E30 320 missing under load

[l33-lsh]

Taken all leads out and spark plugs, they all seem to be sparking and look in okay condition..?

[johnono]

Put a starter cable from the hanger on the block to the damper strut mount / ground and see if it helps ;)

[l33-lsh]

So just an earth from the block to the earth on top of the suspension mount.

[johnono]

Yep, it might help

[l33-lsh]

No difference a˜a

[parkin10]

I had a miss fire I could not cure on my 325
tuned out to be the rota arm which looked good but the spark was arking out on the end of the cam shaft right though the arm its self!
I could just see the smallest blue speck on the under side of the arm
I only saw it by chance
new bosch arm put that right

[l33-lsh]

Ok will try new arm. I put new plugs on just to see as they were due a change. I drove up the road fine and then give it a little bit of boot and then it started again.

[parkin10]

don't just buy an arm for the sake of it
make sure theres some thing wrong with it first
there not cheap from bosch and I wouldn't buy a cheap copy

[l33-lsh]

All seem to be sparking, I've taken all leads and plugs out and sat them ontop of the rocker.

Took the new plugs out that I've been running for couple of days and cylinder 6 is wet and black. Not too bad tho.

[l33-lsh]

Also just add on first start up from cold it's seems fine then rev it a few time then it starts missing.

[Brianmoooore]

Also just add on first start up from cold it's seems fine then rev it a few time then it starts missing.

That makes a considerable difference to the diagnosis! Beginning to look like a C191 or blue temp. sensor problem.
What age is the car?

[l33-lsh]

It's a 89 318 shell and previous buyer put a 320 in it.

[Brianmoooore]

Any idea on the age of this M20B20? 2 litre came with a range of management systems, depending on age, ranging from positively pre historic to relatively modern. Engine ECU type number would help.

[l33-lsh]

I've just changed the blue plug for a new 1 ad made no difference. Been under intake manifold ad found that c191 connector and moved it about and it revved better.

[Brianmoooore]

If you have a C191, then you must have a later engine, not the ancient stuff.
C191 problems are much more common than a fault with the sensor itself, so TEST FIRST.
You'll probably find that the wires in the lower half of the C191 have rotted through.

[l33-lsh]

Had the loom out to strip the c191 wires, all back in and no spark can't think that I've done anything wrong. God that's pi*sed me off.

[Brianmoooore]

C191 has nothing to do with sparks. How many other things did you disturb/remove to get at the C191?

[l33-lsh]

Whole loom out to ecu as I wants to test continuity from ecu and the wires were corroded so needed a good going over.The c191 was defiantly faulty as when I moved the original wires it was missing and then move it again it was fine.

[Brianmoooore]

Check that there is power at the ignition coil + terminal when the ignition is on, by connecting a 12 volt bulb of at least 5W between this terminal and body earth.

[l33-lsh]

I have a screwdriver with a bulb in it and a earth lead. Connected earth clip on the battery and positive end on the + on the coil and it lit up

[Brianmoooore]

Far from a 100% reliable result, but a 1000 times better than testing with a meter! We'll assume that ignition switched power is getting through.
If you've had the whole loom out, are you sure you've connected the two three pin rectangular plugs under the diagnostic socket the right way around?
Are you sure you've fitted the two relays under the cover on the inner wing by the air meter in their correct sockets?

[l33-lsh]

Which is the right way around on those 2 plugs.
How can I test those relays?

[l33-lsh]

Bump

[Brianmoooore]

Signal wire of the crank sensor socket goes to pin 48 of the ECU, and from the cylinder ident. socket goes to pin 31.
Relays are unlikely to be faulty - you have to check that they are in the right sockets.
Unclip the sockets and check the wiring to them. Only one socket has any wires to the centre pin, so this is where the five pin DME relay goes.
The four pin relay is for the fuel pump, and this plugs into the socket which has a green/purple wire going to pin 87.
Other relay socket is empty on most E30s.

[Osamam3]

Brian you are a good man and quite helpful, don't change.

[l33-lsh]

Ok cheers. Will check to tomorrow. Another look over the car, the distributor cap looks pitted on the brass points so I'm changing that and rotar arm. Just seems strange now I've took loom out is packed up. Everything is common sense and you can't get anything wrong expect from those 2 plugs. If it plays me up it will be megasquirt

[l33-lsh]

Tried new rotar arm ad dizzy cap. And those plugs I've tried both way round( the 2 plugs that is possible to get the wrong way around near the air filter)still no spark!

[Brianmoooore]

Disconnect the connector to the crank position sensor again, and measure the resistance of the sensor's coil (measure between the two pins of the plug closest to the lead).
Should be about 540 ohms.

[l33-lsh]

Ok will try tonight. Just a tad weird after the looms been out now it's not working. The loom is so simple on these motors

[Speedtouch]

Perhaps try a replacement loom?

[l33-lsh]

507ohms at crank position sensor

[l33-lsh]

Bump

[l33-lsh]

Bump

[Speedtouch]

You still haven't told us which ECU you have, e.g., is it an 0 261 200 172?

The later 0 261 200 381 type were reknowned for blowing diodes in the idle control circuit, which may have something to do with your problem...

Missing under load may be down to an inlet manifold gasket leak - try spraying WD40 around it at idle, and if it briefly raises the idle speed then you have a leak. Also check all rubber hoses around the injection system, as any splits will also cause such issues.