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Author: Subject: BMW injector question...
Nickp

posted on 30/11/13 at 09:53 PM Reply With Quote
BMW injector question...

Any BMW E36 experts on here?
I've got a 323i M52B25 (2.5) engine that I've been using to mock up in my Haynes chassis. It came without an inlet manifold / injectors as the guy had sold the M50 (325i) one that he'd fitted to 'derestrict' the M52. However it did come with the 'chipped' ECU.
I was always planning to use a M52B28 (2.8) engine and today I've collected a complete (hopefully good) bottom end off a mate and also an M50 manifold for free If the bottom end's Ok then I plan to transfer the head etc, which I believe are the same, off the 2.5 onto the 2.8 bottom end and use the M50 manifold.
Questions are-
Will the 'chipped' 2.5 ECU work OK with a 2.8?
Which injectors should I use? The 2.5 (Green?) ones that I presume would go with the ECU or the 2.8 (Pink?) ones that I think were original fit on the 2.8? The green ones seem cheap and plentiful on ebay, pink ones less so.

I suppose I could register on one of the many BMW forums, but someone might see me over there

Cheers,
Nick

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zetec

posted on 1/12/13 at 12:02 AM Reply With Quote
The map in the ECU should be for a set of engine charactoristics, and I doubt a 2.5 will be the same as a 2.8 when it comes to fuel needs and airflow, it might well run the engine but it wont be at it's best.

My advice would be to get the engine fitted as you intend and then get the ECU, or an aftermarket ECU, mapped on a rolling road. This will then mean you are getting the full potential.

The flow of the injectors will also depend on the fuel presure and ECU opening times, best bet is to ask who has fitted what and use this as a starting point, also find out what fuel presure they are running them at. If you are running a fuel pump/regulator from a BMW this will make life easier.

Check out the web site for Emerald ECU, lots of advise and basic ideas about mapping etc.

As a start running a standard engine/ECU/injectors etc from a donor will at least give you a running engine and then you can decide and experiment from there...."Internet forum" tuning is not always the way to go, nothing worse than having an engine you have spent lots of time and money on only to find it makes nowhere near the power you expect. I would have thought there were loads of complete 2.8 engines around to save rebuilding from 2 different ones. The BMW engine, if I remember right, runs VANOS so you will need to factor this in.





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Nickp

posted on 1/12/13 at 07:48 AM Reply With Quote
Ta for the reply. I could go out and get a running donor but then there's the hassle of buying, dismantling and scrapping etc etc And why when I've got all the bits I need already? Also I'll know the engine will be spot on when it goes in. The bottom end can be thoroughly cleaned and checked and the head can have a de-coke and a bit of a gas-flow too while it's off. The 2.5 and 2.8 are the same engine bar the 300cc capacity increase. The 2.8 will want more fuel but how much will the BMW ECU self compensate via the lambda sensors? Would the larger pink injectors make up this difference? Maybe the ECUs are the same, just different injectors? I suppose a set of the smaller 'green' injectors would at least make the engine more emission / IVA friendly?
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SteveWallace

posted on 1/12/13 at 12:10 PM Reply With Quote
From what I've read on the BMW forums, you will need a 2.8 ECU. I don't know if the 2.5 and 2.8 heads are the same or not. The usual modification is to us an M50 inlet manifold and throttle body to increase the power of the 2.8 as they were restricted, but I've not heard of anyone using the whole head. I would have thought that you will need pink injectors as you will end up with a 2.8 engine and not a 2.5, so more volume and therefore more fuel needed per cycle for the same fuel to air ratio - but this is just an informed guess.

I do have a spare set of pink injectors and fuel rail which came with my donor 2.8 engine. I've never used them, but they look OK. I've also got a spare 2.8 ECU but this has not been chipped and so would need to be reprogrammed to run on another engine as I don't have the matching EWS and key chip. Happy to agree a price if they are any good to you.

There is a chap on e-bay who will re-program 2.8 ECUs to I) remove the need for EWS ii) remap for better performance and iii) remove the limp home mode that all 2.8 and 2.5 BMW ECU's will default to if they do not receive a signal from the ABS sensors. From memory, if you send him your own ECU the cost is £105, or £155 if you don't have one.

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Nickp

posted on 1/12/13 at 12:27 PM Reply With Quote
Ta for the reply.

I'm pretty sure the heads are the same, it's just a stroke increase on the 2.8 so don't see why anything will be different TBH. I've got the M50 manifold and TB and the 2.5 ECU was 'chipped' to allow for this apparently. The 2.5 ECU may work fine with either injectors but you're probably right in saying it should have the pinks. I'll take the injectors off you and possibly the ECU if it's the right money, then I'll have all the bases covered U2U me a price and I'll get back to you.

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MarcV

posted on 5/12/13 at 12:02 PM Reply With Quote
There are at least VANOS differences;
M50 -> No Vanos
M50TU -> single vanos on/of
M52 -> single vanos on / of
M52TU -> dual vanos (not on E36 I think)

So the M50TU had might be the same as the M52 one. Not sure though.

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Daf

posted on 5/12/13 at 02:35 PM Reply With Quote
I used to have an E30 with an M50 in it, then I upgraded to an M52 2.8 - I can confirm the 2.5ECU won't run the 2.8. The general rule is the 2.5 ECU won't run the 2.8 properly without a complete re - map.
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rodgling

posted on 5/12/13 at 05:11 PM Reply With Quote
I think I may have some 328 parts taking up space in my garage which could be useful - inlet manifold, injectors (both colours I think), throttle bodies, loads of the ancilliaries, etc. PM if you need any of these.
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