what is the difference - BMW Forum

chattyman · 03-06-2012, 10:48 AM

between the 256s4 and the 256s5 engine.. was the 256s5 built for the facelift 3 series from 2002. and would this work in a 1999 3 series e46. as mine is the 256s4..

Lord Vader · 03-06-2012, 12:38 PM

From what I can tell their is no difference. The displacement is the exact same. From what I can tell the S5 one is newer. Would it work? Yes.

Jack Dabsy · 03-06-2012, 02:20 PM

I agree with Vader... It is an M52 engine regardless of the "s4" or "s5". The s5 formed part of BMW's engine range re-vamp in 2002 (Very minor alterations) !

chattyman · 03-06-2012, 02:39 PM

was wanting to know. as when i enquired about a possible engine replacement at a local breakers yard they told me that it had to be the same as what was in. but never told me about the difference between the s4 and s5. said if it was fitted with a s4 then you have to put a s4 in... thanks for all your help. regards alan

Jack Dabsy · 03-06-2012, 02:40 PM

You should hopefully get the replacement unit with the ECU's as a rule, anyway...
If not, then a re-program "may" be required...

chattyman · 03-06-2012, 02:44 PM

hi. is the ecu unit in a x reg 525 e39 the same as the e46.

Jack Dabsy · 03-06-2012, 02:48 PM

Probably, but it would still need "Matching"...
Always try to aquire the original ECU's (ECM) with a replacement unit - saves pain and money later...

chattyman · 03-06-2012, 02:59 PM

thanks. just ive been offered a complete engine and ecu from this x reg 525.

Jack Dabsy · 03-06-2012, 03:19 PM

Hehehehe If you're happy with the price then go for it matey... Is it CONFIRMED as a good runner and a bit of warranty?

Lord Vader · 03-06-2012, 04:52 PM

Quote:

Originally Posted by chattyman

hi. is the ecu unit in a x reg 525 e39 the same as the e46.

I think this depends on the year of the E46 your gonna transplant in. The E39 used a different engine then te E46 dependent on model year. The ECU itself in terms of the unit should be the same. It's the software you would have to worry about. As Dabsy said a "re flashing" might be nessecary.

chattyman · 03-06-2012, 04:59 PM

mine is a e46 1999. the 525 is a 2000. said it was very good runner 82000 miles. m54tu25 engine

Lord Vader · 03-06-2012, 08:04 PM

What's the reason you need to swap engines?

Jack Dabsy · 03-07-2012, 12:38 PM

Double Vanos?