Only firing on 3 cylinders

[hd_andy]

Hi all,

I have a 1988 325i and its only running on 3 cylinders. It appears to be running on 1,3 and 5. There is a strong smell of fuel and lots of unburnt fuel going out the exhaust.

There is a spark. I have replaced the DIzzy cap and rotor arm anyway as they both looked in need of replacing.

I swapped over the injector wiring from injector 1 to 2 and that got 2 running again.....

So is there any common wiring issues to be aware of? What route does the wiring take?

Also can anyone recommend a fault code reader?

The check light has also started flashing

Thanks

Andy

[andrews]

Check spark plugs and HT leads, also all the ignition system connections. Their faulty can cause misfire in cylinders

[SPADGE]

Check the connecting plug that links the injector loom to the engine loom as these can be troublesome.
Its located on the right hand side of the engine block beneath the inlet.

[sati]

Check the HT Leads , i had same prob only 1,3,4 were running , swap leads from an escort and its was running fine .

[StuBeeDoo]

Sounds like you have a wiring fault on the injector loom. The injectors are in 2 banks of 3 - 1, 3 & 5 and 2, 4 & 6.
Take the loom plug under the inlet manifold apart and clean all the terminals. If that doesn't cure it, next step would be to try another injector loom - one that's known to fire all 6 injectors.
HTH
Stuart.

[hd_andy]

Thats really helpfull thanks very much guys, I will check it out tomorrow.

Andy

[town325i]

if you need an injector loom i have one i no is good you can have it for £15 posted

[Brianmoooore]

Injector loom without a doubt! Check under the lower rubber boot for a rotted wire.

[hd_andy]

Hi again,

I have cleaned up the plug and reconnected it and now it wont start at all!!!

Have disconnected and reconnected a few times and still no joy, I think i have probably broken the wire when I disturbing the plug

Does anybody know what sort of voltage you should get at the injector plugs?

Cheers

Andy

[zimmer-320i]

dont quote me but iirc its 5v

[andrews]

When I claened injectors on mine I used the battery voltage to move injector( i.e. 12 volts, m40 engine). hd_andy, I think you have broken the weakness of injector wiring. Check the nearby to the plug wiring. probably it'll help

[Ant]

its the lower section that breaks, remove the upper plug, remove the lower section and peel the runner boots back on both, should all become clear then

I'm with Brian, Defo an issue @ this connection

FYI there should be 12V at all the injectors with the ig on, engine NOT running,

Repair the loom( cut it back towards the starter til you get good clean wires to connect too !! ) if the same 3 injectors are still "dead" then check for 12V, assuming the feed is OK, then replace the ECU

[hd_andy]

Ok, just an update and a big thank you.

Firstly big thanks to town325i for getting me the wiring loom so quickly - you are a star!

It was indeed the multiplug.

Firing on all 6 again

It is however still overfueling. Big clouds of smoke when booting it. The wiring to the ECU temp sender seems ok so I am hoping its just the sender. Going to change it anyway as its only a tenner. Otherwise I guess I need to look at the other ECU senders AFM etc.

All good fun so far though!! Thanks again for your help guys this is a great forum!

Cheers

Andy

[town325i]

glad it helped you out mate

[Brianmoooore]

How well did you check the fresh loom?
A common cause of over fueling on M20's is a different broken wire in the plug and socket.

[town325i]

i never had no trouble with over fueling when it was on my car

[hd_andy]

Yeah the loom looks good, might be worth checking the lower wiring loom connector again i guess but it all seemed ok....

[no2lurch]

the loom below the multi plug is rotten on mkine causing over fueling problems...

[Brianmoooore]

You say you've changed the injector loom?
It's the engine loom side of the plug and socket that gives trouble.

[Chase007]

Any news on this prob mate?

[hd_andy]

Hi guys.

Yes, I changed the ECU temp sensor (blue one) and now no more white smoke!!!!

BUT I now have a small cloud of blue smoke (!). Basically from cold its fine and then when it reaches running temperature you get blue smoke on hard acceleration.

So to me that sounds like rings, going to do a compression test this weekend to find out for sure. Cant understand why that would have happened its only on 117k and its got a pretty comprehensive service history mainly BMW.

It might be replacement engine time next week then! Whats the going rate for a 325i engine and are there any differences to be aware of?

Andy

[zimmer-320i]

i have/get a small puff of blue smoke i think its leaking stem seals but its not bad at all but what to expect froma 20 year old motor that problery had more than a few thrashings!!!

i dought its rings as it would be constant, but maybe brian knows??

tho mine is hardley noticble and only castch a glimse of it some times

[AlpineAde]

i have/get a small puff of blue smoke i think its leaking stem seals but its not bad at all but what to expect froma 20 year old motor that problery had more than a few thrashings!!!

i dought its rings as it would be constant, but maybe brian knows??

tho mine is hardley noticble and only castch a glimse of it some times

Under what conditions?

If under deceleration, long periods of idling or on initial start up then seals/guides would probably be a good call.

Other things could be piston blow by/shot rings ~ usually happens under high loads.

Are you sure it's intermittent?

[zimmer-320i]

its very rarely happens, say if im rolling along at 40 and drop down a few gears to over take i have noticed a few times a small puff of clearblue smoke comeout,
dosnt smke under idle or start up nor under most conditions,
(unless the breather pipe has residue init??)
saying that it was only doing that when i first brought it, may have been the thin old crap oil it had,
not noticed it latley but its been getting darker in the evening so maybe why i havent noticed it, so ill keep a eye,
so if it intermitent like now and again what should i be addressing?

and dont say a B25 swap lol

[Albinojay]

Mine drops down from 6 to 3 when it gets very very low on petrol. I this normal?

Any other car I've owned just conks out lol

[AlpineAde]

its very rarely happens, say if im rolling along at 40 and drop down a few gears to over take i have noticed a few times a small puff of clearblue smoke comeout,
dosnt smke under idle or start up nor under most conditions,
(unless the breather pipe has residue init??)
saying that it was only doing that when i first brought it, may have been the thin old crap oil it had,
not noticed it latley but its been getting darker in the evening so maybe why i havent noticed it, so ill keep a eye,
so if it intermitent like now and again what should i be addressing?

and dont say a B25 swap lol

Keep an eye on it.

Perhaps get a mate to drive behind you and have him keep an eye open when you give it some wellie. See what he reports.

Engine swap? Why would I say that? If you like whatever engine you run, then run it, I say.

The smoke thing has three levels of expense, basically. White smoke = nothing, usually condensation evaporating away from when cold, no biggie. Black smoke = a little more expensive, usually indicating rich running...injector issues, computer issue, sensors, usual stuff. Blue smoke = expensive to bloody expensive, unfortunately. Blue smoke = oil drinking. Think pistons/rings = rebuild, worst case scenario.

Or you could always just source a second hand 2 litre.

But all this is jumping the gun until you see exactly where/how your smoking situation arises. How's the oil consumption? Compression OK? How hard do you push the car?

The real problem is in the "intermittent" nature of your issue. They're a bugger to solve...so that's why I reckon if you can get a mate to have a good look at the car as you drive it you might be able to learn a little more.

[zimmer-320i]

6 TO 3????