Posted: Mon Jan 09, 2017 11:41 pm
So any one know what voltage the Thor injectors operate on?garrycol wrote:Does anyone know if the Bosch injectors from the Thor/Motronics system work on 12v or some lower voltage?
Thanks
Garry
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Bosch injector testing
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Posted: Mon Jan 09, 2017 11:48 pm
All injectors run off a 12v supply.
When people add resistors it is to reduce the current draw as the ecu was not designed to run that type of injector ( ie peak/hold vs saturated )
It is not about changing the voltage they work from.
When people add resistors it is to reduce the current draw as the ecu was not designed to run that type of injector ( ie peak/hold vs saturated )
It is not about changing the voltage they work from.
Posted: Tue Jan 10, 2017 4:25 am
Thanks for the information - surely the Motronic ECU would be designed and capable of operating its Bosch injectors.
I appreciate this may not apply if some other ECU is being used.
Cheers
Garry
I appreciate this may not apply if some other ECU is being used.
Cheers
Garry
Posted: Tue Jan 10, 2017 9:53 am
The mod to the MS (if you experience problems) is documented along with the fix on the MS site manuals. It's an internal mod, so not something everyone would be happy doing.dyno wrote:Yes, best to build a set out of several used / cleaned injectors if batch fire. Not to complex. They call it "pared" or "matched" injectors. Just check the injectors which come close and done. I was also using the biggest for that little extra. Indeed, no adjusting possible. It's correct or not.
If you want to "balance" different rated injectors, be sure you do it using the ECU you want to use in car. This because open and closing times must be taken into account. At least, I would do it. I prefer injectors which are correct to start with. I ALWAYS check injectors before use just as I ALWAYS check jets in carbs before use.
I did used the separate 12 Volt supply for both injectors as ignition (as I always do) but still problems. Called Phil and had no idea why it was not working. the switch to high impedance fixed the problem so I was happy it was working and job done.
Posted: Tue Jan 10, 2017 10:01 am
If it's anything other than the flapper system, it will have high impedance injectors anyway. Motronic would be the Thor system with green injectors.garrycol wrote:Thanks for the information - surely the Motronic ECU would be designed and capable of operating its Bosch injectors.
I appreciate this may not apply if some other ECU is being used.
Cheers
Garry
Easy enough to check what the injectors are with a DVM. High impedance are 10 ohms plus. Low, less than 5 ohms.
The flapper was designed in the 1970s. It's analogue, so more difficult to do clever tricks with.
Posted: Tue Jan 10, 2017 10:22 am
Thanks - the Motoronic system and injectors are all Bosch - everything before was Lucas - now the injectors may be the same but should not be assumed to be so.
Cheers
Garry
Cheers
Garry
Posted: Tue Jan 10, 2017 1:08 pm
The injectors on the first RV8 engine - the flapper system - were Bosch too. As were all the other bits, except for the ECU, which was Lucas. And there were several different injectors used on the RV8, depending on the injection type.garrycol wrote:Thanks - the Motoronic system and injectors are all Bosch - everything before was Lucas - now the injectors may be the same but should not be assumed to be so.
Cheers
Garry
You'd also need to check the physical injector fitting if not using the ones for that manifold. The hole in the manifold is a different shape between hotwire and flapper, for example. And you do need a decent seal there.
Posted: Tue Jan 10, 2017 7:18 pm
I don't know whether they can be driven from +12V directly, or require a lower voltage (or resistor), but I will have to find out before testing them!
Chris.
Chris.
Posted: Tue Jan 10, 2017 7:42 pm
Straight 12v off a spare alarm battery, but these are chevy truck injectors, not that it should make a difference ?
Posted: Tue Jan 10, 2017 7:43 pm
High impedance ones can - but are obviously not designed to be energised for long periods.ChrisJC wrote:I don't know whether they can be driven from +12V directly, or require a lower voltage (or resistor), but I will have to find out before testing them!
Chris.
Posted: Tue Jan 10, 2017 10:36 pm
ALL the injectors are powered via 12v.
The difference is how the ecu turns them off and on. And testing an injector by simply opening it flat out is not the correct way to test flow. Although it will test they do open/close and flow something.
A proper flow test will be triggering the injector as it is designed to be triggered and at various pulse widths so you get a flow pattern throughout it's entire operating range. 100% open is not and should never be in that range
The difference is how the ecu turns them off and on. And testing an injector by simply opening it flat out is not the correct way to test flow. Although it will test they do open/close and flow something.
A proper flow test will be triggering the injector as it is designed to be triggered and at various pulse widths so you get a flow pattern throughout it's entire operating range. 100% open is not and should never be in that range
Posted: Wed Jan 11, 2017 9:32 am
Remember too the time they take to open is voltage sensitive. ECUs generally compensate for this internally, by altering the pulse width with supply voltage.
If building a sophisticated test rig, I'd be inclined to use a regulated 12v supply to take this out of the equation - rather than a battery.
If building a sophisticated test rig, I'd be inclined to use a regulated 12v supply to take this out of the equation - rather than a battery.
Posted: Wed Jan 11, 2017 11:33 am
My injector tester has several functions from simple pulse (as wide as you want and variable simulated engine speed) up to a cleaning service with ultra sonic bath. But when we talk about testing the injector capacity, it's the same in all tests and is a continue open flow of 15 seconds. That's the injectors max flow (x4 in minutes).
It's indeed so your injector probably need 1 msec to open so you need to be aware you never get these max values unless you keep them open all times. Reason why they usual advice to take no more as 80 - 85% of max injector flow in account when you select the injectors.
The open and closing time very from injector to injector, go's up with fuel pressure, with lower voltage and also depend what make ECU you are using. The internal driver and how they get activated do have influence, maybe small but it does.
It's indeed so your injector probably need 1 msec to open so you need to be aware you never get these max values unless you keep them open all times. Reason why they usual advice to take no more as 80 - 85% of max injector flow in account when you select the injectors.
The open and closing time very from injector to injector, go's up with fuel pressure, with lower voltage and also depend what make ECU you are using. The internal driver and how they get activated do have influence, maybe small but it does.
Posted: Fri Jan 13, 2017 10:25 am
Only the flapper with the resistor pack ran the injectors at less than 12v. To test these you need 3v, can run two 1.5v battery's in series.I don't know whether they can be driven from +12V directly, or require a lower voltage (or resistor), but I will have to find out before testing them!
Chris.
The Thor/motoronic injectors run at 12v, so any 12v source should be fine.
I had running problems on my flapper system and by using the 3v battery could audibly hear the faulty injectors which would not 'click' open.
Tom.