Sudden idle drop and stall
 

I have just finished my DIY turbo build. I have a 91 1.6 running a Saab T25 turbo and BEGI rising rate FPR running at 5psi.(not fine tuned the FPR yet). When car was cold, engine idled fine during first start up. Once warmed, I turned off for approx 30 min whilst I got the timing light together to retard ignition.
When I restarted, the engine would barely keep a 500rpm idle and that was with the idle screw maxed out. I hadn't touched a thing since starting it cold and am now stumped and frustrated that the car wont hold a decent idle.
Any help would be much appreciated.
Cheers, Andy

Lots of things come to mind: vacuum leak, CAS is way off, screwed up air flow meter...

Thanks for your response. I dont think its the CAS or vacuum leak as I hadnt touched a thing in the engine bay. I cant see how the flow meter could get screwed up either in the space of 30 minutes?

timing belt skipped a tooth?

what does afr read, timing

OK, I found my problem, I had a vacuum leak on the plastic cross over pipe leading to the intake manifold. I did recall inadvertantly knocking it but didnt realise it had cracked. I had a hole about 1cm in diameter. I have sealed the hole and the car now idles properly again. My issue now though is that I cant find the broken piece of plastic and think now it has been sucked into the intake manifold. I have removed the cross over pipe and it is not there so I now believe it must be lodged deep in the intake manifold .

Can someone tell me what will happen to this plastic piece if I dont strip the intake and remove it or will there be some sort of secondary filter system to stop the plastic chip from doing any damage?!

There's no secondary filter. Engine would go nom nom on plastic.