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Message: <blockquote data-quote="LCP" data-source="post: 5092" data-attributes="member: 2424"><p>I got hold of a used Hiop chip for my M50B25TU 325i(M)... decided to put in the chip myself, so here goes the steps, plus photos...1) Disconnect the -ve lead of the battery<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step1.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />2) Remove the two round clips holding the foam rubber insulation, and remove the foam rubber piece<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step2.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />3) Remove the fusebox cover, and unplug the rearmost relay for easier access. Remove the ECU compartment cover, held by five size 8 bolts.<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step3.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />4) Two shots of the ECU, gently unclip the cable loom from the cover<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step4a.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /><img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step4b.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />5) Remove the ECU gently from the compartment, and finally undo the connector locking clip and remove the connector from the ECU.<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step5.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />6a) Open up the ECU by undoing the clips (which are actually part of the aluminium cover). The EPROM chip is the one with the plastic cover on top of it. The chip is sitting on an IC socket.<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step6a.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />6b) Macro shot of the stock EPROM chip. It's a Texas Instrument chip, with customised markings, but I believe this is a 20nanosecond 27C512 EPROM.<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step6b.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />6c) Macro shot of the Hiop chip. This chip is meant for stock M50B25TU.<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step6c.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />6d) The Hiop EPROM in place, taking care to put the pin 1 location (notch on the chip) the same way as the stock chip, else there will be some holy smoke...<img src="http://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step6d.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" />6e) and 6f) View of ECU PCB after the EPROM swaphttp://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step6e.jpghttp://i76.photobucket.com/albums/j37/cplim/E36EPROMswap/Step6f.jpgRefittting is the reverse of the above procedure.Improvement is noted for mid and high rpm, especially more from 4000rpm onwards, car pulls much harder from that point, all the way till the redline.LCP</p></blockquote><p></p>

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