How wrong is the wrong ECU?

[Morat]

Folks
I'm having trouble with my car and the only thing left to try is the ECU. Chris-w is a complete star and sent me an ECU to try out. My own stupid fault is that I didn't give him the numbers on my ECU to make sure we had the same thing.

So, how bad is it to plug a 172 ECU into a car that came with a 173 ECU? I really only want to test it for an hour or so (the current problems start after 15-20 minutes everytime). If its a nono, please let me know because I'm tempted to plug it in and give it a try!

Thanks for any advice.


pics:
original

loaner

[Ant]

172= 320

173= 325

the swop is ill advised unless you fit the 173 chip into the 172 ecu, then fit.

HTH

[Morat]

Dagnabbit!
Thanks Ant. I think I'll buy another one off ebay incase the chip itself is playing up.

[Morat]

HAH, well I couldn't resist.
The car runs better with the wrong ECU than it does with the right one!


WTB 173 ECU...

[Chris-W]

That ECU came out of a 325...!

That one ran well too

[Morat]

mebbe it has a 325i chip? Is there any way to tell?

[Chris-W]

Back to Ant on this game of tech help tennis....

[Theo]

Sorry to hijack thread somewhat, but I have an ecu out of a 325i auto, the numbers read;

1726683 001 078 Bosch number - 0 261 200 380

Is this a 320i ecu as well Ant?

[Morat]

aargh, I don't know what to do now.

Took the car out with the replacement ECU, it ran OK. Idle was fine, it revved OK. Warmed it up and then drove 30 miles (with a stop in the middle) and it wasn't bad... the occasional misfire and some raggedness but much better than it had been with the old ECU. But, I stalled it in traffic and it took mebbe 30s total cranking to get it running again. On the way back it was fine under power, poor at part throttle - but still far better than with the old ECU that would suddenly overfuel the poor beast until it choked to death. When I got back the idle was wandering between 600 and 1500 rpm with periods of nice steady 900 in between.

Do I get a guaranteed 325i ECU?
Do I guess that the ECU must be a 325i chip in a 320i case because it ran at all and look for other faults?
Do I put the original ECU back in and figure that there must be something else wrong?
Do I put the current roughness down to the ECU being new to the car and still learning the fuelling?

I'm leaning towards getting a known-good ECU (even tho the current one came out of a good 325i) just to eliminate the doubt.

Like I said above
argh!!!

Morat

[Ant]

all the ECUs are the same on the post facelift cars, only the chip dictates the application

using the 320 ECU in the 325 will result in the ignition timing being a little out due to the stroke change etc, however the fuelling is possibly about right, dependant on whether the original 320 it came from had the 715 inj's with a 2.5 Bar FPR.

380 is from a 325i
381/2 is 320i
172 320i
173 325i
073 325i
069 325i
157 318i
387 318i
175 318iS

there are some oddities out there, but thats the regular units...

Morat, just swop the chip from your original 173 into the 172, the net result is the same