JennyTales24
Probationary Member
- 1
- 0
- Mar 5, 2022
-
Stevens Point,
Wisconsin
Hi, first post on the site, found no info here after doing a 3.8 throttle swap so I figured I'd write one up.
I discovered this swap as a possibility on the neon forums, and digging through their forums for hours I had a plan. I put 2 throttle bodies together, one for my stock auto RS, and one for my buddy's fbo 5mt GS, to get 2 benchmarks. Both cars have been daily driven for a month since this swap with no issues to confirm it does work.
This throttle swap is probably the best bang for buck with minimal modification. It's a direct bolt on compared to the jJeep throttle, with a bit less modification for a bit bigger opening. The Jeep is a 55mm vs the 3.8 van has a 58mm. The downside is you can't port the 3.8 throttle past 59mm where you could go to 62mm with the 4.0.
Caravan throttle body is the left side one, stock 420a is the right one.
What you need for the swap:
3.8 throttle body from 98-00 Grand Caravan or Chrysler Town and Country or possibly the Plymouth 3.8 van of the same year with the sensors on it (cost me 25$ at my local yard)
Sheet of gasket maker
Dremel and a cutoff wheel
T15, T20, T25 Torx bits
13mm
And about an hour in the garage
The 3.8 throttle actuates in the opposite direction of the 420a throttle. To make it work, you have to disassemble both throttle bodies, and swap the throttle shafts. To do this, you remove the IAC and TPS, pull the snap ring holding the throttle shaft in place, remove the 2 screws holding the butterfly in place, slide the butterfly out, then slide the throttle shaft through. Repeat on both throttle bodies, keeping the body, butterfly, sensor screws and IAC of the 3.8 throttle, and the sensors, shaft, shaft screws and throttle spring form the 420a.
Alright, so now you should have 2 disassembled throttle bodies and one pile of parts to make one throttle body. Clean everything in the keep pile with carb cleaner to get rid of any carbon buildup and to make it nice and shiny again.
Now its time for reassembly. To make the Eclipse shaft fit in the 3.8 throttle body, you have to cut off about half of the plastic spring seat, and to accommodate the larger butterfly, you have to notch out the slot for the 58mm butterfly
I left part of the seat on to show how far down you've gotta cut but you have to cut it all around
Now, with the shaft notched, slide it into the throttle body with the spring on, load the spring, slide the butterfly in, and screw it down. Screw in your throttle position sensor.
All that's left now, is the IAC. You use the Eclipse IAC with the tip of the 3.8 IAC. The tip unscrews from the sensor, unscrew both, screw the 3.8 tip into the Eclipse sensor. Install the IAC into the throttle body
Okay now you should have a fully assembled 58mm throttle body ready to bolt into your eclipse. Now its time to address the gasket. The IAC ports slightly overlap so you cannot just use the 3.8 gasket or the Eclipse gasket. Since I had both gaskets on hand, I lined them up on the sheet of gasket maker and traced the outside of both. You should be able to do the same with just the outside of both throttle bodies, lining up and tracing one at a time to make a gasket
And with the gasket made, you can install your new throttle body. It made a noticeable difference in both cars. You breathe on the pedal and it's at 2500rpm, It feels marginally faster, and it's incredibly more responsive. For the 30$ I spent, I couldn't be happier and figured it'd be worth sharing for those interested in another option for a cheap throttle body.
I discovered this swap as a possibility on the neon forums, and digging through their forums for hours I had a plan. I put 2 throttle bodies together, one for my stock auto RS, and one for my buddy's fbo 5mt GS, to get 2 benchmarks. Both cars have been daily driven for a month since this swap with no issues to confirm it does work.
This throttle swap is probably the best bang for buck with minimal modification. It's a direct bolt on compared to the jJeep throttle, with a bit less modification for a bit bigger opening. The Jeep is a 55mm vs the 3.8 van has a 58mm. The downside is you can't port the 3.8 throttle past 59mm where you could go to 62mm with the 4.0.
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Caravan throttle body is the left side one, stock 420a is the right one.
What you need for the swap:
3.8 throttle body from 98-00 Grand Caravan or Chrysler Town and Country or possibly the Plymouth 3.8 van of the same year with the sensors on it (cost me 25$ at my local yard)
Sheet of gasket maker
Dremel and a cutoff wheel
T15, T20, T25 Torx bits
13mm
And about an hour in the garage
The 3.8 throttle actuates in the opposite direction of the 420a throttle. To make it work, you have to disassemble both throttle bodies, and swap the throttle shafts. To do this, you remove the IAC and TPS, pull the snap ring holding the throttle shaft in place, remove the 2 screws holding the butterfly in place, slide the butterfly out, then slide the throttle shaft through. Repeat on both throttle bodies, keeping the body, butterfly, sensor screws and IAC of the 3.8 throttle, and the sensors, shaft, shaft screws and throttle spring form the 420a.
Alright, so now you should have 2 disassembled throttle bodies and one pile of parts to make one throttle body. Clean everything in the keep pile with carb cleaner to get rid of any carbon buildup and to make it nice and shiny again.
Now its time for reassembly. To make the Eclipse shaft fit in the 3.8 throttle body, you have to cut off about half of the plastic spring seat, and to accommodate the larger butterfly, you have to notch out the slot for the 58mm butterfly
You must be logged in to view this image or video.
I left part of the seat on to show how far down you've gotta cut but you have to cut it all around
Now, with the shaft notched, slide it into the throttle body with the spring on, load the spring, slide the butterfly in, and screw it down. Screw in your throttle position sensor.
All that's left now, is the IAC. You use the Eclipse IAC with the tip of the 3.8 IAC. The tip unscrews from the sensor, unscrew both, screw the 3.8 tip into the Eclipse sensor. Install the IAC into the throttle body
Okay now you should have a fully assembled 58mm throttle body ready to bolt into your eclipse. Now its time to address the gasket. The IAC ports slightly overlap so you cannot just use the 3.8 gasket or the Eclipse gasket. Since I had both gaskets on hand, I lined them up on the sheet of gasket maker and traced the outside of both. You should be able to do the same with just the outside of both throttle bodies, lining up and tracing one at a time to make a gasket
And with the gasket made, you can install your new throttle body. It made a noticeable difference in both cars. You breathe on the pedal and it's at 2500rpm, It feels marginally faster, and it's incredibly more responsive. For the 30$ I spent, I couldn't be happier and figured it'd be worth sharing for those interested in another option for a cheap throttle body.
You must be logged in to view this image or video.
