Idle adjustment question, Idles high or slowly stalls Options

[BillC]

I have an idle adjustment question for all you D-Jet gurus:

I can adjust the idle air screw on the throttle body so the car idles at 1600 RPM, and it will happily idle at 1600 all day long. If I turn in the screw just a little bit, like 1/4 turn, the car will slowly drop idle speed down slower and slower until it stalls. I can blip the throttle to keep it running, but it just wants to slow down and stall. This is all when the car is fully warmed up.

How do I get the car to idle steady around 1000-1200 RPM? 1600 is just too high.

Car is a '73 2.0 with factory D-Jet. I installed new Standard Products FJ67 injectors, and the fuel pressure is 29 psi. There are no leaks in the intake side, and the idle adjustment screw is about 2 turns out (so there's plenty of adjustment available in both directions). The MPS hasn't been messed with, and the ECU looks like the correct unit. All new vacuum lines, fuel lines, pump & filter, and fresh gas. New @JeffBowlsby engine and alternator wiring harnesses.

Known issues: it has the wrong CHT sensor (it's the one that's commonly available) and I think the TPS board has worn traces. I finally found the right CHT and ballast resistor, and I also have a 914Rubber replacement TPS board, and I will install both of them when I get a chance. However, I don't think either of those should keep it from idling at a reasonable RPM.

[BillC]

So, I installed the 017 CHT and 270 ohm ballast resistor. I also replaced the circuit board in the TPS and adjusted it according to the video on 914Rubber. Unfortunately, drivability is worse (now has a big part-throttle stumble), and I still can't get it to idle down where it should.

However, I may have found the issue(s):
-- First, the ECU is part # 0 280 000 037, which Brad Anders' page says is for a '72-'73 1.7 (it doesn't have the the CU13X marking for a '73 2.0).
-- Second, the MPS is 0 280 100 043 (039 906 051), which Brad's page says is for a '74-'76 2.0. It is also labeled "Remanufactured by Fuel Injection Corp".

This is what I get for not double-checking everything from the DAPO(s). (IMG:style_emoticons/default/headbang.gif)

So, at a minimum, I need to make the parts match.

If I get a '74-'76 2.0 ECU (0 280 000 043 or 044), that should work with my MPS and the previous CHT, right?

[Olympic 914]

Part of your problem may be that the tuning on the 043 MPS is leaner than that on the 037 MPS.

you can see the figures on Anders site

However the 043 MPS CAN be adjusted to the same spec as an 037 MPS and beyond.

Also, since your 043 MPS has been rebuilt, you really don't know what its settings are.

If you have access to a vacuum pump and a Wavtec meter you can check and adjust your MPS.

There are many that profess that all the FI parts MUST match.

I somewhat disagree.

I have 25,000 miles on my rebuilt engine and it runs great. but it will not idle on a cold start. (I just deal with it) after about 1 mile it will idle fine.

My setup on a 2056 is the same ECU you are running, a 037 (its the original from when the car was a 1.7) CHT is the 012 and I do not have the 270 Ohm ballast resistor installed. also the MPS is a 043 unit that I have adjusted to richer than the 037 specs (again 2056)

I don't have those numbers in front of me now.

Now I have done a bit of tuning on the MPS using a wideband AFR that is installed under my dash and I regularly monitor.

Both the 017 and 012 CHTs read about the same when hot < 90 ohms, all the ballast resistor on the 2.0L does is trick the 037 ECU into richening the mixture.

So, I installed the 017 CHT and 270 ohm ballast resistor. I also replaced the circuit board in the TPS and adjusted it according to the video on 914Rubber. Unfortunately, drivability is worse (now has a big part-throttle stumble), and I still can't get it to idle down where it should.

However, I may have found the issue(s):
-- First, the ECU is part # 0 280 000 037, which Brad Anders' page says is for a '72-'73 1.7 (it doesn't have the the CU13X marking for a '73 2.0).
-- Second, the MPS is 0 280 100 043 (039 906 051), which Brad's page says is for a '74-'76 2.0. It is also labeled "Remanufactured by Fuel Injection Corp".

This is what I get for not double-checking everything from the DAPO(s). (IMG:style_emoticons/default/headbang.gif)

So, at a minimum, I need to make the parts match.

If I get a '74-'76 2.0 ECU (0 280 000 043 or 044), that should work with my MPS and the previous CHT, right?