Replaced 325i head and now only firing on 2 cylinders!SOLVED

[scot]

Took out the plugs and found cylinders 1 and 6 are getting fuel but not a sniff in the others.

Any ideas??

[Speedtouch]

Have you checked the connector below the inlet manifold (which feeds the two banks of injectors)?

[scot]

I didnt see a connection down there? The injector wires bunch together then dissapear into the loom...

[scot]

Heres a pic of my spare pre facelift loom

No plug on the older loom

[Speedtouch]

Are all earths in place? Use a multimeter to check whether there is continuity between the injector sockets and the appropriate terminals of the ECU plug.

[scot]

Earths are all connected. Electrics are my weak point! i've got a multimeter but besides testing the battery i really wouldnt have a clue how to test for continuity...

[Speedtouch]

It's easy - put it on a low resistance range (0-20 ohms, say), and hold the two probes together; it should then read 0 ohms, indicating continuity.

Now put one probe on one injector terminal and the other on the appropriate ECU terminal and verify that it's got continuity (i.e., reading 0 ohms).

Of course, you'll have to try both injector terminals to work out which goes to the ECU, since one will go to earth.

To do that, hold one probe to earth and establish which of each of the injector terminals is earthed - mark with a crayon or similar.

Then you can continuity test the other terminals.

How many pins does your ECU socket have - 35 or 55?

[scot]

Ok that doesnt sound that hard to do

Will give a go tomorrow evening

Cheers!

[scot]

Just counted 35 pins on the ecu connector

[Speedtouch]

According to this diagram, on an early 35-pin ECU, the injector outputs are on pins 14 (for pots 1-3) and 15 (for pots 4-6):

http://www.armchair.mb.ca/~dave/BMW/e30/e30_86.pdf

If you're getting fuel on pots 1 and 6, this suggests that the wiring to the ECU is probably OK, and that the problem must lie with the supply to the injectors on 2-5.

Ignore my earlier comments on checking the injector earths; the other side of them is powered with the ignition on, and they are then switched to earth by the ECU.

So, you instead need to set the multimeter to a 0-20V voltage range and test to see that power (+12V or so) is reaching the appropriate side of the injector plug with the ignition switched on.

[scot]

I would have had an answer tonight except my multimeter has died a battery acid death!

This one has been highly reccomended to me. Any good??

http://www.machinemart.co.uk/shop/produ ... -010911080

[HairyScreech]

http://www.maplin.co.uk/digital-multime ... ement-4402

i have been using one of these for about 8 years, so far it hasn't missed a beat and the battery warning only came on the other week, they are pretty damn rugged.

[scot]

Right just checked all the injector plugs and each is showing 12.3 volts...

Also had a go at the continuity test which came up with continuity on ecu pins 14,15,33,34 and 35 for each injector plug?!

Oh and i swapped no1 injector for no2 and 6 for 5 and it now no longer fires on any cylinders!

I'm baffled and quite fed up now

[buzz6353]

Scot

have the injectors been sitting for a long time??

[scot]

They were refurbed by injector tune about 6 months ago. I did give them a tap as advised to free them up...

Could they be seized/blocked?

[Speedtouch]

Only way to find out is to remove each one and check to see if they squirt with a decent conical pattern into a glass jar.

Have you tried fresh fuel in the tank?

[scot]

Yeah i drained the old petrol and cranked the engine over with the fuel line disconnected from the injector rail to flush the old fuel through

[Speedtouch]

Another trick you could try is to spray some carb or brake cleaner down the throttle body intake then crank the engine over - this sometimes kicks them into life if they've been left standing for a while.

[HairyScreech]

If 1 and 6 are getting fuel but nothing else then i doubt its electrical as the injectors are batch fired. 1 common live and 1 common earth for each batch of 3.

a test trick is get an led the same resistance as the injectors and replace 1 injection with it. It should flash as the investors are pulsed.

I think this is moat likely to be a mechanical issue.

Have you checked to see if you have spark at each cylinder?
Have you checked to see if the crank sensor is functioning correctly?
A loss of crank signal will prevent start.

[Bally]

basic one are the injectors seated correctly, the clip can still go on even if ot fully pushed in.

[scot]

Just tried another 073 ecu courtesy of Mr Topless

No difference unfortunately.

Will take the injectors off tomorrow and give them a blast through.

How do i check the crank/flywheel sensors?

Thanks

[HairyScreech]

The simplest thing to do will be take a plug out, put it in the ht lead and rest the threads on the head, make sure you have good consistent spark.
Because no/intermittent spark and no/intermittent injection suggests a crank sensor issue as the ecu needs the crank sensor to know the engine is turning and to fire the plugs and injectors.
Does the rpm gauge move when turning the engine over?

If you search for info on the prefacelift or motronic 1.1 crank sensor then they are known to cause issues including the trigger peg falling out.

[HairyScreech]

Oh and sounds stupid but is your fuel pump running?
Wouldn't be the first time i have heard of what seems to be non firing investors only to find the fuel pump is out, the injectors are firing and there's no fuel pressure to let out.

[scot]

Not had chance to do anything this evening

BUT i forgot to mention i changed the gearbox and flywheel while the head was off...

The flywheel is a billet steel cnc job and has the tab added for the crank sensor.

Which part of the flywheel does the speed sensor read from? as i've noticed this flywheel has had all the metal engine side of the ring gear removed.

Heres a pic

[HairyScreech]

I,m not sure, however one does read the ring gear and the other reads the pin.
They also need to be the correct way around.
I have had little dealing with pf cars aol perhaps someone else can elaborate further.

[dubownerbilco]

this is still an issue which needs sorting as the car is sat in his garage getting dusty!

[scot]

Ok virtually all of the injectors were stuck! Inc the spare ones.

dubwonerbilco came over for some inspiration and to kick me up the butt and its solved

We did manage to get 3 of the injectors running ok with a home made injector cleaning kit (a battery and carb cleaner) but the other 3 had bad spray patterns. The engine ran but missing quite a bit as you'll hear on the video

Please excuse the jacked up hot rod rear end! It's got 60/40 Kw springs from my old facelift 325i which was obviously alot heavier! Anyone with some tech 1 springs of the same drop want to swap?



http://s434.beta.photobucket.com/user/c ... B.mp4.html