OB
I do not think they are direct replacements, and will not just swap into the engine where the old one came out, but need fitting and fettling.
Greg

 

Paul
Get rid of the 6 CU ASAP and get a 16 CU, if you were not already aware. Much better circuitry apparently, direct swap too.
Greg

 

Cheers Greg, yes James has a contact not far from his house that can get them for about $200 AUD from memory. I think it is definitely on the cards.

 

Yes he has a bunch of 6CU's but no 16's at this point
He sends all the ECU's as a batch for repair/refurb

The 6CU's are taken apart and re soldered as 99% of time they have dry joints
16's are repaired as needed but seem to be a rare fail.

Not sure if this is correct but was told the 6's were hand soldered where the 16's were done in a wave tank. If thats correct it explains the dry joints

Cheers
34by151

 

Hi Greg

I wasn't going to get one myself, I will get a normal FPR for £40.

 

From LUCAS EFI / AJ6 Engineering

16CU Part Numbers and Applications.

All are preceded by DAC.
4118, 4585, 6335 - Lucas ignition, Cat
4119, 4478, 4586, 6336 - Lucas ignition, non-Cat
6337 - Marelli ignition, Cat
6338 - Marelli ignition, non-Cat

Cat versions have 02 sensors
You need to match the 16CU to the type of car that you have

In Paul's case it will be a 4119DAC, 4478DAC, 4586DAC, 6336DAC

Personally if it was my car id go with a modern ECU and not bother
Id go a megasquirt any day of the week but that's me

Cheers
34by151

 

Catching up slowly, my new speed at the moment.

How long since the throttle bodies have been wiped out of the "black goo".

That reeks havoc on the earlier cars, and I see nothing on the later that changes that goo build up.

 

Since you fiddled with the CTS, I would go back and check the wiring, inside the plug you touched, and further back up the loom. Simply disturbing OLD wires can let The Prince Of Darkness take up residence.

 

Mine (1985 HE) has a DAC4585 from a 1988 S3 V12 with O2's.

My multi pin plug has no wires in the related sockets of that plug, and the thing works fine. Damn thing is a missile.

My BASIC understanding of ECU's was, and still is, NO input, nothing to do, so ignore.

That was in 1998, and its still fine.

I reckon going the other way would be a barrel of laughs.

 

That's the case for the first gen of ECU's like the 6CU and 16CU but not the case nowadays

The generation we dealing with here dont have any smarts which can blessing for sure. Fueling based on a single map and little in the way of sensors and no control of spark

At the simplest level a modern ECU this is a baseline map. Each entry has a short term and long term trim. So the Map is constantly changing to tune the engine. That's a little simplistic but gives a basic idea

A modern ECU would go into limp mode or full shutdown with missing or out of spec sensors.

My 2004 XJR was sent into all manner of issues because of an oil change!!!

It ran super rich, overfulled then shutdown (engine fault). The fuel trims reached 25% overfuled. The ECU reported a long list of errors right down to need new cat converters. What was wrong, well the dipstick wasnt fully seated in the tube. This allowed a vac leak sending a bunch of sensors crazy.

Getting back to the issue on the Goose, I dont think the ECU is the cause but its worth testing another (borrowed) unit in the car


Cheers
34by151

 

Yep, the new stuff is horrid.

Wrong oil in a VF Commodore V8 at work recently, sent the engine and trans to mars and back.

A late Audi needed a battey, simple, well NO, the car had to be plugged into the Audi network, and then the barcode of the new battery needed to be scanned, so the system would then turn the car ON. Only issue was, our batteries are NOT Audi batteries, so the guy had to go to the dealer, DUH.

Everything is matched to everything else, so we "normal" people cannot play with it.

 

Heh guys. Thanks for all the info.

In regards to the ECU, I guess it couldn't hurt taking the 6cu out and re-working the solder joints. I have the right gear set up in my shed (once I move the kids toys out the way) as electronics is my background, so I have a half decent Weller Solder station, solder sucker and tools etc to do the job.

Is there any threads on here about servicing the 6cu ECU? If not I'll open her up and take some pictures of findings. I used to repair old Traffic Signal Circuit boards as well as old video games. Yep sure enough, dry solder joints was up there on the most common list.

 

Worth a look mate
I was thinking to drive the goose up my way and we put in one of the spare ECU's then see if any difference

Cheers
34by151

 

Sounds good but I don't have faith in the ole girl getting me there!

She was doing her spluttering performance even before I got her out the driveway the other day...

 

You can still drive tough it but ill see if I can borrow one for you

Cheers
34by151

 

Without the o2 sensors it will be in open loop all the time. The O2 sensors will allow it to switch to closed loop and do limited fueling adjustments based on the o2 readings.

It would be worth checking if you have the feedback plug installed
Its the cable next to the ecu harness with a loop in the plug

If you dont that confirms the 16CU will run open loop with no O2 sensor present
If you do pull the plug and see what happens. The ECU should have no change
If you dont install the loop. If the ECU goes crazy there is no os missing protection. If its the same it ignores a missing o2 staying in open loop


PS the loop is there to disable the o2 and put the ECU into open loop so you can set the fuel adjuster on the ECU

I would not bother too much with O2 if you dont have it. It wont be that effective anyway as the ECU has no knock sensor or timing control

With no knock sensor the ECU would keep the system a tad rich as a protection strategy and not do much to lean it out.

Cheers
34by151

 

No plug on the system to mess with.

It drops into closed loop just fine, with the TPS at 0.34V at the idle split.

It goes into open loop as soon as the micro, or the vac, switch is activated, verified with a sniffer up her backside.

The ECU mixture pot adjusts mixture just fine at idle in closed loop.

I have never opened that 16CU unit, never had the need. It worked fine on the S3, and he simply removed it to fit a Wolf3D????. I slid it into mine in his driveway (mine was having issues with the fuel pump timer circuit), and drove home with it as installed. I fine tuned the thing later that day, and never played with it again.

Car is now in the care of another person, so I have no access to it.

 

Interesting read from the Lucas EFI link LUCAS EFI / AJ6 Engineering

Before all this started to happen I had a bad alternator that we swapped out...mmmmm....maybe just a coincidence but will definately open up my ECU when I get home and at least re-work those solder joints and inspection, or as James says, swap out for a known working spare.

Could just be a coincidence....

 

Might order one of these too....just incase

 

HELL YES.

I would have thought you and Clarke would have plenty of that on hand.