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Discussion Starter #1
Bear with me guys, this is a longish one….but I am fairly confident with the motronic system so have listed lots of tests I have carried out below of the various components! Some tests I just carried out to cross them off the list!

History: Euro S4, has always started perfectly, cold or hot, for the last 6 years and 40,000 miles of my ownership.

It has recently developed a strange ‘intermittent’ no-start problem when warm. Has happened now say 10 times in the last month or two, the very first time on 23 Dec.

With cold starts in the morning, even with this ‘new intermittent problem’ it always fires right up. It runs/drives impeccably. My last journey (moving home) of some 500 miles it ran beautifully, stopped for re fuel, wouldn’t start. 2 minutes later it starts and runs great.

First check I made when this first happened was for spark……and discover no spark.
So this is definitely electric, maybe relays, maybe intermittent ECU problem.

Motronic relay clicks once with KO as it should. However ‘sometimes’ I hear the relay clicking away, basically in sequence with the starter cranking over, ‘click, click, click….’. When I hear this I know it will NOT start. The motronic relay, the auxiliary motronic relay and the VVT relay all feel quite hot when this happens. The Fuel relay is cold. The ECU is also cold. The wiring to the relays is cold. There is no dampness whatsoever in/around the ECU compartment….all as clean as a whistle.

I have 2 spare new motronic/diode relays and by lifting the inspection hatch on the rear shelf, can easily swop it out. Quickly swop in a spare relay (which is obviously cold) and it starts. The relay that has become warm/hot also works once cooled down (a few minutes), and she starts right up!

My question: is it normal for these relays to get warm to hot? I think not. They are not working away constantly, just clicking in/out when you go on the gas/come off the gas.

So guys, a favour.....anybody care to drive around a bit with the ECU inspection hatch removed and feel any relay you can get your fingers on for warmth/heat? (usually 2 are visible under the inspection hatch, you can also put your finger in there and feel the third even whilst driving….the fourth one is not get-at-able)

Things I have checked when problem first occured (obviously the following checks were all carried out on the car that had started up again):

Battery: terminals clean and tight. Battery voltage: 12.94V
Battery drain checks out good: 20 milliamps drain (that is normal clock and radio memory drain)
Cranking voltage: 11.3V (hardtop interior light ‘on’ at the time as the door is open, but fuel supply cut – I have a manual fuel supply shut off switch fitted to my car, that I use for such tests so as not to flood the cylinders). Good.
Crank sensor/CS: Wiring looks good, sensor is mounted tight and is clean (not oil fouled), the Bosch 3 pin connector looks perfect, all pins intact.
CS male plug Resistance test: 536 Ohms. Good (WSM: between 520-600)
ECU > CS volt supply test (Volt DC): 4.41V. Good.
ECU removed, connector plug pins and ECU pin-outs all cleaned with a toothbrush and electrical contact spray.
Continuity from Battery plus to Main isolated electrical connector block G137 on side of ECU mounting bracket: Good.
Voltage from Battery plus pole > G137 (wires removed and cleaned): full Battery voltage.
Coil resistance test: 0,50 Ohms primary and 6,50 K.Ohms secondary (the lowish resistance value is correct for the Motronic coil, both my Motronic coils are the same)
Voltage to coil LT (ignition ON): 12.48V
Alternator: Battery voltage with car running: 13.7 – 13.84V @1500 rpm (Alternator good)
Voltage Regulator: Removed to check condition of brushes, they look fine, hardly worn and both brushes same height.
Fuel Pumps: Can hear main pump running evenly and well, with car running.
Relays: 4 main relays near ECU: all sockets cleaned, wiring all tight, the 2 fuses checked and good.
Relay resistance tests: the 3 Sipea 0440 relays test good at 77 Ohms (between pin 85 & 86). The Motronic red-stripe Relay (and the 2 new spares!) all test good at 650 Ohms (between pin 85 & 86). Relays click with KO.
The Motronic relay clicks on/off as you step on, and, come off the gas. Normal.
Fuse box: dropped it down and cleaned connections on the back, especially thick brown and thick red wire connections (Ignition switch contacts, second row up from bottom looking at the rear of the fuse box)
Air Flow Meter/AFM Resistance tests:
Pin 2+4: 38 Ohms (WSM says ‘about’ 100 Ohms - US version) – this seems to be a bit low, but car is running perfectly, so I am not too worried about this. And I believe the US AFM and the euro AFM have different part numbers, which might account for this.
Pin 3+4: 352 Ohms (WSM says about 400 Ohms) - OK
Pin 2+5: 2400 Ohms (Reference value depends on temperature) – OK for the ambient temperature at the time of this test.
AFM Volt Test (Rubber boot pulled back; Connector back probed; DVM set to 20V DC; once the DVM leads are connected, only THEN turn Ignition “ON”):
1+4 CO pot output: 2.48V (Reference value 2.5V) - OK
3+4 Reference voltage from ECU: 4.97V (Reference value 5.0V) - OK
AFM Flap Movement test (Pull back the rubber boot and back probe the Plug, then open/close the flap with your fingers. You need to remove the AFM from the top of the Air filter box to access the flap for this test):
2+4 (Airflow output): 0.25V with flap closed >> rising steadily to 4.50V with flap fully open [voltage should rise and fall as flap is opened and closed and should do so absolutely smooth, otherwise the track needs cleaning) – OK

