My 89 IROC 5.7 TPI idles very rough and splutters when I accelerate when cold. When I drive for a couple minutes it runs better with just a little hesitation off idle, but when it's cold it's bad and it coughs through the intake. It started doing this after I changed injectors. I checked for vacumm leaks but couldn't find any. I also checked for any loose vacumm lines and couldn't find any. Any suggestions?

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2000 NHRA Edition T/A
Pewter Metallic
A4 3.23 Gear w/GSC's
Whisper lid, MAF Ends, Ram Air Kit, Exhaust C/O
Best 60ft:1.94
1/8th:8.381@86.03
1/4:12.963@108.44

1989 IROC-Z 5.7
Auto w/3.24 gears

 

Does it sputter or splutter? We need to know these things man.

But seriously, is the car showing a check engine light. Have you scanned for codes. The hesitation off idle seems like a throttle position sensor problem to me.
bsa

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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 24# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

Nope, no check engine light. I scanned for codes and got none. On another board someone said it could be a dirty injector but I figured if it's a dirty injector it'd run rough all the time. I have another TPI setup and was thinking of changing the throttle body and see if that helps.

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2000 NHRA Edition T/A
Pewter Metallic
A4 3.23 Gear w/GSC's
Whisper lid, MAF Ends, Ram Air Kit, Exhaust C/O
Best 60ft:1.94
1/8th:8.381@86.03
1/4:12.963@108.44

1989 IROC-Z 5.7
Auto w/3.24 gears

 

I'm having the same problem on my 91 camaro z28 5.7tpi 5 speed and it started happening to me when I deleted my smog pump and put headers on it, did you ever find out what it is?

 

I have the same problem on my '89 305 TPI. when it warms up, its great. Am guessing its either the a) EGR valve stuck, b) Vacuum leak, c) Coolant Temp sensor or d) Manifold Air temp sensor. Anyone know what the symptoms of a bad Manifold Air Temp sensor would be? I have not check engine light most of the time, the light only goes on during a cold day and sitting at a red light., then goes off. Any ideas.