D-Jet ECU question

[brownaar]

Here's the situation:

73 2.0
Had 052 ECU
019 injectors
012 head temp sensor
037 MPS
Car ran with an occasional miss
Decided to replace original wiring with Bowlsby harnesses(these things are great). In the process I thought I'd replace ECU with a rebuilt 043 unit which theoretically is more correct(I know it's a 74 unit but with an 012 head temp sensor and no ballast resistor there should be no problem) for a GA engine than an 052. After hooking everything up, car ran so rich fuel was dripping from the exhaust pipe. I trouble shot the harness and sensors(all was well), replaced the 052 ECU and car runs fine.

Should there be this much difference in the two ECU's or have I gotten a defective rebuilt unit?

Thanks,
Aaron Brown

[Dave at Pelican Parts]

"So rich it's dripping out the tailpipe" is richer than would be accomplished by a mismatch in parts, IMHO.

Check your electrical connections--if the CHT sensor is not plugged in, you may have similar problems.

One of the known failure modes of the D-jet ECU is converting itself to CIS--i.e., the injectors turn on and do not turn off... Substitute your old ECU back in and see if there's any effect.

--DD

[brownaar]

Dave,
I have put the 052 ECU back in and the car runs fine. The CHT sensor was my first thought, too, but it had a good connection. The problem only occurred with the "new"(aka Bret rebuilt)ECU.

[ken180]

I have used 3 different years of UCUs on the same engine with out any problem. They all work about the same with minor differences.

NONE caused the engine to run as "rich" as you describe.

I'll bet you have a bad ECU.

Ken

[Dave at Pelican Parts]

Since the problem follows the ECU, chances are very very good that it is a bad one. Talk to the seller about returning it.

--DD

[Bleyseng]

Using a 037 MPS with a 74 ECU will result in rich running too as the 043 MPS is set up leaner.

Geoff

[brownaar]

Geoff,
True that an 037 MPS with a 74 ECU will result in a richer mixture, but my understanding is that it shouldn't cause the drastic difference I experienced.

Thanks,
Aaron

[Alfred1]

These guys also rebuild d-jet ECUs.

[Bleyseng]

I know, but you are mixing parts which causes all kinds of weird stuff. If I were you I would locate a 73 ECU and install the correct CHT with the ballast as that will run right unless you have other problems. The 73 one is easy to find as its the same for the 1.7 engine.
Geoff

[brownaar]

Geoff,
I am currently running with a 75-76 ECU with the 037 MPS and later CHT sensor. I just wouldn't expect that much difference between the 74 ECU and 75-76 ECU, considering they all use the 012 CHT sensor and 043 MPS.

Thanks,
Aaron

[Bleyseng]

I know the 74-76 ECU are pretty much the same and use the 043 MPS. Why are you using a 037 MPS in the first place as it does have a richer A/F mix than the 043's. I find that the 037's soot up the plugs fairly quickly on the later set ups.

Geoff

[bowlsby]

Thanks for the compliments on the harness Aaron, you are in good hands with Geoff B. I also have a few known good 73 ECUs if you decide you want one, let me know.

Jeff

[Bruce Allert]

Geoff, can a 73 ECU that's been running a 1.7 run a '74 2.0 with a 1.7 CHT? My CHT on the 2.0 went gunnysack and all I have at this time is the (practically new) 1.7 CHT. Since I put that in with the 74 ECU it doesn't start cold as well as it did.

.......b

[Bleyseng]

If you run a 73 ECU (it fits a 1.7 or 2.0) then run a 017 with it along with the ballast resistor. That will along witha 037 MPS make it run right. If you are talking about just making it run you can use anything just to limp along till you get the right parts.
Bosch did its homework on this FI so don't try to mix up the parts!
The 73 1.7 CHT is similar to the 74 2.0L 012 one so its too lean.
Geoff

[Bruce Allert]

Originally posted by Bleyseng
don't try to mix up the parts!
The 73 1.7 CHT is similar to the 74 2.0L 012 one so its too lean.
Geoff

Well then... there's part of my problem! I keep hearing a slight poping while at speed (60 mph+) which I assume is it's running lean. I just found a 2.0 CHT at the Import Auto Parts. Gonna go pick it up

..........b

[brownaar]

Geoff,
The car had an 037 MPS when I bought it. I'll seriously consider switching to an 043. I was trying to go with the 74 setup based on Brad Anders' recommendations.

Thanks,
Aaron

[Bleyseng]

They all (the different years) work well as designed its just that people mix up the ECU's, and MPS's. Now that doesn't work well even if it works.
How's the fuel ecomony? and the plug color?
He recommends the 74 set up as it's the easiest to get the parts for and its non smog. The 73 setup is fine too if you locate all the right parts. (ECU, MPS and CHT/Ballast).

Geoff

[RustyWa]

Aaron, is your 037 MPS a rebuilt unit? Is the case halves held together with rivets or screws?

[brownaar]

Eric,
I have both an original and a rebuilt unit that I've used with my setup and they both work.

Thanks,
Aaron

[RustyWa]

I guess the thing I was wondering about was, if you've got a rebuilt 037 MPS and an ECU for a '75-'76....does it matter anymore that they don't have "matching" numbers?

If you recalibrate your 037 MPS (or it's already calibrated) to the 043 MPS settings, then it shouldn't matter what the MPS is anymore. Right?