'89 300
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Tuned
Joined: Oct 2001
Posts: 483
Likes: 6
From: Pelzer, SC
'89 300
Why does the engine make that diesel kind-of-sound at low RPM when you shift a little early. As you accelerate and the RPM's climb it goes away. The engine is still pullin good @ 1400 rpm and the sound goes away before 2000. I usually shift around 2000. At 3000 it seems to hit a flat spot in the torqe curve so I hardly ever go that high. Besides I am trying to get maximum life out of this engine. 150,000 now.
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
'89 300
I think what you are describing is detonation , pre ignition , spark knock ? There may be a few things causing it , carbon buildup on the pistons , insufficient egr flow , timing not at 10 Deg Btdc . Carbon buildup between the egr valve & where the egr passage enters the intake can get a lot of carbon buildup over time .
More Turbo
Joined: Jun 2001
Posts: 571
Likes: 1
'89 300
I was wandering the same thing. I too thought that it might be detonation. just as an experiment I filled it up with a higher grade gas and tried it. it did help. it still does it but it will pull-out of it about 300 r.p.m.'s earlier. but now I am back to the same old gas.
also, something was mentioned about insufficent egr flow? how can this contribute to it? just curious cause my egr went bad and I just unplugged the vacuum line from it.
also, something was mentioned about insufficent egr flow? how can this contribute to it? just curious cause my egr went bad and I just unplugged the vacuum line from it.
Junior User
Joined: Sep 2001
Posts: 69
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From: Northbridge USA
'89 300
I have a 94 I300 and I get the same exact thing. Mine also gets better if I use a higher grade gas, but I always go back to using regular due to the price. If untreated will it cause any longterm damage?
Thread Starter
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Tuned
Joined: Oct 2001
Posts: 483
Likes: 6
From: Pelzer, SC
'89 300
The engine has done that since I bought it with 12000 miles on it. Now there is 130,000. It does not do it when it is cold. I have not really noticed a difference when I use high octane. Pre-detonation is what it sounds like but my mechanic says he is unsure. I have always kept the truck well tuned and run quality gas in it, but usually 87 octane. Would making the engine pull the truck at a low RPM cause it? Even though the engine doesn't lug or struggle?
Thread Starter
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Tuned
Joined: Oct 2001
Posts: 483
Likes: 6
From: Pelzer, SC
'89 300
Also, there is no sign of detonation on the spark plugs, but I do not know what else it could be.
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Posting Guru
Joined: May 2001
Posts: 1,021
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From: Florida
'89 300
I think it's probably normal cus it sounds like all of our trucks do it? i just thought it was cus it was just struggling a little or something........lol i know that doesn't sound like an educated answer but i never worried about it until now........cus it runs great after i hit 1350 or so.........
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Senior User
Joined: Jan 2000
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From: Glen Flora USA
'89 300
My truck does that too... I have 243,000 on it and it still runs like a charm, I think its a normal 300-6 sound. But after you hit about 230,000 the truck will begin sounding like a vacume cleaner and you wont have to worry about that sound...
Thread Starter
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Tuned
Joined: Oct 2001
Posts: 483
Likes: 6
From: Pelzer, SC
'89 300
Thanks Truckfreak and Rockstar,
Years ago I quizzed many mechanics on that sound and nobody had a clue. I have heard pinging and detonation sounds, the sound of the 300 just aint the same as those.
I have extra well maintained my truck from the beginning using good stuff all the way like parts and fluids and fuel.
I agree with ya'll it must be an inherent sound of the 300-6. And the way she keeps runnin, I can sure keep livin with it.
Thanks
1989 F-150 300-6 5sp. 3.08 4x4 130.000 mi. 32x11.5-15 reg. cab short bed
Years ago I quizzed many mechanics on that sound and nobody had a clue. I have heard pinging and detonation sounds, the sound of the 300 just aint the same as those.
I have extra well maintained my truck from the beginning using good stuff all the way like parts and fluids and fuel.
I agree with ya'll it must be an inherent sound of the 300-6. And the way she keeps runnin, I can sure keep livin with it.
Thanks
1989 F-150 300-6 5sp. 3.08 4x4 130.000 mi. 32x11.5-15 reg. cab short bed
New User
Joined: May 2001
Posts: 13
Likes: 0
'89 300
For what it's worth, I thought the sound coming from my truck was pinging, too, but mine does it when going down a hill, and letting compression slow me down. I've got 195,000 low, low miles on mine, so I'm just glad it still runs!!
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