[Alfisto Steve]

Well it was a week that was - installing engine and tranny in NQS rescue project. Home boy is whipped.

Tried to start it up this afternoon but not joy. Got spark and 40 psi of fuel pressure at engine but no injector pulse. Tested both with Bosch wafer plugged into injector connector and using AutoForce tester. Even swapped out with known good ECU and motronic relay but NADA.

Have 12.35 volts showing on AutoForce tester panel and also at red wire in one injector connector coming from red stripe relay but no Flashing pulse to open injectors. I get same 12.35 volts out of yellow pulse wire at injector connector so current is passing through other 5 injectors and all 6 yellow wires but need to test pin 14 at ECU connector to be sure wire good all the way to ECU. Six red wires merge into one red wire to pin 87 of S12b red stripe relay with diode and six yellow wires merge into one yellow wire going to pin 14 of S11 ECU.

I have to check yellow pulse wire at pin 14 in ECU connector. Must have a disconnect.

Well that is not the problem pin 14 to injector connector continuity fine.

Just ran Moronic Test procedure B self diagnosis and 1-4-1-1 code flashes like running injector testing but injectors do not pulse. Never get 1412 or 1413 tests to run either.

I can run Procedure B on Rosso and 1411 injectors click, 1412 IAC works and 1413 purge solenoid tests will run in sequence.

Opened one injector electrically with test connector to 12v red terminal and and grounded yellow terminal and it bleed some fuel pressure off gauge as injector opened and then tried to start. Engine fired once on that cylinder that had fuel.

Engine ran fine when I tested it out of the car with different harness. This car came to me some years ago on a tow dolly but it will run again someday soon I hope.

 

[Alfisto Steve]

Still no joy no injector pulse so no start. I tested red stripe relay and computer in Rosso and put Rosso red stripe relay and computer in NQS but no difference and Rosso still starts fine.

I am baffled as every test I make checks out fine except for injector drive pulse and book wants me to change computer. Have tried 3 more tested ones and still no difference. even swapped battery as voltage was dropping but no go with a fresh 12.25v battery.

Who has had and fixed a problem like this anyone?

Fuel pressure stays up at 40 psi cranking and does not decay. Rpm/timing sensor pulses and shows 1.9 volts AC with meter (book says 2-4 VAC). I don't have scope but it is working even if VAC a bit low, flashing on auto force tester and firing nice blue spark. Engine ran fine with same RPM/timing sensor when out of car and tested with other harness.

G131 grounds good, engine ground to chassis. G131 wires test good back to computer connector.

Really irks me that I can't find problem. Time for a toddy for the body I guess.

 

[Craig]

G'Day Steve,

Given your results so far, sounds like you only have two possibilities:

Break in yellow wire between injectors and ECU pin 14

or

Ecu pin 19 not connected to ground.


Disconnect ECU and measure resistance/continuity between pin 14 and and yellow wire at an injector.

Disconnect ECU and measure resistance/continuity between pin 19 and ground.

 

[Alfisto Steve]

G'Day Steve,

Given your results so far, sounds like you only have two possibilities:

Break in yellow wire between injectors and ECU pin 14

or

Ecu pin 19 not connected to ground.


Disconnect ECU and measure resistance/continuity between pin 14 and and yellow wire at an injector.

Disconnect ECU and measure resistance/continuity between pin 19 and ground.

Did both tests today but will recheck to be sure as I had continuity at pin 14 to one yellow wire at injector connector for injector 5 and pin 19 continuity to G131 ground checked good too.

It is really baffling.

Even though I had spark and pulsing with RPM/Timing sensor test but VAC test (simulating scope wave length) was 1.89 VAC not 2.0 to 4.0 VAC I changed S31 RPM/timing sensor and got about 3.0 VAC now but no difference.

I changed coil too as resistance was low. Again these don't make injectors pulse but grabbing at straws now.

Last thing before happy hour was to jump with my truck running to get voltage up to 13.7 volts in hope I could wake up computer as voltage was dropping sometimes below 11.5 when cranking as battery getting low again.

Only thing it did was make engine starter really spin engine over faster.

It has to be a wire problem.

