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Short Rough Idle After Start Up

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Old 04-27-2024, 06:43 PM
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Short Rough Idle After Start Up

Good evening all.

This will be relatively long but i want all of the factors to be known.

Drove my 1991 chevy camaro rs 305 tbi on a 20 minute round trip, turning at a red light the engine shut off. cranked right back up, drove to the nearest grocery store and popped the hood to look around and it died then as well. Cranking it for a third time, it cranks up, but sounds like it has the worlds most aggressive cam. its been 3 days, and this is now the norm. hasnt shut off since, but the rough idle is making me paranoid it will at any point.

What ive replaced:
IAC, MAP, temp sensor (both), oxygen sensor, knock sensor, TPS, PCV valve, EGR valve, ECM, ICm, cap, rotor, plugs, wires, full tbi rebuild, IATS, fuel filter, radiator, water pump, heater and radiator hoses, harmonic balancer, belt, purge valve, gas cap, and tensioner.

Had to replace the stock fuel return line with a rubber one, but hasnt given me trouble so far. ECM has an aftermarket chip, but its been in there since i bought the car 2 and some years ago with no trouble. fuel pressure was tested maybe 6 months ago, good at start, idle, and under load. Vacuum lines in the engine bay are semi rednecked, but again, no trouble thus far and they all look to be in one piece, unless there are some outside the engine bay im unaware of. purge solenoid also semi rednecked with jb weld (broken and not made anymore).

Thank you everyone for any ideas you may have, and for sitting through that mess
Old 04-27-2024, 10:02 PM
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
Axle/Gears: 10bolt 4.10 Posi w Lakewood TA Bars
Re: Short Rough Idle After Start Up

Sounds like lack of fuel or a large vacuum leak.
Check your TBI base gasket.
Also manually work the EGR valve. It could be stuck open.
Old 04-29-2024, 07:18 AM
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Re: Short Rough Idle After Start Up

Went outside to make sure the EGR solenoid was plugged up correctly, found out the EGR valve had burnt a pin hole in the vacuum line. Issue solved, glad it was simple but sorry to waste time.
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