Decresing Fuel Comsumption

[Dizmo]

The other day i cleaned my AFM with contact cleaner and it has made my fuel consumption increase. before i cleaned it i was getting 420km outta a tank, now its down to 330km (same drivin style). I have a rb20det, stock ecu, not cat, fmic, r43 turbo and 7psi boost.

Can i lean out the mixture using the stock ecu?

What are some ways of decreasing fuel economy? (dont say lift up the right foot coz i drive like a granny mostly)

[paulr33]

apexi safc piggyback fuel computer will do this for you

[Dizmo]

i wanted to change the mixture without piggybacking, just using the stock gear.

[paulr33]

ecu remap or piggyback computer

remap or apexi safc

you need to bend the afm signal to make the ecu think more air is coming into the system than actually is, so it leans it out based around the "apparent" amount of air thats coming report (reported by the afm bender)

[danielson]

get a auto electrician to wire up a resitor in series with your afm.... you will have to work out the values tho

[Dizmo]

ok so how to i go about 'bending the signal'. Use a resistor like danielson said or is their another way?

[dangerous_daveo]

I was getting 500+kms to a tank before a chip, its now 550kms+ to a tank out of my rb20 cefiro on 12psi on an rb20 turbo.

I think you have another issue that needs to be addressed to sort out your fuel economy. I cant see how a piggy back or chip can solve the problem straight off. So you sort whatever it is out first, then go from there.

[Suspense]

i only get 300km to a tank... 15L/100km and thats cruising too

????

[paulr33]

dont you dare use a resistor. get it tuned properly. youll certainly put the engine at great risk by using a stuid method such as an inline resistor.

either

1) get an safc and get it tuned

2) get a remapped ecu and get it tuned

3) get an aftermarket ecu and get it tuned

you should also make sure your onboard oxygen sensor is working and has been replaced recently (they last around 50,000k's)

[Dose Pipe Sutututu]

you say that you don't have a cat running in between the exhaust system..

I recommend you put it back in.. firstly you won't get a fine and it should give you better fuel economy

[rob82]

you say that you don't have a cat running in between the exhaust system..

I recommend you put it back in.. firstly you won't get a fine and it should give you better fuel economy

How the f**k does a cat give you better fuel economy???

Dude just take it to a mechanic that knows what he's doing. Get him to check the base timing is correct and that the 02 sensor is trimming, check fuel flow and pressure(just for safety), have the injectors cleaned and then get a chip if it is still shite.

The problem with getting buildup on your MAF is that it desensitises the hot wire element therefore it reads that there is less air coming in and leans the engine out. Once you cleaned it it went back to being typically nissan programming rich.

[Busky2k]

SAFC wont help with fuel economy. If you lean it out on low loads and RPM, it doesnt take long for the ECU to learn around it and attempt to maintain your AFRs at 14.7.

Its easily demonstratable if you have a wideband as I was doing my own testing with an SAFC a while ago.

I would replace your O2 sensor and then do an ECU reset. What did you clean your AFM with? Please don't say WD40!

[Abo Bob]

That's only at cruise and idle. If you had 14.7 on power your engine would blow.

Turbosmart have got a new fuel cut defender thingie that is fairly cheap bends the afm signal.

Check out FCD3 here

[Busky2k]

Hence "low loads and RPM" as I mentioned.

[Dizmo]

I cleaned the afm with contact cleaner.

should i replace the O2 sensor thats on the exhaust?

HAving no cat doesnt improve fuel economy it just there to pass emissions.

Can the stock ecu be 'tweaked' to improve the mapping?

[rob82]

I cleaned the afm with contact cleaner.

should i replace the O2 sensor thats on the exhaust?

HAving no cat doesnt improve fuel economy it just there to pass emissions.

Can the stock ecu be 'tweaked' to improve the mapping?

Yes and Yes!!

[my_gtr32]

What he said.

Try and reset you're ecu first. Factory programming will be rich but it's possible that a reset may help things. Apparently after a reset, as the ecu re-learns it makes larger adjustments at first, then only slight changes after that. Dissconnect you're battery, step on the brake pedal a few times then reconnect the battery or leave it off for longer. Should do the trick. It can't hurt and it's free.

How the f**k does a cat give you better fuel economy???

Dude just take it to a mechanic that knows what he's doing. Get him to check the base timing is correct and that the 02 sensor is trimming, check fuel flow and pressure(just for safety), have the injectors cleaned and then get a chip if it is still shite.

The problem with getting buildup on your MAF is that it desensitises the hot wire element therefore it reads that there is less air coming in and leans the engine out. Once you cleaned it it went back to being typically nissan programming rich.

[RANDY]

you need to bend the afm signal to make the ecu think more air is coming into the system than actually is, so it leans it out based around the "apparent" amount of air thats coming report (reported by the afm bender)

Surely this would be the other way round? For better economy, you'd want the ECU thinking it's getting less air, so it squirts less fuel into the mix? More air would call for more fuel normally, right?

I would have guessed that if you clean the crap off the wire in the AFM, the wire is more exposed to the actual air coming in, which would cool the wire down and tell the ECU to squirt more fuel. (as the ECU measures the voltage of the wire based on the heat the wire retains from the voltage being applied to it)

If the wire is protected by gunk, it would stay warmer and not see so much air, and the ECU will give it less fuel to mix with?

Correct me where i'm wrong, but i've cleaned everything on my car, and I get BAD economy... I was really hoping a SAFC would help fix this.

[RB30-POWER]

Give it a general tune up first.

New plugs, new O2 sensor, check timing, clean injectors, fit a new air filter element into the airbox. (piss of pod filter if you have one).

Check that the water temp sensor is reading/working correctly as this is used for cold start enrichment.

And see how you go.

[RANDY]

Done everything except the injector clean already. Including cleaning AFM.

Someone mentioned wynn's injector treatment, and that it made a huge difference for them, so that's my next step now.