More ECU/MPS/CHT..., From the other side of the pond Options

[chmillman]

I didn’t want to hijack the thread below this one started by Jose, so I am starting a new one (sorry if this is not a good idea).

I am also having some work done on my 2.0 D-Jet and some similar issues. My car is officially a ’74 – built on 1 November 1973 - but it has a ’73 (Euro) engine number (GB007311) as well as a ’73 ECU and MPS (both 037). I have been unable to get any info from Porsche as to whether the motor is original or not - as the car was built in late '73, it might be original, but the car was restored in France in 2011, no idea if they changed the motor or not.

Back to the FI- in addition to cleaning and testing the injectors, changing the hoses, etc. my FI guy has found and fixed a bunch of stuff – frayed and dicey connections etc. He is however unable to get the ECU tuned so that both the CO and HC values are within their suggested ranges at the same time. The car has some light hesitation at low speeds and loads - like when driving at a steady state in a 50kmh city zone.

The MPS checks out OK both for vacuum and static resistance tests. It was rebuilt by Fuel Injection Corp. in CA in the summer of 2014 - culdn't get any more info than that from them.The 270 ohm ballast resistor is there and OK. My FI guy thinks it might be one of those fairly rare cases where some components in the ECU are cooked. Pulling it out of the car and sticking your nose inside the connector hole, it smells a lot like old overheated electronics – in comparison to a couple of others he has in storage which hardly smell at all – or maybe a bit of a musty smell.

I have another ECU in good condition to test – but it’s an 0 280 000 040, not an 037. It does have the same VW part number - 022 906 021 E. According to the info I found this is also supposed to work with an 037 MPS…





Maybe doesn’t need the 270 ohm ballast resistor on the CHT sensor. Anyone have any experience with this? This is Euro stuff I know, so some of the USA model info will not apply.

Speaking of the CHT sensor, that is also wrong. It’s not an 017 (unobtanium), but it’s not an 012 either. IIRC it’s an 003 – which I have seen various info about, some of it conflicting. Richer at cold start or remedy for excessive fuel consumption... In any case I think we will replace that with an 012, as an 017 seems to be out of the question.

More coming as we progress on this hopefully this week.

[emerygt350]

I don't think you need to go there yet. The wrong cht can cause terrible issues. Just pull it and compare first.

Lots of known working ECUs out there. I have an extra 037 I picked up for 60 dollars on eBay. They seem to be very robust.

The only difference in the mps would be the diaphragm material being weaker. Nothing else you can sanely replace in that thing. "Tuning" the mps was probably setting it to some predetermined point. You should tune it to your engine and modern fuel. Particularly with a euro version engine.

[chmillman]

I don't think you need to go there yet. The wrong cht can cause terrible issues. Just pull it and compare first.

What I understood is that when the engine is warm, the CHT should have nearly no resistance, and that the ECU will basically ignore anything less than 300 ohms - i.e. if the engine is warmed up, connecting the CHT input from the ECU to ground (bridging the CHT) the engine should still run normally. Maybe I got that wrong. So the difference would be how the engine actually behaves during the warmup phase - assuming of course that the CHT actually works as designed and is not open circuit, shorted out or intermittent.

[quote name='emerygt350' date='Jul 28 2025, 12:51 PM' post='3216989']
Lots of known working ECUs out there. I have an extra 037 I picked up for 60 dollars on eBay. They seem to be very robust.
{/quote]

Wow - didn't find anything here anything near that price... The 040 I have here cost a lot more than that. Will keep looking. I assume the US model 037's are however different than the Euro models? GA/GC motors vs. GB?