what's better over-all, EFI or carb? i have a 1979 280zx with fuel injection, but was wondering if going with a carb would be better for fuel efficiency and/or performance. oh ya, and any suggestions on why my car sucks to start up every morning (being cold out is definitly not the problem) all your comments will be very helpful.

 

For fuel efficiency, no not really. Unless you ran it super lean then you probably woudl see worse fuel consumption through a carb setup as the fuel is not atmomized as well through jets as it is through a fuel injector.

For performance, you will also see better gains though PFI but it has to be tunned properly. You will see carb setups on race applications vs. street applications because it is simple. There is no electronic part ot go wrong, and to make adjustments all you need is a flat head screwdriver. :P


The cold start im not to sure about. But chances are your car has a cold start injector, or a unit that adjusts the fuel being deliverd on cold start. If the injector or unit is not functioning properly it will cause the car to have trouble starting when cold.
.2cents

Berz

 

A cold engine isn't caused by cold weather. It's the temp of the coolant. And normal operating temp is something like 180-195 degrees on these engines. And anything below I think like 140 is considered "cold". But several things can cause a hard start condition. A weak or worn ignition system can definitely cause starting issues that are most prominent when the engine is cold. Check your cap, rotor, plugs and wires. The ignition is the most prominent cause of hard starting so I'd definitely look into that. Other parts to check within the ignition would be the distributor air gap and initial timing. I can almost gaurantee if all those are in good working order and your battery is up to par then you shouldn't have a hard start problem anymore. But then again some cars are just plagued with hard starting in the morning. It's a fact of aging life .

Oh, and unless you're building a dedicated race car stay away from those carbs. For what it would cost you in time and money to do the swap you can rewire your FI system and work out any faulty parts and have a far superior system to any carb setup for street use. While you may be able make adjustments with a screwdriver to a carb setup, you shouldn't need to make any adjustments to a properly tuned FI system at all once it's been tuned.

 

If the PGFI is not set up with differnt maps for differnt situations then a carb setup coudl be benificial in certain situations. eg. have a low grade of gas available where you FI setup was tuned to run a higher grade, elevation changes ect ect.
A carb offers alot of easy adjustability. I use then on my race cars becaus of there simplicity and ability to make considerable power. Im sure i coudl get more out of PGFI but there is far to much to go wrong in a car thats running in excess of 24hrs without any inspection.

On my street car i run Microtec stand alone, and it is almost infinitly adjustable, but you require a laptop and variosu cabling and knowledge of how the fuel maps work. With a carb you are basicly just tweeking things here and there to get the best fell when on the track :P

Berz

 

Oh I think carbs are great for the track. There they can be tuned for a particular purpose and tuning for different situations isn't needed or a bother because, well, it's a damn race car right? So you tune it just for the curren situation The problem with carbs on the street is they CAN NOT be tuned for ANY situation. A carb that can do this is called TBI, but then it's still considered fuel injection. carbs can't account for air density on their own. This has to be tuned in and even then only for a certain set parameter. As far as fuel grades and what not on FI, I'm developing a mod for the FI L28 right now that'll allow easy adjustment of the FI systems fuel enrichement map with the simple turn of a ****.

Just a quick edit too that ties into the hard start problem: The cold start valve and high idle actually are for "cold weather" not just a cold motor. So if it's cold mornings that you're having trouble with then Berz may be right there. But I thought you said it wasn't cause of cold weather.