running rough no idle
 

have an 80 928 here that starts but will not idle. it will rev up but i cannot put a load on the engine. have checked fuel pressure coolant sensor was replaced. i was thinking the air flow meter? what else could cause these symptoms.

Replace all old Vacuum Hoses. Go through all the Grounds and clean them. I used Maf Cleaner from the auto Parts Store and removed and cleaned mine.

Post Pics of your Engine.

Yes sounds like a Big Vacuum Leak Perhaps
Block off the Air going in to the Air Flow Meter ( Rag in your Hand ) Somewhat with motor running
If the motor starts running smoother that's a big sign of a Vacuum leak .
Trick:
with car outside run water Garden Hose on low ) over all Vacuum lines and look for the leak >
A Huge Leak will Evan Cause steam from the Exhaust from the water
It will not hurt the motor just don't spray the Electrical area's ( like the injector wires ) too much
You May have a Rubber Vacuum Boot broken or damaged like under the Air Flow Meter

what is the fuel pressure spec?

about 50 on the rail running

Just a guess. I have had a very rough running engine that would not idle when cold. I could keep it running by modulating the throttle. Once the engine got warmed up, the engine would idle and would take a load and run fine. After a little snooping, I found that one of the rubber sleeves that connect the main air distributor to the individual intake manifolds was cut. I heard an air leak coming from the connection. I pressed on the sleeves until I found one that caused the air leak noise to dissipate. I was able to loosen the clamps and move the sleeve slightly. That solved the problem. I eventually replaced all 8 of those sleeves. http://forums.pelicanparts.com/uploa...1318362498.jpg

mine is also ideling rough .... runs .. ok ish .... when it was ideling i sprayed iit w carb cleaner ... one of my rubber connectors and 2 of my intake gaskets are leaking, i have all new gaskets, conectors and fuel hose, going to go through it and replace everything ,,,,, that should work out a few of th bugs :)

Yup, all those suggestions is called an Intake Refresh. Remove your Spider and redo ALL the rubber hoses, couplers and Vacuum lines. Replace all the spider Gaskets. Run some Maf Cleaner Spray from the Auto Parts store while you have the Afm out.

Replace Spark Plugs, check your wires for cracks, same for the Cap(s).