Well, my wife's 91 Ragtop 2.0 OHC TBI engine finally died, so I picked up an inexpensive 92-94 PFI replacement. At first I was going to put the TBI parts on the newer engine, but I realized I'd really rather do the swap since the TBI engine about as strong as granny's scooter just before the battery dies. So I'm in the process of pulling the engine (taking a break now to rest my sore feet). The wiring harness is disconnected from the car and will come out with the engine. I have a 93 pcm and harness here and I'm going to head to the junkyard tomorrow to get the throttle and detent cables, maybe the instrument cluster, and the factory intake tube and air filter housing. Along with new oil pan and valve cover gaskets, I have a new timing belt and a fuel pump and strainer from a 3.1 turbo Gran Prix to bump up fuel pressure. Although I see some differences between wiring connectors under the dash, this doesn't look like it's going to be too tough of a job. But unfortunately I forgot the camera, so no pictures of tonight's work.

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I've been working this for about a week, in between other projects. The engine drops right in, of course. The next step for me was to make the engine wiring harness. It has to be a hybrid because some of the connectors in the body of the '91 are different than the 93. I also had to add a/c controls to the harness I used. I decided to switch to the 93 style a/c controls which use a pressure sensor rather than multiple switches on the back of the compressor. I'm also going to use the 93 compressor, although either one would have worked. To build the harness I started with the 93 engine half. The windshield wiper wires come from the driver's side of the '91 and they come through the passenger side on the '93. The easiest solution was to remove the wiring from the 91 harness all the way to the bulkhead connector and install it in the 93 harness while removing the original wiring from the 93 harness. Next up for me was to wire the blower correctly. A non-a/c car has 3 blower speeds while a/c cars get 4. The high blower speed is controlled by a relay mounted on the passenger's inner fender on a/c cars. So again I removed the wires from the 91 harness and added them to the 93, while removing the original 93 wiring. This move required separating the pass through connector on the passenger's side of the firewall and digging out the clear sealant inside. I found that spraying the sealer with green CRC brake clean then digging the sealer out with a pick or screwdriver worked fairly well. The connectors between dash harness and engine harness on the passenger's side need to be switched over, and there's a couple of wires which can be deleted from the 93 harness during this process. All ABS related wiring can be removed. There's a bunch of it including major power and ground wires, 2 rear wheel speed sensor wires which pass through the bulkhead connector on the driver's side, fromt wheel speed sensor wiring, ABS and brake light control wiring, and a few others. When re-assembling the pass through connector I needed something to replace the clear sealant GM used. I came up with a product called "Seal All" at Advance Auto and it looks like 2 tubes of the stuff should do the job. Put some in, let it dry, put more in... Since there hasn't been much interest in this I'm not going bother getting much deeper into the wiring details. Today I'll work on installing the harness and throttle cable and modifying the fuel lines.

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Car started Thursday night. What a difference... PFI engine is much more refined, much better runner. And there's mo power at least in the short drives around the block. Maybe Sunday or more likely next week I'll have it fully together for final road testing.

At least I can point to this thread if anyone asks "how hard is it to convert my car..."

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When switching to PFI does that get rid off all the distributer cap and rotor and what not?

Yes, provided you use the PFI ecm. The coils are mounted underneath the intake manifold and the crank sensor is under the A/C compressor.

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very interested in this my 91 TBI is getting tired, so you changed the fuel pump, harness and ecm pretty much??

This is something I was thinking of doing down the road. Your swap is done correct, how did it turn out? The PFI throttle body is also larger isn't it? I wanna do this to my little 90 sunbird turbo, Shouldn't make much a difference if it is turbo or n/a I wouldn't think.

seanski, I used ecm, fuel pump, and wiring harness. I used the fuel lines which came with the engine but replaced the quick connect ends with the threaded ends from the TBI engine. I also used the throttle cable and trans detent cable from the 94. If you want cruise to work you'll need a cruise cable from a 94. You'll also want a/c hoses and an a/c pressure sensor from a 92-94 if you want the a/c to work correctly.

Dan, I'm very happy with this swap. The engine is much smoother, runs better on the highway, and doesn't leave me feeling like a deer in the headlights when I try to merge with traffic. But it's nothing like my '89 turbo Bird. The PFI throttle body is larger than the turbo throttle body. I've put a pfi intake on my turbo car and know just what the differences are between the two. The biggest issue is that the fuel line setup is different, and the DIS ignition from the 94 is not compatible with the 7749 turbo ecm. Otherwise the 94 engine will drop right in. In fact, the 94 is essentially the 90 turbo engine with higher compression cast pistons and no turbo.

One final note: The 94 ecm expects more speed signal pulses per mile than the 91 trans delivers. My speedo currently reads 10-13 mph on the highway. I'll probably end up changing the speed sensor and replacing the sensor drive gear with a metal reluctor wheel. I'll post an update when I solve this.

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nice progress!


**changes are here**

I don't know if I'm reading this correctly, is the swap easier, harder, or not possible on my 90 SB turbo?

All things are possible with enough time and money.

If I were installing the 94 engine without turbo and I wanted a quick and easy swap I'd use the turbo intake manifold and injectors with the 94 engine, install the distributor in the end of the cylinder head, use the '94 exhaust manifold and call it a day. That's going to be about the quickest way to do it. The turbo ecm will work without boost as long as you use the MAP sensor that came with it, and the wiring harness and fuel lines are already set up for the turbo parts.

But since the 94 engine is so close to the turbo engine why not replace the pistons and rods in the 94 with the ones from the turbo powerplant and keep the turbocharger?

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