The problem just happened again today: started perfect in the morning, go for a drive, come back to the garage, turn off engine, open the garage door, try to start, hear the ominous “click…click…click” of the motronic diode relay (and it feels hot) and it will not start….replace relay with cold one (spare) and it starts.

I really do not know what else to test: does it sound like an odd ECU problem to anyone??
Could the motronic temperature sensor be at fault, maybe sending odd signals (intermittently) to the ecu? Can’t imagine this tbh, as the car runs faultlessly (when it starts!)
 

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Admittedly I know little about the Motronic system but it seems like the relays should not get noticeably hot. Are the connections where the relay plugs in tight & clean? Looseness &/or corrosion = resistance = heat. Just a guess...
 

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Discussion Starter #4
Crank sensor.
I had the exact same issue. Sensor tests fine until heated. Problem got progressively worse after each failure,
thanks Eric
connections are clean and tight

Aldo, did you just come across the CS fault by chance with your car or how did you narrow your problem down to that?
I will re-test the C.sensor next time it happens and see if I notice a difference when it is hot, eventually replace it.
 

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Aldo, did you just come across the CS fault by chance with your car or how did you narrow your problem down to that?
I will re-test the C.sensor next time it happens and see if I notice a difference when it is hot, eventually replace it.
My experience was similar to yours. My CS tested fine so I discounted it and searched other possibilities.

A fine poster here suggested replacing the CS.
Problem solved.
Of course there's no guarantees that this is your problem but it sounds very similar to my experience.
 

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Hi Dom,
Did you get anywhere with this problem?

I've been meaning to check the relays for you but haven't had chance to drive either of the cars until today. I am in France and have today had a great blast along the autoroute and then the smaller roads near Chinon, in the Loire.

Anyway, I checked the temperature of those relays by sticking my fingers in there? After a short run or a long run the red stripe and the one adjacent to it were noticeably warm to hot, whilst the other two less accessible ones were cool.

Good luck with the problem,

Nick
 

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Discussion Starter #7
Thanks Nick!
Good to know the relays do get warm/hot under normal working conditions (I was worried about that, and discovered with the passenger window open 2 inches and the inspection hatch removed, you get a lovely stream of cold air going right to those relays:))

at the moment I am waiting for the problem to re-occur.....then jump out the car and measure the ohms of the Crank sensor..........but as these intermittant problems never rear their head when you need 'em to, I am still waiting......bloody thing is behaving (never thought an alfa driver would say that!)

I did measure the ohms with the car hot, and it was normal.

