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Manifold swap/timing/pinging 


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 Post subject: Manifold swap/timing/pinging
Posted: Wed Mar 05, 2008 12:42 pm 
Oompa Loompa

Posts: 31

Joined: 1st Apr 2007

Ride: NC Fairlane

Location: Country
WA, Australia

Hi over the weekend i fitted a new intake manifold. Put everything back together reset timing etc.

Now it pings between 4-5000rpm. timing is spot on 30degrees. Supposedly the sweet spot for a 5.0 is 32-34degrees, which when it is set there it pings from about 2500 and up.

Should i take it back to 28deg or less?
Is there really that much extra air going into the motor to make it ping?
Would the HI6 interfere with initial timing setting?
The timing doesn't seem to move away from the initial timing settings when the self test wire is disconnected.
Motor is totaly stock except intake and spacer, HI6 and k&n aircleaner. Run only on premium unleaded.

Any help, advice, suggestions appreciated.
Posted: Wed Mar 05, 2008 11:32 pm 
EFI Guru

Age: 52

Posts: 4300

Joined: 5th Nov 2004

Gallery: 28 images

Ride: 351 Vogue,XH 5.0,'17 5.0 Stang

Location: Perth
WA, Australia

Starting with the most likely after an intake swap....Have you caused a vacuum leak with the swap? This will cause unmetered air to enter and lean out the mixture causing detonation.
Otherwise is your balancer ok(ie; not slipped). What's your fuel system like? Fuel filter, pump, injectors etc? Has the car been driven lightly and carboned up the combustion chambers?
The Hi-6 does have a very slight effect on timing but only if you set your timing without it hooked up. The spark energy is greater so it tends to jump the gap earlier which of course means pre-ignition.
If you can't find any other reason then certainly reduce your base timing.
When you say your timing doesn't seem to move away from base can you describe the conditions you tested it under?

Posted: Thu Mar 06, 2008 10:37 pm 
Oompa Loompa

Posts: 31

Joined: 1st Apr 2007

Ride: NC Fairlane

Location: Country
WA, Australia

Hi Pete, we've met before through Clampy.

Back to the prob.
Checked for vacuum leaks and there dont appear to be any.
I dont think the balancer has slipped. It has not ever been touched as far as i can tell.
Fuel filter was changed in the last 12months.
Injectors are very clean.
Fuel pump is stock but seems ok.
Since moving to the country the car has seen a lot of cruising at 100-110 or 2000-2250rpm. Is otherwise driven pretty gently most of the time. :D
I have backed the timing off to 28 degrees and it seems ok...
Checking the timing, according to the FMC book page 9-1-11.
Engine warmed, AC off, park etc.
Spade teminal in self test input plug etc.
I have noticed that every time i start the car it revs to nearly 2000rpm irespective of the self test being grounded or not...
And each time i check the timing it is the same weather or not the self test is grounded or not...
That is the same within and outside the time frame FMC say...
Maybe i need to get their diagnostic hooked up to it?
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