Engine noise with acceleration
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Junior Member
Joined: May 2022
Posts: 15
Likes: 1
From: Austin, Texas
Engine noise with acceleration
A crackling noise has recently started coming from my engine. It only happens when I’m driving at least 30 mph, usually between 1700-1800 rpm before the truck shifts, and almost always when I’m driving uphill. It doesn't happen when I'm at higher speeds and a constant rpm, only when I increase pressure on the gas pedal, and the noise gets louder the more I step on it. It occurs with either gas tank selected under these conditions.
I’ve tried to replicate it at home by revving it at idle, and I don’t hear anything even at full throttle. I’ve also tried jacking the truck up and revving it in drive, but can’t replicate the same sound - I do get what sounds like marbles rattling around a can coming from within the cab.
I have videos of both situations. The marbles-in-a-can sound begins around the :25 mark in the video when the truck is in gear and revving around 3,000 rpm. In the other video taken on the highway, the crackling noise starts right at the beginning of the video and lasts for a few seconds.
The check engine light is not on, and I haven't been able to pull any codes with the paperclip test. It may not be relevant anymore, but on a road trip I took with the truck last year, after a few hundred miles it would barely start when hot and was throwing a 172 code: Oxygen sensor not switching – system is or was lean – Single, Right or Rear HO2S – Fuel control. Fuel pressure was low at the injectors so I replaced the fuel pump in the front tank, which fixed the low pressure and no start problem, and threw in a new O2 sensor, and haven't seen this code since.
What I’ve done so far: checked the spark plug gap was set to .044, checked base timing was set to 10 BTDC, and tried running it on 89 octane fuel. No dice. I'm wondering if the marbles sound is the same sound as the crackling on the highway, but it only sounds different because of the road sounds and wind added in. I humbly welcome any advice on what else I should look for.
I’ve tried to replicate it at home by revving it at idle, and I don’t hear anything even at full throttle. I’ve also tried jacking the truck up and revving it in drive, but can’t replicate the same sound - I do get what sounds like marbles rattling around a can coming from within the cab.
I have videos of both situations. The marbles-in-a-can sound begins around the :25 mark in the video when the truck is in gear and revving around 3,000 rpm. In the other video taken on the highway, the crackling noise starts right at the beginning of the video and lasts for a few seconds.
The check engine light is not on, and I haven't been able to pull any codes with the paperclip test. It may not be relevant anymore, but on a road trip I took with the truck last year, after a few hundred miles it would barely start when hot and was throwing a 172 code: Oxygen sensor not switching – system is or was lean – Single, Right or Rear HO2S – Fuel control. Fuel pressure was low at the injectors so I replaced the fuel pump in the front tank, which fixed the low pressure and no start problem, and threw in a new O2 sensor, and haven't seen this code since.
What I’ve done so far: checked the spark plug gap was set to .044, checked base timing was set to 10 BTDC, and tried running it on 89 octane fuel. No dice. I'm wondering if the marbles sound is the same sound as the crackling on the highway, but it only sounds different because of the road sounds and wind added in. I humbly welcome any advice on what else I should look for.
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
Block up the tailpipe at idle, and use a mechanic's stethoscope without the hard probe (open tube) to find any exhaust leaks FORWARD of the muffler.
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The marbles sound is normal for the 4.9L. This page explains how to read codes, and lists several reasons you might not get any (but you should ALWAYS get at least a pass code):
(click this text)
(click this text)
The marbles sound is normal for the 4.9L. This page explains how to read codes, and lists several reasons you might not get any (but you should ALWAYS get at least a pass code):
(click this text)