Tweet
I got some good info from this site in order to get this done. Already posted on A-body.
Needed to change the LIM gaskets on my 1996 Ciera and decided swap the heads and intake manifolds for the larger 3400 and later 3100 ones. This is a pretty popular swap in the N and W body communities, and I know of at least SilentWing's A body (1994 Ciera) with this swap. I used the heads and throttle body from a 2002 3400 Grand Am, and the upper and lower intake manifolds from a 2001 3100 Grand Prix (because I happened to throw the Grand Am manifolds on my sister's car before I started on my own, ha). To my knowledge, this is the first time that the more modern 56mm plate throttle body has been swapped in on an A body.
This is the front end of a 1996-1998 W or H body 3800 throttle body. This one in particular was off a 1996 LeSabre. I hacksawed this off a the junkyard, just after the MAF. As you can see, a short piece of correct-sized rubber intake hose has been attached to the hacksaw end. It's attached with some stuff from Home Depot called Stick 'n Seal. I plumbed this in ahead of the 2002 Grand Am throttle body with my Ciera's original MAF mounted in it, in lieu of the Ciera's original setup, wherein the MAF mounts in the throttle body.
This is how I tested the special MAF piece for measurement accuracy. Here, you can see the MAF in the center of the photo mounted into the throttle body. In the bottom right corner, you can see the air duct has been pulled off the air cleaner and the new MAF piece is plumbed in right ahead of the throttle body. With everything set up as pictured, I used my OBDII scan tool to measure the MAF reading for several different throttle position readings. Then, I moved the MAF out of the throttle body and into the new piece on the right, where the duct tape is in the picture. Then I stuck the duct tape over the hole in the throttle body where the MAF had been. I then measured MAF readings for the same TPS readings. My results showed very little disparity--less than 1%. My earlier attempt at an alternate MAF setup was the more obvious one--most mid-90's and up 60 degree engines have a MAF that is designed to be inline in the intake ducting. My sister's 1996 3100 Grand Prix has such a MAF. However, it gave large discrepancies in reading of up to 30%. Another option I considered was the 3300 MAF piece. It's much like the piece I sawed off the LeSabre, but bolted onto the throttle body as opposed to built into it. However this piece had a small airflow diameter and would have been restrictive. My piece's diameter was much larger than the throttle plate on the TB I put in.
Top end is disassembled. Ready to install 2002 Grand Am heads, with a fresh valve job. On the right you can see the throttle cable I used. I thought a 1996 3400 U-van cable might be a perfect fit and it was close but I still had to rig it a bit as it was a touch too long. The original throttle cable for these 1994-1996 3100 A-body cars is goofy and would have never worked, moral of the story is that you have to replace it with something. Anyways the big-valve heads go on just like the old ones, just remove and transfer any brackets (I had two).
The LIM is known to require just this one modification--the water pipe coming off the back of thermostat housing. On the old LIMs, this pipe goes on with a threaded fitting. On the new LIMs, it's a 'press-in' pipe. Pictured is the new LIM. I chopped the press-in pipe that came with this LIM down to an inch-long stub, then installed it back in its hold with fresh gray RTV. I took the old pipe (right of this picture) out the original manifold, and removed the threaded fitting off the pipe. I used about a 2-inch piece of correct-sized rubber water hose to join the stub in the manifold and the old pipe, which conveniently provides an inlet and outlet for the throttle body. Alternatively, others have used a 7/8" NPT tap on the new LIM and simply used the old pipe and fitting. My local hardware store stocked 3/4" NPT but not 7/8".
And the main consideration with the UIM is the EGR. The vertical-mount EGR that came with the manifold must be used, along with its tube to the exhaust manifold--the old tube won't work. You can see the thermostat housing plumbing below.
Wiring for IAC, TPS, MAF, IAT, etc. If you use the 56mm plate throttle body like I did, you must undo the jackets around these wires for all the plugs to reach.
New TPS has a different plug style but same three wires, right down the the colors. Just have to chop off old plug wire in the correct plug for the new TPS. You can also see the new throttle body plumbing here, a couple carefully chosen molded rubber hoses from AutoZone work well.
The U-van throttle cable was a bit long. I threaded it through the thing it goes in, out the hole at the end, and put an aluminum sleeve at the knob end of the cable to get rid of the slack. It works fine but is a bit sketchy for permanent use.
The intake duct that originally went to the 2002 Grand Am's throttle body must be used. I used Stick 'n Seal to attach my MAF rig to the end of that duct. And yeah, for the time being, some Home Depot dryer duct runs from the MAF to the original air cleaner.
One thing I did not grab from the Grand Am and need to get is the ventilation hose from the rear valve cover to the intake duct. That's another thing you need in order to use the new throttle body.
Car has been going 50 miles round trip to work since I finished this last Thursday and feels great. About the same off the line but the difference is huge at higher speeds and revs, speeding up 50 to 70 on the highway for example this engine used to be a dog but now much more responsive.
