Can you tune the ECU?

[TomoHawk]

Is it possible to tune the ECU on a '78 280Z for more power or better fuel economy? What, if anything can you do to the ECU? Should it be swapped for something else?

I'm looking for fuel economy (currently at about 17 ,mpg- would like to see 20.)

[280zx Fever]

To my knowlege you cannot adjust the ECU at all.

Want better fuel econmy ? go lighter on the right foot

[2ManyZs]

In a word, nope... you can do a little with adding resistors to some of the sensors to control fuel mixture.. but not sure about what or how it's done...you'd have to get a book on the Bosch FI to find out how to do that..there is a book on the subject, called "How to Tune and Modify Bosche Fuel Injection" that covers a little of it.. but I let that book go with the race car...

There used to be a little rheostat you could buy for the EFI 280's that was called a "fuel enrichment circuit" that mounted in the wiring off the temp sensors on the thermo housing.. but haven't seen one of those in years...

[TomoHawk]

I suspect that my engine is running a little rich ( from looking at the spark plugs) that's why I was asking.

[dozer171]

http://demo.cs.brandeis.edu/postscript.dump/Ltronic/Injection.html

this site gives you all the internals of the jettronic system, and some tricks for more power.

there are VERY few things you can do, such as the 240SX T.B., you can adjust the a/f ratio by using the adjusting screw on the side of the AFM, you can loosen the spring inside so it opens quicker, add a potientiometer between the temp sensor and the computer to make it think it's a bit cooler to dump more fuel.... etc.

are your injectors leaking? when i had EFI before the carbs, i was getting around 20 around town, 24 or so on the highway... or your fuel pressure regulator? are you blowing smoke out the tail pipe like you're running rich?

[TomoHawk]

Originally posted by dozer171

are your injectors leaking? or your fuel pressure regulator? Are you blowing smoke out the tail pipe like you're running rich?

No smoke out the tailpipe, but the tip is sooty inside. Can you explain what you mean but the injectors/regulator leaking?

[dozer171]

the injectors leak by not closing all the way. this can happen because of a bent pintle inside, dirt, or both. when they don't close, they constantly leak a small or large amount of fuel depending on how open they are. the fuel pressure regulator can also be bad if the spring inside has worn out over time, or the diaphram inside has gone bad. if the spring inside is worn, too much pressure is going to the injectors, which can cause a rich condition. if the diaphram has gone bad, it has ripped, which would allow the motor to draw fuel through the vaccuum line that attaches to it, causing a REALLY rich condition. if you have a fuel pressure tester, hook it up, and i believe the pressure should be around 33.6 (?) psi.

[TomoHawk]

Thanks,

I will have to look at all that stuff. It won't be easy or simple, but it looks like it will have to be done.

[Daniel]

While not a efi man.Dozier's test is really easy.If you put a fuel pressure tester in the fuel line it will either hold pressure or leak down.If it holds you're better than you thought.If it leaks then the elimation begins.

[Tiburon]

Check the condition of your injectors, the fuel psi regulator may also be stuck shut....dumping too much fuel into the engine....

ALso check the cold start valve located just behind the TB assembly....(there is a fuel line going into it...) at times their valving gets weak and starts dumpig fuel into a warmed up engine, causing a rich condition....wasting precious fuel and ruining gas mileage.

Also check the O2 sensor (if it has it) and replace if not done so....(Use a nissan replacement as these match voltage requirements of the ECU)

A calcified therm time witch will also cause a false rich condition....as it will give the ECU voltage readings of a cold engine thus duming more fuel into the engine. (this also happens when you run too cold of a thermostat)

Check your AFM and make sure it is properly adjusted/working. After a long period of time the sping inside starts sagging and the readings are AWOL.

With a cam, headers, 2.5 exhaust, custom cold air intake, all new sensors,

new air flow meter, 16 inch wheels with 225/50 tires, 77 5 speed transmission and the stock 76 R200 rear, I managed to average 27 mpg on the flat stretch of US 101 between Salinas and San Luis Obispo at 65 mph.

Any more questions shoot me an email.