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 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.