KE70 ignition problem

[J0RD0]

Hi all,

My little corolla is having some issues which is driving me nuts because i cant seem to figure it out.

Car details -
84 ke70
135 000 ks
motor stock 4k

The problem -
well i picked the car up a couple of months ago and apart from this little ignition problem the car is in perfect running order. The problem is that once the car get to operating temperature when stopped at the lights it all of a sudden it feels as if its running on 3 cylinders, the car shakes and shuders but it doesnt actually stall.

Since i bought the car i have converted it from auto to manual and replaced plugs, leads, dizzy rotor button, dizzy cap, the coil with a 2nd hand one and had the points re-gapped and had timing checked. All new parts were replaced separately one at a time and it still the problem occurs. I have had the car running when it starts to idle bad and taken the leads off one by one to see if it is a particular cylinder thats not getting spark. Each lead pulled off made it even worse so it was no particular cylinder.

The car doesnt always do it at every set of lights, id say it happens 75% of the lights i pull up at every day. Another thing is that if you start the car and let it warm up the problem wont actually occur unless you take the car out for a 5 minute before it start to happen so i think it may be a heat related problem.

I havent done a compression test but the motor is running fairly healthy with an average of 550km to a tank which is normal and has always been run on bp ultimate.

Any suggestions or pointers as to what you may think it is? Did i miss something to replace?

any help would be appreciated!

[spoon]

try changing the setting of the warm up lever which i think is under the air cleaner, from winter to summer - stop a bit of heat entering the airbox, may help a bit...

have you checked the timing - maybe causing the engine to run too hot

[KENut]

I'd try changing the coil again.

Mine had an issue where the needle valve in the carby would stick open once it got hot, but you're getting heaps more kms/tank than I was. Might be worth looking at.

Also, is there a filter between the pump and carby? Check under the needle and seat, stock they have a little filter in there, but if not bits of rubber from the pump and lines get into the carby, even with 'good' fuel like bp ultimate

[Dazza]

I would be checking to see if the ignition timing stays steady at idle. It is common for the springs in the mechanical advance mechanism of the distributor to stretch or break which will let the timing move all over the place at idle but as the revs are increased the timing will stay steady and advance only as revs increase like normal.
Another thing to check would be the carby. If the butterfly of the second barrel doesn't close completely when you lift your foot off the throttle, your engine will run lean at idle. The throttle shafts could be a bit sticky. All you need to do is give the throttle shafts a squirt of CRC or WD40 or something similar and open and close the throttle shafts by hand a few times to work the CRC in.
It could also be a small vacuum leak at the base of the carby or manifold gasket and it could also be a leaking PCV valve in the rocker cover.

[oldeskewltoy]

I too recommend looking @ the distributor... but I'd check it with a dwell meter attached. What you are checking for is any change in the dwell angle. Result could be worn distributor bushing allowing side ways movement in the shaft

[oldcorollas]

bit of crap floating aoudn in the carby, or partially stuck in the idle jet passages?
have you tried altering the idle mixture screw while the engine is hot?