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engine stall, miss. Retarded to death[200/82] posted by Lawrence on
Saturday, 29 January 2000, at 10:33 a.m.
Greetings,
The problem with my daughters car turned out to be a faulty hall
effect switch. The symptoms: The car would start and run fine. when i raised the engine rpms it would begin to miss. After the car got nice and warm it started to sputter and it would eventually die. once it cooled off
it would start and run. Until it got nice and warm and...
Now I remember that I didnt have the engine miss at first. I caused
the miss. What did I do. Well, I put a borg warner ignition coil on it.
I got it from pepboys!. Replacing it with a volvo coil made the miss go away! Draw your own conclusions.
In trying to solve the stalling problem I was watching the ignition
with my timing light. The ignition appeared strong. I did notice this:
as the engine ran worse and worse the timing retarded, off the scale.
Replacing the hall effect switch solved the problem.
Id appreciate very much if someone could explain, in laymans terms,
how that switch failed . My engine was retarded to death? Yuk!
I also found a psychotic temp sensor.
Also my hats off to the guys and gals at Sacramento Volvo service(svs) in Sacramento, Ca. Once again they saved the day. Friendly, courteous, and expert service. They even washed and vacuumed the car!
Also thanks to all the guys and gals on this board who provided input. Thanks for taking the time.
Lawrence
Re: engine stall, miss. Retarded to death[200/82] posted by abe crombie on
Saturday, 29 January 2000, at 11:45 a.m.
The ignition ECU gets a digital signal from hall switch. The signal is a nominal 5V out of ignition ECU that is grounded by Hall Switch to drop it to approx 0V making this digital signal. The 5V to 0V drop indicates one crank position (something like 110 degrees BTDC) and the return to 5V indicates another crank position has been passed (60 degrees BTDC ?). The ignition ECU determines not only that the crank is at a certain position but also how fast the engine is turning from the time between these two points. These two items are needed for the computation of when the ignition ECU will stop the ground of coil causing spark discharge.
If the Hall switch has a bad internal transistor then the period of ground may be affected and not give a clean 0V to 5V signal but rather a 0V ramping back to the 5V level. The ignition ecu in this case will go to a more or less fixed calculation based solely on the first 5V to 0V drop. The ignition timing will be more or less fixed at 6 deg BTDC (Assuming a base setting of 12 deg BTDC).
Re: engine stall, miss. Retarded to death[200/82] posted by Lawrence on
Saturday, 29 January 2000, at 9:18 p.m.
Greetings,
Thanks for the response.
But Im still a little bumfuzzled. Normally my car is set at 12deg
BTDC , but when it started to malfuction really bad, it retarded to something like 15 deg ATDC, maybe more. It was pass 0 DEG way off the scale. The car stopped running!
Isnt 6 DEG BTDC like a limp mode that would enable you get home, or at least off the road ?
What would cause the timing to act in this manner .
THANKS
--Lawrence
Re: engine stall, miss. Retarded to death[200/82] posted by abe crombie on
Sunday, 30 January 2000, at 2:06 a.m.
The failure of your hall switch may have caused it to delay the initial 5V drop to 0V. In this case the limp home timing is a product of a calculation based on that event which might put timing most anywhere.