325 ecu in a 320

[paulisa]

if i fit a ecu from a 325 into a 320 will i gain any power and more important fuel economy my 325 with a chip is far better than the wifes 320 both cars are auto i now get about 28mpg but hers only manages 20 mpg next thing is it a strait swap over with no wiring probs

thanks Paul

[Speedtouch]

Doubtful: the ignition and fuelling maps are quite different, so the car would probably just run like a pig, if at all.

The ECUs should be a direct swap if both are later Motronic 1.3, and you could use a 325i ECU successfully if you put an appropriate 320i EPROM in it. A Mild chip could improve the mpg of a 320i auto significantly - I could supply you one for £30 posted if interested...

[paulisa]

are the 320,s normally so bad on fuel compared to a 325 if it wont damage the wiring i may just try swapping ecu see what happens

[Speedtouch]

I found both my chromey 320i (L-Jet manuals) gave around 26mpg on average, 30 if used gently.

It should give better than 20mpg, unless used in heavy traffic alot.

[paulisa]

maybe a good service might be a start was told it had been serviced recently when i bought it but dont know what was done other than cam belt and oil change

[leeparkes]

Ive had both 320i & 325i and mpg was very close,sounds mad but the 325i gave slightly better mpg (unless its a motorway run)

[Speedtouch]

are the 320,s normally so bad on fuel compared to a 325 if it wont damage the wiring i may just try swapping ecu see what happens

Please let us know the results of this, if you go ahead with it...

[paulisa]

will swap them over after the gp and give it a run up the road ( well hopefully anyhow if it runs)

[paulisa]

well here goes fitted the ecu complete with wild chip from my 325 into the 320 it started instantly and sounded crisp when reved took it for a run of about 5 miles driving at 30mph it holds just over 30mpg on the instant thing on dash gave it some welly on the open road and what a differance over the standard ecu (that looks never to of been removed from car before) only thing is the tickover was a bit hunty ranging from 700-900 rpm. so refitted original ecu at a constant 30mph instant mpg was reading just over 20 put foot down at same place as with my ecu fitted and it did accelerate but no way as quick as with my ecu and reving engine was no where near as crisp so now i need to buy a 325 ecu with a speedtouch wild chip for the 320

[Speedtouch]

Interesting stuff! PM sent.

Cheers,

[jay528ise1985]

Just thought I'd add to this...

I have just fitted a 325i afm and 3 bar fuel press regulator to my 320i, which already has a 325i throttle body and a mild speedtouch chip - She really responded well to the afm and fpr and now flies, with a lovely deep induction growl and further improved response and low & mid range shove.

My MPG gauge reads higher at any given speed now but I think it's more to do with the fact it gets a signal from injector opening times which should be lower with the higher fuel pressure and lesser signal given by the afm for any given amount of air flowing in.

I will do some acceleration times, max speed and economy runs once I have removed the eta engine from my boot (yes, it's still in there, 2 months on...)

[Speedtouch]

You've been running about with an eta engine in your boot for 2 months?!

[jay528ise1985]

Well I just never seemed to get round to it...!!!

[Speedtouch]

Doesn't it affect the handling somewhat? I imagine the rear springs must be down on the bump stops all the time!

[hongkongfuey]

Just thought I'd add to this...

I have just fitted a 325i afm and 3 bar fuel press regulator to my 320i, which already has a 325i throttle body and a mild speedtouch chip - She really responded well to the afm and fpr and now flies, with a lovely deep induction growl and further improved response and low & mid range shove.

My MPG gauge reads higher at any given speed now but I think it's more to do with the fact it gets a signal from injector opening times which should be lower with the higher fuel pressure and lesser signal given by the afm for any given amount of air flowing in.

I will do some acceleration times, max speed and economy runs once I have removed the eta engine from my boot (yes, it's still in there, 2 months on...)

what about sticking in some 325 injectors

[jay528ise1985]

Speedtouch re the handling the back end grip is superb, won't even start to twitch even in the wet! I just wish I could stop the atrocious understeer and general lack of front end grip in the wet.

Hongkongfuey re the 325i injectors they don't seem to be necessary, she performs very well as is - I would have liked to have done a dyno run just to see whether she was fuelling correctly and to see what sort of bhp & lb/ft it was giving but I shan't get the chance now as the 2.7 is going in this week! All I can say to anyone with a 320i is with a little bit of intelligent fettling you will transform the performance and you keep that lovely free revving short stroke engine - I will really miss that cos it's so easy to match the rev's when you're heel & toeing or just blipping on downchanges