Have you upgraded your fuel injectors?

[Tiger]

I am starting this thread to see if anyone has upgraded their fuel injectors. Stock BMW injector are single hole pintel design. More modern injectors are 4 holes. Lots of places say it will increase your fuel mileage over EPA spec.

So I am curious. Who done it and what was the result?

I read some old threads on bimmerforum and one guy with E32 740i has some major problem... got only like 8-10 MPG... and just by fuel injector change, he jumped into 17 MPG. Thinking of this guy's problem with such a low mileage... he had some serious engine problem... maybe major vacuum leak and lots of other things. Now, I don't know if this is real or not... so that is why I want to start a thread for the people who done it.

[genphreak]

It provides silghtly better atomisation, but since it is not part of the manifold design et al, you are likely not to have any benefit as there may be other things that change as well, such as pintle caps. Putting in inectors that have different flow rate is crazy unless the cams AND fuel maps have been changed, so worse economy will result. Stock injectors are as good as they can be for the engine, after all, if they weren't the Original Owner would have been better to buy a GM branded vehicle instead...

I say this having changed the injectors on M30s and M50s. Stock were as good, if not better. The ECUs take a long time to bed-in, so it is not smart to have the wrong injectors as the ECU starts out setting its mixtures way out instead of slightly out, so takes a long time to set the duty cycles correctly and over fuels during this time- not good for the catalytic converter. This happens every time you disrupt the 12V supply (Eg. disconnect the battery)- and may increase fuel consumption as the factroy injectors are absolutely right. The replacements may, (or may not)- who really knows?

[Tiger]

So you are saying you changed the injectors to a newer type... what is the result of your fuel mileage? Tell me about your upgrade what injector did you put in?

The fuel injector upgrade I am talking about is simply same spec but different port design. Not drastic increase in capacity of fuel injector.

It doesn't matter in my case because the everything will be different again... new everything and tight engine... no vacuum/air leak.

[h2oyo]

I have upgraded my injectors to the yellow's. I did this after resealing the top end and installing new valve cover gaskets on my 540. It did smooth out the idle and the car seemed to be more responsive at the lower end (0 through 3000 rpm). The car always pulled hard from 2500 up. The fuel mileage didn't really change. I do all city driving with some highway once or twice a month to visit my brother. My average mileage is 17.5 to 18.5 depending how heavy my foot gets and how often. I didn't feel the mileage was bad being a V8 and the fact that I love to feel the pull in the seat of your pants. I would say it was well worth the little work is is change them. Just make sure you have a couple extra injector o-rings as they are easy to cut. As for the bedding in, I have always found that when I do disconnect the battery for work I will drive the car around close to home to make sure everything is as it should be. I will then jump on the highway and cruise the car at highway speeds. Drive the car like you normally do. I have never had any issues and it seems to me that the car makes its changes because of the battery being disconnected within 10 to 30 minutes of my cruising drive. Good luck and enjoy.

[Tiger]

That's the injector I bought... Bosch 0280150710 19lb injector with modern 4 hole design. 18MPG is fantastic based on your driving habit...

The fuel injector has the same flow and spec as original. Only difference is the 1 hole and 4 hole type. I'll pick up a few extra orings... just in case.

I am on a quest to see if I can eak out 20 MPG in city.

[Bill R.]

Hi Stan,
I've done it on a number of cars but none of the v8's. On my 535 it made a slight difference in gas mileage but that may also have been just because the mustang injectors were much newer than my old injectors. I did notice a definite difference in idle smoothness and response. Not a huge difference but since the injectors were so cheap any improvement was well worth it.

[bubba966]

That's the injector I bought... Bosch 0280150710 19lb injector with modern 4 hole design. 18MPG is fantastic based on your driving habit...

The fuel injector has the same flow and spec as original. Only difference is the 1 hole and 4 hole type. I'll pick up a few extra orings... just in case.

I am on a quest to see if I can eak out 20 MPG in city.

Just coat the o-rings with a little bit of fresh motor oil before you seat the new injectors. Makes 'em slide right into place w/out harming the o-rings. Much easier to install them like that than trying to do it with the injectors dry.

Not sure if you'll get 20 in the city. You can probably get close though. What software you running? My mileage increased a good bit running EAT software over stock. Stock I was getting 26 highway, EAT w/MAF that was on it's way out I was able to get 29.5

[leicesterboy15]

Please tell me more about these injectors? Do you have a link? Google brings up Ford injectors when I put in the model no above. Especially interested in smoothing out my idle, looks like the total is around $200 for 8 injectors, is that right? Do you know if this is a US only thing or will they work the same on euro cars with euro fuel?

