Alfa Romeo Forum banner

21 - 37 of 37 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter #21
Regarding ECU voltage (and I think MES and maybe more failures can be due to that), after spending some time on elearn I'll clean up positive with relays J10/J15 (Fuel pump, EFI), fuses in battery box + the one underneath the wheel. Negative for ECU are not from the main battery lead (A1B-C1-C10C) but on C10A which I couldn't locate yet.
Therefore it may explain that ECU has voltage difference while the main body / engine is par : ECU earth is elsewhere.
 

·
Registered
Alfa 166 Super, Gtv 6 Phase 1 (916), Alfa Mito QV
Joined
·
72 Posts
Off topic in your cases: Rotten injectors are constantly drooling (too much unburnt) diesel into the cylinder and along the cylinder walls this diesel works through to the oil pan. On a german car channel they showed a 1.9jtd Fiat Doblo. Engine almost dead, making horrible clonging sounds and the "oil" level ca.2 cm/almost an inch over top...
 

·
Registered
Joined
·
42 Posts
Discussion Starter #23
I've just checked my battery voltage at idle as seen by the ecu using mes and I'm not seeing the spikes that you are so it appears that you have a bad connection somewhere in the ecu's supply. If with your graph running you wiggle the ecu connector, its fuses both on the battery and in fuse boxes and the harness and tap the ecu itself, you may see the problem, but my money would still be on the main earths. A pain to get to, jacking the car and removing the under-
tray but on a sixteen year old car it should be done as preventative maintenance anyway.
hi,
I have a favor to ask you. Can you please, on your car, try to see if MES stalls/stops when cranking ?
I saw a comment in another topic stating it may be usual to MES to drop while cranking and the starter is taking too much current. But this is impact MES and/OR OBD, no the ECU itself I guess.
Thanks
 

·
Registered
Joined
·
42 Posts
Discussion Starter #24
Some news ! (rather good this time)
I cleaned up the Positive side of the supply : fuse case, and most of all : relays behind the battery. On the 20V there are 3 : I guess Heater Diesel, Ignition (ECU), Fuel Pump. 2 black 20A, 1 red 30A.
Mine is missing the cover. They were rather dirty, and the seatings as well (grease/black compound all on the base).
I swapped the red one to the AC one (PN 46520422), should be J10 (30 A), so the Ignition one.

It started immediatly. Doesn't mean anything though...BUT : now voltage readings are much higher and no spikes anymore. Between 13.6 and 13.9 all the way. So whether it solved the issue or not, at least this is something !
 

·
Registered
Joined
·
799 Posts
That is good news, I think you will probably find that has fixed it, ecus don’t like low voltages. I disconnected my injectors and cranked the engine for ten seconds while monitoring battery volts. Mes stayed connected, the minimum voltage, at starter engagement was 8.9V.


Incidentally, my boost hose split a while ago and coated those relays with oily goo, so yours might have split in the past, or perhaps now? Worth checking.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #26
THere is this goo but I think the problem is that I miss the cover (unique part for the 20V, so not easy to find anyway) at all. By the way, do you confirm that you have 2 black 20A relays (B047e/46520411) and one red (A727 26520422 - which should be the ECU one) behind the battery ?
The red one, also on the AC Comp is not supposed to be on that car if we believe ePer... I'm rather thinking of a mistake ?
 

·
Registered
Joined
·
799 Posts
Mine are under that cover (which is dry and dusty) so not visible, but according to the information on the cover those relays are the injection relay, fuel pump relay and diesel heater relay and according to elearn they should all be 30A.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #28
Yep...in all elearn schematics, J10, J15 and J17 are 30A but in eper they are 20A for Heater + Fuel Pump and none is described for the injection. This seems to be the same on my car.... There are dark zones in ePer as I cannot find the AC relay anywhere, I wanted to compare the PN to the one in the ECU...
If you have a couple of seconds to compare your relays, just to know if someone messed up with 2nd hand relays or just a wrong eper/elearn statement
thanks ;)
 

·
Registered
Joined
·
799 Posts
Funnilly enough I have plenty of moments just now, here is what I have:
934576

Contrary to the positions indicated on the cover they are:
Driver's front left Fuel pump 20A 46520411 Black
Front right: Diesel heater 30A 46520422 Red
Rear right: Injection 30A 46520422 Red
 

·
Registered
Joined
·
2,732 Posts
To me all this is pointing to a high resistance terminal/connection somewhere in the wiring. I'd start checking the main wires from battery terminal to starter motor and on the negative to the gearbox earth connection via the left hand inner wing junction. It may be more in depth but that would be a good place to start.
 

