Big Time Poster
The best injectors?
I'm contemplating replacing the injectors on my 1993 525i M50 motor.
Am I better to stay with the OEM injectors, or is there a "favourite" upgrade that I should consider?
I'd prefer them to swap straight in, but would consider changing fuel rails or mounts or whatever if there is a definite advantage to do so and the cost isn't horrific.
Any advice?
ss2115.
BMW 525i Touring - 1993 (current drive car).
DS23 Citroen Safari - 1974 (restoration and modifications).
Golf MkIII - 1997 (fun car and daughters learn-to-drive car)
3 Grand Master
You can get plug N play replacement injectors. FiveomotorsportOriginally Posted by ss2115
You shouldn't need to change the rail, just pop in the new injectors and go.
If you are looking for increased power or something, this is not the first place to start.
Vee ave vays of dealing vid your kind...........
Big Time Poster
No - not looking for power gains, but I thought it worth asking in case any owners had found a particular injector or particular size/flow rate to work better in the M50 engine.
Perhaps be smoother with a different spray pattern or better starting or perhaps show fuel consumption improvements with no performance lost - stuff like that.
ss2115.
BMW 525i Touring - 1993 (current drive car).
DS23 Citroen Safari - 1974 (restoration and modifications).
Golf MkIII - 1997 (fun car and daughters learn-to-drive car)
Grand Master
I find mine is smoother on idle and under acceleration with the refub'd Bosch design II 19lb injectors I put in a while back... They have the four hole pintle design whereas the others were single pintle apparently so the spray pattern wasn't as effective. I didn't notice any performance gains, I just done it as I was under the impression my old ones were leaking a little.
1995 XJR: 4.0L S/charged straight 6 Auto
What... It's not broken??? I can still fix it
Big Time Poster
Thank you. Thats just the sort of info I was looking for - owners experiences with alternative injectors.
ss2115.
BMW 525i Touring - 1993 (current drive car).
DS23 Citroen Safari - 1974 (restoration and modifications).
Golf MkIII - 1997 (fun car and daughters learn-to-drive car)
Super Moderator
some interesting stuff about injectors
http://www.wellsmfgcorp.com/pdf/counterp_v5_i1_2001.pdf
excerpt:
PLUGS AND SHORTS
Injector problems fall into two groups: mechanical and electrical. Bad fuel and water in the fuel have damaged many injector nozzles and/or pintle tips. You can identify mechanical problems by a visual inspection of the fuel spray pattern.
Listening for an injector’s click (or its absence) can point to the first injector to observe. If grit or contaminated fuel get past the main filter, they’ll quickly plug the small mesh filter in the
top of the injector. Deposits formed from fuel droplets that evaporate after an engine shuts off can form gums and tars that clog an injector or skew its spray pattern, preventing the fuel
from vaporizing completely. Sometimes such deposits prevent the pintle from seating completely, so the injector dribbles fuel. While
fuel cushions the injector pintle’s closing against the seat, it’s still a mechanical part and will eventually show wear and begin to leak. Even the slowest unmetered leak can often transmit more fuel than we want at unloaded warm idle, as we saw above.
Most failed electrical circuits first become a short circuit and then quickly burn open, but with fuel injectors, you often notice driveability problems before the injector shorts completely.
An injector that loses electrical resistance can have an interesting and puzzling effect. The usual way a coil changes resistance is by melting the thin insulation between adjacent windings
of the wire. The failure does not occur all of a sudden. If the coil has 100 loops of wire, a short across the insulation between two loops can reduce the coil’s resistance by no more than one percent, even if all the current went through the partial short circuit. Such a short may not noticeably affect the injector. It could be very hard to detect with even the best ohmmeter since new injector’s resistance vary more than that and temperature changes
account for even more. As the resistance goes down, the current goes up, as current goes up so does the heat. The heat increase will melt the next most vulnerable insulation barrier until it also forms a short. Before long, that partially shorted injector pulls
noticeably more current than the others. It is rare for an injector to burn all the way shorted or open. On most vehicles the PCM will shut the injector off to protect the driver transistors when the current exceeds or falls below a certain threshold. Some cars shut off all the injectors if any are shorted or open.
But before that happens, you may find the following: Often two injectors or even entire banks of cylinders fire together, particularly
on earlier fuel injection systems and on engines with waste-spark ignition. The injector with lower resistance draws more current because electricity always follows the path of least resistance. Increased current to the partially shorted injector may ‘starve’ the paired injector of current so it can’t lift its pintle and its cylinder
gets little or no fuel. We then have the odd circumstance that the good injector does not spray enough for combustion but the defective one keeps working – not for long, but long enough to leave a diagnostician puzzled.
Usually fuel injectors operate and spray once for each complete engine cycle. Some vehicles use additional squirts for cold starting, acceleration enrichment or for other special conditions. Some vehicles have more than one set of injectors (and more than one set of intake runners) for each cylinder, employing the second set only under conditions of very high power demand and high engine speed. But the way individual injectors work in these systems is the same as in everyday vehicles.
Fuel volume will intensify as the injector’s Current flow increases.
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