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Whats this thing do?....(with pic)

2K views 9 replies 5 participants last post by  Brent79 
#1 ·
Ok, I have been having a problem with my 88 Spac MPFI.
In the morning when the engine is cold, the engine turns for a good few seconds before it starts, then when it does, it shudders and bangs like hell, untill it is warmed up a bit.
Also it feels a little down on power, and uses a bit more fuel than usual.
I had the timing checked, its spot on. I'm thinking my best bet is to take the thing to UltraTune or something, and get them to check it over.
Whilst I was under the lid, I noticed this thing (see picture), it looks like some kind of resistor or something, is this right? Its the green and yellow thing, located right behind the engine, Anyway, on the bottom of it, its all melted, like it overheated or blown. Could this be causing any kind of problem?

Thanks :)

David
 

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#2 ·
Resistor

I dont know exactly why its there, but i think its to prevent overloading of the battery. It connects between the starter circuit and ground.

Brent
 
#3 ·
I think that it's a diode. These things only allow current to flow one way. Is that a hole on the bottom? If so, I,d replace it.

Find out which circuit it controls because there may be a bigger problem. These things don,t blow unless something is wired up wrongor short circuit.
 
#4 ·
Ive just been reading about it and image is correct...
It is a diode howver there should be 2 of these things one blue and one green/yellow - one is a resistor and the other a diode.
They connect in series between starter circuit and ground.. They are inplace to stabilize the groud circuit.

Brent
 
#5 ·
The diode is wired in againt the normal flow of current from the battery:

Battery(+)------/\/\/\/\/-------|<------(-)ground

This configuration is supposed to protect the electrical system from ground shorts and to feed and currect back to the batt.

Brent
 
#7 ·
no.. its there to stop back EMF from the starter motor solenoid (or the starter itself, perhaps) from spikeing and damaging electronic devices in your car. the diode clamps the spike, which is a current in the opposite direction of the one applied to the coil - hence its reverse direction. these circuits are very common, but i didnt realise there was one in the car!
 
#8 ·
Thanks for the replies and info guys!

Well, I figured out what was causing the banging!!!
The bloody passenger side engine mount had lost ALL 3 BOLTS!!! and the mount is broken as a result.....the engine was resting on the Oil Pressure Sensor!!! Thats why the bloody gauge stopped working!!!
Could have been VERY serious if I hadn't found the problem!
Also, my gerabox was vibrating when Reverse wasa selected (auto) and has not stopped, must have been cause the whole lot was out of alignment or sumfin!
Ok, so those diode and resistor things aren't SERIOUS or anything, I can just replace the blown one when i get time?

Thanks again
David
 
#10 ·
Ahhh yes, that would be about right jason!

Brent
 
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