mattipuh

I have currently some ignition issues.
Did the variocam pad maintenance in which I removed the cams + normal belt + waterpump job.

we assembled the cams with dial gauges, and assured that in #1TDC we got right amount of inlet lifter movement.

However, now when the car is set up, it runs only with 1st and 4th cylinders.
Have maintained injectors (thought they were stuck), new spark plugs, rotor, coil and distributor are quite new (replaced less than year ago), MAF 1.5 years old. Have checked 50x that spark plugs are in correct slots. Mechanically everything should be working.

symptoms are weird in that sense that I would think all four would be off.

What could be the culprit? Could the cam setup be wrong? IS there any adjustment with rotor in relation to cranks, so that spark would be fired in wrong place? Or can rotor be located only in one place? I think rotor position can be changed aswell, if cam bolt is loosen...?


Don't know exactly what to do, might need to re-check the cam position in relation to crank.

Lemming

Spark plugs wires are incorrectly installed. Don't ask me how I know

mattipuh

thanks for comment Lemming, this is what everybody says.
However, mine should be quite trivial because Bremi-distributor has numbers for each plug + wires have number to which cylinder they go. knowing numbers from 1-4 makes quite sure each plug goes to right place. I haven't tried setting them up agaist the numbering on distributor and wires, might of course do it, but sounds quite long shot.

actually, with old plugs the car ran with 1 and 4 cylinders, but now with new plugs it doesn't start. could car be so sensitive to the spark plug gap? I measured new plugs and they had 0.7. spec says 0.7 + 0.1, does this mean that gap should always be 0.8, or is it like tolerance 0.7-0.8?

mattipuh

In addition, tested with friends wires and got similar results a week back. 2 and 3 cyls were dead.

mattipuh

should the speedo be jumping aswell with 968 when starting, or is there some differencies in compared to 944's? Mine speedo is dead solid when starting, but 968 has the speed sensor in the tranny (based on which I presume the situation in my car does not necessarily mean any problems)?

tried with fresh DME relay, no difference.

mattipuh

thought of getting the ignition timing lamp to see if 1cyl plug actually fires spark when exhaust cam gear is at 1cyl TDC-mark. if it does, then there's problem with ignition hardware. if it does not, then the ignition timing setting is wrong.

RajDatta

If I remember correctly, the cylinders fire in pairs. Have you checked the speed/reference sensor behind the cam gear housing?
Did you confirm that your rotor is in the correct position in reference to TDC. Since it can go 3 seperate ways, you should make sure that the rotor is pointing in the right direction at tdc, as per the factory manual.

Krag50

#1 TDC we got the right amount of lift?? Inlet happens on the rotation before compression. True TDC is both valves closed on the number one cylinder for the compression stroke., there should'nt open valves. The manual doesn't describe this very well.

AaronR968

If the speedo is bouncing then my vote is for ref sensor. When my tensioner was done that was the culprit for my running issue.

mattipuh

speedo does not bounce, but rpm-meter does.
should the speedo bounce in 968? I understood speed is measured from abs?


found cracked distributor cap yesterday, tomorrow maybe new one in car and test to ignite, hope it'll start. rotor has been confirmed to be directing to right direction 1st. cyl is sparked at timing mark, or 1mm later than 1cyl TDC.

Vilhuer

Rotor should only mount in one way as holes and screws are not uniform distance from each other.

RajDatta

Never tested it but now you have my curiousity. I will give it a try to see if the rotor can only be installed in one position.
Raj

Lemming

I was not aware of this either?

MC 968CS

My tacho was flicking aggressively recently and engine was cutting out intermittently. We replaced the flywheel sensor which feeds the tacho, and it was fixed. Apparently - there is a cheaper BMW part number for that flywheel sensor, same sensor but longer wire. Bosch 026121000. Good luck

Vilhuer

Triangle hub piece is same part as in 32V 928 which means one of three threads is offset.