[Tiger]

My car is still stock ECU.

[Tiger]

I find the factory spec tolerance of 3 to 5% differential interesting... it is almost 1 lb of fuel delivery difference if you are on extreme end.

I am trying to figure out how an owner of 740i was gettting only 8 MPG where he drives and then suddenly got 17 MPG by changing injector and O2 sensors. Unless his fuel injectors are all coked badly to begin with.

On another post... some guy in CA did an interesting thing... he took out the fan clutch and installed electric one instead. He claimed to get 31 MPG on his M50... he did install newer fuel injectors.

[Tiger]

BTW... the injectors you installed... were they cleaned or used?

[Tiger]

Yes, the Bosch fuel injectors were used in Ford cars... particularly Ford Mustang but lots of their cars and SUV used the same injectors.

I bought a set of injectors... cleaned and flowed... and picked so all 8 injectors are within 1% tolerance of each other. This would really smooth out the engine. Stock tolerace level is 3 to 5%... which means if you got two that is supposed to give you 19 lb of fuels per hour... one will be short by 1 lb of fuel... that's huge!

It doesn't matter if you got euro or not... it is based on engine size and amount of fuel needed to satisfy the demand. My stock injectors are 0280150778... so you can compare with yours... should be same injectors.

[bubba966]

My car is still stock ECU.

Get some conforti or EAT software. E3 sparkplugs. Red Line or equivalent in the diff. Amsoil 0w30 or equivalent in the engine. Square PS2's all around.

All that with your new injectors & gaskets will give you pretty impressive mileage. Should be better than most M50TU 525's...

[Tiger]

I am going to put in Amsoil 75w140 differential fluid.

Just changed the oil to Mobil 1 0w20. I can hear and feel the difference just by starting the car up.

Already got great tires.

I may bite on the EAT in future... just want to see what I can do in stock ECU form.

[bubba966]

I am going to put in Amsoil 75w140 differential fluid.

Just changed the oil to Mobil 1 0w20. I can hear and feel the difference just by starting the car up.

Already got great tires.

I may bite on the EAT in future... just want to see what I can do in stock ECU form.

75w140 is too heavy for the diff, go with the 75w90. I've got the Amsoil severe gear 75w90 sitting around waiting to go into my diff, but it had redline 75w90 installed not too long before I bought it and doesn't need changing yet.

My car had mobil 1 in it when I bought it, and I'd not put it back in personally. Would rather put dino juice in than mobil 1. Have delo synth in it now, but will go back to the amsoil 0w30 on the next change. The delo is fine, but not quite up to the same level as the amsoil.

[Tiger]

Doesn't our limited slip requires 75W140? That is why I bought it. I also have 75W90 for my other cars. Mine is also severe gear too.

I only use Mobil 1 because it is readily available and cheaper when on sale. Gan't really get the cost down on the Amsoil. Try the 0W20... it is all we need. I am using it on my BMW before I deploy it on all my cars. My SUV uses 5W20 and the car ran great since new...

I read Bob the Oil Guy... and he recommends 0W20 synthetic oils for everyone.

[bubba966]

You put a limited slip diff in your car? Shouldn't matter LS or not. An LS diff requires certain properties to prevent clutch chatter in the LS unit. Most oils need an LS friction modifier added, but the Amsoil severe gear oil doesn't need any additives for a LS diff. Looked up the requirements for a '93 M5 which does have a factory LS and it specs the same 75w90 a non-LS diff would use. I suppose you could put the 75w140 in there, but it'd hurt your mileage.

I might try the Amsoil 0w20 at some point, but I'm not putting Mobil 1 in there.

[Tiger]

My car is a 1994... it doesn't have traction control so factory install limited slip. Yours is 1995 and probably does have traction control so factory install open differential.

Yeah, I looked it up... Amsoil say 75w140 for limited slip... then I looked at the spec for 75w90 and it said to be compatible with most limited slip... seems like all synthetic one are compatible with limited slip... I am going to put in 75w90 in... if it chatters, I'll just add their modifier. Thanks for the tip!

[bubba966]

Only US spec E34 with LSD as standard than I'm recalling was the M5. Yeah, I've got ASC+T & an open diff. But ASC+T was an option and non-ASC+T cars still had open diffs. You have the build sheet or seen the markings on the diff telling you it's a LSD? Maybe is, maybe isn't...

