GM Chevrolet Cosworth Vega E.F.I. - ein D-Jetronic-Fahrzeug

Hallo Freunde,
schon lange war mir in den Bosch-Vergleichslisten ein Saugrohrdruckfühler (0 280 100 120) aufgefallen, der als für 'Vega-TC - 2l' benannt war.
Grund genug, der Sache mal nachzugehen.

Ergebnis: Dies ist ein weiteres D-Jetronic-Fahrzeug vom Hersteller GM.
chevyvega.wikia.com/wiki/Chevrolet_Cosworth_Vega

Seht hier ein Schema der Einspritzung: www.cosworthvega.com/cosworth_vega_electronic_fuel_in.htm

Die Einspritzung weist die typischen Komponenten auf - teilweise in modifizierter Form.

Beispielsweise sind die Triggerkontakte ('speed sensor') als Reedkontakte ausgeführt.
Wie deren Aufgabe als reine Drehzahlsensoren wird jedoch auch die Funktion des Drosselklappenschalters vom Autor offenbar fehl- bzw. überinterpretiert - Positionsinformationen wird der DKS nicht geben, außer Leerlauf und Volllast.

Der SDF original Bosch - als Hersteller des Gesamtsystems wird Bendix genannt, der Hersteller, von dem Bosch einst die Lizenzen für die D-Jetronic erwarb.

Interessant bleibt es auch weiterhin auf der Entdeckungsreise... es gab wohl noch andere GM (Cadillac)-Modelle mit D-Jetronic. Ich muss mal weiter suchen...

Noch was zum Vega: Ein vergleichsweise wirklich seltenes Fahrzeug. Nur 3508 Stück wurden in 18 Monaten gebaut.

Und: Im Gegenverkehr hätte ich den für einen Camaro gehalten, gebe ich zu.

Gruß
Norbert





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Hallo Norbert,

wie geil ist das denn? Da gibt es einige Abweichungen, aber den Saugrohrdruckfühler erkennt man auf Anhieb. Das Steuergerät ist anders als das der D-Jetronic, es hat auch nicht unseren Stecker. Der Drosselklappenschalter ist laut Doku ein Positionsschalter. Das System hat also Wurzeln bei Bendix und Bosch, ist aber doch eigen. Was für ein Entwicklungsaufwand für die paar Fahrzeuge. Das System steuert sogar neben der Benzinmenge auch die Luftmenge.

Ich habe inzwischen gesehen, wie bei Jaguar das Hallsensor-Board funktioniert. Dazu wird im Verteilerfinger ein Magnet verbaut und darunter sitzt das Board. Leider passt das so nicht bei den Bosch Zündverteilern. Und leider meldet sich mein Kontakt für die Jaguars von der Concours d'elegance bisher auch nicht zurück. Ich hoffe noch.

Norbert, bleib dran!

Hallo Ihr Lieben,

also wenn ich das richtig sehe, kommen Einspritzventile, SDF und Drosselklappenschalter sowie Druckregler von Bosch. Bei Bendix gab es ein Gebiss, was separat vom Zündverteiler saß. Das haben sie sich also bei Lucas abgesehen. Zusatzluftschiber und Zusatzluftventil sind genau wie das Stteuergerät anders.

Den Drosselklappenschalter beschreiben sie als Positionssensor, aber das ist er natürlich nicht. In der sonstigen Beschreibung passt er mit dem von Bosch überein und sieht auch so aus.

Hi,

today Mark, the owner of the Cosworth Vega webiste www.cosworthvega.com MarkaRock has joined us. He is willing to support me with their 0 280 100 120 MAP sensor for reference measurements. Now we are trying to sort out a reasonable way of transportation. Packages from the US to Germany and back are so damn expensive and then there is the German customs that needs to be convinced that there is no taxable sales. They try everything to charge 19% VAT on estimated values and transport costs.

Hopefully we find a way and welcome Mark!

What we found out so far is that the Chevrolet Cosworth Vega EFI runs with a mixture of Bosch and Bendix based components. Only MAP sensor, fuel pressure regulator and throttle switch are from Bosch. Would be intersting to learn how they have solved ECU and trigger contacts.

Danke. Meine Deutsch ist nicht sehr gut.

I am a member of the Cosworth Vega Owners Association, and I am a webmaster for the www.cosworthvega.com website, the official website of the association.

We do not have any significant technical information about the Cosworth Vega EFI system on our website. I am trying to gather more information to add to the website.

