Bmw 535iM with 528i engine. Injectors Question

[Bmw.wp]

Hi Everone.

My car have a 528i engine and i recently replaced one injector. Now the mechanic told me, i'll get more power if i replace the 528i injectors with 535i injectors.

what's your view on this.? My car is the M535i E12/8 model.

thanks in advance.

[GripGreg]

So, let's see, your engine is a 2.8i?? In a 535i body/car???
If this is true, you may need to change the ECU which is in the glove box.
Someone with more knowledge will, I'm sure, get on board here. I just had to ask those questions.
More info, please. Greg

[Bmw.wp]

So, let's see, your engine is a 2.8i?? In a 535i body/car???
If this is true, you may need to change the ECU which is in the glove box.
Someone with more knowledge will, I'm sure, get on board here. I just had to ask those questions.
More info, please. Greg

Hi Greg

i dont know about the ecu, i bought the car like this and see run quite fine. just had a miss on idle, and when check it out it was injector 3 that was dead. bought another one and the miss on idle is gone. when i chat with the mechanic he told me that the 535i injectors in a 528i engine will give more feul = more power. but i dont want to do that and abuse the engine. if its save than i'll maybe will consider it.

thanks

[GripGreg]

Where are you located? Is there a concern about smog inspection?

[Bmw.wp]

Where are you located? Is there a concern about smog inspection?

I'm from South Africa. I still needs to take here for Roadworthy (smog) inspection.

i just don't want to modify the engine with bigger 3.5 injectors if i'm going to abuse the 2.8i in the process. I was thinking along the lines of a little more power than the normal 2.8 with 2.8 injectors.

in other words i will leave it standard if its not worth doing a modification like this.

I think i need so save up and buy myself the original 535iM engine then.

[Mike W.]

No, BMW generally put more than adequate injectors on the cars so upsizing the injectors would do no good at all. And many times they used the same injectors on different sized engines, your E12/28 is something we never saw, but in the regular E12 era they used the same injectors on late 528i's and the same era 635's, so they may well be the exact same ones. If your injectors are fine, they're fine, no need to change them.

[Bmw.wp]

Hi mike thanks for your advice . I will then leave everything standard.

No, BMW generally put more than adequate injectors on the cars so upsizing the injectors would do no good at all. And many times they used the same injectors on different sized engines, your E12/28 is something we never saw, but in the regular E12 era they used the same injectors on late 528i's and the same era 635's, so they may well be the exact same ones. If your injectors are fine, they're fine, no need to change them.

[wkohler]

The injectors on the 2.8 and on the 3.5 are the same. I did some cross-referencing before replacing mine.

[Blaise]

The injectors on the 2.8 and on the 3.5 are the same. I did some cross-referencing before replacing mine.

I am no expert, but I don't think that it is that simple. I am doing some homework on the subject for my 3.5 conversion and find that the later 3.5's used a higher flow rate injector.

It is probably true that SOME 3.5l used the same injector's as the 2.8l.

You can compare those used in our E12 and those used in an early 1990 735i (E32)...which used the M30B35 (3.5L).

http://users.erols.com/srweiss/tableifc.htm

[wkohler]

The injectors on the 2.8 and on the 3.5 are the same. I did some cross-referencing before replacing mine.

I am no expert, but I don't think that it is that simple. I am doing some homework on the subject for my 3.5 conversion and find that the later 3.5's used a higher flow rate injector.

It is probably true that SOME 3.5l used the same injector's as the 2.8l.

You can compare those used in our E12 and those used in an early 1990 735i (E32)...which used the M30B35 (3.5L).

http://users.erols.com/srweiss/tableifc.htm

Yeah, it's that simple. I'm not talking about the later motors. I have an M535i with a 3.5L motor which uses the same injectors as the 528i. I didn't figure we'd be discussing injectors that aren't even the same physical dimensions.

[Blaise]

The injectors on the 2.8 and on the 3.5 are the same. I did some cross-referencing before replacing mine.

I am no expert, but I don't think that it is that simple. I am doing some homework on the subject for my 3.5 conversion and find that the later 3.5's used a higher flow rate injector.

It is probably true that SOME 3.5l used the same injector's as the 2.8l.

You can compare those used in our E12 and those used in an early 1990 735i (E32)...which used the M30B35 (3.5L).

http://users.erols.com/srweiss/tableifc.htm

Okay, you're right.

I am using the stock E12 manifold on a euro M30B34 using motronic 1.3....so need different injectors. That's what made me chime in. Thanks for clarifying.

