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| 3800sc Swap Complete Parts List (Page 12/13) |
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enicho1
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DEC 26, 07:35 AM
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I am hoping you might have some advice on where I can start looking for a throttle issue I’m having.
I bought a 1984 Fiero 3800 supercharged conversion from an auction, and has the 4T65E Automatic Transmission.
It will start and idle fine, but trying to drive down my street causes it to sputter and die out if I try to give it only the slightest amount of gas pedal.
I have to just idle it in and out of my driveway or down the street.
I tested the fuel pressure at 41 psi at idle (using a fuel test kit gauge on the Schrader valve on the fuel rail), and did several throttle rev bumps. It holds fuel pressure, but not sure of the fuel psi when I try to drive as I don’t have an actual fuel gauge inside the car.
The boost actuator moves by hand (engine off) and it will move a little when rev bumped (I can see it slightly move).
I also put a vacuum pump on to make sure it will work and seems to be operating properly using a test hand pump hooked up to it.
For the boost solenoid, I put my ohm meter on the boost solenoid pins and get no resistance, just open… so I know that it is bad.
However, I would assume a bad boost solenoid would be poor performance but I would think I could still drive the car… I don’t know though.
I just ordered the boost solenoid, and I will install it when it gets delivered.
I have also replaced the coil packs and the ignition control module (when I installed new coil packs).
I’m at a loss right now and not sure what to focus on.
I bought it at auction so I don’t know much about the engine other than there is a tag on the engine and transmission indicating Jasper Engines.
It has a long snout supercharger.
I was looking at parts referencing a 2004 Grand Prix GTP, and the coil packs, ignition control module, and boost solenoid all so far are correct replacements.
There doesn’t appear to be any vacuum leaks that I can find.
I’m at a loss and hoping there are suggestions on what I could look at next.
Forgot to add that there isn’t any codes triggered either. It’s an OBD2 computer also with the scanner port mounted on the trunk wall for easy access (not that it matters on the scan port location, but just figured add all the details I know) .
The fuel gauge doesn’t work either, which initially caused me to spin my own wheels on trouble shooting why the car wouldn’t start after parking it back in my driveway after several test drive runs.
I added a gallon or two and continued my journey on trying to figure this problem out.
Anyway, I’m stuck so hopefully someone has an idea or two…or three or …. Twenty ideas…  [This message has been edited by enicho1 (edited 12-26-2024).]
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AustinH
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DEC 26, 02:50 PM
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| quote | Originally posted by enicho1:
I am hoping you might have some advice on where I can start looking for a throttle issue I’m having.
I bought a 1984 Fiero 3800 supercharged conversion from an auction, and has the 4T65E Automatic Transmission.
It will start and idle fine, but trying to drive down my street causes it to sputter and die out if I try to give it only the slightest amount of gas pedal.
I have to just idle it in and out of my driveway or down the street.
I tested the fuel pressure at 41 psi at idle (using a fuel test kit gauge on the Schrader valve on the fuel rail), and did several throttle rev bumps. It holds fuel pressure, but not sure of the fuel psi when I try to drive as I don’t have an actual fuel gauge inside the car.
The boost actuator moves by hand (engine off) and it will move a little when rev bumped (I can see it slightly move).
I also put a vacuum pump on to make sure it will work and seems to be operating properly using a test hand pump hooked up to it.
For the boost solenoid, I put my ohm meter on the boost solenoid pins and get no resistance, just open… so I know that it is bad.
However, I would assume a bad boost solenoid would be poor performance but I would think I could still drive the car… I don’t know though.
I just ordered the boost solenoid, and I will install it when it gets delivered.
I have also replaced the coil packs and the ignition control module (when I installed new coil packs).
I’m at a loss right now and not sure what to focus on.
I bought it at auction so I don’t know much about the engine other than there is a tag on the engine and transmission indicating Jasper Engines.
It has a long snout supercharger.
I was looking at parts referencing a 2004 Grand Prix GTP, and the coil packs, ignition control module, and boost solenoid all so far are correct replacements.
There doesn’t appear to be any vacuum leaks that I can find.
I’m at a loss and hoping there are suggestions on what I could look at next.
Forgot to add that there isn’t any codes triggered either. It’s an OBD2 computer also with the scanner port mounted on the trunk wall for easy access (not that it matters on the scan port location, but just figured add all the details I know) .
