Auto Ix vs Manual IX

[CrazyPrime]

So what is the difference between the two? I know obviously the transmission and the transfer case but what about the front diff? Front drive shaft? Just wondering a guy is selling a auto ix for parts or rebuild and it looks interesting.

[4x4_e30]

Autos have 4.10 diffs front and back, manuals have 3.91's. Front driveshaft is the same. The rear half of the manual and auto transfer cases are the same, so parts can swapped between the two.

[CrazyPrime]

I would assume the engine is exactly the same?

[101]

yes. The engine is exactly the same.

[nando]

basically it's the same except the front and rear diffs, shifter mechanism, transmission, and front half of the transfercase housing. none of the driveshafts or mounts are different.

[packratbimmer]

The ECU is likely to be different #351 instead of #173 for example. I have several of these 351 ECU's from auto iX cars. They seem to idle poorly. Anyone else have similar experience? I have had much better luck with 153 or 173 ECU's.

[nando]

the 351 isn't specific to automatics. There are at least 10 different versions of Motronic 1.3. I had a 524 in mine.

the 153 was a piece of junk - much more prone to failure, not much in the way of diagnostics. it's more likely to have idle issues than any other M20B25 DME. the dual board design is way over complicated, but such was the state of electronics in the mid 80's.

[packratbimmer]

Yes, the 153 is not as good as the other units, but the idle is good. I have had one 153 fail in my 25 years with E30 cars. No other failures with ECU's EXCEPT 351 poor idle issues. Well - lets not include M10 318i L-Jets - LOL

Let the flames begin - LOL

Funny how ALL of my 325iX automatics came stock with the 351 and I have never seen one in a RWD car - EVER.

We are talking probability here?

If you look hard enough, there is at least one document out on the internet that will support the notion that most/many/maybe all 351 ecus came from AWD/automatic/325iX cars. Please correct me if I'm wrong, but also throw some hard evidence my way.

I am merely posing a question based on my experience.

Can anyone chime in with a 351 that came stock in their RWD 325I?

EVERY 351 that I have had has had a poor idle (around four) - I even had a factory Turner chip for it - the idle was poor. Pop in a 173 and boom - perfect idle.

So...If your idle is poor, you have tried everything and you have a 351 ECU...try your buddies 173 just for kicks...it will take 5 minutes of your time.

[Dirty325ix]

Hmm I have always had idle issues with my engine setup an dit has only been hooked up to 2 different automatic 325ix's
has anyone else heard of a 351 idle issue
maybe I should snag a 173 for giggles and try it

[packratbimmer]

Yes - It is weird!!!

My 351 ran awesome with the Turner chip at open throttle, but idled bad like the other 351 brains that I had (I have had four - one of which was a complete non-functioning unit).

I tried the Turner chip in an expendable 173 and guess what - the 173 ran with a bad idle - HMMMM???? Did Turner copy the 351 chip and just tweak it??? As seen in the pic below, Turner implies that the chip will work in 351/330 hardware.



My novice/humble conclusions are as follows:

1) The 351 chip is the culprit and not the hardware - in essence, the 351 is labeled as such simply because of its unique tune for some reason (perhaps iX specific or maybe iX/automatic specific)???
a) I would like to try an appropriate chip in the "351" box/hardware, but I am not sure which one to try. I do not think that the 173 is strictly compatible. For instance, SSSquid offers chips for the 173, 380 and 524/525 - not sure if any of those match the "351" box/hardware so to speak.

2) Maybe the chip was programmed differently for BMW simply for the ABS system that is unique to the iX??? The iX ABS functions differently during deceleration in anticipation of snow/ice.

[nando]

The hardware is actually the same on all 173 and later versions.

Ix abs doesn't have any programming, its all hardware controlled. Every motronic 1.3 has that capability they just don't have the abs system.

[packratbimmer]

That is probably why the bum chip worked in my 173. I'll have to try the inverse experiment. "173 and later versions" is not very specific. Still curious about the reason all of the chip manufacturers ask for the box/hardware information (if they are all the same) - is the chip size different? What is different about them?

Anyone out there with an original manual iX OR RWD that came stock with the 351??? I have not seen one yet, but my sample is small obviously.

My cars that came with the 351 were as follows:

1988 automatic, two 1989 automatics and a 1991 automatic - all of the ECUs are junk (as far as idle goes). I will try one with a stock 173 chip sometime and see what happens.

[nando]

My 91 had a 524.

It might be software. Physically there's no difference, even the traces of the pcb are the same. Maybe the 351 software is bad?

[packratbimmer]

That's what I am thinking. I am going to try a stock 173 chip in it and see if that works.

[nando]

It should