June 24, 2018, 10:26:36 AM

Author Topic: DDEC II, the saga continues....  (Read 8474 times)

Offline Sean

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Re: DDEC II, the saga continues....
« Reply #15 on: May 27, 2010, 10:10:15 AM »
... the injectors are not electronic injected they are manually injected. ...

... on mine, there is a fuse that powers the left bank and a fuse that powers the right bank. If one or both of these fuses blows, the engine will either run very badly or not all ...

OK, this is one of those "you're both right" moments...

On the DDEC two-strokes, the injectors are mechanically operated by pushrods, in much the same way fully mechanical injectors are operated (as opposed to, say, a high-pressure common-rail system found on more modern engines).  However, there is also a small solenoid in each injector that is opened and closed electrically on command from the ECM, which controls the fine injection timing and amount of fuel delivered to each cylinder.

If the ECM does not call for fuel, the solenoid does not open, and the injection plunger instead pushes all the fuel through the bypass pathway and back to the return.  No fuel goes to the cylinder.  This is, in fact, one of the ways to test your injectors -- the DDR or Pro-Link will let you set any particular injector to zero-fuel to see if there is any effect on the engine.

If the injector bank fuse blows, no fuel will be delivered to that bank, even though the engine is turning and the injector pushrods are operating.

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com

Offline wayneswirld2

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Re: DDEC II, the saga continues....
« Reply #16 on: May 27, 2010, 10:36:52 AM »
As near as I can tell at this point, the injectors are NOT firing fuel into the cylinders. 

IF it ain't broke, don't fix it.  But then again, if it's on your bus...do some damned maintenance to it.  It'll break eventually.

Offline robertglines1

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Re: DDEC II, the saga continues....
« Reply #17 on: May 27, 2010, 10:51:36 AM »
from past post on DEC problems...a socket connector was not tight(making good contact) ....DEC works on a need for a narrow range of voltage.must be above 11.9 volt if memory serves me correctly..if you haven't ck voltage to pin do so.. DEC works on 12 volts :so even a weak or bad battery can cause confusion,depending on where the 12 volt tap is....just throwing things I would ck without code reader..
Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana

Offline stevet903

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Re: DDEC II, the saga continues....
« Reply #18 on: June 02, 2010, 07:31:23 AM »
Correction to my previous post, that was for DDEC III, not II.  Sorry guys!!


a.  Turn ignition off.
b.  Jumper pin A to pin M on the 12 pin DDL connector.
c.  Turn ignition on and observer the codes flashing on the CEL.  Example: Code 13 and 21.

1 flash - (short pause, 1/2 sec)- 3 flashes - (long pause, 3 sec) - 2 flashes - (short pause, 1/2 sec)- 1 flash

This will continue as long as the pins are jumpered with the ignition on.

FYI - Codes can only be cleared with a DDR or Pro-Link - removing the battery cables will not clear codes.