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325i engine swap

4K views 6 replies 3 participants last post by  OreoGaborio 
#1 ·
Hey guys long time no call... :blink: Just had a quick question, I have an 89 325i conv. My engine just went to shit, it had a small knocking a year ago and it turned into an ugly loud knocking a month ago, I purchased an engine from a 91 325is for 350.00 which I started swapping over this past weekend. The engine is out and I'm just transfering everything over to the new one... my question is, is this engine going to work with my own ecm? Also I saw on the head of my old one that is has a "2.5" molded into the side of the head and the new one has a "2.5 and a 2.7 right on top of the 2.5, is this gonna make a big difference on my performance of my car? This is only FYI for me, just need to know if I'm going to have to buy a new ecm or not... thanks fellow e30 freaks... have a good one. :cheers
 
#3 ·
Well my car is a testimony for BMW engineering, I drove my car about 40 miles on the bad engine at 80 mile per hour on 5 cyl. But the car ran strong it just wounded like me piston was going to puncture through the block at anytime. But I need to get the number to the ecm from that car to compare... thank you sir for the 411. :rock
 
#4 ·
it's referred to as ECU, not ECM

and the reason why there's a 2.7 stamped on the block as well is beacuse there was also an m20b27... or a 2.7L m20... ie the ETA engine (the engine in the 325e, 325eS and 325)... they shared the same block, but the eta had a longer stroke
 
#5 ·
Thank you Oreo, sorry for the confusion... :guns. Well I know the difference between the I and E 2.5 and 2.7. But my initial question was will I need to buy the "ECU" from the "is" for my car to run properly. I hace access the the "ECU" to purchase, please help me because I will install the engine this weekend and so that I can have time to buy it.
 
#6 ·
Originally posted by flipsgonetopless@Dec 10 2003, 06:49 AM
Thank you Oreo, sorry for the confusion... :guns. Well I know the difference between the I and E 2.5 and 2.7. But my initial question was will I need to buy the "ECU" from the "is" for my car to run properly. I hace access the the "ECU" to purchase, please help me because I will install the engine this weekend and so that I can have time to buy it.
if you have access to it, deffinately ask the seller what the last 3 digits of the ecu are
 
#7 ·
if you setarted w/ an m20b25 (325i/325iS/325iX engine) and you're swapping to another m20b25, you shouldn't need a new ECU... but if the ECU you have now is motronic 1.1 & you have access to one that's motronic 1.2, i wouldn't see why you woulnd't swap em.... but i'm not sure if they're a direct plug & play upgrade... your best bet is to get the last three digits like MrM3 said
 
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