1984 4+3
Thread Starter
Intermediate
Joined: Jun 2020
Posts: 31
Likes: 0
From: Fulton,NY
1984 4+3
Don’t want to beat a dead horse here, 1984 corvette 4+3,Runs great maybe a little lean seems like at around 1800-2000 rpms but we can talk later about that. After warm up and a shut off I get a dead hesitation off idle After a restart, This is after it’s at temp, Happens every time, TPS was defective when I bought it so it’s new, .54 volts, New fuel pump, new rebuild on the throttle bodies no idle issues, new cap rotor coil module plugs wires all AC Delco, It’s more annoying than anything but no check engine light new O2 sensor 🤷🏼♂️ Just looking for anyone that’s been here Thank you
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Don’t want to beat a dead horse here, 1984 corvette 4+3,Runs great maybe a little lean seems like at around 1800-2000 rpms but we can talk later about that. After warm up and a shut off I get a dead hesitation off idle After a restart, This is after it’s at temp, Happens every time, TPS was defective when I bought it so it’s new, .54 volts, New fuel pump, new rebuild on the throttle bodies no idle issues, new cap rotor coil module plugs wires all AC Delco, It’s more annoying than anything but no check engine light new O2 sensor 🤷🏼♂️ Just looking for anyone that’s been here Thank you
Pro
Joined: Apr 2001
Posts: 744
Likes: 13
From: Lenoir City TN
Don’t want to beat a dead horse here, 1984 corvette 4+3,Runs great maybe a little lean seems like at around 1800-2000 rpms but we can talk later about that. After warm up and a shut off I get a dead hesitation off idle After a restart, This is after it’s at temp, Happens every time, TPS was defective when I bought it so it’s new, .54 volts, New fuel pump, new rebuild on the throttle bodies no idle issues, new cap rotor coil module plugs wires all AC Delco, It’s more annoying than anything but no check engine light new O2 sensor 🤷🏼♂️ Just looking for anyone that’s been here Thank you
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
If its just after it restarts... possible it hasn't gone to closed loop and any compensation it would have isn't there and it does it.
Also. .54 is a little high on tps. .525 is better.. are you measuring that with the scan tool or back probing?
Also. .54 is a little high on tps. .525 is better.. are you measuring that with the scan tool or back probing?
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Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
The engine doesn't care. It cares about the fuel pressure though. What is the fuel pressure?
First, if you replaced it with an '84 CFI fuel pump, it's somewhat likely that it could struggle to reach proper fuel pressure -the '84 pump design is weak.
Second, who knows what the regulator is set at? Spec is 9-12 lbs, IIRC. That range represents a whopping 25% swing. Is it likely that it'll run as good at 9 lbs as it should? Not very.
Third, these car typically seem to "like" about 13 lbs or so -above the high end of the spec. SO...it's quite unlikely that your pressure is where the engine would "like" it to be.
Finally, you didn't mention a fuel filter replacement.
If I were you.....I'd check the fuel pressure.
First, if you replaced it with an '84 CFI fuel pump, it's somewhat likely that it could struggle to reach proper fuel pressure -the '84 pump design is weak.
Second, who knows what the regulator is set at? Spec is 9-12 lbs, IIRC. That range represents a whopping 25% swing. Is it likely that it'll run as good at 9 lbs as it should? Not very.
Third, these car typically seem to "like" about 13 lbs or so -above the high end of the spec. SO...it's quite unlikely that your pressure is where the engine would "like" it to be.
Finally, you didn't mention a fuel filter replacement.
Runs great maybe a little lean seems like at around 1800-2000 rpms. After warm up and a shut off I get a dead hesitation off idle After a restart,
Thread Starter
Intermediate
Joined: Jun 2020
Posts: 31
Likes: 0
From: Fulton,NY
Just replaced the filter today,The throttle bodies were rebuilt with new regulators two weeks ago, Nothing I mean nothing has changed the way it runs, It’s not horrible as I said earlier but not a vast improvement either, Could possibly be in expecting more from the old girl than she has to give as far as running goes, It’s all new except for the EVM and Map sensor, neither of witch I think there’s an issue with Thank you
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Sounds like you're talking yourself out of checking the fuel pressure.
I'll throw this out there: A properly running Crossfire should be SHARP, quick, feel fast and fun, all the time. Cold, warm, hot...all the time. It shouldn't have any "dead hesitations", or whatever. It should feel punchy, strong and have killer throttle response.
I'll throw this out there: A properly running Crossfire should be SHARP, quick, feel fast and fun, all the time. Cold, warm, hot...all the time. It shouldn't have any "dead hesitations", or whatever. It should feel punchy, strong and have killer throttle response.
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Just replaced the filter today,The throttle bodies were rebuilt with new regulators two weeks ago, Nothing I mean nothing has changed the way it runs, It’s not horrible as I said earlier but not a vast improvement either, Could possibly be in expecting more from the old girl than she has to give as far as running goes, It’s all new except for the EVM and Map sensor, neither of witch I think there’s an issue with Thank you
Last edited by Buccaneer; Jul 2, 2020 at 01:13 AM.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
I have a friend with a built 409 in his 'vette, and he was surprised how nicely my CFI '84 runs!!! That white one is my friends car, and we're having fun chasing a couple of ZR-1's on a twisty mountain road!