p8 pro on sbc

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
jpr.racing07
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p8 pro on sbc

Post by jpr.racing07 »

I need help again ??????? can't get sbc v8 to run it runs for a second then back fires through the carb with the odd flame the firing order is 18436572so have pared 1&6 8&5 4&7 3&2 waisted spark is this right ?????? any ideas what could be wrong jeremy
stevieturbo
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Re: p8 pro on sbc

Post by stevieturbo »

Did you resolve the missing tooth position ?

When cranking, with plugs removed if need be ( and also disable fuel ) is ignition timing at a sensible confirmed setting with timing light that would allow the engine to start.

Once that's done, start low with fuelling and increase until it starts.

Job done.
Rob Stevens
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Re: p8 pro on sbc

Post by Rob Stevens »

I think double check that correct pairing of cylinders is done, i.e number 1 at tdc, is number 6 also at tdc connect this to coil driver number 1.
Rotate engine 90deg to find next pair of cylinders at tdc, connect these to coil driver number 2. etc.
And as Steve says double check the setting of the crank sensor in relation to the missing tooth. On the P8 you are limited as to where the sensor can be, you need to reference the gap position to tdc on cylinder 1

Rob
jpr.racing07
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Re: p8 pro on sbc

Post by jpr.racing07 »

This thing is starting to do my head in have checked everything check crank trigger 70 degree's BTC checked plug lead pairing . As soon as I give the carb a bit of throttle it fires then pops back through carb then we flames . Any idea's cam over lap ,damaged crank trigger or may be a coil ???????
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ignitionautosport
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Re: p8 pro on sbc

Post by ignitionautosport »

it sounds obvious I know, but checked with a timing light on cranking?
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stevieturbo
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Re: p8 pro on sbc

Post by stevieturbo »

ignitionautosport wrote:it sounds obvious I know, but checked with a timing light on cranking?
Nevermind obvious, over the years on these and other forums it seems most people never bother their arse to to this most basic and vital task when installing a new ecu.

Not saying the OP hasnt, but it MUST be done. How some people get theirs running without doing it is beyond me, as they'll have no clue what their timing actually is ( although some probably dont care as long as it runs lol )
jpr.racing07
Posts: 55
Joined: Sun Feb 12, 2012 5:11 am
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Re: p8 pro on sbc

Post by jpr.racing07 »

Do you think after spending nearly 10k on building a 600 bph plus all Ali Chevy that I wouldn't be bothered to check the timing with a light but as the crank pulley is in a recesse in the back of the tub it's not so easy , I suppose I could always just cut a large hole in the side of my Gould . I had only asked for advice on what could be wrong thought that was the idea of this forum , ????...
Roverdose
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Re: p8 pro on sbc

Post by Roverdose »

unfortunatly this forum gets a lot of people on who dont do some very basic checks and wonder why the ecu cant run their engine properly!

timing light is the only way to be sure, if the crank pully is inacessable then you'll never get an accurate position. if its worth that much id get it out and fit it on a dyno to get a base tune on it.

Drew
jpr.racing07
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Joined: Sun Feb 12, 2012 5:11 am
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Re: p8 pro on sbc

Post by jpr.racing07 »

Thanks Drew over here in jersey we don't have a dyno, will see if I can get a tdc mark on the ring gear which I can see a small section of, and then spin it over with the plugs out and see what I have on cranking .
stevieturbo
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Re: p8 pro on sbc

Post by stevieturbo »

As Drew says, unless the OP confirms what people ask we have to assume they either dont know, or havent done it.
You cannot simply assume the timing is right, more so if the engine wont start.

And when using wasted spark, the timing light will flash double actual timing. If the map says 10deg, this will appear as 20deg at the crank pointer ( dial back lights anyway, Ive never used a static light so not 100% sure how they read )
Either way, not important as you'll verify timing at different rpm's and timing figures so it will become apparent what is correct or not.
But again anywhere in the range -5 to 20deg should see the engine have a very good chance of starting and running.

http://www.dtafast.co.uk/Downloads/Manu ... d%20P8.pdf

Your symptoms do sound a bit like either wrong timing, or coiuld be as simple as the plugs are now soaked.

And coil packs can be awkward sometimes, so are you absolutely sure each pair of outputs are firing when they should be. Unfortunately DTA does just offer a block ignition test, and not individual outputs which would be much handier.

Are the plugs clean and dry, or are they soaked ( I always say bin soaked plugs )

Again, confirm the basics first ensure spark is acceptable to actually start the engine, and only then start increasing fuelling from a low figure so as not to flood the engine

Dont worry about startup, cold start, compensations etc etc. Just grab the entire fuel map and work with it until the engine has warmed up and get a good stable idle when warm. Then after that you can revert back and add compensations for when it is cold.
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