This weekend I did the Jeep throttle body modification authored by Metal Jim at http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html. In addition, I also bored out my intake manifold to match the diameter on the throttle body. DAAAAMN! Huge difference, I am very happy with the results, it feels so good! Thanks Jim! However, I had a few minor problems and have a few questions.

My car now idles at 2400 rpm. Could this be a vacuum leak, or a spring tension problem?

Directions on mounting the spring was a little unclear to me. Any info that can tell me exactly how will help.

How about resetting the ECU? The provided link for boring out the throttle body instructs you to reset the ECU once everything is assembled, should we also do this? Could this be related to my idle problem?

My gas pedal is very touchy now. I am barely pressing down on it (less than a couple of inches). Spring tension related maybe?

Off the record: Looking inside my manifold, I noticed how rough the inside surface is. Will smoothing this out also give a power gain?I assume it will, can someone post a link that will tell me how to do this?

Any info would be very helpful, and thanks in advance!:thumbsup

I actually reset my ecu after trying to troubleshoot my idle and cel problems after installing my 60mm tb, once reset everything was ok. This is how I did it, first disconnect the ground wire and wait for about 10 min then reconnect it, start it up and you should be ok.

Glad to see another jeep conversion :thumbsup

The high idle is most likely either a vaccuum leak or a throttle cable adjustment issue. Get the engine running, pop the hood, and see if you can lower the idle by turning the throttle shaft all the way closed by hand. If the idle goes down at all, then you have to loosen the throttle cable more. If it goes down to normal, then you only have to adjust the cable and you should be good to go. If it doesn't go all the way down to normal then you have a vaccuum leak. Make sure the idle port it sealed properly. Inspect the indents on the gasket and make sure that it is sealing well. Also make sure that the TB is tightened down good.

You used one of the Jeep springs right? Install the spring on so the bent end is against the shaft's spring rest. There's a picture in the writeup, it's the last picture in the spring section. It shows how the spring should be inserted onto the shaft. It's one of the smaller pictures and I guess it's a little hard to see, but look close at that one. It shows how the bent end of the spring rests against the spring rest. Then when you install the shaft, wind some tension on the spring untill you can fit the straight end of it into the little divot on the base of the TB. This little divit is at "center bore" right on the base plate. I outlined the divot in green in the picture where I discuss modifying the base plate.

Generally throttle response is a bit more touchy with the bigger TB. It could be a bit more drastic for you right now cause of the high idle. It might get a little better after you fix the problem, but yeah - it should be a bit more touchy.


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

ok Jim I will give these a try, won't be able yo get to it untill the weekend though. I can manage it for now. Today I plugged in a datalogger and got two error codes, hoping you might be able to help:

P0403 and and P1294

I know P0403 is for the EGR valve, which I went ahead and blocked off at the same time I did this mod. The other we couldn't figure out. I would look it up in my manual, however I don't have it here at the moment.

Another thing I am looking for, do you know of any good write up's for for porting and polishing out our intake manifold, runners, and exhaust manifold? I found a pretty good write up at neons.org, but I don't know if it is exactly like ours. Thanks!

Thanks for the write up and info:thumbsup

P1294 is target idle not reached within 200rpm. That should go away once you fix the high idle.

Here are some of my pictures and thoughts about porting the intake manifold - http://forums.2gnt.com/dcboard.php?az=show_topic&forum=32&topic_id=141

I have ported the exhaust manifold. Again, with the exhaust manifold it is impossible to get all the way in all of the runners. There is quite a bit of accessable casting flash that can be removed. You can thin out the X in the collector quite a bit. You can open up the outlet on the collecter a little and give the outer walls in the collecter a much smoother angle to the outlet. I did as much as I could with mine, but it really didn't give that much of a gain(nothing noticable).


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

Wow thats a pretty long post, I will have to read that later because right now I just don't have the time.

What tools did you use for your porting? Did you use a dremmel to do everything? If you did, what did you have to buy? I want to port and polish my exhaust manifold before I do the intake manifold and runners because I have never done this before and I want to get the feel for it first. I know The exhaust is harder material, though I will compensate for that. I did find some cheap Pacesetter headers in the JC Whitney catalog under $200, I was thinking of maybe going that route for the time being.

Ultimately, with my Eclipse, I want to attempt the 2.4L transplant. This project, I know I will have to combine what I have learned over the past year (i did a lot of research and reading), and my job skills (I am a Design Engineer for NASA) to get this done. In addition, I can get help from some electrical and mechanical engineers that I work with. However, before I do this I have to finish paying the car off (3 more payments!), and not get layed off (thanks to George W!).

Oh yeah, before I go, since the Jeep Throttle Body conversion is your baby, do you mind if I measure, model, and make a drawing with precise calculations for this? The reason I ask, when I take off the intake and exhaust mainfolds, and the runners to port and polish them, I plan to measure up, model them into CAD, and create precise drawings for use if someone wants to take them to a machinist or get them extrude honed. I may even do some sort of stress, heat, and air flow analysis to determine the best possible configuration.

I am going to do all your suggestions this weekend, find my problem, and fix it. I think it is something with the throttle cable, because, when I take my foot off the gas, and it starts idling high, I pull the gas peddle up a little from the bottom and it goes down.

Again, thanks for all the info and the post! I have been smiling ear to ear since I did this and honestly, I can't wait to smoke a couple Honda's and Acura's. If I run into any problems I will try and make a post this weekend to get an answer. Again, I can't thank you enough!

oh, sorry for the long post

Need a 3D CAD model or drawing for a part or assembly? I can help, e-mail me at Pas_Eclipse@yahoo.com for info.

Yep had the same problem. Had to readjust the throttle cable so that the plate would fully close. Just in case readjusting doesn't work . . .
http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=46548
Another topic that might help.

Btw I have the Modern Perf. 60mm Tb.