I am going to check pin outs again 1 through 35 with close attention to pin 14 and 19 as you said.

 

[Craig]

Oops sorry, ECU pin 16 to ground (not 19, that's the coil ground ).

Internally, the ECU connects pin 14 to pin 16 via a transistor to fire the injectors.

My reasoning:

You have spark and fuel pump both of which only happen if the ECU has a crank (CAS) signal. You also have 12V at the injectors (both sides) which means the yellow wire is not being pulled to ground via pin 14 qand pin 16.

 

[Alfisto Steve]

She RUNS!

Oops sorry, ECU pin 16 to ground (not 19, that's the coil ground ).

Internally, the ECU connects pin 14 to pin 16 via a transistor to fire the injectors.

My reasoning:

You have spark and fuel pump both of which only happen if the ECU has a crank (CAS) signal. You also have 12V at the injectors (both sides) which means the yellow wire is not being pulled to ground via pin 14 qand pin 16.

My son saved my bacon by talking me through some Basic Wiring 101.

Actually pin 14 yellow was being pulled to ground but a bit early before computer had a chance to do it's transister thing via pin 16 to G131 ground. The problem was #2 injector connector red and yellow wire female terminals were unlocked and pulled out into rubber boot and touching each other just as my son surmised that two bare wires somewhere in harness were touching each other. Locked terminals back into connector and taped back together remains of petrified rubber boot as I wasn't in the moood to look for a new boot tonight.

It moves forwards and backwards in driveway (no headlights) but didn't test drive it. Still have a bunch of red and yellow icons to troubleshoot systems and a bit more to make it ready to drive.

If I had pulled all injector connectors Friday and checked each one then I would have saved myself some time but I sure did learn a bit about system. BIG IF but I hope I learned from my mistake.

 

[Craig]

I get same 12.35 volts out of yellow pulse wire at injector connector

You cheated, you cheated, you gave me false information!

Nah, just kidding, intermittent faults can be really nasty. I'm guessing the wires only touched while cranking.

Congratulations!

 

[Alfisto Steve]

You cheated, you cheated, you gave me false information!

Nah, just kidding, intermittent faults can be really nasty. I'm guessing the wires only touched while cranking.

Congratulations!

I did get the same 12.35 volts because wires were touching when I had meter red lead in yellow wire both at pin 14 and #5 injector connector. I guess if wires weren't touching I may have gotten less with injectors resistance.

Do you have wiring schematic/logic of internal working of motronic ECU? How did you know that pin 14 grounds/triggers injectors by ground to pin 16. that info not in shop manual wiring diagram.

 

[Craig]

Do you have wiring schematic/logic of internal working of motronic ECU? How did you know that pin 14 grounds/triggers injectors by ground to pin 16. that info not in shop manual wiring diagram.

Yes, sort of, maybe. Had a harddisk crash yesterday, currently operation off old laptop. The wiring diagram isn't lost, I just can't get it yet. Will let you know.

 

[Craig]

Making progress on the computer front, so here's the diagram/s. The Opel Omega is the closest for the 164 (ignition and no VVT) but the TS one has more info on the Alfa pins.

 

[Alfisto Steve]

Making progress on the computer front, so here's the diagram/s. The Opel Omega is the closest for the 164 (ignition and no VVT) but the TS one has more info on the Alfa pins.

Thanks for that info.

New Day here and time to go watch the F1 race with Alfa pals.

 

[Craig]

Old day here, time to go to bed.

 

[AlexGS]

The problem was #2 injector connector red and yellow wire female terminals were unlocked and pulled out into rubber boot and touching each other just as my son surmised that two bare wires somewhere in harness were touching each other. Locked terminals back into connector and taped back together remains of petrified rubber boot as I wasn't in the moood to look for a new boot tonight.

Embarrassing

Thank you for this report - I think it reiterates that even with seemingly many electronic components to fail, it is often the simplest of things. I have a similar story to report from last week with an Alfa 155 V6. The speedometer didn't work. I tested the sender with a scope and found no waveform, so I substituted another sender that had a healthy pulse. The instrument cluster was still dead. I took the cluster apart and couldn't find anything wrong, so I tested the wiring which, in true Alfa tradition, had a three-pin plug at the cluster and at the sender: sender plug: power, ground, signal, and cluster plug: power, fog lights (!), and signal...

