E30 Zone

PLEASE HELP! MY J REG 325I CAB IS RUNNING VERY POOR AT IDLE AND CUTS OUT WHENEVER IT FEELS LIKE IT. ALSO AT CONTINUOUS REVS THE ENGINE SPEED WILL CHANGE EVEN THOU YOU HAVENT MOVED THE THROTTLE. HAVE CHANGED THE ECU FOR A 2ND HAND ONE AS FOUND WATER INGRESS IN OLD ONE. HAVE NOTICED THAT WHEN THE CAR PLAYS UP THE ECONOMY GAUGE, TEMP GAUGE AND REV COUNTER GO SPASTIC THEN IT CUTS OUT. STILL SUSPECT OF THE ECU BUT WOULD BE STRANGE TO HAVE SOURCED A FAULTY ONE THAT DOES THE EXACT SAME THING AS MY OLD ONE. ANY HELP OR AREAS TO LOOK AT WOULD BE GREATLY APPRECIATED.

What have you changed apart from the ECU? I imagine the ECU you have put in now ends with xxx173? That is the correct one for a 325i

Right; well firstly; a bad idle can be caused by so many things; it's just a matter of tackling the problem progressively; nothing difficult!

1. Check your hoses!

Check the hose that goes from the AIR FLOW METER to the THROTTLE BODY; for a tear or any rips; you need to take it off; held with three jubilee clips and should be off in a matter of minutes.

Upon investigating this, clean your TB with CARB CLEANER; it should be silver, and I assume it may be quite dirty; clean it with the engine off; open the butterfly and clean inside too!

Now the IDLE CONTROL VALVE is also connected to this rubber boot that you've just disconnected; remove its electrical plug; and give it a good clean to with carb cleaner.

Now replace these items; having cleaned them and replaced the boot if nec. And then see what happens to the idle?!

2. Air leak test

With a can of carb cleaner or WD 40; spray around the inlet manifold area with the car on and idling. If you notice any change in tone; that means that the carb cleaner has been absorbed and you have a vacuum leak. Spray around the inlet manifold, around the ROCKER COVER and near the TB

Failing this, next step down!

3. Injector Loom wiring

This can be found by the bottom of the engine; from the passenger side; underneath the TB; it's a circular plug attached to a metal rail; you won't miss it; if you remove the boot in section above; you'll be able to access it easier!

Unscrew this carefully; and have a look at the pins; are they corroded, what the condition like here. The injector signal; temp signals and ecu info goes through this plug; so if it's not getting through; your ecu wont be happy. I suggest some ELECTRICAL CONTACT CLEANER, give it a good clean.

The other half of the plug has a rubber boot to protect the wires; remove this and see the condition of the wiring; please do be gentle!

Having done this, allowed all to dry and reassembled; now what happens to the idle?

3. ICV

If still it hasn't solved it; then I suggest its time to replace the IDLE CONTROL VALVE for a known working unit. Knowing it's a J reg, it should be the T- SHAPED ICV; they're a bit hard to come by at the mo, but looks in the E30 PARTS FOR SALE section; I'm sure you'll find someone breaking a car with one!

After having cleaned it and then fitted it; what are the results now of the idle.

4. BLUE AND BROWN TEMP SENDER

This BLUE temp sender allows the ECU to determine whether to cold start and how to fuel the engine correctly along with other parameters obviously; however it plays a crucial part in the engine running.

these two senders; both very cheap from BMW, are located next to one another, near the front of the engine near the rad, you wont miss them, on the drivers side near the front; they are screwed into a metal water housing; one has a blue top; the other brown!

Replacing these; won't affect your idle however; but will improve the general running if they haven't been changed in a long time; very easy to change and highly recommended.

If this fails also........then sledgehammer time.......no joking

5. AIR FLOW METER

Now an important fact here is that the AFM is not involved in the idling if I'm correct; however the running of the engine depends quite highly on this meter working correctly! Basically replace it!

This should; if the previous was faulty improve your constant revving problems; but won't affect the idle! Please do wait on more experienced zoners to correct me on that!

6. Tappet adjustment

If they aren't adjusted correctly; then the M20 won't be happy; have a look here how to do it

Click here for valve adjustment

Report back after having done all this; and see what goes

Hope this helps, I'm tired now from writing all that, need a cup of tea

Saboor

That's a fine wee list of fixes there Sabs. Well written that man !!

Just one point I would bring up though re the above. I believe that it's better to spray some carb cleaner onto a rag to clean out the TB. Spraying cleaner inside the TB is not a great idea IIRC....

Mods, could the above fixes perhaps be made into a tech article ?

Nice post, Saboor.

I've seen point number 3 in action. The car ran like a pig. Lots of nasty corrosion.It will get to a stage where too much is just that: too much, and "communications" break down. Once cleaned up there was a resumption of normal service. Amazing transformation to watch, actually.

Edit: got me number wrong!

That's a fine wee list of fixes there Sabs. Well written that man !!

Just one point I would bring up though re the above. I believe that it's better to spray some carb cleaner onto a rag to clean out the TB. Spraying cleaner inside the TB is not a great idea IIRC....

Mods, could the above fixes perhaps be made into a tech article ?

thanks George; tbh i got the courage to write all that after you so very kindly gave me the willpower to keep the Sport and fix her!

thought id pass it onto fellow Sport owners too; we all need a bit of encouragment with these cars sometimes i think, be a AFM or a cracked DIZZY; they can do your ba**s in literally!

