve, unlike the 73 and earlier models.

These are the basics of what I have checked. I have not gone aheaad and checked flow on injectors, though it is on my list of open items.

Today I pulled the MPS to check the part number. It is the correct part number for a 2.0, but not for a 74-75. Its the proper part for a 73 2.0. Since the 73 2.0 has a different vacuum system, more of a closed circuit with the crankcase, I am theorizing that this sensor is expecting to see higher pressure numbers than the later system, and could be causing it to instruct the computer to operate at more of a lean condition.

Any thoughts from those with more experience than I would be great. I am climbing the learning curve here, and am way past clueless and now at the stage where I know enough to be dangerous.

Thanks in advance!!

[Highland]

Just FYI when Mr. Injector refurbished my injectors they came back with new seals; so now I have a spare set of seals.

If I had known this I would not have bought a set of injector seals.

[Morrie]

Hi Guys,

I had to go out of town for a week but while I am away I wanted to give a bit of an update.

Airbox Leak/ Smoke Test Failure: I disassembled the system and pulled the air box. after sealing it up and testing it independent of the system I now believe that the leak was not in the box itself but rather at the connection to the intake runner boots. The boots are soft and pliable and appeared to be snug. I decided to try using hose clamps for now as an experiment and smoke it again. If this solves the problem then I will install a new set of intake boots.

I do have a question on wiring I am hoping you guys can help me with. I want to mention that I did thoroughly inspect and clean all the EFI grounds and made sure they are properly attached. Chassis grounds are next. On the wiring that goes to the AAR and Thermotime switch. I see a small gauge white wire coming off the EFI harness and a larger gauge black wire with a red stripe coming off what I will call the engine harness. I don't trust anything from the previous owner so I am asking if someone can help me out with some direction. In looking at Jeff's diagrams it appears as if the TTS is the small white wire coming off of the D-Jet Harness and the AAR is the larger black wire that comes off the engine harness. Does that sound right?

Thanks guys....

[JeffBowlsby]

the TTS is the small white wire coming off of the D-Jet Harness YES

the AAR is the larger black wire that comes off the engine harness. Does that sound right? NO

Thanks guys....

Black/Red on the IGNITION harness goes to the coil. As does the Black/Purple.

White wire with a box connector goes to the AAR. Wire on the AAR is red.