[urq] Ideas for rough running continued

[Ingo Rautenberg]

OK, fuel pressures check out - system ~90 PSI regulated after warmup 55 PSI. 
What's been replaced so far with known goods: ECU, idle valve, fuel distributor, warm up regulator.  
Fuel flow test 18 seconds 750 ml. Vacuum feed directly from back of IM to ECU.
Fuel pump jumpered to run when ignition on regardless.

Ongoing symptoms:

low (600-650 rpm) idle (rough)

When proper duty cycle 45-55% adjustment is made (frequency valve buzzing), car will make it out of the driveway (steep) and then up a not-so-steep (10-15 degree) incline 200 ft and then stalls and won't restart.  Fuel pressures unchanged.  Roll down backwards into driveway (or not), turn CO adjustment two to two and a half turns to the right and car starts (every time -- but won't idle).  Still runs funny and duty cycle now 5%.  

So, I'm thinking replace airflow meter (have feeling it's sticking) or does this also sound like it could be a clogged exhaust?  What throws me is that I can consistently turn the CO screw to richen the mixture after stalling and it will start (but not idle).  Still stumbles, though.  And the soot out the back is black/gray.  I was thinking crank/flywheel position sensor might be intermittent (wouldn't that suck), but doesn't explain being able to start the car when enriching mixture.  Also, have tendency to have backfires through air meter...

Ingo (still mit ailing '84 Urq and WX motor)


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