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Username Post: 1994 Chevy c1500 5.7 backfire issue        (Topic#348749)
Caleb94chevy 
Forum Newbie
Posts: 3

Reg: 12-17-17
12-17-17 07:48 PM - Post#2718306    

Hey all would Appericate any help. I’ve got a 1994 5.7 tbi c1500 that backfires when warm with more than half throttle applied. I don’t know how to fix I’ve changed spark plugs and wires cap and rotor ain’t very old new temp sensors and ignition coil and tps. Thanks for any help.



 
rockfangd 
"5th Year" Gold Supporting Member
Posts: 2430
rockfangd
Age: 32
Loc: Utica ny
Reg: 04-13-10
12-17-17 08:22 PM - Post#2718309    
    In response to Caleb94chevy

I would be checking the timing. If the timing is off that would cause a backfire as the cylinders are not firing at the right time.
There should be a FAQ on it.
Also check your injectors. See if they are misting properly or if they are dribbling
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Edited by rockfangd on 12-17-17 08:24 PM. Reason for edit: No reason given.

 
bowtie44s 
Valued Contributor
Posts: 3963
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
12-18-17 05:31 AM - Post#2718335    
    In response to Caleb94chevy

It could also be a flat cam lobe. It's really hard to diagnose without more information.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
Caleb94chevy 
Forum Newbie
Posts: 3

Reg: 12-17-17
12-18-17 08:52 AM - Post#2718340    
    In response to rockfangd

Fuel spray pattern seems good when just checking with a flashlight no dripping that I’ve noticed. Timing is at 2 BTDC with timing advance wire disconnected. So not bad for a tbi shouldn’t hurt it to much. Runs at around 25 degrees at idle tho.



 
Caleb94chevy 
Forum Newbie
Posts: 3

Reg: 12-17-17
12-18-17 08:54 AM - Post#2718341    
    In response to bowtie44s

To check that I just pull the valve covers off and watch the rockers lift right?



 
bowtie44s 
Valued Contributor
Posts: 3963
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
12-19-17 10:08 AM - Post#2718430    
    In response to Caleb94chevy

Yep, if you have a flat lobe, it will still move, but not nearly as much.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
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