Mercedes 1972 4.5 liter and obviously an 8
 

recently put a petronix into my 72 and it ran and then it didn't run? Mechanic states issue is not all injectors are getting voltage because four of the injectors show low voltage which inhibits their ability to work and four work. wen the accelerator is depressed, all injectors are getting voltage and all are putting fuel into the engine with the engine idling as the whole engine is getting fuel. When the accelerator is no longer depressed, back to low voltage to the injectors and not running? Any suggestions? Have been driving the car since 1999 and I do like the car except that the gas mileage doesn't match what the book advertises ? ( Not quite 26/19 )? Thanks

Welcome to Peach Russel!

Bump for a new member and some tech help

As you are asking about an after market addition to your engine you might find it difficult to get specific advice here.

Does your new ECU give any error / fault codes?

Do petronix give support for their products? Have they got a forum?

A few years ago, I casually looked into getting a '73 280 SE 4.5. I'm pretty sure it was mechanical fuel injection. I'm used to hearing of Petronix as a maker of ignition components. Do they do fuel injection too?

Kinda been working on the same question!

Through 1975 the M116/117 engines were equipped with D-Jetronic injection, which is an electronic system using pulsed injectors driven by an analog ECU. The primary load sensing method is manifold absolute pressure (MAP).

As far as I know, Pertronix is not in the injection business, just ignition.

Right thanks for the heads up Frank. I got the wrong impression - thought it was all aftermarket.

I've read around a bit more on the subject Jetronic - Wikipedia, the free encyclopedia

And found this chapter on startek for the M117 engine (albeit fitted to the R107) but it will probably help =>

http://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M117_45/074-040.pdf

"Testing electronically controlled gasoline engine" = section B described what to do with a multimeter (section A goes on about a Bosch tester that probably isn't all that more complicated but I guess might do different things)

Just a question and a reply to some responses that I received? THE petronix is available for the 280SE and isn't supposed to interrupt the fuel injection? The injectors are firing ( at idle) on the odd injectors but not on the evens which makes a poor idle and doesn't run correctly? It will idle at about 500 RPN's and does rev at times but as I stated, the evens are not opening up? Tried a different set of fuel injector points but that didn't do anything? Is this just a wiring issue or do the points have anything to do with the odds being the only injectors to open up?

rh:

1) Why the nine month hiatus? [This is a question, signaled by the use of a question mark at the end of an interrogatory sentence.]
2) To return to your initial post of January of this year, what was the running condition of the engine prior to installing the Pertronix? Why was the decision made to install the Pertronix?
3) Inasmuch as there is neither mechanical, nor electrical connection between the ignition system and the fuel injection system, the change to the ignition system should not have any influence on the injection system. [This is a declamatory sentence, ended with a period.]
4) As you describe the situation, the loss of half the injectors is associated with the closing of the throttle to the idle position. The idle position is detected by a switch on the throttle body. Look for a fault in either the wiring harness, or in the ECU, that involves the idle position switch.

Frank:
 

Thank you for the input? I will check that out? The car runs good but the original issue was the gasket in the distributor was bad and I received a suggestion to go to electronic fuel injection instead of worrying about the points and rotor? The car would run good until the car warmed up and then it would stall out? After the car cooled down, I would clean the points and could drive the car until the engine warmed up ( the oil would get hot and become gaseous and would cover the points and no spark? Added the petronix and then the car was driven by the mechanic for a couple of miles, but when I attempted to pick up the car, it wouldn't run beyond idle? The car is rough cosmetically but ran good until the distributor issue.