Mototron pics, videos, injector roundup

[Nick Gustas]

No, I don't have other bosch injectors or RS4 to test.


anyhow, here's the tip of a Mototron:



Crappy side shot:



Size wise, it fits perfectly with the same fuel rail spacers as a Bosch greentop injector.

To make them work with a K03 chip and a 85mm maf, I had to dial back base fuel pressure to about 2.6bar. The problem with running such low fuel pressure in our cars, is that the rail pressure has to be pulled down about another .8bar by the regulator at idle or slow cruise to keep the 2.6bar at the tips of the injectors.. With the backpressure in the fuel return hose, and the pressure needed to run the siphon pump in the fuel tank, you can't do it. Fuel pressure doesn't drop down far enough at idle.

I poked around in the gas tank, and found restrictors in the fuel return lines, these are designed to keep the fuel pressure in the return line up so the siphon pump in the rear of the tank will have enough pressure to operate. I removed the restrictor in the nozzle directly over the fuel pump, and that seems to be enough to fix the problem. Hopefully the siphon pump will still work, if not, I guess I'll have a 12 gallon tank for a while. If it doesn't work, there is also a chance I didn't get the siphon pump back in the right spot after I pulled it out of the tank while exploring. It's a total PITA to fish those lines around and get them back where they belong, don't pull them out if you don't need to! Good thing we only have one fuel level sender and it's right by the fuel pickup, empty is empty..


Other than that little fuel pressure at idle snag which left the car feeling soft leaving a light just off idle until I fixed it, (but otherwise ran awesome) they work just great. I have my startup enrich at 115% and my warmup at 85%, (thanks Mike2kS4!), primary at -20%, and all other settings are default. I'll probably tweak for power sometime soon, but the car starts and daily commutes perfectly, hot starts, cold starts, restarts, short trips, coasting to a stop with the clutch in and on the brakes, idling in 2nd gear, gently bogging a start with a loaded trailer, holding 2000rpm in neutral for extended periods, etc. It's the only injector besides greentops that has stayed in more than a day. (yeah, probably should have bought rs4s in the first place ) At the moment, I have no desire to put the greentops back in ever.


On to the meat!


Frame captures of patterns with helpful lines drawn in:



Videos, mjpeg video, GSM audio, .avis, right click save as:

2000 Audi S4 stock injector

40lb delphi redtop, Grand National injector, don't recommend for the S4

42lb delphi bluetop, runs "ok" I'm sure proper tuning might make it work well.

42lb bosch greentop, the injector homebrewers and old school AWE S3 owners know and love, works pretty well most of the time. Leaves side valves gunky after many many miles, warmup and cold start can be iffy if you don't have the right settings and a squeaky clean combustion chamber, erratic flow at low injector pulsewidths.

60lb siemens mototron Got flow?! With 728cc/m at 4bar this baby probably has enough flow potential for most everyone, for now Of course that makes it a bit harder to tune with a smallish maf on a homebrew setup. Custom tuning, or a larger maf+hybrids make it a possibility. I'm really impressed with the wide range of fuel mixtures that the car will happily run on when supplied by this injector, I think that covering the entire intake port with a fine mist really helps ensure a homogenous fuel mixture vs bearly tagging the inner edge of the outer two intake valves. The precise metering at low injector pulsewidths helps too.

[PSmalls::DoggieStyle]

Now you need to test 38# Delphis. Mine seem to work flawlessly.

IIRC Piggie tested both 38 and 42 Delphis, but noted a wider pattern similar to greentop or better.

[Marin S4]

[Nogaro Stg3]

what would you suggest? I want an injector that wont cause bad cold starts and idling problems. What are my choices?


thanks!

[lemieux@curbside]

why isn't these something smaller with that spray characteristics?!

[Nick Gustas]

That said, I and many others have had better than decent success with greentops, it's just not always a stock like experience.

[Nogaro Stg3]

Mark at Autospeed told me he had some other kind of injector, not the RS4 but as good or better....and cheaper..

[Nick Gustas]

I'd like to see the Volvo R "Green Giant" spray pattern, PN: 9202100. Or the pattern of the new injectors AWE is sending out with their kits. Those could be the ticket for normal K04 setups.

[denic992-- JAYHAWK]

[Nick Gustas]

of the mototron.