A rattle when driving

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91v2500

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Hey GM fam, I need y’all help again with my truck. Here’s my problem, while accelerating I get a rattling sound. I’m not sure where it’s coming from and it does not happen when gassing it in park or neutral. I’ve changed the complete tensioner, catalytic converter, there’s no loose clamps on the exhaust. My next move is to change the knock sensor. And there’s no check engine light on also. I’m open for suggestions and any information, thank you!!!
 

Ricko1966

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There has to be more info. With that description it could be change in the cup holder to pliers in the rear compartment.
 

91v2500

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No change in the cup holders, no pliers in the rear. Also there’s no bells hanging from the rear view mirror. Now that we’ve gotten those out the way. I gave the best description I could, the sound is coming from up front somewhere under the hood. There’s no loose bolts with washers anywhere.
 

Ricko1966

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No change in the cup holders, no pliers in the rear. Also there’s no bells hanging from the rear view mirror. Now that we’ve gotten those out the way. I gave the best description I could, the sound is coming from up front somewhere under the hood. There’s no loose bolts with washers anywhere.
Look the description already got better, now we know it's from the front.Tensioner,then cat now knock sensor,I couldn't rule out pliers change,bells,etc.
 
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91v2500

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Thanks for the direction, I think it may be a pre detonation from what I’ve read and heard
 

Ricko1966

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Look for the post by @SirRobyn0 help need someone who knows more about esc than me the last couple of days @AuroraGirl has put up info on troubleshooting esc.
 

gmbellew

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Hey GM fam, I need y’all help again with my truck. Here’s my problem, while accelerating I get a rattling sound. I’m not sure where it’s coming from and it does not happen when gassing it in park or neutral. I’ve changed the complete tensioner, catalytic converter, there’s no loose clamps on the exhaust. My next move is to change the knock sensor. And there’s no check engine light on also. I’m open for suggestions and any information, thank you!!!
if the Knock sensor is bad, you would know. it does a self test under mild acceleration, if it doesn't detect knock it sets a code. I had a bad knock sensor once and it self tested til you could actually hear it.

not saying it isn't knock, but if it is, the sensor is probably good if it isn't throwing a code.

you could try some premium fuel to see if that helps?

if you have a scanner or aldldroid and a Bluetooth obd1 scanner you could see if anything is funky with a sensor or the fuel trims.
 

91v2500

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if the Knock sensor is bad, you would know. it does a self test under mild acceleration, if it doesn't detect knock it sets a code. I had a bad knock sensor once and it self tested til you could actually hear it.

not saying it isn't knock, but if it is, the sensor is probably good if it isn't throwing a code.

you could try some premium fuel to see if that helps?

if you have a scanner or aldldroid and a Bluetooth obd1 scanner you could see if anything is funky with a sensor or the fuel trims.
I have an obd 1 not a Bluetooth but there’s no codes. I read that some times if they are bad it would give a rattling sound during acceleration. I used to use premium gas but I switched back to regular when my truck was running rough, but I always use fuel treatment in my truck also.
 

gmbellew

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I have an obd 1 not a Bluetooth but there’s no codes. I read that some times if they are bad it would give a rattling sound during acceleration. I used to use premium gas but I switched back to regular when my truck was running rough, but I always use fuel treatment in my truck also.
a scanner will let you see what the ECM sees at each sensor, monitor fuel trims, watch knock counts, etc.

you could run through the diagnostics on the Knock sensor, but I'd expect it to set a code if the module or the sensor went bad. but I guess if it were that easy, there wouldn't be a diagnostic procedure.

it only performs the self test 1 time per start. so if you my hear it multiple times on the same drive, it isn't doing a self test. it could be actual knock. knocking sounds like a fast rattle to me.

if it is knocking, all the ESC does is retard timing. it doesn't set a code when it detects knock.

i am assuming your check engine light works?
 

SirRobyn0

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Thanks for bringing me into this thread @Ricko1966

There is a LOT of information on the ESC system used on the carbureted rigs 305 mostly a few 350's got the system too. If @91v2500 wants to see that thread it is here >> https://www.gmsquarebody.com/thread...-knows-more-about-esc-system-than-i-do.33216/ << If you go to the last page post #168 has the stuff @AuroraGirl posted. BUT keep in mind that info is geared towards the carbureted trucks.

