Weird firing problem

[whatthe?]

Went off to the drags tonight, finished a run and noticed that my car sounded like it was running on 5 cylinders. Took it home and unplugged each lead from the coil pack, every one made a difference to the idle. Checked the plugs, all fine. The car also has developed a starter motor rythym similar to a car with really bad timing, sort of turns over slowly once then 3 quick turns than another slow one etc.
By these symptoms is it likely Ive slipped a tooth on the timing belt? cant think of anyhting else......

[Cruiser97_80]

Could be a BHG, remove your spark plugs and have a look at them.

[whatthe?]

doesnt overheat, plugs look fine. If it was BHG causing loss of compression I'd expect removing the spark lead from the offending cylinder to make little or no difference to idle (same for rooted rings or stuck/ burnt valve). Removing any spark lead from the engine at idle makes it worse.

[Cruiser97_80]

yeah it just that i have had cars with only mild bhg problem that still idle smooth till you get it under load was just a thaught

[whatthe?]

Nah, sounds crap at idle too . Doesnt get any better or worse through the rev range. Thanks for the suggestion though

[whatthe?]

Hrm, the plot thickens.... stuck a long screwdriver in cylinder 1, turned the engine by hand to TDC according to screwdriver, and it matched up with timing marks on timing cover and crank pulley. so far so good. Took off the top timing cover, marks on cam gears line up as well. Now I'm stumped. Compression test next i guess, as everything appears to be where it should be....
If compression proves to be ok, whats my next port of call? Could a dead CAS cause this? I wouldnt have thought it'd be able to cause an irregular starter motor tempo such as I have

[Hydra]

I've seen this before after letting some others have a quick play with my car (which means a fair few revs!). It went away soon after for me. I concluded that it's a fuelling problem but I have nothing to base that on. It still drove ok.

Tried dropping power to the ECU to "reset" it?

[whatthe?]

Not yet, but that doesnt really explain the weird cranking problem does it?

[ViPeR_NiPPleX]

got a wideband o2 meter? could be an injector not firing or sticking open a bit ?

[Hydra]

No, not really. That itself is very odd.

But in a way it might? The ECU determins the timing from the CAS, which might explain the the cranking/idling. If the ECU is playing silly buggers then it might give that effect. I've never played with a 7M though so I am just putting ideas forward

[whatthe?]

got a wideband o2 meter? could be an injector not firing or sticking open a bit ?

Injectors are all reading 12v so theyre getting power. Cant really check whether theyre grounding by myself though. Dont have a wideband 02 handy unforunately. Once again it's the irregular cranking that makes me think it isnt fuel delivery related

[whatthe?]

No, not really. That itself is very odd.

But in a way it might? The ECU determins the timing from the CAS, which might explain the the cranking/idling. If the ECU is playing silly buggers then it might give that effect. I've never played with a 7M though so I am just putting ideas forward

Hey, I'll give anything a shot. Might chuck another CAS in too to strike that off the list as well

[LeeRoy]

Are you doing this in real-time so to speak?

[whatthe?]

Yep, although I just did something dumb and think I rooted my starter motor so it may be bed time

[oldcorollas]

tried putting a timing light on it? are the timing marks on the crank pulley? can the CAS slip out of adjustment?

could try unclipping injectors one at a time and see if they all make a difference to rpm?