Throttle Body issue
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Trailering
Joined: Feb 2024
Posts: 20
Likes: 1
From: East TN
Throttle Body issue
Hello!
I have a Manual 4 spd/overdrive 1988 f150 with the 302 5.0 engine, I recently cleaned the throttle body, changed the egr valve, IAC valve, TPS sensor, and air filter in order to fix idle problems. I now have a sticking gas pedal that causes it to run wide open every time I hit the gas. went to order new throttle body from Rock Auto and they're out of stock. I could only find BBK performance throttle bodies online, and holy crap are they expensive! also, they have what looks like an extra vacuum port in between the two throttle ports on the body that mine doesn't have. will those throttle bodies work in the event I can't find the exact one I need? or is there a way I can fix mine? any tips appreciated.
I have a Manual 4 spd/overdrive 1988 f150 with the 302 5.0 engine, I recently cleaned the throttle body, changed the egr valve, IAC valve, TPS sensor, and air filter in order to fix idle problems. I now have a sticking gas pedal that causes it to run wide open every time I hit the gas. went to order new throttle body from Rock Auto and they're out of stock. I could only find BBK performance throttle bodies online, and holy crap are they expensive! also, they have what looks like an extra vacuum port in between the two throttle ports on the body that mine doesn't have. will those throttle bodies work in the event I can't find the exact one I need? or is there a way I can fix mine? any tips appreciated.
Fleet Mechanic
Joined: Aug 2015
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From: Candy Mountain
Hotshot
Joined: Jun 2015
Posts: 12,783
Likes: 2,422
I don’t understand how the throttle is now “sticking wide open” after you cleaned it. Did you break the return springs when you cleaned the throttle body? With the engine off, disconnect the cable and then manually open the throttle. Does it snap closed or is it staying wherever you left it?
Are you sure the TPS is oriented correctly? It is possible to have the tabs on the throttle body and sensor wrong which will send the wrong (open throttle) voltage to the computer.
Why did you replace those parts in the first place? The BBK part has three vacuum ports because it is generic replacement for all years. It comes with vacuum caps to block off the unused port(s) for your application. IMO, they are junk. If yours is actually broken, I would find a used OEM part.
Are you sure the TPS is oriented correctly? It is possible to have the tabs on the throttle body and sensor wrong which will send the wrong (open throttle) voltage to the computer.
Why did you replace those parts in the first place? The BBK part has three vacuum ports because it is generic replacement for all years. It comes with vacuum caps to block off the unused port(s) for your application. IMO, they are junk. If yours is actually broken, I would find a used OEM part.
Thread Starter
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Trailering
Joined: Feb 2024
Posts: 20
Likes: 1
From: East TN
I don’t understand how the throttle is now “sticking wide open” after you cleaned it. Did you break the return springs when you cleaned the throttle body? With the engine off, disconnect the cable and then manually open the throttle. Does it snap closed or is it staying wherever you left it?
Are you sure the TPS is oriented correctly? It is possible to have the tabs on the throttle body and sensor wrong which will send the wrong (open throttle) voltage to the computer. Why did you replace those parts in the first place?
Are you sure the TPS is oriented correctly? It is possible to have the tabs on the throttle body and sensor wrong which will send the wrong (open throttle) voltage to the computer. Why did you replace those parts in the first place?
Thread Starter
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Trailering
Joined: Feb 2024
Posts: 20
Likes: 1
From: East TN
Fleet Owner
Joined: Oct 2005
Posts: 20,784
Likes: 1,751
From: Kentucky
The extra ports are for the EVAP system. Some model years/engines use one port, others two ports. Then you have the early EFI with no ports. Perfectly fine to cap those off if not needed in your application.
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Cross-Country
Joined: Dec 2023
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From: Los Angeles
If the BBK throttle body has an extra hole for air that your truck doesn't use, you might have to close it up if your engine doesn't need it. But you have to be careful doing this to make sure air doesn't leak where it shouldn't.
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Thread Starter
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Trailering
Joined: Feb 2024
Posts: 20
Likes: 1
From: East TN
Thank you! I did not know if I could cap that or if it needed to be hooked up to something. Rock auto has one for manual trans and another that does not specify. Thank you again!
Thread Starter
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Trailering
Joined: Feb 2024
Posts: 20
Likes: 1
From: East TN
I don’t understand how the throttle is now “sticking wide open” after you cleaned it. Did you break the return springs when you cleaned the throttle body? With the engine off, disconnect the cable and then manually open the throttle. Does it snap closed or is it staying wherever you left it?
Are you sure the TPS is oriented correctly? It is possible to have the tabs on the throttle body and sensor wrong which will send the wrong (open throttle) voltage to the computer.
Why did you replace those parts in the first place? The BBK part has three vacuum ports because it is generic replacement for all years. It comes with vacuum caps to block off the unused port(s) for your application. IMO, they are junk. If yours is actually broken, I would find a used OEM part.
Are you sure the TPS is oriented correctly? It is possible to have the tabs on the throttle body and sensor wrong which will send the wrong (open throttle) voltage to the computer.
Why did you replace those parts in the first place? The BBK part has three vacuum ports because it is generic replacement for all years. It comes with vacuum caps to block off the unused port(s) for your application. IMO, they are junk. If yours is actually broken, I would find a used OEM part.
this is the one that is currently on my engine. right above the red tag there is an added port on all the other throttle bodies, just wanted to clarify that we are talking about the same port.
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
Hotshot
Joined: Jul 2020
Posts: 10,331
Likes: 2,585
From: Near Salt Lake City
I would get a good used throttle body from the junkyard
In the future, clean the plate every 30k miles
Only clean one using carb foam with the engine running
Never soak one or remove the staked in throttle plate screws
In the future, clean the plate every 30k miles
Only clean one using carb foam with the engine running
Never soak one or remove the staked in throttle plate screws
Hotshot
Joined: Jun 2015
Posts: 12,783
Likes: 2,422
I use throttle body cleaner because it is supposed to be safe for coated throttle bodies.
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