LH injectors: low impedance ok without resistor pack

rpruen · Post by **rpruen** » Thu Mar 10, 2005 11:21 pm

I have found from a reliable source....

As the subject says, you can fit low impedance injectors to your LH fuel ECU without any other modifications than to plug them in.

I have been running with this setup now for some time, and everything works as it should.

Note: Just to make sure! This doesn't apply to the non turbo 480 engines.

Richard

tobi480turbo · Post by **tobi480turbo** » Thu Mar 10, 2005 11:25 pm

Hi Richard,

THX for the useful information!

tomorrow my resistors are going to get removed

Regards

Tobi

dbsvolvos · Post by **dbsvolvos** » Thu Mar 10, 2005 11:54 pm

Any Reasons ?

480_rocket · Post by **480_rocket** » Fri Mar 11, 2005 10:19 am

Does the LH need to relearn a bit? The driver won't cook? Let us know

good news though, didn't want to cut into my loom and find somewhere to mount the res+cap

tobi480turbo · Post by **tobi480turbo** » Fri Mar 11, 2005 1:34 pm

Hi,

as far as Richard told me the driver is fine so far ... it seems to be getting a little bit warmer than before but is working fine

and if you put bigger injectors onto the engine your MAF has to be modded in fact of running the higher flow rate of bigger injectors.

regards

Tobi

480_rocket · Post by **480_rocket** » Fri Mar 11, 2005 2:14 pm

Yep, i got a Saab MAF at home, just need to plug some values into my spreadsheet to get the injector size I need.

martinholmesuk · Post by **martinholmesuk** » Fri Mar 11, 2005 2:24 pm

no maf work was needed on mine with my low impedance injectors

rpruen · Post by **rpruen** » Fri Mar 11, 2005 7:06 pm

martinholmesuk wrote:no maf work was needed on mine with my low impedance injectors

Not quite true Martin!

Even not at all true realy.

You have an old style MAF (the early ones are scaled differntly) and your injectors happen to exactly match the fuel requirements of the engine, with the early MAF. Freaky coincidance, not pre planning

You also have high impeadance injectors.

Richard

rpruen · Post by **rpruen** » Fri Mar 11, 2005 7:13 pm

480_rocket wrote:Does the LH need to relearn a bit? The driver won't cook? Let us know good news though, didn't want to cut into my loom and find somewhere to mount the res+cap

No it samples the injector resistance on startup, and does the peak and hold curents electronicaly. So there is no learning required as such.

The reason for more heat is that the output transistor is dropping more voltage to supply the correct current, so gets a little warmer. Everything is within the spec for the ECU so it will be fine.

As mentioned you will still need to scale the injectors and MAF to work together. If you are planning to fit a Saab MAF then go slightly rich on the fueling, and use an adjustable pressure regulator to drop the fuel pressure to trim the mixture to the right level.

Richard