The fuel gauge doesn’t work either, which initially caused me to spin my own wheels on trouble shooting why the car wouldn’t start after parking it back in my driveway after several test drive runs.
I added a gallon or two and continued my journey on trying to figure this problem out.
Anyway, I’m stuck so hopefully someone has an idea or two…or three or …. Twenty ideas…
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Hey couple of checks -
0 - always check engine codes... Good that you did but always start there! Autozone/Oreillys/Advance/Napa have good scanners you can ask to use for free.
1 - Make sure you put more than a gallon or two in the tank - try at least 5 gallons - the baffling in the tank is not great and the pump will run dry if you hit the throttle since that will cause the fuel to slosh to the back of the tank.
2 - Check out the diagrams for the vacuum routings in this post under "Supercharger, connections, and routings": https://www.fiero.nl/forum/.../HTML/139530.html#p9
3- that boost solenoid really can just be removed and the nipple vented to atmosphere instead of connected as in the diagram. It is only a boost relief under high boost conditions, and not normally used on a Fiero because the harness makers don't usually include the wiring for it.
4 - Ensure that your fuel pressure regulator is boost referenced with a vacuum hose going to the lower intake manifold, as shown in the diagram.
Good luck!
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enicho1
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DEC 26, 05:27 PM
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| quote | Originally posted by AustinH:
Hey couple of checks -
0 - always check engine codes... Good that you did but always start there! Autozone/Oreillys/Advance/Napa have good scanners you can ask to use for free.
1 - Make sure you put more than a gallon or two in the tank - try at least 5 gallons - the baffling in the tank is not great and the pump will run dry if you hit the throttle since that will cause the fuel to slosh to the back of the tank.
2 - Check out the diagrams for the vacuum routings in this post under "Supercharger, connections, and routings": https://www.fiero.nl/forum/.../HTML/139530.html#p9
3- that boost solenoid really can just be removed and the nipple vented to atmosphere instead of connected as in the diagram. It is only a boost relief under high boost conditions, and not normally used on a Fiero because the harness makers don't usually include the wiring for it.
4 - Ensure that your fuel pressure regulator is boost referenced with a vacuum hose going to the lower intake manifold, as shown in the diagram.
Good luck! |
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Very much appreciated!
Thank you for the help
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Will
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DEC 27, 08:29 AM
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| quote | Originally posted by AustinH:
3- that boost solenoid really can just be removed and the nipple vented to atmosphere instead of connected as in the diagram. It is only a boost relief under high boost conditions, and not normally used on a Fiero because the harness makers don't usually include the wiring for it.
Good luck! |
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You're not talking about the bypass solenoid, are you?
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AustinH
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DEC 27, 03:02 PM
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| quote | Originally posted by Will:
You're not talking about the bypass solenoid, are you? |
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I am. I have run it that way for a while. I think it still comes open during idle but not during boost. Reason being is because James did not wire up the solenoid in my harness, which would switch it to lower intake manifold pressure or vent to atmosphere depending on whether it the computer wants to bypass the boost. Instead of switching between, it is just always vented, to atmosphere in my case. Would be curious to how others set it up.
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enicho1
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DEC 27, 05:54 PM
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enicho1
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DEC 27, 08:11 PM
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I installed a new boost solenoid, but I tried a couple things with the vacuum hoses.
I also filled it full of gas (10 gallons of 91 octane).
I took one of the caps off the boost solenoid and plugged on that free boost actuator vacuum hose (that 2”-3” that wasn’t connected to anything else).
So now the boost solenoid has 2 vacuum lines plugged into it.
I drove the car all around and it ran fine now, no more sputtering and dying out.
However, it didn’t feel like I had any engine power or any torque.
I then unplugged that vacuum line from the boost solenoid and put the cap back on it.
That is how it originally was (as in the photo), and took it for a drive.
Now I hear the whine a lot louder from the supercharger and it much better torque and power wise.
However, it’s not the monster I was expecting, but at least it drives and is quick.
I’m guessing the problem was not enough gas in the tank.
The gas gauge does seem to work as it is now showing full, but when it was dead empty, it showed I had between a quarter and a half tank (more than a quarter, but less than half tank).
When I put about 5 gallons in, it put it to about three-fourths of a tank.
Anyway, my temperature gauge doesn’t work, so I need to get that figured out.
My speedometer also doesn’t work.
The RPM and battery gauges do work though.