Needed to change the LIM gaskets on my 1996 Ciera and decided swap the heads and intake manifolds for the larger 3400 and later 3100 ones. This is a pretty popular swap in the N and W body communities, and I know of at least SilentWing's A body (1994 Ciera) with this swap. I used the heads and throttle body from a 2002 3400 Grand Am, and the upper and lower intake manifolds from a 2001 3100 Grand Prix (because I happened to throw the Grand Am manifolds on my sister's car before I started on my own, ha). To my knowledge, this is the first time that the more modern 56mm plate throttle body has been swapped in on an A body.
This is the front end of a 1996-1998 W or H body 3800 throttle body. This one in particular was off a 1996 LeSabre. I hacksawed this off a the junkyard, just after the MAF. As you can see, a short piece of correct-sized rubber intake hose has been attached to the hacksaw end. It's attached with some stuff from Home Depot called Stick 'n Seal. I plumbed this in ahead of the 2002 Grand Am throttle body with my Ciera's original MAF mounted in it, in lieu of the Ciera's original setup, wherein the MAF mounts in the throttle body.
This is how I tested the special MAF piece for measurement accuracy. Here, you can see the MAF in the center of the photo mounted into the throttle body. In the bottom right corner, you can see the air duct has been pulled off the air cleaner and the new MAF piece is plumbed in right ahead of the throttle body. With everything set up as pictured, I used my OBDII scan tool to measure the MAF reading for several different throttle position readings. Then, I moved the MAF out of the throttle body and into the new piece on the right, where the duct tape is in the picture. Then I stuck the duct tape over the hole in the throttle body where the MAF had been. I then measured MAF readings for the same TPS readings. My results showed very little disparity--less than 1%. My earlier attempt at an alternate MAF setup was the more obvious one--most mid-90's and up 60 degree engines have a MAF that is designed to be inline in the intake ducting. My sister's 1996 3100 Grand Prix has such a MAF. However, it gave large discrepancies in reading of up to 30%. Another option I considered was the 3300 MAF piece. It's much like the piece I sawed off the LeSabre, but bolted onto the throttle body as opposed to built into it. However this piece had a small airflow diameter and would have been restrictive. My piece's diameter was much larger than the throttle plate on the TB I put in.
Top end is disassembled. Ready to install 2002 Grand Am heads, with a fresh valve job. On the right you can see the throttle cable I used. I thought a 1996 3400 U-van cable might be a perfect fit and it was close but I still had to rig it a bit as it was a touch too long. The original throttle cable for these 1994-1996 3100 A-body cars is goofy and would have never worked, moral of the story is that you have to replace it with something. Anyways the big-valve heads go on just like the old ones, just remove and transfer any brackets (I had two).
The LIM is known to require just this one modification--the water pipe coming off the back of thermostat housing. On the old LIMs, this pipe goes on with a threaded fitting. On the new LIMs, it's a 'press-in' pipe. Pictured is the new LIM. I chopped the press-in pipe that came with this LIM down to an inch-long stub, then installed it back in its hold with fresh gray RTV. I took the old pipe (right of this picture) out the original manifold, and removed the threaded fitting off the pipe. I used about a 2-inch piece of correct-sized rubber water hose to join the stub in the manifold and the old pipe, which conveniently provides an inlet and outlet for the throttle body. Alternatively, others have used a 7/8" NPT tap on the new LIM and simply used the old pipe and fitting. My local hardware store stocked 3/4" NPT but not 7/8".
And the main consideration with the UIM is the EGR. The vertical-mount EGR that came with the manifold must be used, along with its tube to the exhaust manifold--the old tube won't work. You can see the thermostat housing plumbing below.
Wiring for IAC, TPS, MAF, IAT, etc. If you use the 56mm plate throttle body like I did, you must undo the jackets around these wires for all the plugs to reach.
New TPS has a different plug style but same three wires, right down the the colors. Just have to chop off old plug wire in the correct plug for the new TPS. You can also see the new throttle body plumbing here, a couple carefully chosen molded rubber hoses from AutoZone work well.
The U-van throttle cable was a bit long. I threaded it through the thing it goes in, out the hole at the end, and put an aluminum sleeve at the knob end of the cable to get rid of the slack. It works fine but is a bit sketchy for permanent use.
The intake duct that originally went to the 2002 Grand Am's throttle body must be used. I used Stick 'n Seal to attach my MAF rig to the end of that duct. And yeah, for the time being, some Home Depot dryer duct runs from the MAF to the original air cleaner.
One thing I did not grab from the Grand Am and need to get is the ventilation hose from the rear valve cover to the intake duct. That's another thing you need in order to use the new throttle body.
Car has been going 50 miles round trip to work since I finished this last Thursday and feels great. About the same off the line but the difference is huge at higher speeds and revs, speeding up 50 to 70 on the highway for example this engine used to be a dog but now much more responsive.