I have a CS on order.

I will of course keep the thread updated as soon as I know something more positive.
 

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Anxiously awaiting responses here. I have the same problem. Very frustrated. Seems if I boost the battery, it starts no problem. I am about to remove the alternator and have it rebuilt because I do notice that when I have the flasher and lights on, the gauge does dip to bellow 12 V.

But one out of 5 tries....click...click....nothing. Wait and then it starts, sometimes. Very unpredictable.

Mine is also an S4 (93)

Mario
Ottawa
 

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The S4s do seem to suffer from current drain when left for a while ( a week or two) without being driven. I keep mine either on a battery trickle charger or with the battery disconnected when they are left for a while.

The other issue is one that the circuit to the starter solenoid is not great. There are threads here on how to add a relay to give a bit more juice for the solenoid. e.g. this one http://www.alfabb.com/bb/forums/spider-1966-up/388746-starter-relay-wiring-question.html
 

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spiderserie4:

You have almost 13 volts available at the battery, but 11.3 cranking volts? That seems like a lot of lost voltage.

Another-- did you use the red button to pull Motronic codes off the ECU? (assuming there are any stored codes)
 

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Discussion Starter #11
spiderserie4:
Another-- did you use the red button to pull Motronic codes off the ECU? (assuming there are any stored codes)
...euro S4 spiders do not have the red code button.

at the moment the problem is not re-occurring, now that I sorta want it to (not really!)
 

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Decided to tackle my unpredictable no-start (click...click..click) issue on the weekends. I had the alternator rebuilt last weekend and changed the belt too. But it still wasn't charging right.

Saturday I started at the back cleaning grounds with a dremel, changed the battery ground cable, changed the positive battery connector, cleaned the relay connections, changed all fuses for new ones. Now it works fine. Battery charges strong, keeps a charge, and stable.

It actually (touch wood) runs and drives better. Not sure what it was, but I suspect the battery terminals weren't allowing a proper current.
 

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Yup. I just resolved the same issue the same way! What really made it pop like new again (wipers strong, he'll even the cig lighter) was adding a second ground cable from the top of the engine to just underneath the hood latch.


Sent from AutoGuide.com Free App
 

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Discussion Starter #14
not that I have been doing much driving lately (car is in the garage with the w/screen out)
but one thing I decided to look at again today was the Crank sensor.
As I said before it ohms out fine, so although I have a new one in the trunk, i don't want to put it in until the problem arises again (so far it hasn't!)

Anyway when I took it off today, there was a thick sticky mess on the end (like bubble gum mixed with oil and grease!).....now I am not sure if this has anything to do with my intermittent no spark problem, but I cleaned it and put it back......we'll see!

If nothing else, makes me feel better that I at least found something!:)
 

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Discussion Starter #15
just updating this old thread of mine:
I put in a new Crank sensor shortly after my post above, and in the last year have had no problem. Starts every time.

Special thanks to aldo for the tip that although the CS might ohm out fine, it might still be faulty:)
 

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Stupid question...Is it "plug and play" on a Series 4 Spider? That is, just remove and replace...or do you have to measure position?

Mario
Ottawa
 

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Plug and Play for S3's ( 2 at the bellhousing) and S4's as shown here.

Not sure if other years have them.

Vin
 

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Which sensor did you replace again? Is it the black or gray one (connector color)? I think one is a crank sensor and one is a reference sensor.

I'm searching for a solution to my hot start issues, also, and most everything fuel and spark related are new...
 

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Which sensor did you replace again? Is it the black or gray one (connector color)? I think one is a crank sensor and one is a reference sensor.

I'm searching for a solution to my hot start issues, also, and most everything fuel and spark related are new...
S4's only have the one sensor at the front crankshaft pulley.

S3's have the 2 at the bellhousing:

1 - the top sensor is for RPM, the bottom is reference point (TDC)
2 - RPM sensor to black connector; TDC sensor to gray connector

Good luck,

Vin
 
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