Electrical system causes misfire?

[TXcoyote]

Russ from across the pond here. Just finished my Rover V8 conversion on my 280i and had to sort through several FI issues. I had alot of bad surging initially at around 3k on the rev counter. Redid the injectors, whiich helped a little, replaced the air bypass valve which also helped a little. )2 sensors are fine and the ECU is fine (I have 2 and it goes the same). I just replaced the coil and TPS and all of a sudden it stopped stumbling.......... until I took it for a ride with the lights on! My guess is that the alternator cannot handle the increased load resulting in a weak spark. Any other thoughts?

[chedder]

Hi Russ, try relacing the ignition amplifier on the side of the distributor, these can cause all sorts of strange problems when they start to fail.

[P100]

try disconnecting your alternater and running the car with it disconnected, but make sure that the battery is good first.

I have come across some alternaters with a bad AC pack that interfers with the engine ecu at certain revs and causes interference.

This causes all kinds of faults, misfires and problems.

Hope this helps

Roy

[adam quantrill]

How does it drive, anyway?

[TXcoyote]

I should probably mention that I am still using the alternator from the V6 which has about 10 amps less charging power. I was thinking of what the alternatives might be other than the Lucas unit spec'd in Steve Heath's Wedge Bible.

Adam, runs like a scalded dog! especially with the Crower cam, lightened flywheel and T-5. It will be featured in the January edition of the US TVR club magazine.

[adam quantrill]

Result! Bet it sounds much better too (misfires notwithstanding)!

[TXcoyote]

adam quantrill said:

Result! Bet it sounds much better too (misfires notwithstanding)!

Snarling is the best way to describe it.

Chedder, I have a replacement amplifier but it has spade connectors and the original one has a plug. Any wiring diagrams available for it?

New Alternator arrives tomorrow so between those two hopefully problem will be solved.

[TXcoyote]

Problem fixed! Actually both prolems fixed! I replaced the alternator as I was having several shaky charging issues but the surging/misfires remained. Then I replaced the ignition amplifier, and all of a sudden the problems disappeared. Thanks for the advice fellas. Now everything is new and running sweet!