73 2.0 djet idle problem Options

[jasons]

Car is a 73 2.0, new TPS, new FI Points, new TS1, existing TS2 (its the 017), all intake runners, hoses, gaskets, and PCV are new, injectors were cleaned and serviced by witchhunter. Also all parts are correct for the 73 2.0. I put a 270ohm resistor in too. Car seems to run lean at idle (I have an air fuel meter).

I had the wrong TS2, because I replaced it with what I thought was the correct replacement. Upon further review, I put the used 017 piece back in.

The car had been sitting when I bought it, so I dropped the motor to take care of a few problems, and I refurbed the FI while I was at it.

Car seems to have good power and pull hard, but it doesn't seem to idle quite right. It oscillates between, 1000 and less than 500, while the air meter reads lean. Air bleed and the knob both effect idle, but I can't get it to stabilize or richen up on the meter.

Also, I have a euro-race header and MSD. Should I play with the resistor or the FPR to richen the car for these parts?

[Demick]

First thing - unless your O2 sensor is a wideband O2 sensor, then do yourself a favor and get rid of it. They are pretty much useless on these motors.

Now that it's gone, what is the indication that you are lean at idle? General sign that it is lean, is that the motor will do the 'lean idle hunt'. It won't hold a steady idle speed, but will fluctuate up and down (in the 500 to 1500 rpm range). If it is doing that, then you need to richen it up a bit at idle. If it holds a steady idle speed, then it is not likely that it is lean.

If you do need to enrichen it, first try the knob on the ECU. I forget which way does what, but turn it one way and the lean idle hunt will get worse. Turn it the other way and it should get better. Don't worry if it raises your idle speed as you say, you simply need to readjust your idle speed with the idle speed screw on the throttle body. If you cannot get the lean idle hunt to go away even with the knob turned fully rich on the ECU, then you have to look for another source of the problem (sounds like you are already well on your way with that).

Demick

Edit: just read your first post in more detail and see that you are experiencing the lean idle hunt. Try to adjust the knob on the ECU to fully rich and see if you can get it to go away. 2nd thing I would do is check the numbers on all of the FI components (MPS, ECU, etc) to make sure they are correct for your motor. Then start looking for any vacuum leaks. Could be almost any one of the vacuum connections in the engine compartment that causes it to run lean.

[jasons]

First thing - unless your O2 sensor is a wideband O2 sensor, then do yourself a favor and get rid of it. They are pretty much useless on these motors.

Now that it's gone, what is the indication that you are lean at idle? General sign that it is lean, is that the motor will do the 'lean idle hunt'. It won't hold a steady idle speed, but will fluctuate up and down (in the 500 to 1500 rpm range). If it is doing that, then you need to richen it up a bit at idle. If it holds a steady idle speed, then it is not likely that it is lean.

If you do need to enrichen it, first try the knob on the ECU. I forget which way does what, but turn it one way and the lean idle hunt will get worse. Turn it the other way and it should get better. Don't worry if it raises your idle speed as you say, you simply need to readjust your idle speed with the idle speed screw on the throttle body. If you cannot get the lean idle hunt to go away even with the knob turned fully rich on the ECU, then you have to look for another source of the problem (sounds like you are already well on your way with that).

Demick

Edit: just read your first post in more detail and see that you are experiencing the lean idle hunt. Try to adjust the knob on the ECU to fully rich and see if you can get it to go away. 2nd thing I would do is check the numbers on all of the FI components (MPS, ECU, etc) to make sure they are correct for your motor. Then start looking for any vacuum leaks. Could be almost any one of the vacuum connections in the engine compartment that causes it to run lean.

Thanks thats good advice. I was questionable about the 02 sensor, but my header had the 02 bung, and a friend gave me a brand new 02 unit, so I figured I would try it out.

When I adjust the knob to fully rich, it does get better, but it still hunts a little. When I had the motor out of the car, I checked all the parts to make sure they were 73 2.0. All the hoses are new and they are the braided German variety. The intake runners are new. The TB Gasket, I made out of gasket material. There shouldn't be any vacuum leaks, but that doesn't mean there isn't one. This car has the fuel pump relocated to the trunk. Could the long run to the engine reduce the fuel pressure? On Brad Anders site, he says too much advance could cause this too. Any thoughts on that?

Also, the plugs show little sign of combustion. They are new and still look new. Not black, not white, not caramel color. They only have about 15 miles on them.