Not sure why Amsoil would quote a 540 w/LSD needing 75w140 and say the M5 needs 75w90 when the diffs are the same except for the gear ratios.

[Tiger]

I did see S stamping on the differential... I do recall see my car spec sheet with LSD. It is a real bear to turn the car in parking lot... seriously. It is like a 35' turning radius when backing out.

[Mordan]

hello,
i bought 6 yellow ford injectors in the USA for 100 dollars. 4 pins holes. Still need to install them. :)

[genphreak]

If you change them out, you need to make sure they flow the same rate. If they are very similar, then all is fine. The trouble comes if you install injectors with a higher rte, even thugh the ECU adapts, it takes time and isn't ideal anyhow. High rate and low rate injectors cost the same, the ones the car has stock are as good as any. BUT.... how can you know if the rate is the same? It depends on pressure and they seldom quote that. I think you'll find M50 and M60 all have 4-spot injectors anyhow BTW. My old M50 does. :)

Oh and be very very wary about what many say online, buttometers love reset ECUs...

[LPGguy]

There are no "upgrades" for the low impedance 325e injectors. In new stock form they flow well over the requirements of any eta motor, at around 18.4lb/hr. Just send your injectors out to any service center for ultrasonic cleaning and ANSU flow matching.

Should cost you $70-80 to have that done.

[Tiger]

Update... I delayed the project so long... but finally got the engine back together.

The 19lb yellow injectors I got is way too much fuel. I started it up and it ran strong but I could never get it to stop the fuel smell... my exhaust is puffing white fuel smelly smokes. I did run the car for at least 40 minutes worth... all various idling and revving times... not 40 minutes all at one time.

If you guys got any advice, I really would appreciate it. Right now I am seeing if Mark can reprogram a chip for the larger injectors or I go back to factory... have the old one professionally cleaned and benchmarked. I'd like to get the car running and back on the road... 8 months is enough of sitting.

[h2oyo]

Is it possible that after sitting so long that the car is just smoking and will clear up with running? The smell of gas, are you sure you do not have any leaks? I did this on a V8 but I have only loved it. no problems with this at all. The biggest issue is that almost a year to the date of doing all the work I had to change out the PCV valve again as it got a hole in it and didnt idle or drive well. After about 1.5 hours (working carefully) everything is back together with new gaskets on the PCV and intake, idles fine and drives great. Let us know how things turn out for you.
Johan





Update... I delayed the project so long... but finally got the engine back together.

The 19lb yellow injectors I got is way too much fuel. I started it up and it ran strong but I could never get it to stop the fuel smell... my exhaust is puffing white fuel smelly smokes. I did run the car for at least 40 minutes worth... all various idling and revving times... not 40 minutes all at one time.

If you guys got any advice, I really would appreciate it. Right now I am seeing if Mark can reprogram a chip for the larger injectors or I go back to factory... have the old one professionally cleaned and benchmarked. I'd like to get the car running and back on the road... 8 months is enough of sitting.

[Tiger]

At this point, I can only suspect it is because I wait so long to install the yellow injectors that it may have cause some sticking and possibly stuck open. 8 months is too long for injector to be waiting before install... for those injectors that has been cleaned. New injectors are different story.

Another possibility is that I got a bad batch of injectors.

The latest is that I have sent my original injectors to service and I got it back already. I have full report of my original injectors... which is now baffling me. The report said that my injectors are now pushing 240cc/min and at that specification, the injectors are 22lb/hr! All online sources specified that my injectors are supposed to be 190 or 200 cc/min. Original condition is 222, 234, 234, 234, 228, 234, 228 and 228cc/min and after all cleaning... they are all 240cc/min.

At this point I wouldn't rule out the yellow mustang injectors... Clearly the capability is similar to stock injectors... I need to do more diagnostics before I can conclude anything.

h2oyo, what kind of fuel mileage are you getting with your current injectors? What was your fuel mileage before? Your inputs are greatly appreciated.

