Pinging and Dieseling

kbldawg · Apr 1, 2009

I just put a 97 Explorer 5.0 motor w/ GT40P heads in my EB.

My first test drive with motor and there was a lot of hesitation when driving, it was fine at idle.

So, I restabbed the distributor and that took care of the hesitation, but now it's pinging like crazy. It gets a little better the higher the rpms are, but it's still there.

The pinging seems to be better the more retarded the timing, but when I do that I get some light dieseling when I shut it down. I bumped the timing back up a little and the dieseling is gone, still pinging though.

Do I need to run higher octane fuel or should I get a timing light on it? Will adjusting the carb any help with the pinging? (mc 2150) The exhaust smells really rich.

Chad

Viperwolf1 · Apr 1, 2009

Put a light on it. Sounds like too much advance causing the pinging. Dieseling could be too high idle speed or hot spots in the chamber. Has anything been done to the motor like milled heads or high compression pistons?

kbldawg · Apr 1, 2009

Viperwolf1 said:
Put a light on it. Sounds like too much advance causing the pinging. Dieseling could be too high idle speed or hot spots in the chamber. Has anything been done to the motor like milled heads or high compression pistons?

As far as I know the engine is bone stock.

Is the high idle speed the screw on the carb behind the throttle?

Oh, and would having the dizzy one tooth off, cause the timing marks on the dampner to be off?

Viperwolf1 · Apr 1, 2009

1) Yes
2) No

68ford · Apr 1, 2009

pinging can be a sign in your case of the timing still being to retarded. i had my timing to retarded once with mu stock engine and it would ping, only reasoning i think of is the engine is running so inefficiently that the cylinder temps go up from it burning so poorly. get a light and advance it if it still retarded.

76Broncofromhell · Apr 1, 2009

Retarded timing does not cause pinging.

Pinging is preignition of gasoline which in effect is dieseling. You have a few things that would lead to this:

1) Timing is extremely advanced
2) Engine running extremely lean
3) Firing order is off

My guess is you put the plug wires in the 1-5-4-2-6-3-7-8 as per the book when the Exploder motor takes the 1-3-7-2-6-5-4-8 firing order.

68ford · Apr 1, 2009

i didnt say it does, a said it can.. its not the actual late timing, its what it does to the flow of the engine and the poor running condition it creates.

seen it many times and once personally.

answer this, how is retarded timming impossible to cause pining, yet when timing is too retarded and the ignition is turned OFF and engine intake charge will continue to ignite on its own and try to keep running? its no different, its a poor running condition, a poor mixture condition and along with heat.

68ford · Apr 1, 2009

76Broncofromhell said:
Retarded timing does not cause pinging.

Pinging is preignition of gasoline which in effect is dieseling. You have a few things that would lead to this:

1) Timing is extremely advanced
2) Engine running extremely lean
3) Firing order is off

My guess is you put the plug wires in the 1-5-4-2-6-3-7-8 as per the book when the Exploder motor takes the 1-3-7-2-6-5-4-8 firing order.

if he had his wires that way, wouldnt that make 5,4,3 and 7 fire at tdc exhaust stroke? if thats the case i think he wouldnt be only complaining about pinging.

76Broncofromhell · Apr 2, 2009

Retarded timing means the ignition fires on the power stroke (ATDC), advanced timing means the ignition fires in the compression stroke (BTDC).

That means detonation can't happen under retarded timing. I'm not trying to pick a fight with you over definitions, but this is what pinging aka detonation from ignition timing is caused by. Other causes are from protruding objects in the combustion chamber absorbing too much combustion heat and causing preignition such as spark plugs electrodes (the reasoning behind heat ratings) and combustion chamber edges (open vs. closed).

You realize that gasoline ignited under less pressure (e.g. late on the power stroke or on an engine with low compression) actually burns colder, and less complete hence the black smoke and higher emissions.

302s will run on the wrong firing order at idle, fairly smoothly I might add, but will have shit for power once a load is applied. From my days working at the parts store, I would say 90% of SBF engine swaps problems were from the elusive 351W firing order.

kbldawg · Apr 2, 2009

I'll get a timing light on it tonight and see what it says. The only problem with that is I think my timing marks are wrong or something else is all screwy. I had a timing light on it once already but the marks were way below the pointer.

I'm running an after market dampner. (performance products 80007)

Yes, I'm using the 351w firing order.

bigmuddy · Apr 2, 2009

kbldawg, your firing order is correct. Try advancing the dizzy and which will bring your idle up, then back the idle screw out a few turns. That old two barrel carb you are running may be running out a little lean at higher speeds which would cause the pinging.

Guys,
the 5.0 as far as I know is a bone stock explorer motor with the GT40P heads, with 90K on the odometer.

Ben

kbldawg · Apr 2, 2009

bigmuddy said:
kbldawg, your firing order is correct. Try advancing the dizzy and which will bring your idle up, then back the idle screw out a few turns. That old two barrel carb you are running may be running out a little lean at higher speeds which would cause the pinging.

Guys,
the 5.0 as far as I know is a bone stock explorer motor with the GT40P heads, with 90K on the odometer.

Ben

When it's running lean, that means not enough fuel, right? Nevermind, stupid question.

blubuckaroo · Apr 2, 2009

How can this motor be a bone stock '97 and have a carb? If you have changed to carb you may be fighting as cam ground for fuel injection.

kbldawg · Apr 2, 2009

The context of the question was about whether the engine's internals had been modified. The answer was, no, as far as I know, it is bone stock.

Not sure what you mean about I "may be fighting" and "cam ground for fuel injection".

Are you saying that I am fighting a loosing battle trying to get the carb to run properly on a fuel injected motor?

blubuckaroo · Apr 2, 2009

No, It will work but being a smogged motor there is less lob seperation than an aftermarket cam would have.
I've had similar pinging problems under moderate throttle and traced it to the vacuum advence coming in too soon because of my RV cam. Test it by pluggung off the vacuum line to the advance to see if it clears up. If it does you can try adjusting it a little at a time till it pings then back it off.

kbldawg · Apr 2, 2009

Guys, the timing is set at 20.

kbldawg · Apr 2, 2009

blubuckaroo said:
No, It will work but being a smogged motor there is less lob seperation than an aftermarket cam would have.
I've had similar pinging problems under moderate throttle and traced it to the vacuum advence coming in too soon because of my RV cam. Test it by pluggung off the vacuum line to the advance to see if it clears up. If it does you can try adjusting it a little at a time till it pings then back it off.

Ill give that a shot after I get it timed. Thanks man!

Viperwolf1 · Apr 2, 2009

kbldawg said:
Guys, the timing is set at 20.

20 BTDC is too much. 10 would be better.

kbldawg · Apr 2, 2009

Viperwolf1 said:
20 BTDC is too much. 10 would be better.

It's still pinging at 10, but not nearly as bad as it was. Definately an improvement.

Viperwolf1 · Apr 2, 2009

Take it down some more.

Pinging and Dieseling

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