With that said Korey, I haven't a clue if your noise is pinging, a rod knock, a loose fender or something entirely different and neither do the rest of the guys because we can't hear it from here. Could you please take the truck out for a drive and record some audio of the noise. You can just use your phone and take video doesn't matter what we see it's what we hear. Pinging is a pretty unique sound and I'm sure anyone of us could tell that from say a cat rattle in a recording. Once you have captured the video upload it to youtube and link it to the sight.
 
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AuroraGirl

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Hey GM fam, I need y’all help again with my truck. Here’s my problem, while accelerating I get a rattling sound. I’m not sure where it’s coming from and it does not happen when gassing it in park or neutral. I’ve changed the complete tensioner, catalytic converter, there’s no loose clamps on the exhaust. My next move is to change the knock sensor. And there’s no check engine light on also. I’m open for suggestions and any information, thank you!!!
does this noise happen if you are in park/neutral and you ramp up the revs? if you coast in neutral while rattling (So while moving) does it go away?
 

AuroraGirl

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Number: 93-03-6D
Section: 6D
Date: AUGUST 1992
Corporate Bulletin No.: 166001R
ASE No.: Al, A6, A8

Subject:
NEW DESIGN SPARK PLUGS

Model and Yew:
1991-93 ALL PASSENGER CARS AND TRUCKS WITH GASOLINE ENGINES

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO., 91-234A-OB, DATED JULY 1992. THE 1992 AND 1993 MODEL YEARS HAVE BEEN ADDED. ALL COPIES OF 91-234A-OB SHOULD BE DISCARDED.

In 1991 GM introduced a new design spark plug for use in all trucks equipped with gas engines. These new design spark plugs have a ceramic insulator which is approximately 1/8 inch longer than the insulator used in previous model years.

The longer length spark plugs, which conform to S.A.E. and I.S.O. Engineering guidelines, magnify the problem of cracked insulators because currently, most spark plug sockets are not of sufficient length to properly engage the shell hex. If the spark plug shell hex is not fully engaged in the spark plug socket wrench, the socket may **** at an angle and cause insulator cracking and/or breakage during plug installation or removal.

When servicing these new design spark plugs, make sure that the spark plug socket being used is deep enough to accommodate the longer length insulator. The spark plug socket wrench should conform to the proposed S.A.E. and I.S.O. world standards for spark plug socket wrenches. Spark plug socket wrenches that conform to these standards are designed to accept the lengthened spark plugs and allow full engagement of the hex nut on the shell of the spark plug.

Use of a spark plug socket which is NOT deep enough may result in the ceramic insulator becoming cracked above the spark plug shell.

Note:

SOME CRACKS IN THE INSULATOR M" NOT BE VISIBLE. SUCH CRACKS MAY LATER CAUSE A SPARK PLUG TO MISFIRE. SPARK PLUG MISFIRES ARE OFTEN MISDIAGNOSED AS A SLIPPING TRANSMISSION, DEFECTIVE TORQUE CONVERTER CLUTCH, ENGINE IMBALANCE, OR MALFUNCTIONING FUEL SYSTEM.


Number:91-375-10

Section:10

Date:JULY 1991

Corporate Bulletin No.: 161602


Subject:
RATTLE FROM "B" PILLAR CAB MOUNT CUSHION AREA


Model and Year:
1991 C/K TRUCKS

FIGURE 1
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FIGURE 2
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Some 1991 C/K trucks may experience a rattle from "B" pillar cab mount cushion area.

SERVICE PROCEDURE:

To correct this condition it is necessary to increase torque on the cab body and radiator support mounts to the following revised torque specifications.

1.Body mount bolt (P/N 15611432) from 60-90 N-m. (44-66 lbs.ft.) to 75-95 N-m. (55-70 lbs.ft.)(Figure 1).

2.Radiator support mount (P/N 15538569) from 40-55 N-m. (30-40 lbs.ft.) to 50-63 N-m. (37-46 lbs.ft.)(Figure 2).

The revised torque specifications started with the following VIN breakpoints:

Ft. Wayne ASM1GCDC14K0MZ168782

Oshawa ASM2GCHC39N1M1191836

Pontiac East ASM1GBGC24J4ME175532

 
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