I want to install a boost gauge to see what is actually happening, and an oil pressure gauge would be nice too.
I appreciate the help.
I will update when I get these gauges fixed and/or figured out.
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AustinH
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DEC 27, 09:58 PM
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| quote | Originally posted by enicho1:
Figured I would post some photos of the engine.
The Solenoid has 1 vacuum line attached and the 2-prong plug, the other 2 vacuum ports on the Solenoid are capped off.
The boost Actuator has 1 vacuum line attached on the upper port, the lower port has a short vacuum hose attached (about 2”-3” long) but it isn’t connected to anything else.
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Very nice setup.
I don't have that solenoid at all but looks like it's wired on your rig; you could keep it or you could cap it off.
You can see that the bottom hose coming out of the round boost bypass valve diaphragm (what you called actuator) is already vented to atmosphere. It should have been going to 1 of the 2 ports on the solenoid switch (not sure which one) if it were hooked up properly. You may have a vacuum leak through that solenoid; cap that off or hook it back up properly to the boost bypass valve diaphragm (what you call actuator). This may be messing with your boost signal from your MAP sensor.
| quote | Originally posted by enicho1:
Can you tell what type of 3800 this is (Type 3 or Type 4 … or L32 or L67)?
The fuel pressure regulator is connected to a vacuum port on the intake just under the snout… under the supercharger (photo)
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This is a L67 Series II 3800 Supercharged motor.
The regulator connection looks good.
| quote | Originally posted by enicho1:
I took one of the caps off the boost solenoid and plugged on that free boost actuator vacuum hose (that 2”-3” that wasn’t connected to anything else).
So now the boost solenoid has 2 vacuum lines plugged into it.
I drove the car all around and it ran fine now, no more sputtering and dying out.
However, it didn’t feel like I had any engine power or any torque.
I then unplugged that vacuum line from the boost solenoid and put the cap back on it.
That is how it originally was (as in the photo), and took it for a drive.
Now I hear the whine a lot louder from the supercharger and it much better torque and power wise.
However, it’s not the monster I was expecting, but at least it drives and is quick.
I’m guessing the problem was not enough gas in the tank.
The gas gauge does seem to work as it is now showing full, but when it was dead empty, it showed I had between a quarter and a half tank (more than a quarter, but less than half tank).
When I put about 5 gallons in, it put it to about three-fourths of a tank.
Anyway, my temperature gauge doesn’t work, so I need to get that figured out.
My speedometer also doesn’t work.
The RPM and battery gauges do work though.
I want to install a boost gauge to see what is actually happening, and an oil pressure gauge would be nice too.
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You just experienced the boost bypass valve being in bypass mode 100% of the time vs. not on at all. You may have plugged it into the wrong port on that solenoid. Either way, the solenoid, if not working, probably needs to be removed from the system, and that line going to it needs to be capped off, and the lower boost bypass actuator diaphragm just vented to atmosphere, or maybe you could leave it the way it is.
The supercharger whining is when it is under boost, that is a good step
5 gallons + 2 gallons = 7 gallons. 7/10 gallons = ~3/4 tank so i would say that is accurate. Otherwise a new fuel sender can be bought here - https://www.fierostore.com/...px?s=60912&d=240&p=1 otherwise you can rig something custom, it's just a potentiometer on an arm. It may be the arm is getting stuck inside the tank and needs to be bent carefully into the right position.
Now you need to get it a good tune!
Check my wiring diagram section for info about the speedometer: https://www.fiero.nl/forum/...HTML/139530.html#p11
You can buy a speedometer "buffer" circuit described in there if your car does not have one: https://reddevilriver.com/h...peedo-buffer-circuit
Anyways, any time! Good luck!![This message has been edited by AustinH (edited 12-27-2024).]
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enicho1
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DEC 27, 11:22 PM
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Right on!
Thank you very much!
I really appreciate the help and everything.
This is great.
👍
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Will
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DEC 28, 08:02 AM
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| quote | Originally posted by AustinH:
I am. I have run it that way for a while. I think it still comes open during idle but not during boost. Reason being is because James did not wire up the solenoid in my harness, which would switch it to lower intake manifold pressure or vent to atmosphere depending on whether it the computer wants to bypass the boost. Instead of switching between, it is just always vented, to atmosphere in my case. Would be curious to how others set it up. |
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Yeah, bypass valve very necessary for driving anywhere other than on a drag strip
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