Not being sure of where the ground was coming from at the sender, I ran another set of wires from sender to cluster, and checked the pulse of the substitute sender at the cluster. It was there, but the cluster didn't work. At that point I pronounced both the cluster and the original sender faulty. Sent to an instrument specialist!

Both parts came back, sender was indeed faulty but cluster was not faulty. They were reinstalled in the car, but still didn't work. I wasn't called back to sort it out (funnily enough), but I am told that the eventual problem was a backed-off connector pin in the sender plug (my reputation probably now in tatters, oh well, perhaps I will get to work on my own cars now). That doesn't explain why my substitute sender pulse didn't work - but there is an explanation for that, too. The wiring for the three-pin plug of the substitute was different, so my 'pulse' was on the wrong pin... this was, of course, hard to know because the original sender had no pulse at all on any pin... I had assumed that Alfa Romeo would not have changed the wiring of compatible plugs. Bad mistake.

It moves forwards and backwards in driveway (no headlights) but didn't test drive it. Still have a bunch of red and yellow icons to troubleshoot systems and a bit more to make it ready to drive.

If I had pulled all injector connectors Friday and checked each one then I would have saved myself some time but I sure did learn a bit about system. BIG IF but I hope I learned from my mistake.

More to the point, *we* might learn from the mistake

I guess you are now going to have some fun chasing the brake pad wear/fluid level/coolant level/windscreen washer level icons...!

-Alex

 

[Alfisto Steve]

My instrument cluster story on this car is that voltmeter pegged to 16v as soon a key turned on. Changed cluster to get a correct reading of 12+ volts.

 

[ChazzyD]

So Steve, Non Quick Silver gets a new name? Quick Silver II? Nice work thinning the "rescue queue". You only have one non runner now?
Charles

 

[Alfisto Steve]

So Steve, Non Quick Silver gets a new name? Quick Silver II? Nice work thinning the "rescue queue". You only have one non runner now?
Charles

Probably she will get the new name once I get some more semi-flyable gripes worked off such as spongy brakes.

Yep OLD NERO only non-runner but some vital organs have been harvested so maybe not really feasible to try to save the whole world one 164 at a time. I know that maybe a bit upsetting to Del, but I may have to draw the line as to when is enough already.

 

[dstephens]

ECU Test connector

So, how do I use the test connection on the ECU to pull codes from my 90 Alpha Grad? At the moment it won't start and I've been going through all the threads trying to trouble shoot it. No luck yet. Symptoms. Engine turns over; timing light flashes so I think I've got a spark; check engine light flashes during cranking; sputters like it's ready to start but just doesn't quite make it; fuel pump runs if I put power to it. Thought if I could pull the fault codes without the engine running, maybe that would give me a clue as to what to try next.

 

[MrT]

if the car sputters, shoot some fuel or other burnables in to the intake. If it starts, then you have a fuel starvation problem to troubleshoot, and that's at least a very valuable hint.

Michael

 

[Alfisto Steve]

Real 90 Spider Series 3 with Motronic ECU?

So, how do I use the test connection on the ECU to pull codes from my 90 Alpha Grad? At the moment it won't start and I've been going through all the threads trying to trouble shoot it. No luck yet. Symptoms. Engine turns over; timing light flashes so I think I've got a spark; check engine light flashes during cranking; sputters like it's ready to start but just doesn't quite make it; fuel pump runs if I put power to it. Thought if I could pull the fault codes without the engine running, maybe that would give me a clue as to what to try next.

So do you have a series 3 spider body with series 4 motronic system?

Does engine front crankshaft pulley have many teeth on it or is it round and smooth?

 

[dstephens]

Haven't put any starter fluid in the intake yet. Well give that a try tonight. One of the things I've noticed, is that the fuel pump relay does not come on until I start to crank on the starter. Then I can feel and hear it click on and off with the same timing as the check engine light flashing. This leads me to think it might be an input to the ECU, but I could be wrong.

Don
'90 Alfa Graduate