I have a 1988 740 turbo wagon that I recently acquired with a rich running condition. I've worked on these for a while, so I figured it would be an easy fix. It's got some miles on it so I replaced/went over all the common culprits. Cleaned PCV nipple, checked all vacuum hoses (replaced a few). replaced two intercooler lines, new ECT sensor, new FPR, new O2 sensor, new plugs and coil wire. Still, the car runs a little rich, worse at hot idle. All grounds are good for motor. All four injectors are ticking like they work. I also tried adjusting the richness out of the 007--not enough adjustment available to clear it up.

The problem is not huge, it is a slight rich smell with a idle miss every 2-3 seconds at hot idle and in gear--also enough that the car would fail emissions.

Finally I went through the entire Chilton's manual diagnostic at the ECU, AMM and injectors.

The only discrepencies were these:
1.) AMM gets .5v less than battery when checked at AMM terminals 1 and 5.
2.) AMM shows 3.0 ohms at AMM terminals 6 and 7 (specs say it should be 3.7 ohms.
3.) Injectors uniformly showed 2.5-2.6 ohms accross the leads (book said approximately 16 at cold--car had been run about one hour previous to tests.)

I am frustrated...usually I would have it fixed in an hour...but I am also past my level of certainty....

Is any one of those three things enough to cause the richness?

I think the injectors are not the problem as they tick normally and are uniform in reistance. So, is the 3.0 instead of 3.7 ohms the culprit? I have never known an AMM to cause just a slight rich situation (car runs fine with plenty of power, but is always a bit rich). Usually there are other problems....

I've spent a bit on parts already. I'd like to be sure before shelling out the $$$ for an AMM.

Thanks.