Does bosch 172 acu have rev limiter..

[Brdjo]

Does bosch 172 (m 1.3, from m20b20) ACU have rev limiter? And on what range?

[Brdjo]

Anyone? I am kinda confused a have two 172, the one on car and he does not have rev limiter, but second does have about 6500rpm.. which one is fake? xD is there any option to remove or add rev limiter on existing chip?

[Brianmoooore]

172 should have a rev. limiter on fuel injection, but AFAIK it can be changed by 'chipping', or, if you run LPG on a mixer system, it will be ineffective.

[Brdjo]

Hmm, funny thing I do not have LPG, but my 172 definitely have no rev limiter of any kind..

[Brdjo]

I have some news about this one, and need any help from you guys..
I just confirmed that my ECU (172) have limiter when conected on e34 m20b20 , but in my car (e30 m20b20) limiter do not work.. any suggestions what to look for?

[Brdjo]

Any thoughts...?

[Speedtouch]

They have a factory rev limit of 6,250 rpm, which is programmed into the EPROM ('chip') in the ECU. If it works on the E34, then it should work on your E30...

What revs have you seen out of it? Some 'chips' are reprogrammed to raise the rev limit to as high as 7,000 rpm or so.

[Brianmoooore]

Are you sure the E30 tacho. is reading correctly, and not telling you the revs. are higher than they actually are?

[Brdjo]

Couple of times it revs past 7000rpm, like 8000 or so.. Tacho seems ok, but definitely will be checked.. I have strobe light and i will compare readings... Is there any possibility that the cluster can trick the chip and mass with it?

[Brianmoooore]

Is there any possibility that the cluster can trick the chip and mass with it?

None whatsoever. Rev. counter is driven from a dedicated output on the engine ECU, using a signal processed from the crank position sensor. Rev. limiter also uses this signal, but is internal to the ECU, and there's no feedback to the ECU from the tacho.
A four cylinder E30 'coding chip' fitted to the instrument cluster of a six cylinder car will make the tacho read 50% higher than it should, so the rev. limiter won't cut in until an indicated 10,000 RPM or so.

[Brdjo]

Thanks I thought so, but just to be sure.. My cluster is swapped before i got the car, the coding chip numbers are: BMW13, 1381635, 11.87, 002.

[Speedtouch]

That's correct for certain models of 320i (probably pre-facelift), according to RealOEM:

http://www.realoem.com/bmw/enUS/partxre ... series=E30

However, I'm presuming your E30 is a facelift, if it is running Motronic 1.3, so maybe you have the wrong coding plug/cluster?

[Brdjo]

Yes my car is facelift, 1988. Hmm, the cluster is blue from back that should be cluster for facelift, but plug is maybe wrong.. What plug number should I have? All i can find that this one is for e30 m20b20...

But think this one is ok, facelift is from 9.87 with 1.3 motronic.. and plug is 11.87...

[Speedtouch]

Yes, you're probably right, it should be the correct one. Maybe worth taking it out and refitting it again. Also, what condition are the SI batteries in? If they are worn out, they may affect the operation of the other instruments.

http://www.e30zone.net/e30zonewiki/inde ... nstruments

[Brdjo]

I think I found what is the problem with limiter xD
on idle it's gone wild...

[Speedtouch]

Yes, decidedly odd!

[Brdjo]

Bit of an update
I fix the cluster (four months ago), now everything is working even my constipation gauge.. But still no limiter

I found a spare 173 bosch ecu, and wanted to ask you guys can i run 173 ecu on stock m20b20?

[Brianmoooore]

Same thing, as long as you swap the main 'chip' over. It will run with the 325 'chip' , but timing and fuel maps will be incorrect.

[Brdjo]

Thanks for clearing that up..

[Brdjo]

Just an update, limiter started to work with second 172 chip.. guessing someone was playing with old one..