Regards

Saboor

Later 380 ECUs had extra diodes in the idle control circuit that are prone to blowing, so you're best off replacing with a 173 if you haven't already got one.

Thanks all for your help. Have the 380 ecu, i'll try the wiring and other stuff first, if nothing comes up i'll source a 173. Just trying to get motivated after a heavy night out, but a lovely day, so a strong coffee and off i'll go. I'll keep you all informed. Thanks.

ps. Sabs thanks for that hope the fingers ok this morning lol.

Ah mate; had a kip after writing that! its the hot days, dont help! keep us informed! I have a sneaky feeling its your ECU!!!

Theres one going on ebay cheap at the mo; bid for it if you can

Saboor

Great write up saboor that will come in very handy for alot of zoners including me.

Great write up saboor that will come in very handy for alot of zoners including me.

thanks mate! Didnt know it was that informative; rightfully putting back what i took i think!

Well finally got to the bottom of it. Went and borrowed a snap-on scanner and plugged it in, came up with an undoccumented code, so plugged my old unit back in and that came up with control unit fault, so on the grounds that both units do exactly the same I can only assume that I need an ecu. Checked all lives and earths in the multiplug and there all there, and appears that have lost outputs to injectors intermittantly. So after ripping out most of the underdash and wiring have got to the bottom of it! . Probably bite the bullet and buy a new one if I cant get one from the guy I got the other one. Also if I run a 173 wont that affect my lambda sensor as mine is a late vehicle with a lambda, although I have dumped the cat, as it melted a few years ago. Also any one know the best place to get a decent plug in chip? Thanks for all your help i'm know going to veg as now sunburnt and still recovering from a night on the vodka redbull and getting in at 4 this morning.

Im a bit confused by what youve written there

If you are lossing INJECTOR SIGNALS then thats not a good thing; and its not something i dont think you can resolve from under the dash; you need to check the injector loom in the engine bay i.e. the circular plug i was telling you about earlier on.

The xxx173 ecu wont be affected by the lambda; but how do you even know that the lambda is operating correctly; im not sure how you take them out; but do a search on the zone, becasue if you aren ot using your cat, theres no need to keep it; id get rid of it and eliminate one more parameter!

No nee to buy them new, just buy the correct one! If you want a performance chip; then either a Person called Speedtouch on the zone, who does CHIPS, very good at that too, or then EVOLVE CHIPS which are custom programmed at appx 50 quid i think or then ANT at A-TECH........but get the car running mint fiorst, becasue these chips will need to be on a good running car before youll notice any difference

Well i hoope youve fixed it; looks like you have but well elts see hey!

Maybe you should put up your location in your profile; that way someone local maybe be able to give you an ECU to test with!

Regards

Saboor

Loosing the injector signals from the ecu. Lambda sensor is working as on live data on scanner can see a nice fluctuation of voltage, also double checked at lambda sensor so no problem there. But to be honest i'll probably dump it. Wouldnt want to try someone elses just incase theres a fault on the vehicle that could destroy theres, unlikely as have checked most of the pin out and appear to be ok, but just in case. as far as im aware just disconnecting the lambda should be enough, this is how you adjust the co from the maf sensor when taking emissions from the sample pipe. Thanks for all your help and i'll get my location added.

I'd suggest swapping out that 380 ECU for a 173 as a matter of priority. You won't do any damage if the cat has been removed, and you could disconnect the lambda sensor if you wish, in fact you could try that initially. I had a problem with surging on my Megasquirted Sport, and switching off the Wideband sensor (similar to Lambda sensor but more sensitive) by selecting open loop mode cured it.

Otherwise it seems the ECU is constantly having to correct itself in accordance with what the O2 sensor is telling it in closed loop mode, which can interrupt the normal flow of things...

Great list Sarboor, One thing I've noticed that isn't included in the list though is the TPS which should also be checked. You need to test resistances - there's plenty of threads on here showing what they should be.

Just a small input from me - although I'm taking more from this than I'm giving!

Great list Sarboor, One thing I've noticed that isn't included in the list though is the TPS which should also be checked. You need to test resistances - there's plenty of threads on here showing what they should be.

Just a small input from me - although I'm taking more from this than I'm giving!

thank you for the compliment buddy!

You very right in the fact that a lot of things are missing; not forgetting yours, the TPS, but lets be honest, we could go on forever i think you'd agree:

TPS
CPS
COIL
HT LEADS

Though i should add those in there; the slighlty light hearted may give up upon reading it, lol! i would!

I still dont know how to test the TPS though! just replaced it, lol!

TPS SEEMS OK, RESISTANCES FINE AND ADJUSTED CORRECTLY. TO BE HONEST I BUZZED MOST WIRES FROM THE ECU, ALTHOUGH IN THE BACK OF MY MIND I ALWAYS THOUGHT IT WAS THE ECU AGAIN, JUST HAD TO CHECK TO BE SURE IN MY OWN MIND. HAVE A SECOND HAND 173 ARRIVING TOMORROW COST 30 QUID, SO NOT BAD CONSIDERING. I'LL KEEP YOU INFORMED AND ONCE AGAIN THANKS FOR ALL YOUR HELP. ONCE SHES UP AND RUNNING I'LL SORT OUT THAT CHIP. SPEEDTOUCH I'LL BE IN CONTACT SOON.