ECU Light Flashing, Lumpy When Cold, Down On Power

[anyone4apint]

Hi Guys,

I have a 172 cup and its making me pull my hair out.

If I don't drive it for a few days, when I turn it on it will be very lumpy. When driving down the road, power seems to be ok, and then just vanishes, then comes back. The check engine light will then flash a bit and turn itself off. If I give it some right foot, it feels really down on power. After about 2-3 mins everything is magically ok - power comes back, no engine lights, feels much smoother (although obviously not smooth as these things never are!).

I have done all the usual stuff recommended on the forums - changed the plugs, cleaned the TDC sensor and cleaned the throttle body. I have an ODB2 reader but its not logging any codes (I dont have access to a live readout one). I am drawing a bit of a blank now. It could be the lambda (is there two on the cup, one pre and one post cat?), possibly coil pack, but I dont want to go replacing parts at random.

Any ideas?

 

[haimsey]

I had this issue about this time last year, i changed plugs, cleaned sensors and tb. Then replaced coil pack and that cured it (for my car anyway).
Think the coil pack was reasonably cheap at euro car parts and comes with a garuntee too

 

[anyone4apint]

Thanks Haimsey.

I just fixed it. Hurrah. For some reason (like an idiot) I decided to carry on working on it at night as it was annoying me. After putting it all back together by torch light, I turned it on and it was idling rough still. Bloody annoying. However, in the dark of night I could see small flashes coming from under the inlet manifold.... the bloody HT Lead (number 1) was shorting on the block! Took the HT leads off and examined them all, low and behold number 1 had a small hole in it where it was shorting from. Some insulating tape later, boom, problem solved!

It has never run so smooth. I think all the work I did cleaning the throttle body, TDC sensor, etc were not the root of the issue - it was this bloody short the whole time. That said, cleaning them certainly has had its benefits as its never run smoother. I am a happy camper. I am also bloody relieved as I would NEVER have seen that in the daylight.