Yeah, it's that simple. I'm not talking about the later motors. I have an M535i with a 3.5L motor which uses the same injectors as the 528i. I didn't figure we'd be discussing injectors that aren't even the same physical dimensions.

[Bmw.wp]

so with a higher flow rate 3.5 injector the car going to be more powerfull then. am i correct. if considered they the same.?

[DEMIURGE]

Firstly, I want to say that in my opinion, Mike and Chris are right - the old M30 injectors are identical (e12 era). Then in e28 era - they are the same also, but with another new geometry (same 19 lbs/hour) and in e34 era with only B30 and B35 engines - the injectors are with different part number and color, but the flow rate is similar (I'm not 100% sure).
So Blaise is right also...

Let us examine these two possibilities:
1. Injectors are with the same flow rate. Nothing new happens - the same amount of fuel, the same power.
2. Injectors with higher flow rate.
a. If your engine has no lambda (oxygen) sensor - the only thing will happen is overriched mixture, a very slight power increase under heavy loads and more fuel consumption. And I'm not speaking about the smog inspection case.
b. Your engine has lambda sensor - the the ECU will correct the overriched mixture to normal by shortening the injectors "open" time.
The result will be - the same output power.
Of course you can make some tests with tightening the spring of the AFM, change the ECU chip with new remapping (only for Motronic) and some other not advisable things... or change the ECU to MS2 (Peter Florance knows about it more then us put together)

So, in first place - you have to check - have you a lambda sensor and after that, if you have one - is it in good working order. If your lambda is faulty - the ECU already put the engine in overriched mixture position.

My personal advice - use the stock injectors for this engine with the stock ECU. They have a very serious reserve in the fuel flow rate. Everything depends on the ECU adequate commands. The only use to switch to aftermarket or other injectors is, when they use some new revolutionary way to spray and atomize the fuel.

[Bmw.wp]

Firstly, I want to say that in my opinion, Mike and Chris are right - the old M30 injectors are identical (e12 era). Then in e28 era - they are the same also, but with another new geometry (same 19 lbs/hour) and in e34 era with only B30 and B35 engines - the injectors are with different part number and color, but the flow rate is similar (I'm not 100% sure).
So Blaise is right also...

Let us examine these two possibilities:
1. Injectors are with the same flow rate. Nothing new happens - the same amount of fuel, the same power.
2. Injectors with higher flow rate.
a. If your engine has no lambda (oxygen) sensor - the only thing will happen is overriched mixture, a very slight power increase under heavy loads and more fuel consumption. And I'm not speaking about the smog inspection case.
b. Your engine has lambda sensor - the the ECU will correct the overriched mixture to normal by shortening the injectors "open" time.
The result will be - the same output power.
Of course you can make some tests with tightening the spring of the AFM, change the ECU chip with new remapping (only for Motronic) and some other not advisable things... or change the ECU to MS2 (Peter Florance knows about it more then us put together)

So, in first place - you have to check - have you a lambda sensor and after that, if you have one - is it in good working order. If your lambda is faulty - the ECU already put the engine in overriched mixture position.

My personal advice - use the stock injectors for this engine with the stock ECU. They have a very serious reserve in the fuel flow rate. Everything depends on the ECU adequate commands. The only use to switch to aftermarket or other injectors is, when they use some new revolutionary way to spray and atomize the fuel.

DEMIURGE

Thanks for your input.

When i bought the 535iM i was under the impression that the engine is still an standard 3.5l. when my friend check it out he said "nope" this is a 2.8l engine.

So if the previous owner change the 3.5L to 2.8 but leave the Ecu of the 3.5l still in the car, then what happens.?

Just Curious.

Thanks for all the input.

i still going to keep my car as standard as possible. No Modifications

[Mike W.]

When i bought the 535iM i was under the impression that the engine is still an standard 3.5l. when my friend check it out he said "nope" this is a 2.8l engine.

So if the previous owner change the 3.5L to 2.8 but leave the Ecu of the 3.5l still in the car, then what happens.?

Just Curious.

Thanks for all the input.

i still going to keep my car as standard as possible. No Modifications

No problems. The system measures how much air is going in, and a couple of temp inputs, and injects fuel accordingly. It doesn't know or care how large the displacement is, if it's say half throttle with a 3.5 or .75 throttle with a 2.8, it just sees air and tries to match it with the right amount of fuel. Get too far off what it expects and there will be problems, say a 500CC engine or a 6L one, but 2.8 and 3.5 are plenty close enough.