75 3.0 issues

[deano]

Hey guys,

My recent trip to Phillip island didn't go as planned.

It was the first outing of my 164 3.0 engine, my original engine needed a rest.

Car ran fine for a week before pi, no issues etc.

Went out for the warm up lap, just out of turn one it stalled and couldn't be started again.

Went through the checks: timing was fine, it had spark and it had fuel, Too much fuel. The injectors seem to be jammed wide open. They are filling the cylinders with raw fuel that leaks out of the headers And from the bottom of the engine pipes.

In the weeks since, we have swapped air flow meters as well as changed fuel rails which I have a spare. No difference.

I did notice that two fuses had burnt out and have been replaced however no difference.

I'm wondering whether anyone with a 75 potenziata is willing to lend me a motronic computer to plug into
My car to test to see whether it's the computer itself. I'll  change the throttle position sensor when I get a chance but other then that, I'm lost.

Has anyone else experienced this before?

Cheers

[deano]

Yes rails and injectors. This 164 engine was in a mates car and has sat in my shed for two years until a month ago. The part number on these injectors was different to the ones in my 75 v6. It ran with the those injectors whilst it was in an alfetta sedan club car with a motec so we left them in there and it ran fine for the week before pi. We changed them after pi for my 75 v6 injectors hoping to fix it but no.

Correct me if i'm wrong however I believe there is no cold start injector in these motronic v6s.

[Duk]

There is no cold start injector with the Motronic system.

From what I could tell about the Motronic 4.1 system, it drives all of the injectors simultaneously.
You could try removing an injector plug, then switch the ignition on. With a digital multimeter, 1 pin should be 12 volts or there abouts and the other will be switched to earth by the computer when it opens the injectors.
Set the multimeter to test continuity and earth 1 lead to the block and stick the other test probe in the pin that isn't at 12 volts. If you get continuity, then there is definitely something wrong inside the German box of sparks.

[deano]

An update:

My ECU is at fault. I was lucky enough to have a lend of a 164 Q Manual ECU which ran the car straight away however given the slightly different map on the 164 chip, the car ran rich and rough.

Under slightly incorrect advice, I purchased a standard 164 ECU into which went my chip and again, the car ran but far worse compared to the first ecu with it stalling and failing to rev out past 5000 rpm.

So Benincas had a look at both ECUs and it turns out my original one has two failed transistors and with those replaced and my chip re-installed the car still does not run so the short has damaged it in other ways.

So my options now are:
1) Buy an Autronic and spend the time wiring it into the car and getting it right. In the long run the best option given the intended use of the car however would like to avoid it as a roll cage is higher on the list.
2) Track down an original 75 Potenziata Motronic ecu (0 261 200 141)
3) Leave the car sitting out in the backyard thinking about what it's done

[Duk]

An update:

My ECU is at fault. I was lucky enough to have a lend of a 164 Q Manual ECU which ran the car straight away however given the slightly different map on the 164 chip, the car ran rich and rough.

The 164's use slightly smaller injectors than the 75 Potenziata's do. 189cc/min vs 200cc/min or about 5% different. The 164 injector open times should be slightly longer because of that and so the Potenziata engine would run a bit rich when run by a 164 computer. This shouldn't make a huge difference to the running of the engine.
NO, the thing won't make more power because it has slightly bigger injectors and longer injector open times.
There is a bigger potential difference, though.
The 164 engine may locate the CAS in a different spot than the Potenziata's engine.
For some absurd Bosch/Alfa Romeo reason, there are 2 sets of CAS mounting bosses on the front plate of the engine, maybe the 164 engines used the more retarded/lower (retarded by at least 20 degrees) set of mounting points.
Double checking where the 164 Q located its CAS would be a very good start.

If you plan to keep the engine near enough to standard, just keep the factory set up and have a 164 computer retuned (a bigger air flow meter would be a benefit, too).
Get in contact with Festy on the AlfaBB, he's a fellow Aussie who is trudging his way though the factory Motronic system and might be able to help you out with the converting the original Potenziata's maps into the 164 computer.
Double check those CAS mounting points are the same between the Potenziata and the 164Q first.

[festy]

The injectors you were running to start with weren't low impedance by any chance?
That would probably sort-of work for a while, but after a bit of a sustained run at high load (i.e. high injector duty cycle, like maybe a track day?) you'd burn out the ECU's injector driver... likely resulting in an internal short to ground which would lock the injectors on constantly 
That could damage the injectors too, their internal coils don't like that at all.

So you have an original ECU that's been repaired (type 141?) but still has faults, you tried a standard 164 ECU (117?) and that ran, but not very well - what's your plan from there?
If you can't track down the correct replacement ECU, I can probably re-map a chip for you to get it running half reasonably by transferring a couple of the key maps from the 141 chip across and adjusting the injector base times - but it may take a few goes to get it just right.

[festy]

The link to the SZ ECU information that was posted in your thread on AlfaBB indicates that the BF43 chip from the 141 ECU runs in the 117 ECU correctly. I'm not surprised, I know that the 75 1.6IE chip runs fine in the twinspark ECU...
My information lists the BF43 (097) chip as being for both SZ and 75 3.0 (there's also a different chip for the 141 that was only used in the SZ AFAIK) - the BF43 chip has multiple sets of maps, and assume is like the 75/164 ecu where the "personality" is set by the wiring harness... so grounding a specific wire would switch between 75 and SZ maps.
What's the number on the sticker on your original chip?

[Domenic]

I have a brand new 164 ecu ending in 117 if you need it to swap over the chips.

At least you have piece of mind its a new unit.
$100 and you can have it