Q. What is the ignition amplifier ?
A. It's the electronic control unit for the ignition system. It contains numerous electronic components (pcb board , chip , transistors etc.) sealed with rubbery/epoxy compound .
Q. What does it do ?
A. During the engine cranking , on Jetronic management the amplifier receives pulse signal from the distributor via magnetic pick up coil , or from the crank angle sensor and ECU on later Motronic management and uses this signal to open and close the ignition coil ground circuit , in order to fire up the spark plugs .
Q. Where is located ?
A. Inside the engine bay , on the aluminium plate on the LH side inner wing on early Ph1 and Ph1.5 cars , and on a small aluminium plate on the RH side next to the timing belt cover on later Ph2 cars (will add pics of both later ...)
Q. What are the symptoms of a bad ignition amplifier ?
A. Misfiring (usually in the mid rev range)
Hard starting from cold/hot
Symptoms are more common when the engine is fully warmed up to the operating temperature .
Q. Is there a difference in between ignition amplifiers for 1.6 and 1.9 engines ?
A. No , they're all the same and thus interchangeable . There is a difference in between new and old items with regards to pin numbers , the old amplifiers had 6 pins and new ones usually have 7 pins , but both of them work just fine (additional pin No7 is tacho out signal , and it's unused on 205 Jetronic/Motronic management)
Q. How can i replace it ?
A. Replacement is easy . Unbolt the battery negative terminal first , locate the amplifier , unplug the amplifier connector , use 7mm wrench or socket , unscrew the two front screws and discard the amplifier from the aluminium plate .
Important note : Whenever you attempt to change or disturb the ignition amplifier you must re-apply the thermal transfer paste/heat soak jelly at the back of the amplifier , as this protects the amplifier from overheating (when the amplifier overheats - it fails).
This paste/jelly can be bought in a computer store , any type of heat soak paste/jelly will do just fine ask for : silicone heat transfer compound , or PC CPU heat transfer paste .