I would add to what the moderator said that the injectors are also Bosch units. The part number is 0 280 150 030

I do not know what the "ECU and trigger contacts" problem is. It does not sound like a problem we have encountered. Perhaps we call it something else. Our ECU was made by Bendix. We are working with an Electrical Engineer who is using an old schematic, comparing it to the circuit board in the ECU, and creating a new schematic for us. We hope to post it on the website in in the next month or two, along with technical information about the various components of the EFI system.

I am looking forward to learning from this website and the members of this forum.

Mark

Hi Mark,

welcome here! There was no problem we discussed with the Cosworth Vega. We just noticed that it did not have Bosch components for ECU and trigger contacts and that it is mixture of Bosch and Bendix.. But as they used an old Bendix ECU and trigger contacts, it would be nice to have a picture of those. I know that the original Bendix system had trigger contacts separate form ignition distributor.

It sound interesting that you build a new ECU. Will you use it with existing MAP sensor? Iy yes, you wil have to build up a similiar circuti as Bosch did. Because MAP sensor is integral part of that electronics. It will not be possbile to use digital chips for that. Why do you not just repair Bendix ECUs? We do that here for all Bosch and Jaguar / Lucas ECUs if necessary. But mostly they run extermely reliably.

I would be curious to see the inner of your ECU via picture. Maybe it would be possible to redesign a Bosch ECU for the Cosworth Vega. Who knows.

Here is a picture of the top of the Bendix ECU circuit board.

Also, here is a picture of all of the EFI components.

What we call the "speed sensor" is probably the equivalent of the "trigger contacts" you mention. It is a reed switch, and it is synchronized to the distributor, so that the ECU knows when to open each injector. While it is called a speed sensor, its main function is to tell the ECU where the engine is/when the valves are open/closed. In doing this it also tells the ECU the engine RPM. I will try to get a good photo of it an post it.

We are trying to make a new schematic, not a new ECU. Some members have built their own ECU using modern components and a laptop. All I am trying to do is document for our website the technical specifications of our original Bendix system.

Mark

Hi Mark,

interesting, Bendix has already used a few ICs at that time.But of course they still need transistors. Without that they aould not have been able to interface the MAP sensor. However that means also that they should have done some tuning as well.

The 0 180 150 030 injector seems like the yellow one, just ist has no fuel hose connected to it. I will follow your work whenever possible. An interesting project!

Hi Mark,

having looked at your ECU picture, I believe to see some tuning resistors there as well.

The injector is the yellow one, but it is a 280, not a 180.

I do not know enough about electronics to say whether the resistors are tuning resistors or not. I have heard that phrase used (tuning resistors) but only with regard to the circuit inside the Coolant Temperature Sensor and the Air Temperature Sensor. They have identical components inside, and use the temperature sensitive characteristic of a 2n2905 transistor to measure the temperature. The circuit is a Vbe multiplier circuit with the transistor and either two or three tuning resistors. The sensors output voltage that ranges from about 2.4v when cold to about 1.7v when hot.

As I understand it, the ECU "reads" the CTS voltage and uses it to adjust the injector pulse width to ensure the proper fuel mixture at that coolant temperature.

Mark

Hi MArk,

0 180 was a typo, should read 0 280 150 030 .

What is CTS, does it mean MAP sensor? The tuning resistors in good old Bosch tradition are the ones that are above the PCB board in a kind of bridge.Such tuning is needed in analogue electronics to compensate for tolerances in switching levels and amplifications of semiconductors. Bosch has up to 42 of them. Bendix seems to have digitalized of that circuit what they could by using ICs. E.g. the flip-flop reading the trigger contacts could be an IC if you switch to 5V level.

All I am trying to tell you is that when you rebuild such an ECU, you will also need to tune the analogue part. It is not just copying the components of an original PCB.

CTS means Coolant Temperature Sensor. This sensor is located in the thermostat housing.

ATS means Air Temperature Sensor. This sensor is located in the intake manifold.

They differ in the way the temperature sensitive transistor is physically "connected" to the medium (coolant or air) being measured. The CTS uses a thermal paste to connect it to the case of the sensor which comes in contact with the coolant.

According to the shop manual: "The ECU receives the [output[ signal from the water [coolant] temperature sensor and uses it as one of the factors in determining the amount of fuel enrichment required. As coolant temperature rises, the output of the temperature sensor is changed. With this change, the ECU recalibrates the need for fuel enrichment and changes the duration of the fuel injector opening."

