Winter fuel; warm weather; dieseling

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Curious if a few days of warm weather running 'winter fuel' can aggravate a slight dieseling issue I have on my B2300.

Went to Southern Maine on X-mas day where temps were quite balmy and my 2300 dieseled badly under slight load on the highway (2K-2.5K rpm)

It was bad enough for me to pull off and top off with 91, which didn't help much. Vehicle seems to be mildly prone to this; I usually tailor my driving style to avoid it, but this day it was pretty bad. I read there is a knock sensor under the manifold, apparently for nothing?

Looking for suggestion on what might be causing this and if it can be resolved; I'm figuring more volatile winter fuel on a warm day detonates more readily.

100K miles; 2.3L duratech; usually 87 or 89 Valero fuel.

Thanks.
 
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I thought dieseling was when the engine continues to run after the ignition was off?
 
Originally Posted By: Rand
I thought dieseling was when the engine continues to run after the ignition was off?


I guess that's right. I should have used 'pinging'
 
Originally Posted By: Rand
I thought dieseling was when the engine continues to run after the ignition was off?


It is. I believe the OP is referring to pinging/knocking.
 
Back when I was daily driving a carbureted, analog-ignition car, I definitely noticed more pinging (not dieseling, as pointed out) on winter gas. Also a tendnecy to vapor lock. The car wouldn't vapor lockn on a 105-degree summer day siting in traffic with summer gas, but on an 80-degree day in winter it was a given. Winter gas is the pits.
 
for fuel related issue, you can always try a dose of redline si-1 (don't need whole bottle, maintenance dose).

While I don't have issues with a car, it worked wonders for my lawnmower which was more fuel sensitive.
 
Originally Posted By: simple_gifts
I read there is a knock sensor under the manifold, apparently for nothing?


The sense I get is that the engine will be listening for knock that is detrimental or harmful for the engine. Apparently, the higher toned pinging noise we sometimes hear isn't harmful to the engine. A think a sharper pitched and lower toned knock sound can indicate more severe detonation (the proper term for pinging), but higher pitched noise may be allowed.

If it's something new, check your EGR valve. EGR actually cools the combustion chamber and reduces an engine's tendency to ping. Your EGR valve could be malfunctioning or the passages could be clogged, making an operating valve ineffective.
 
Go down one heat range on the plugs. I notice NGK is now listing colder plugs for a number of engines which didn't have a problem with gas with less butane in it.
 
Thanks for the responses. I changed out the plugs maybe last summer to Autolite Platinums; the car pinged before also. I use Amsoil PI every year and also use FP occasionally.

I think EGR is a good start; i guess I totally forgot about that possibility.

Pretty sure it isn't the runner flap, because if I tank up with 93 it doesn't do it.

Temps are dropping, so I'll road test it and see if it is temp related.
 
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My Grand Marquis pings lightly under heavy acceleration or load using regular all the time. Runs fine and gets the same mileage on premium as regular but makes pinging noise. On the highway trips I usually use regular as I am not accelerating or loading engine much on road trips unless in the mountains. In town I do prefer the premium as no pinging. I guess it depends how much it pings - all the time or under a load. Can you justify running the premium such as better fuel economy or performance? For me it normally depends on the cost difference between them. If it's 20 cents difference I normally get the premium for 40 cents I normally pass as it's not needed.
 
Originally Posted By: HerrStig
Go down one heat range on the plugs. I notice NGK is now listing colder plugs for a number of engines which didn't have a problem with gas with less butane in it.


Why would butane cause detonation?

Its octane number is generally given at about 93 RON / 90 MON , equivalent to a (US) AKI of 91.5.

Isn't that higher than all but Premium US petrol (93 AKI)?
 
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My 2002 F-150 with the 4.6 started pinging lightly at part throttle in the semi winter weather using regular fuel in 2005. It's not bad enough to pay a bloody fortune for higher octane fuel. By me 89 octane is around $0.50 more per gallon than regular and 93 octane is around $0.70 more per gallon than regular. It's not worth it for the intermittent light ping I get with regular fuel in the winter months. There is no hard spark knock just an occasional light spark ping at light throttle.

Whimsey
 
So those of you that are hearing pinging, does that mean that it is beyond the ability of the knock sensors to retard the timing? Or is something not working properly?
 
Originally Posted By: kschachn
So those of you that are hearing pinging, does that mean that it is beyond the ability of the knock sensors to retard the timing? Or is something not working properly?


I think all the automakers have concluded that a slight amount of audible light pinging is completely acceptable and harmless. The knock sensors keep the engine out of the heavy detonation range where damage can occur. The difference sound at that transition is subtle, but once an engine is actually into the detonation range you can really tell something isn't right. The knock sensors can pick it up before your ear can.
 
Originally Posted By: spk2000
My Grand Marquis pings lightly under heavy acceleration or load using regular all the time. Runs fine and gets the same mileage on premium as regular but makes pinging noise. On the highway trips I usually use regular as I am not accelerating or loading engine much on road trips unless in the mountains. In town I do prefer the premium as no pinging. I guess it depends how much it pings - all the time or under a load. Can you justify running the premium such as better fuel economy or performance? For me it normally depends on the cost difference between them. If it's 20 cents difference I normally get the premium for 40 cents I normally pass as it's not needed.


I also owned a 96 grand marquis that pinged a lot unless I used high octane. I cleaned the mass air flow sensor (MAF) and the problem would go away. This had to be repeated every several months but I could run on 87 octane with no pinging after the cleaning.
 
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