compiled by Steve Blackham
I had over 50 listees respond to my request. Thank You all!
"Have you had any problems with your FI system this year?"
Other comments (6)
Temp Sensor #2 (7): "Intermittant Misfire, rough idle, richness"
AFM (mostly contact plate) (7): "Misfiring or cutout at a particular range"
Aux Air Valve (2): "idle and starting problems"
Connector problems (4): "intermittant cut out and starting"
Cold Start (1)
Fuel Pump (1)
Double Relay (1)
Altitude Switch Label (1) "backwards" created richness problem
The fact that the temp sensor #2 was a trouble spot didn't surprise me but I didn't expect to have this many AFM contact plate problems. I guess 20 years of friction of the control arm swinging over the contact plate is predictable to cause failure. If you haven't found a good spare for the AFM maybe its time to be putting away alittle to send to Bus Depot for a new one ($150 up).
Notice that no one mentioned a problem with the ECU!
Almost without exception, everyone voiced satisfaction with their Bosch FI System. With a simple multi meter test most problems can be easily diagnosed and corrected.
Karl von Salzen mentioned that he replaces his Temp sensor #2 every year.
Karl says: " I don't change it once a year just to change it. I change it once a year because that seems to be it's lifespan! I consider it a maintenance item. At first I thought it was a AFM problem. I would swap with another and all the problems would go away for a week. Then they would come back so I would put my original AFM back on. Problems gone again for a few days/week. Replace the #3 temp sensor and the problems were gone. I haven't been able to explain the one year life span. The one I have in now has lasted almost 2 years so far. This one I put in dry after I cleaned the threads of anti-seize. I believe the anti-seize was insulating the threads and causing the sensor to read 'open'. This one also hasn't had the problem of loosening up on it's own once a month where I have to retighten it. Seemed like it was 'check the oil, check the tightness'. Now it stays tight."
I personally would worry about stripping the threads on the head with this much replacement so I'd recommend just testing the sensor regularly:
Put ohm meter contact between #13 and #17 ground. This tests the
Temperature sensor II. At 68 degrees it should be between
2000-2900 ohms. (700-1000 @122 degrees; 200-400 @ 176 degrees; and less than 200
at operating temp). Testing this at the Harness to ECU plug will
test whether there is a problem in the harness too.