V8 converted to Bosch Ignition - Bad Fuel Consumption

**Rezley** · 21st October 2010, 09:31 PM

Hi All,

Have completed the Lucas to Bosch ignition conversion as per bee uteys instruction (thank you, very helpful) and whilst I think it may be running slightly smoother my fuel consumption via the gauge has increased alot.

I've so far managed 230kms from 3/4 tank. Normally I'd have achieved over 300km by this point.

I did notice revs at idle drop off and pick up at the traffic lights today but no missing under load or loss of power.

Where should I be looking first? I haven't checked the plugs yet but plan to and swap coil out for a spare I have. Any other ideas?

This could all be totally unrealted to igintion conversion but has just happened since.

Thanks,
Rez

**BigJon** · 21st October 2010, 10:43 PM

Did you check ignition timing after modification?

**Rezley** · 22nd October 2010, 06:13 AM

No,
I figured it wouldn't have changed since the dizzy wasnt touched?

Rez

**bee utey** · 22nd October 2010, 08:20 AM

Please, check the timing with a light. The pick-up senses the point of firing slightly differently as the Bosch amp triggers at a slightly higher voltage. So extra advance of around 5 degrees may be needed. Aim for around 6 to 10 degrees BTDC at idle.

**Rezley** · 22nd October 2010, 03:22 PM

Originally Posted by bee utey

Please, check the timing with a light. The pick-up senses the point of firing slightly differently as the Bosch amp triggers at a slightly higher voltage. So extra advance of around 5 degrees may be needed. Aim for around 6 to 10 degrees BTDC at idle.

Cheers Bee Utey, will get timing light onto it and sort it out.

Rez

**BigJon** · 22nd October 2010, 03:41 PM

I think I will put this conversion on my to do list for next week when I am at home. The current ignition system seems to be working OK, but it could always be better.

**Rezley** · 24th October 2010, 07:26 PM

Originally Posted by bee utey

Please, check the timing with a light. The pick-up senses the point of firing slightly differently as the Bosch amp triggers at a slightly higher voltage. So extra advance of around 5 degrees may be needed. Aim for around 6 to 10 degrees BTDC at idle.

Ok, put timing light on it tonight. It's sitting on 6 degrees BTDC.

Any further suggestions?
Should I swap out the coil? I did use an old one from a Camira...

Rez

**bee utey** · 24th October 2010, 09:15 PM

I have around 1 in 10 failure of the Camira coil but when they fail they hardly run at all. Smooth running indicates wrong timing or somewhat rich mixture usually. Try another coil perhaps but it's a low possibility.

It might still be timing, check your TDC mark from no.1 plug hole. I have just purchased a ducky tool for this purpose off a forumite, it consists of an old plug body with a piece of clear hose attached. You dip the end of the hose in a tin of light oil and mark the oil level in the hose at about 10 degrees BTDC and aim for the middle between there and the same oil level ADTC.

**Rezley** · 25th October 2010, 08:20 PM

I've bumped timing up to 10 BTDC and cleaned out IAC. Will see how the second half of this tank goes.

Is MAF a possiblilty?

Rez

**bee utey** · 25th October 2010, 08:54 PM

While you are under the bonnet check the temp sensor for the injection, that's the one with a two wire plug. It's supposed to read 180 ohms (?) or so across the two terminals, with the engine warm.

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