Bosch Motronic problem

[Todd Knighton]

Don Irwin wrote:
> 
> Car had low compression and was difficult to start and not v. performant.
> Changing  piston rings without any difficulty but since then it will not
> run for more than a couple of seconds.  Starts well but quickly dies - as it does
> so I hear the Air Flow Meter (AFM) flap dropping back and the fuel pump cutting
> out.
> The AFM has been checked by a Bosch agent - he says its ok .
> The ECU can only be tested on the car and Bosch say it rarely fails. As its
> not running cannot get it to a garage !
> The temp sensor (adjacent to the injectors) is ok (say Bosch ) altho if
> I disconnect this the car will run (unevenly) for ~ 30 secs before cutting out .
> When cranking the engine all injectors deliver fuel .

	Sounds to me like a pretty good sized vacuum leak.  The car will start
because the system injects a precalibrated amount of fuel into the
thing, regardless of what the afm says.  It dies, cause there is not
enough airflow by the afm to give the system fuel.
	The thing will run with the water/cylinder head temp sensor, because
that will give an overly rich condition.  The thing thinks it's -30F out
or something.
	Check for a missing line, or split boot, or something like that.
	
Todd Knighton
Protomotive Engineering