DDEC II ECM life expectancy

Sam 4106 · July 10, 2016, 12:22:43 PM

We have been sitting in Bismarck, ND at Interstate Detroit Diesel since Friday afternoon waiting for an ECM for our 8V92 DDEC II. It's supposed to be here tomorrow morning. When we arrived here by being towed, the engine was only running on one bank with barley enough power to move the bus. The tech hooked up the diagnostic computer and thinks the injector driver is faulty, but won't know for sure until he changes the ECM. If it turns out to be the ECM that will be the second failure in about 20,000 miles. I think they should last much longer. The engine has 111932 miles since new. Opinions?

Thanks, Sam

luvrbus · July 10, 2016, 01:23:17 PM

As long as the cooler plate is not plugged and heat shield is in place it should outlast the engine.I service a generator with a 8v92 DDEC ll it has been running since 1990 10,481 hours never a miscue yet

belfert · July 10, 2016, 02:47:19 PM

Are you sure the fuse to the other injector bank isn't just blown? I remember reading about several buses here having that issue.

Sam 4106 · July 10, 2016, 03:33:43 PM

Cliff,
Would a plugged cooler plate cause the engine to starve for fuel? And, where is the heat shield you refer to?

Brian,
Power to the injectors was one of the first things I checked befor calling for a tow. It is also the first thing the tech checked. He also checked power at the injector harness and homed all of the injectors thinking it could be injectors. His conclusion was a faulty ECM. Hopefully we will know tomorrow and be on our way again.

Since the bus will barely move under it's own power Interstate let us stay in the bus in their parking lot and provided a 20 amp outlet for us to plug into. Temp in low 90s today so we are running the gen for A/C.

Thanks, Sam

luvrbus · July 10, 2016, 06:27:58 PM

Sam, it should be on top if you have 1.If it is your ECM again I would check my electrical supply if it is off a center tap the DDEC ll is 12V only they do not like spikes .They will handle a few spikes @ 14V but not many then they are toast,battery charges are their worst enemy you might need to look at upgrading the harness and going to a DDEC IV using straight 24volt for your MCI

good luck

ArtGill · July 10, 2016, 06:35:05 PM

The injectors on each side connect to the DDEC using different plug. In Florida, a number of years ago we were stuck for 4 days, replaced three injectors and then found the plug was loose on the DDEC. Double check that plug on the DDEC.
Art

Sam 4106 · July 10, 2016, 08:02:02 PM

While we were waiting for a tow I checked the voltage to the injectors at 12.76 VDC and I also removed all of the connectors on the ECM and cleaned them with electrical contact cleaner. There was no corrosion on any of them. The first thing the Interstate tech did was check the injector voltage and then removed the connectors from the ECM to look for corrosion and test the harnesses. His conclusion was to replace the ECM.

Cliff, I looked for a heat shield and there was an indication in the paint on top of the cooler plate that there was once a shield attached. I will fabricate a new one when I get home. The power source is off a center tap so I may have to check the voltage regulator and possibly adjust it.
I mentioned to the tech that if I needed an ECM maybe I should switch to DDEC III and he responded that he didn't think I could. Now you are suggesting going to DDEC IV. Is that really possible ? If so what is involved?

Thanks, Sam

luvrbus · July 10, 2016, 08:38:28 PM

Sam,if your engine serial number is a very,very early DDEC then you cannot do the upgrade all he needs to do is find the service kit number and it comes with everything including the ECM,sensors, harness and heat shield.
Lot of DDEC lV in the 6v92 and 8v92 running around,here is service kit number for the 60 series DDEC ll to the lV look it up it tells you what is involved and not much.
I helped a friend a couple of weeks ago upgrade his 11.1 DDEC 11 to the lV so he could use the Eaton auto shift

good luck

Scott & Heather · July 11, 2016, 08:12:41 PM

What else might someone width an 8v92 ta gain by going to ddec 4? Better shifting? Response?

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luvrbus · July 11, 2016, 08:28:05 PM

Quote from: Scott Bennett on July 11, 2016, 08:12:41 PM
What else might someone width an 8v92 ta gain by going to ddec 4? Better shifting? Response?

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Yep faster response, they run cooler, more monitoring,less problems,wider range of HP setting ,not voltage sensitive and you can use any type electronic controlled transmission just a better system by far

Oonrahnjay · July 12, 2016, 04:33:13 AM

Quote from: luvrbus on July 10, 2016, 06:27:58 PMSam, it should be on top if you have 1.If it is your ECM again I would check my electrical supply if it is off a center tap the DDEC ll is 12V only they do not like spikes . ...
good luck

Yes. The first thought that popped into my head was "you don't have ECMs that are dying, you much more probably have something that is killing them".

Boomer · July 12, 2016, 10:27:03 AM

When I tried to upgrade my 6L71TA DDEC II to III or IV I got nowhere with Detroit Diesel, they said it could not be done. Could not find any kit at the parts counter, although the parts gal was brain dead. Put on a reman II ECM and it's working great and gives me all the info I need for my Silverleaf however it was for a RH engine and the firing order for a lefty is different. Simply had to rewire the injector harnesses for LH firing order.

luvrbus · July 12, 2016, 11:19:27 AM

DD changed the firing order on the 8V92 about the middle run of the DDEC ll when they changed suppliers for the DDEC control,if you have the right cams it is not a problem to upgrade to the DDEC lV on a 8V92 or 6V92 they never allowed or furnish parts for the DDEC V upgrade on a 2 stroke that I can find anyways

robertglines1 · July 12, 2016, 11:20:48 AM

11.6 V Dc minimum requirement for DDEC to function. Just a point. FWIW

Iceni John · July 12, 2016, 01:02:32 PM

Does anyone here with DDEC II have a picture of their heatshield? I have only a small shield over the five connector plugs on the right side, and there's no sign there was any shield larger than that over the rest of the ECM. I can easily(ish) make a shield from two layers of polished stainless sheet, but how to best attach it is not obvious to me right now! I don't want to bolt it directly to the ECM because that will conduct heat straight onto the cooler plate.

Why did Detroit put their ECM right under the hot exhaust? Surely they could have found somewhere else cooler to put it?

Thanks, John