The V8 Owners Forum -

Chaps,
I have some Bosch 0 280 155 787 injectors that I would like to have checked / tested before sticking back into my engine. They are those fitted to a 4.6 Range Rover.

Has anybody has this done?, any recommendations where?

Thanks,

Chris.

I did all mine myself, followed the video and pay attention to the spray pattern, all done in less than an hour

Neat - thanks!

Chris.

JSF55 wrote:I did all mine myself, followed the video and pay attention to the spray pattern, all done in less than an hour

I would say that's more like testing them rather than cleaning them.
I would want to know that they are all flowing the same, so I would get 4 or 8 plastic measuring cylinders like these:
http://www.ebay.co.uk/itm/like/17242070 ... 931&crdt=0

Get a fuel rail, pump and washer bottle/header tank from a scrap car and make a little test rig. Megasquirt has a special injector tester mode.

stevieturbo wrote:http://injectorcleaning.co.uk/

Marlin motors in Bletchley (where we do the dyno days) have one of those. But the cost of getting 8 rv8 injectors done was close if not the same price as buying a new set.

Quite true, but I guess it depends why he wants them tested or cleaned.

If to prove and diagnose a problem....then it can be worthwhile.

If it's just because he wants a fresh set or to ensure they are ok but no underlying problem, then just buy new.

stevieturbo wrote:Quite true, but I guess it depends why he wants them tested or cleaned.

If to prove and diagnose a problem....then it can be worthwhile.

If it's just because he wants a fresh set or to ensure they are ok but no underlying problem, then just buy new.

I understand if you want them clean and cost as much as new you prefer new. But please note, very often, new or used, the flow can be 10% and even more difference (I've seen 20% lowest / highest in one set). I've tested several Rover V8 sets from one and the same engine must say, 10% and more is not uncommon in a Rover engine. I'm wondering how many Rover V8 blocks had an overheating problem and crack behind the liner for this reason. Probably as many as all other reason together.

We had a Chrysler V6, broken piston. Customer bought a new set of injectors to be sure. I've tested the new set, they where even more out as the old ones. Needles to say we made a set form 6 used and 6 new injectors (used the highest numbers).

BTW, I've got my own injector tester for years, reason I know this issue is very common.

Does anyone know if the Bosch injectors from the Thor/Motronics system work on 12v or some lower voltage?

Thanks

Garry

If high resistanc , 12 Ohm for example it is 12 Volt, if low resistance, 2,5 Ohm or so, it's low voltage. You will need a resistor in line to lower the voltage and current of if you have a Megasquirt, you can setup for low resistance injectors.

Please note, I had an engine running, Megasquirt EXTRA with low resistance injectors, had the software setup (no extra resistor) and had serious troubles. The low resistor injectors fired back into the ECU and I had all kind of backfires at several points in the rev range. Seems like you may need a capacitor sometimes to get rid of these voltage spikes. I've switched to high Ohm injectors and no more issues.

I take it if the flow varies between injectors and they are clean, with batch injection you can only balance them by choosing from others which have been tested too? In other words, they can't be adjusted?

Things like an MS3X have a driver per injector and can be set to correct imbalance between injectors.

I decided from the out when going MS to get rid of the resistors on my SD1, and used the PWM settings on MS2 to drive the original low impedance injectors directly. That has worked perfectly for many years. The other option is to use a peak and hold circuit - an additional board. It's the current flow through the resistors which is the important bit.

However, some have reported spikes on the MS power rail when using PWM to drive low impedance injectors. I don't have this problem - but there is a fairly simple mod to sort it if needed. It involves disconnecting the +12v feed to the injector drivers from the MS 12v rail, and running an independent +12 feed to them from the main relay. If I've remembered correctly.

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.

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.

I just want to be sure mine work before I stick them back into a rebuilt engine.

Chris.

I would do exact the same. I always test all injectors before fitting