89 305tbi start/stall no power cold
09-28-2016, 09:18 AM
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89 305tbi start/stall no power cold
So on my Camaro I have been having a problem for awhile of an extended crank(3-5 seconds colder it is the longer it seems), surge to 1500 rpm, come down and sputter out to a stall. Start it back up immediately same thing. If after I start it I rev it and hold the rpm around 1500-2000 it will stay alive and if I do this for a minute or so it will then start to idle.
If I attempt to drive it light throttle I get gradual acceleration, the more throttle I give it it starts to fall on its face, all the way to the point that I managed to get it to back fire out the intake when I floored it for a second. If I let off the throttle as this is going on it actually starts to pick up. Once warmed up it runs fine.
Fuel pressure is good, ect is good, tune up was done little under a year ago. Not even a month ago I replaced the map sensor when this was occurring and that cleared it up for about a week or two and then it came back. Plausible map went defective? Unfortunately I haven't had access to a scan tool since then so I haven't been able to plug in to see what reading the pcm is getting.
If I attempt to drive it light throttle I get gradual acceleration, the more throttle I give it it starts to fall on its face, all the way to the point that I managed to get it to back fire out the intake when I floored it for a second. If I let off the throttle as this is going on it actually starts to pick up. Once warmed up it runs fine.
Fuel pressure is good, ect is good, tune up was done little under a year ago. Not even a month ago I replaced the map sensor when this was occurring and that cleared it up for about a week or two and then it came back. Plausible map went defective? Unfortunately I haven't had access to a scan tool since then so I haven't been able to plug in to see what reading the pcm is getting.
10-14-2016, 12:15 PM
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Car: 1985 Pontiac Trans Am WS6
Engine: 360ci sbc
Transmission: T-5 non-WC
Axle/Gears: 3.23
Re: 89 305tbi start/stall no power cold
I have the same issue, my guess is computer issues, going to junk my current quadrajet soon, hopefully it won't run as rich and it will start better
10-14-2016, 03:59 PM
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Car: 1988 Trans Am
Engine: L03
Transmission: 700R4
Axle/Gears: 10 Bolt 2.73 Open
Re: 89 305tbi start/stall no power cold
I hate it when we (owners) don't have the proper diagnostic tools to help zero in on issues like this. I'm not a fan of throwing parts at a car.
That said, what the OP is describing could pass as a coolant sensor failure (or a lot of other things). Since TBI does not have a "choke", the computer is looking at coolant temp and ambient air to make decisions on mixture richness. Without a properly functioning coolant sensor, it's a like a carb with no choke...lousy driveability cold, OK warm.
So that might be worth a look.
That said, what the OP is describing could pass as a coolant sensor failure (or a lot of other things). Since TBI does not have a "choke", the computer is looking at coolant temp and ambient air to make decisions on mixture richness. Without a properly functioning coolant sensor, it's a like a carb with no choke...lousy driveability cold, OK warm.
So that might be worth a look.
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