The ATS uses a spring, one end of which slips tightly over the head of the transistor, and the other end of which presses tightly against a small aluminum disc which comes in contact with the air. (This disc is electrically isolated from the sensor body.)

According to the shop manual: "The air temperature sensor is locate in the bottom of the inlet manifold, in the number 3 intake runner. The sensor incorporates a temperature sensitive transistor that transmits varying amounts of current to the ECU. The current flow becomes a factor in establishing the need for fuel enrichment."

Hope this helps.

Mark

Thanks Mark,

we call them NTC 1 and NTC 2. I am a bit surprised that it should be a temperature sensitive transistor. Even todays technology would rather be a temperature sensistive resistor liek an NTC.

Hi Mark,
Welcome to the forum.
My car is a GM, too - but totally unknown in the USA.
As well was your car totally ubknown to me - as I wrote, I would have mixed it up with a Camaro.

I looked at some technical details - maybe we will examine and discuss some aspects of the E.F.I. here.

But I was really astonished to read the car had 110 hp. This seems to be an uncorrect value for such a complex designed engine.

Could you please tell us the correct statistics and performance of your car, perhaps in this thread : jetronic.org/de/forum2/jetronic/208-cars...e-wurden-gebaut#1781

Regards
Norbert

Norbert

I will post information on the Cosworth Vega in the thread you suggest. I will need a few days to put together the information and a picture. I need to do some research to make sure my memory is accurate--for example, I seem to remember that Car and Driver magazine named it the fastest American production car in 1975. Now, that may be surprising with only 110HP under the hood, but remember this was the first year that American cars were strangled by the new EPA emissions regulations, and Detroit's engineers hadn't yet figured out how to make power cleanly. So, while in absolute terms the horsepower was low, relatively speaking it was pretty good.

110 HP is the correct statistic. But remember, that this HP measurement is with the engine in full installed trim, with everything attached. It is so-called SAE Net HP. See ateupwithmotor.com/terms-technology-defi...rsus-net-horsepower/

There is a lot more to add--as an example, there is 20 to 30 HP bottled up in the restrictive exhaust/catalytic converter.

It may take me a week or so to put something together with a picture and post it in the other thread--I am going on holiday until January 3 and will not have access to all of my files. In the meantime, if you have any specific questions, I'll be happy to answer them in whatever thread makes the most sense.

Mark

Hi Mark,

I've just watched a Vega Small block in Street Outlaws win against an 11l Chevrolet and another car. He even beat Farmtruck by 7 feet

What an amazing D-Jetronic The little Vega entered the Top10 list with his driver Shane.

Very Interesting!

I had seen injector boots advertised on eBay for the Cosworth Vega and some of our Djet owners have bought them (Before we found out about Repro here) Had no idea that Cosworth was a Djet!

One think I noticed on the Cosworth site, was that their fuel pressure regulator compensates for manifold vacuum. An improvement over our Bosch systems. But how do they use the Bosch fuel pressure regulator? Perhaps they use one from an Ljet?

They also run injectors at between 32 and 39psig. We should too, to prevent hot start problems! But not sure how high we can go with the Bosch ECU. (I run my 350SL at about 32psig)

The Bosch part number for the fuel pressure regulator is 0280160203. Stamped below that number in much smaller characters is the number 522. Also stamped into the case are BOSCH and Made in Germany.

Yes, the fuel pressure regulator has a vacuum port, which it uses to regulate the fuel rail pressure. At idle the rail pressure is 39 psi. At wide open throttle it drops to 32 psi.

I believe the injectors are about 28 lbs/hour units. I have the exact rating somewhere if it is critical.

With the vacuum compensation and higher fuel pressures, it seems that the Cosworth EFIhas some of the characteristics of the L-Jetronic system. The Djetronic system, many of us have, were designed to run at 2bar (~29psig) and had no vacuum compensation on fuel pressure regulator. Several other differences too.

Found this pdf that describes the Vega EFI:
dl.dropboxusercontent.com/u/54783344/1975-Vega-1.pdf

Hi Graham,

well you have to be careful. It is not a Bosch D-Jetronic system, it only uses some of its components including MAP sensor, yellow injectors, throttle switch and as it looks fuel pump. But the fuel pressure regulator and héspecialyy the ECU are different. ECU is even developed by Bendix and has nothing to with Bosch. But remember that Bendix was the one that originally developed electrojector which is the father of Bosch D-Jetronic.