[h2oyo]

I drive only city miles really. I always get between 17.5 and 18.5 mpg's. I dont drive slow really I keep up with traffic. I'm not trying to lead the band but i'm not at the back either lol. I think I may have picked up 1 or 1.5 mpg's at most. The biggest thing for me was how the idle smoothed out and it may just be me but it seems like the car pulls better at take off and it always has pulled hard after 3000k. I blow through emissions and the car is just a joy to drive. I have heard people say 3 to 5 mpg's but I think if I really tried hard I maybe able to pull high 19's maybe a 20. But that wouldnt be much fun lol. I have always thought that at 18-19 for a V8 i'm doing pretty well and if I want to I can get up and move of course that will drop it big time lol. I know on the highway when I have taken trips to visit Mom or my wifes Mom in Sedona I get 25+ and that is up and down some pretty steep hills and cruising at 75-85 all the way. For me it was well worth the work.




At this point, I can only suspect it is because I wait so long to install the yellow injectors that it may have cause some sticking and possibly stuck open. 8 months is too long for injector to be waiting before install... for those injectors that has been cleaned. New injectors are different story.

Another possibility is that I got a bad batch of injectors.

The latest is that I have sent my original injectors to service and I got it back already. I have full report of my original injectors... which is now baffling me. The report said that my injectors are now pushing 240cc/min and at that specification, the injectors are 22lb/hr! All online sources specified that my injectors are supposed to be 190 or 200 cc/min. Original condition is 222, 234, 234, 234, 228, 234, 228 and 228cc/min and after all cleaning... they are all 240cc/min.

At this point I wouldn't rule out the yellow mustang injectors... Clearly the capability is similar to stock injectors... I need to do more diagnostics before I can conclude anything.

h2oyo, what kind of fuel mileage are you getting with your current injectors? What was your fuel mileage before? Your inputs are greatly appreciated.

[Tiger]

I will pull the yellow injectors and get them tested... I suspect I got bad injectors or I have multiple problems. I am almost finish with major works... new water pump, new intake manifold gasket, mew PCV, new valve cover gasket... now I gotta tackle the fuel filter and check for fuel pressure leak... like I said, at this point, I need to start with a baseline and diagnostics to get this car running again.

1.5 MPG increase is outstanding. right now the car gets 16 on super ultra short commutes... from house to bus stop and back... 16MPG. I did get 24.5 MPG on highway.

I am curious to see how much fuel mileage I get for just cleaning the fuel injectors... they had an example... Honda Civic... average MPG is 28 for 2 months before cleaining... cleaning shows no abnormality... then for 2 months after... they average 32 MPG... same routine.

My injectors were really coked up at the tips but spray pattern is all good regardless... Actually one was really coked up completely and we did scrape away to see the pintle before we sent it in. Car was idling smooth... typical V8 on our car... Will keep everyone updates on the progress.

[h2oyo]

Yeah my original injectors looked pretty bad, I did all the gaskets including under the throttle body. It isnt to bad a of a job. My car has the double fuel filters. One of the L shaped lines had a crack in the inside bend. Just remember to pinch off the lines to keep fuel from running out all over your arm lol.
Johan





I will pull the yellow injectors and get them tested... I suspect I got bad injectors or I have multiple problems. I am almost finish with major works... new water pump, new intake manifold gasket, mew PCV, new valve cover gasket... now I gotta tackle the fuel filter and check for fuel pressure leak... like I said, at this point, I need to start with a baseline and diagnostics to get this car running again.

1.5 MPG increase is outstanding. right now the car gets 16 on super ultra short commutes... from house to bus stop and back... 16MPG. I did get 24.5 MPG on highway.

I am curious to see how much fuel mileage I get for just cleaning the fuel injectors... they had an example... Honda Civic... average MPG is 28 for 2 months before cleaining... cleaning shows no abnormality... then for 2 months after... they average 32 MPG... same routine.

My injectors were really coked up at the tips but spray pattern is all good regardless... Actually one was really coked up completely and we did scrape away to see the pintle before we sent it in. Car was idling smooth... typical V8 on our car... Will keep everyone updates on the progress.

[Tiger]

Yep, did that too... throttle body gasket... and all new torx bolts... lots of them stripped out. You are right... the job is not as bad as it sounds.

[h2oyo]

The most difficult part is either getting the fuel lines off the rail or getting the intake out from under the undisconnected fuel rail lol. Did it both ways. It seems easier to just replace some fuel line and remove it. I did the 6 speed swap also. I now have the water pipe for a manual. I never did really like that water hose fix at the back of the engine. That was a bit of a pain to put back in.
Johan





Yep, did that too... throttle body gasket... and all new torx bolts... lots of them stripped out. You are right... the job is not as bad as it sounds.