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**Threehz** · 08-02-2012, 10:00 AM

Welcome bud, you bought the best E30 (besides the M), just don't tell the 325 guys that.

I don't believe 1234 is a code... You sure it's not a 1233, that is the WOT code which makes sense for the symptoms you are describing. It would make sense if it was a TPS problem, do you have any idle issues?

The speedo does not affect anything, and the reason it doesn't work is very likely the battery (you gotta remove the instrument panel)

I've also heard similar problems coming from AFM, you might want to remove the top and clean it, there's videos for it somewhere.

**Simon S** · 08-02-2012, 03:18 PM

Preface: others know more than I do – that is for true.

i.e. I’d advise taking Threehz’s advice under strong consideration.. over my own input. It is like you’re getting crickets here – and I mostly want to be as helpful as logically possible..

1) after reviewing a fault code chart – I am not seeing “1234” either.. (?) - but the fact that it throws that code after symptoms are triggered would lead me to put focus on whatever is throwing that code ..

2) “speedometer does not work” – maybe related/most-likely-not – but I would start thinking about replacing the si batteries and/or also having solder joints re-flowed w/in the instrument cluster. Deteriorating si batteries can cause weird failures – and (possible) deteriorating solder joints can also cause weird failures. Fwiw, the VDO clusters that tend to come in late-model m42 cars tend to be less-problematic than early-model MotoMeter clusters. As far as the battery replacement, my experience is to either go with just battery replacement (cheap (~$40?) – but somewhat difficult) OR replace the whole si board (~$160?) which is worlds easier and comforting in consideration that it is a fresh board in itself + new batteries. Always nice to know how fast you're going..

3) advise to get/replace m42 timing chain tensioner – along with quick inspection of cam sprocket teeth (remove Valve Cover – rubber VC gaskets ‘should’ be reusable)(pointy sprocket teeth = worn)(‘square’ teeth = good). How many miles does engine have on it? If mileage is 150K+, or if cam gear teeth are worn, and/or general maintenance has not been kept up – then we quickly start talking about a whole lot of other parts (~$200-1000+?) for the front of the engine (water pump, fan clutch, t-stat, several gaskets, new/updated timing chain guide rails, coolant & vacuum hoses, the above-mentioned TPS, and bla bla bla..) Most all of these parts are strongly considered “while-you-are-in-there” parts – parts common to failure and need of replacement considering typical age and mileage of these engines. Also considered: “preventative maintenance” in nature.. while most of the individual parts are individually inexpensive – the volume of them do add up.

4) arm yourself with research. Please do not reply to this [my particular] post with more questions (I lack both: more in-depth know-how, and patience to do more research). Individual topics addressed in my answer are all searchable/find-able via this site or via google.

5)

Originally posted by WeeksE30

a failing fuel pump..

given current age of these cars - and possible indication that pump and filter are original - I'd advise replacing pump and filter out of general principal and preventative maintenance..

Closing note: all of the above response is simply what I’d consider/address/tackle if I were addressing similar symptoms. Take or leave..

Advised reading:
Brendan Purcell's site

m42 Maintenance thread in r3v

a well-rounded Mess under intake thread on r3v

realOEM for a 91 318is for parts# look up and shopping list generation.

and go to BluntTech for your parts orders. Easily one of the top best companies to purchase from in regard to service and lowest prices.

**WeeksE30** · 08-06-2012, 07:22 AM

Threez & Simon-

Yep, its definetly a 1234 code. I thought it was odd as well, but check it several times and thats what it keeps telling me. I did find this info on the code...

1234Vehicle Speed Sensor (Speedometer A Signal)This code is stored when no plausible speed signal is detected while driving. The requirements are an engine speed >2500 rpm and under load for more than 10 seconds. Check the speedometer function and the wire to the DME . Also check for codes in the Combi Unit (Instrument Cluster).

Car idles great other than when it first starts up (which i hear is something typical with the M42's?). I've also popped open the AFM and inspected it, everything looked good.

Can you guys tell me, or point me in the direction of where i can find, how to change the battery for the speedo? All the other gauges work fine, does this battery you speak of only power the speedo?

Thanks for all the help.

-Chris

**Threehz** · 08-06-2012, 07:45 AM

I searched around for you and found some resources for the speedo problems.

I would take out SI board and make sure all the solders are still in tact, fix any that aren't, and you probably want to replace the batteries, or at least test them.

Soldering repair - http://www.unofficialbmw.com/speedo/speedo.htm

A thread with some more info on the problem - http://www.r3vlimited.com/board/showthread.php?t=129004

Tips on testing the diff speed sensor - http://forums.bimmerforums.com/forum....php?t=1280189

Where I found all this information ;) - https://www.google.com/search?q=e30+...hrome&ie=UTF-8

And finally, you can just order a refurbished SI board or have your fixed for a cost, but you probably want to make certain that is your problem first. - http://www.r3vlimited.com/board/show...light=si+board

GL

**WeeksE30** · 08-06-2012, 09:21 AM

Threez-

Wow man, big thumbs up to you. Thanks for digging up those old threads, very much appreciate it.

I will tinker with it some more and if i figure anything out I will report back.

-chris

**WeeksE30** · 10-09-2012, 09:17 AM

*update*

Summary:
Car cutting out @ 4,500 rpm in each gear expect first. Very similar to rev limter. Getting CEL code '1234' - speed signal A not detected. Speedo works, tach works.

Ok, so i've continued to mess with this thing and learn as much as possible about the M42 and e30 wiring. Also, i got the speedo to work by re-doing the wiring back by the diff, seems there was a break somewhere.

This is where i'm at now, i need some expert e30 guidance on the wiring. From what i understand there are multiple speed signals that the car relys on, one of which goes to the speedo from the diff sensor, and then continues out to the DME (via c101) - its the road speed signal wire. If the DME doesnt get this signal it detunes the motor, inserts a soft cut, and the VANOS isnt working properly. It NEEDS this signal to function properly.

With that said, I need some help figuring out which wire (color) coming OUT of the cluster is the road speed signal wire. I have determined there is good continuity from the c101 to the DME, so i'm hoping to tie into this wire off the back of the cluster and jumper it over to the computer. Anybody have any ideas which cluster plug (c1,c2,c3) this would wire would be found in? The car was not equipped with cruise control, so there is not a green c6 plug.

I'm so very close to getting this figured out, and i'm pretty sure this will make a SIGNIFICANT improvement when its hooked up. Any help would be much appreciated.

Eager NOOB E30 owner,

-Chris

**mr ilia** · 10-09-2012, 01:04 PM

M42 have no Vanos, so you likely pulled the info for another motor.

Cut off at 4500rpm is likely AFM related. Try another AFM and see if this helps.

**WeeksE30** · 10-09-2012, 02:46 PM

Mr ilia-

Gotcha - thanks. I'm trying to eliminate all "easy fixes" before I start throwing replacements parts at it. That gets expensive, real fast.

I still want this CEL to go away. Any ideas which wire is the speed signal output on the back of the cluster?

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