The V8 Owners Forum -

anyone modded a rv8 dizzy to act as a cam sensor???

Looking at running mine fully sequential now to help with the bigger injectors and help with the hot start issues we have been seeing,

The hot start has now been put down to injector timing,

Any good Tony looking at doing this route over the winter when I convert to TB's with my MS2, the 2nd pic is a sensor from the states Buick IIRC

Here's my take on it using an Allegro two wire gear tooth sensor I already had a few of. Only hand tools needed and no welding.

Coops wrote:anyone modded a rv8 dizzy to act as a cam sensor???

Looking at running mine fully sequential now to help with the bigger injectors and help with the hot start issues we have been seeing,

The hot start has now been put down to injector timing,

What size injectors are you using ?

Biggest I ran batch fire were 750's and had no problems, although my engine is a bit larger.

With batch fire, injector timing should be irrelevant, as it is never timed to specific valve openings...simply as it cannot be
I'd be very surprised if injection timing is in any way part of a starting problem even when you do get it running sequential.

And it should be easy to use any electronic dizzy. A lot of ecu's prefer a single tooth trigger, so just grind off all teeth except one off the trigger inside the dizzy. And weld up or secure the advance mech so it cannot work.
OEM RV8 dizzy uses a 2 wire magnetic pickup from what I can remember

Although the latter itself shouldnt be critical either. There's a fairly large window of operation for a single tooth phase trigger and the position used will still be correct as far as telling the ecu where cyl 1 is.

Thing with just modifying a standard dizzy trigger is that you'd still need to use the cap - as making a custom cover would be quite a job.

DaveEFI wrote:Thing with just modifying a standard dizzy trigger is that you'd still need to use the cap - as making a custom cover would be quite a job.

Exactly, it will cost nothing to do, and its very easy

I'd say it would look odd - a complete dizzy with no plug leads?

DaveEFI wrote:I'd say it would look odd - a complete dizzy with no plug leads?

It would look free and it works.

If you wanted to put some leads in it, you could and route them to headlights etc...just to confuse people

car starts fine hot and cold Stevie.
it goes mega lean when hot after been stood, been doing testing with Dale etc and its down to the injector timing,
so by telling the ecu where no1 is etc we can tell the injectors when to fire,

by setting the ecu to 2 squirts on simultaneous on hot start goes lean then the correction brings it back as it should, so hence why they know its an injector timing issue, and why it looks like its going fully sequen,

oh 440cc injectors which dale said also are not helping as too big, which surprised me lol,

Simplesimon that one looks interesting

Coops wrote:car starts fine hot and cold Stevie.
it goes mega lean when hot after been stood, been doing testing with Dale etc and its down to the injector timing,
so by telling the ecu where no1 is etc we can tell the injectors when to fire,

by setting the ecu to 2 squirts on simultaneous on hot start goes lean then the correction brings it back as it should, so hence why they know its an injector timing issue, and why it looks like its going fully sequen,

oh 440cc injectors which dale said also are not helping as too big, which surprised me lol,

Simplesimon that one looks interesting

Again different people will come to different conclusions

But I can say with confidence any starting issue you have is not down to injection timing, as again with batch fire you have no control over this.
I've ran mine batch for for 13 years and never had issues, I only switched to sequential last year.

Likewise I had the 440's with my RV8, and never once had any problems from the 3.9 and thru the 4.6 variants I used. Always batch fire, never an issue starting hot or cold, nor ever any problems with emissions or driveability which is where large injectors can annoy....but really, most modern injectors these days are very good anyway
The 440 injectors are by no means big.

By all means add a phase trigger for sequential, and this may improve running in some areas slightly.
But there is nothing with your setup in batch fire that should be posing any problem at all.

If it goes mega lean when hot....what is hot ? Some MS guys seem to be obsessive about air temp compensations, which often due to sensor heat soak which is hard to avoid sometimes with sensor placements, standard laws of physics type compensations they they think are needed...really arent needed or wanted at all and often contribute to bad running simply because the readings are false.

Have had 2 different people say its injector timing mate so they tune them for a living so take there word for it,


Regarding the dizzy as a sensor, is anyone making these that you posted Simplesimon???

Here you go Stevie:

https://www.youtube.com/watch?v=5Ie47Bfgbb8

car runs fine from cold right up to temp as it should,
leave car for about 30mins come back and it does this in the video,
power cycle the WBO2 does nothing, power cycle the whole ecu and it cures the lean afterstart issue when hot,

Coops wrote:Have had 2 different people say its injector timing mate so they tune them for a living so take there word for it,


Regarding the dizzy as a sensor, is anyone making these that you posted Simplesimon???

As said, different people will come to different conclusions or come up with ideas they think cause a problem because they maybe dont understand. Some will be right, many will be wrong.

Whether someone does something for a living or not, doesnt mean they are always correct.

The fact it is batch fire and millions of other cars are batch fire with zero problems....your problems simply cannot be injection timing related.


If you have an electronic dizzy it would only take an hour to modify it for a trigger for the ecu with zero cost. Try it first before going nuts spending money then you can look into different solutions once that is up and running.

There are no downsides to running sequential anyway, so go for it.

Interesting vid. My thoughts are that if it truly was 19:1 AFR, the engine wouldn't idle at all.
So IMHO it's more likely to be a problem with either the WB unit or the MS WB input (or of course a software glitch with MS reading the data incorrectly)

Have you got or can borrow a reader for the WB unit? Or alternately, check the voltage at the MS input. It;s usually a 1-5 volt signal or so, and a change from 19:1 to 14:1 would be easy to see. If you've not got one, a JB perfromance breakout board makes intercepting signals to and from an MS easy.

http://jbperf.com/signal_interceptor/index.html

So basically, I don't think your engine is actually running as weak as indicated.

FWIW I've also got a bit of a problem with running for some time after a hot re-start. It also runs weak - about 15.5:1 variable until under the bonnet cools down a bit. It starts ok so cranking fuel is fine - but won't idle. I've played with ATS correction at high temps - but with little success.

As Dave says.

The wideband info you are seeing is NOT correct.

Everything in front of you tells you this.

Firstly the engine runs fine, the engine running does not change with AFR reading, and most importantly as can be seen, injector pulse width is not changing yet displayed AFR does change.