4age ignition problem - v. strange

[78Rolla]

Alright guys - I'm putting it out there...its been playing up on me for a while, and i thought any ideas might help.

Here's the story - I've got a '78 KE30 corolla with a late model 86kw 4age engine in it. Ever since i've had it running its been randomly starting up out of time. But as soon as i hear it running retard, i turn it off and start it up again - normally this fixes it and it runs fine. Sometime it might need 4or 5 restarts to get it to work properly. This almost happens everytime.

I've checked the grounds in the loom, on the block and the battery and they seem fine. It seems like an interference issue, but im not sure. Any suggestions as to what the cause or solution might be? Has this happened to anyone else?

[Vios-GT_07]

hm.. sticky valves? also could be electronic, like a plug wire, coil or spark plug needs a check..?

[78Rolla]

Don't think its sticky valves cause when it runs correctly, it seems fine...could be electric, The coil seems to be working fine - but aside from replacing the leads (which is costly) i haven't tested those either. But i wouldn't expect them to cause the problem randomly...but im not ruling anything out yet!

[Cuzzo]

Dizzy isnt loose and moving on start? or the ecu is adjusting the timing because its getting false readings from maybe a faulty sensor?

What have you checked out so far?

[The Witzl]

have you chucked on a timing light to confirm it's running retarded when it's doing this random thing?

There could be something else at play here - it pays to eliminate other possible causes first.

[allencr]

its been randomly starting up out of time. But as soon as i hear it running retard, i turn it off and start it up again

First, that is pretty much Impossible with electronic ignition, so it has to be something else, unless you put in a mechanical advance distrib. that's sticking.

Bad plug, plug wire, injector.

[TooF]

could it be a dodgy brothers CAS/dizzy unit causing the ecu to think the engine is in a different part of the cycle then it actually is ?

get a timing light out there and check where the timing is first, if the CAS is playing silly buggers then the timing should be all over the shop

[78Rolla]

cuzzo - Dizzy aint loose.

Witzl - I've checked the timing with the timing light, and it runs way out - like 10deg retarded! Its just a stock ecu.

allencr - Because it only happens on ignition, i narrowed it down to ignition related things like the coil, ignitor, dizzy and leads. so i can't see it being related to the injector in any way.

Toof - I'm leaning towards the CAS being the problem at the moment.

I've replaced the ignitor and that did nothing, i have a feeling it could be the sender unit in the dizzy playing up. That would cause the random part and stuff around with the timing. I'll have to get the pro's to check it out soon...

[78Rolla]

Well - the electronic pick up in the dizzy tested fine, however the spark plug leads look to be a bit neglected. I'll get these fixed and hopefully this helps.

It could be an interference problem effecting the ecu, caused by the bad leads ...
fingers crossed.

[78Rolla]

Still got the same problem...

What about the ECU? There's no DTC coming up. I thought the ECUs were pretty tough...otherwise it looks like it could be interference from something.

[maddog]

can you borrow a "known to be good "dizzy from someone and test with it? same with ecu.

[tooch]

Tim, you checked the easy shit like the dizzy cap and rotor, make sure there's no cracks or carbon tracks in them that's making it arc internally?

Shame I don't still have the AE82, we could just swap the dizzy and ECU out to test

[78Rolla]

yep checked all the easy things, the dizzy is in good condition - i had it tested anyway, there aint anything wrong with it. I'm now thinking its looking more like an interference problem, although i want to get the ecu checked just to rule out anything thats a variable...if the ecu is fine, its just a matter of checking to see no wires are close together that shouldn't be!

[tooch]

yep checked all the easy things, the dizzy is in good condition - i had it tested anyway, there aint anything wrong with it. I'm now thinking its looking more like an interference problem, although i want to get the ecu checked just to rule out anything thats a variable...if the ecu is fine, its just a matter of checking to see no wires are close together that shouldn't be!

Good luck, electrical problems suck balls!

[78Rolla]

tell me about it!

Anyone know how much i should be getting charged to have the ECU tested? I got quoted $100 off one place....