ignition timing issue - jumping

[ian o B]

Hi all. Hopeing somone might be able to shine some light on this issue.

While checking ignition timing using a timing light the flash was occuring before then after TDC. No movement of the distributor made any difference.

Its an spi so possibly sensor related just woundering has anyone seen this before? Timing itself is spot on.
Car runs ok until you accelerate hard which results in it cutting out for a second then coming back to rev as it should.

Tried differnt map sensor and relay box for the sake of it.
Willing to buy a diagnostic tool for spi/mpi if somone has one..

[woody]

Timing on an SPI is done via a crank sensor on the flywheel and ecu with the dizzy only being used to send the spark to the correct plug. There is an angle to set the dizzy at for maximun effect. The first thing to check on an SPi is always the condition of the vacumn hoses which must be 100%. A diagnostic check will tell you if the map sensor is functioning correctly.

[ian o B]

Thanks woody.
Have checked all vaccum hoses all are fine.