·
Registered
Joined
·
2,732 Posts
Funnilly enough I have plenty of moments just now, here is what I have:
View attachment 934576
Contrary to the positions indicated on the cover they are:
Driver's front left Fuel pump 20A 46520411 Black
Front right: Diesel heater 30A 46520422 Red
Rear right: Injection 30A 46520422 Red
Go by the wires to the relay multi block connectors. Forget colours or numbers on relays. Go by the wires as it is easy to put the relays out of position.
 

·
Registered
Joined
·
799 Posts
I confirmed the functions with a magnetic field detector: Voltcraft MS-410 Magnetic Field Tester
(magic bit of kit). The injection relay stays on. The fuel pump relay stays on for 12 seconds after key-on. The diesel heater does not energise at current temperatures.

Someone could have swapped my relays around in the past but the car was maintained by Alfa or Alfa specialists before I got it, and I haven’t moved them, so they are probably correct. (Also those current ratings are more than adequate for their functions.)
 

·
Registered
Joined
·
42 Posts
Discussion Starter #33
Funnilly enough I have plenty of moments just now, here is what I have:
View attachment 934576
Contrary to the positions indicated on the cover they are:
Driver's front left Fuel pump 20A 46520411 Black
Front right: Diesel heater 30A 46520422 Red
Rear right: Injection 30A 46520422 Red
Jeez...Mine is exactly the contrary ...

Driver's front left Fuel pump 30A 46520422 Red
Front right: Diesel heater 20A 46520411 Black
Rear right: Injection 20A 46520411 Black

:'(
So I swapped the front left (my red 30A) with the AC Fan (red 30 A).
So my fix would only be on the cleaning side, as I would just have swapped the fuel pump relay, not the ECU.

So you are 100% positive with your tool regarding the relay position (although they may have changed during the life of the car but the layout seem totally identical)
I'll do a check with the wires in case...
 

·
Registered
Joined
·
799 Posts
Yes sure, I’m only assuming the cover accurately describes the relay functions under it if not their layout (though I did remove the pump relay and start the engine, it fired a few times and stalled so I can be sure of that one).


You can confirm the functions by tracing the wiring or as follows: First injection – remove relay and then try to connect mes. Reinsert relay (with ignition off). Then fuel pump – remove relay and listen for absence of pump at key-on. Diesel heater can be assumed, or – I think you can turn it on briefly using mes. Check for volts on the heater’s connector, on the filter, remove relay and repeat.


It’s plausible that just disturbing the relays will have put a bad connection right, though possibly only temporarily. I would replace the injection 30A and pump 20A relays and make sure their connectors are clean. If you subsequently get trouble suspect a wire to terminal crimp joint in the multi-connectors.


Is the car still starting?
 

·
Registered
Joined
·
42 Posts
Discussion Starter #35
Thanks will do that tests, yes.
The car started right away 6 times in a row. Never seen that, it has to have a significant impact. It is not just cleaning, it is cleaning and seeing visible results on the voltage at the ECU.
Let's keep fingers crossed :)
The hose seems good (not original). Will need to check nonetheless
 

·
Registered
Joined
·
2,732 Posts
All this is really quite simple. Our cars are old. Their wiring protection is rather poor. The relays are not sealed.

It all degrades and needs a good clean/new terminals/anti corrosion spray to stop all these electrical bits causing the plenty of problems they usually cause these days. An hour or possibly 2, new terminals, emery cloth or a wire brush and some anti corrosion spray is all that is needed to eliminate causes of unreliability and malfunctions. Why not sort this before it becomes another fault or another broken down Alfa at the side of the road? All the stress is unnecessary.
 

·
Registered
Joined
·
42 Posts
Discussion Starter #37
Yep....This reminds me my old 1981 Lancia Beta on which bad terminals are much more frequent all over the place :)
Will come back to this topic with my relay feedback and MES status with a proper ECU voltage....and hopefully not due to another rough start !
 
21 - 37 of 37 Posts
Top