I have to admit that the planned project car might not just be a project car all along. After trying damn hard to fix the electronic engine control system, I reached a conclusion that fixing the damn car up would cost me quite a lot of money that I’m even better off buying a better base car for another project than pursuing this current one. Swapping the engine to a beastly SR20DE would cost a lot of money and with the cost of gas prices these days, getting a larger displacement engine would make it more of a guzzler.

Still, I was in a quandary on what to do with the Sentra since disposing it with the hard starting and rough idling would be like giving it away. No one would like to buy such a car, not even gullible newbie drivers looking for a beat-up car to beat up some more before they get their brand-spanking new cars.

Aside from the engine swap, I was also considering whether to carb it or not to carb it. Carbing it out would definitely solve the damn starting and idling problems since I’d be ridding the car of whatever faulty sensor there is. Last time I had the car diagnosed and scanned by the dealership, they were pretty sure that the car’s engine control module was f-ed up. So I thought, what the heck, doing this would give me a bit more understanding of fuel management systems anyway.

Here’s a list of the parts that I had to source:

1. Intake Manifold
2. Carb
3. Air Filter and housing
4. Distributor (non-CAS with vacuum advancer)
5. A/C idle-up solenoid
6. Cylinder head gasket
7. Low-pressure fuel pump
8. Assorted wires, hoses, and sockets for electrical

As far as the total damage was, I was able to get most of the parts from the junkyard though me and my mechanic had to source out some things brand new. Since we had to take down the whole intake manifold for the EFI, we figured to give the old engine some cleaning too so we had it top-overhauled too.

Divorcing the EFI system was pretty straightforward and slapping on the manifold, the carb, and the distributor were also quite easy. However, we had to do some modifications on the fuel delivery system since we had to get rid of the high-pressure fuel pump (which was submersed in the tank) and replace it with a low-pressure one to be found in the engine bay. We had to extend the hoses in the tank around 5 inches and slapped on a screen filter. We initially tried to do a bypass system by slapping on a fuel regulator, however, we eventually decided to do it right after hearing horror stories of failed conversions due to faulty pressure regulators.

As for the wiring, the ECM had no more use since all the sensors had been taken out. The check engine light’s now perpetually on. Now, I also have to source out a new instrument panel since swapping out the distributor took out my tachometer. I could simply install a new stand-alone tachometer but I hate having redundant items in the car.

Theoretically, I lost around 10 hp by converting it from EFI to carby. The stock version of my GA16DE gets around 105 hp and the carb version of the same engine (the GA16DS) gets around 95 hp. The car’s old so brake horsepower is definitely lessened. But testing it out, yesterday, I reckoned I got gains in the project. The old EFI system felt stymied by the faulty electronics. This carbed one now just pumps out a lot more torque at the first two gears and then zooms at 3rd gear. Gave a speeding 1995 Civic a run for its money out on the road yesterday. Good thing it was a short run before we hit a bottleneck since the acceleration gave me the whole advantage.

A definite con of this project is that the carbed engine would probably shave off a mile off the former fuel efficiency (22 mpg). I’ll be checking out my fuel mileage for the next weeks and try to be consistent with my driving style to figure that out. But with the sudden “power gain,” that’d be a tough call.

Carb engines are cheaper to tune and tweak but I’m not sure if I’ll go to those lengths with this car. Now that I understand how converting and EFI engine to carb, the car somehow lost a lot of its mystery to me.

Total damage for the project: $500 USD ($150 for the parts, $350 for mechanical and electrical services including machining of head). Yup, it cost a lot but the learning, I think, was well worth it.

Thinking of doing the same? Here’s a great guide that features more detail on how to do the swap.

Now I’m thinking of getting a Daihatsu Charade or even a Toyota Starlet and do a Toyota 4EFTE swap for the next real project car.