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-   -   Car won't start, injectors don't fire. (https://www.scoobynet.com/general-technical-10/818496-car-wont-start-injectors-dont-fire.html)

Dutch Scooby lover 25 February 2010 05:39 PM

Car won't start, injectors don't fire.
 
Hello all.
After a rebuild of my car at my mates home I drove the car home 6 months ago, part finished.

Having the car home I proceded to reverse the manifold and fit bigger injectorsAlso I converted to parallel lines, and blowthrough MAF sensor setup.

Now that the work is finally done I am having a small, but very irritating problem.The car won't start.

I have spark, and fuel pressure in the rails, however the new plugs I also mounted seem to be dry, indicating to me that the injectors don't fire.
Car should be running rich,as it was mapped on 550cc injectors, now on 800cc ones.

I know the injectors work.
I dismounted them, and applied 10v to them, and I can hear them clicking

However, if i mount them in the rails, and remove the rails from the manifold
the paper tissue i put them on stays dry, which also indicates non firing injectors i believe (or do the rails source ground through the manifold ground wire)

I also checked the injector ground and according to the manual I have it should have 0 volt measured to ground regardless if the key is off or on (without the engine running)
This is also the case.
Injector voltage is also ok according to the manual and the voltages it describes.

This leads me to think the PowerFC is faulty, but on the other hand, my removed (but working at the time) stock ECU does have the same problem, leading me to think the PFC is good.

Anybody have any suggestions,as I am clueless what could cause this, and I am geting frustrated.

Dutch Scooby lover 25 February 2010 06:34 PM

I'll add this in a new post, to keep things clear.

The only thing i am uncertain of is the injectors polarity.When I tested them it seemed to make no difference which way i connected them, is this common??

Also, does the ECU ground the injectors, or are the injectors grounded, and the ECU supplies voltage??According to the manual the 12v supply to them has a waveform, so I am guessing the latter (Ecu supplies voltage, injectors are grounded)
If this is the case, why does neither wire at the injector has a good ground to it, they all have resistance to mass, or even no connection to ground at all, regardless of key position.

Could this be a grounding problem.as I have also mounted the battery in the boot.
However, I measure no resistance between the ground point in the engine bay, and the negative pole of the battery or the chassis where I grounded the battery to.What seems weird to me is that the manual states that the grounds of the injectors and the grounds of several sensors (TPS and Idle to name a few)are connected to each other, but the same manual states that the injectors and the sensors have different ground points @ the ECU, wouldn't this lead to measuring problems?

I also ran a separate ground wire directly from the engine bay ground, to the negative pole of the battery to factor out the ground problem, but is does not make a difference.Also I made a separate ground wire from manifold to engine bay ground, as the original one wasn't used anymore, because of the rotated manifold.

I triplechecked my FPR, fuelfilter and both the internal Walbro, and the external Bosch 044.and the fueling system works, as i am seeing pressure at the rails/FPR of 3 bar without a vacuum source connected.

Dutch Scooby lover 26 February 2010 04:43 PM

Fixed, but in a rather rediculous way.
Altered the injector size and latency to some rediculous high values (Size 100%m Latency 2msec, and that seemed to awaken them.
After reversing the size and latency to the correct values I at least got the car idling, but as I converted the maf to BT the scaling was off, so rough idle was expected,


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