Urgent! Fuel consumption...

[Corday]

Hello!

I need urgent help to get my car to run better. Summer is closing in and if i cant bring the fuel consumption down atleast alittle, there wont be much driving this year..... Currently it takes about 4,7 miles per gallon (calm driving).

I did the following upgrades but it still runs on stock tune:

Upgrades: Lid, Fast 90/90, Patriot Performance stage 2 heads, TR Camshaft 224/224-112LSA, Dynatech LT's, Y-pipe and highflow cats, Magnaflow Catback 3" exhaust, Underdrive pulley, Meziere electric waterpump, AIR & EGR delete.

Current issues: Really bad mpg, strange idle (sometimes high and not revving down like it should), slow and blurry throttle response, emission values are not very good.

I bought EFILive about a year ago and played around in the menus abit while it was connected to the car, however i never got any further than that.

Please, if anyone can help me to get the car to run at atleast a sane mpg level, that would be awesome!!!

Car: 1999 Pontiac Trans AM - 5,7L LS1 - Manual 6spd

What do you need from me? I can make EFI-logs while driving etc, and I have an Innovate LC-1 that i did not install yet. Will the numbers from that one be of great help? If so i will install it.

Please be exact and remember im a newb :p

[Happy Jim]

Please be exact and remember im a newb :p[/I]

1st things 1st.

Get the LC-1 Installed.

With your mods the VE table will be all over the place, the only way to get it right is to log some data.......and reference it against the data logged from the LC-1 (autoVE process).

You will be fighting a losing battle without the Wideband.

4.7Mpg....Impressive, I have to take mine to a track to get that :grin:

Rgds

Jim

[Stealth97]

You'll need a lot less fuel at low RPM, and a lot more as torque peaks and past torque peak as horsepower climbs through the roof.

There are tunes out there similar to your setup. Try here in the Tune Repository, or on Holden Crazy (another forum). I know there is a tune out there like yours, because I've seen it! It may have also been on ls1tech.com.

4.7mpg? Wow. Some major issues there. Any fuel injector clips on the wrong cylinder number?

[joecar]

Something is seriously wrong withe the tune and possibly with something else...
- airleaks,
- bad NBO2 sensors and/or MAF,
- bad spark plug and/or wires,
- misfiring,
- other.

[Corday]

1. I have been unable to find any airleaks, but i may have just missed them.... I will continue searching..

2. How can i check if the MAF is ok? The NBO2's has thrown codes previously but i have replaced them and think they are good now.. will have to check again.

3. I replaced the stock plugs with NGK TR-55IX Iridium. Wires are Taylor 10.8mm and they "should" all be fine, i'll check again though..

4. I've had several codes thrown due to misfires, but they are not constant, and can come at any time and place.. I was thinking it was due to the bad tune...

5. Other strange things - Brake system (anti-lock, traction control etc) shuts down randomly and all the lights lit up in the panel, but when i restart the car the system works again for a random amount of time.

Idle:
When i rev the engine to i.e. 4000 rpm then let go of the throttle, it goes down to 2000, then stays there for like 5-10 secs, then it gradually goes down to normal idle..

However:
When i disconnect the TPS (throttle position sensor) the idle gets better when engine is hot. Same effect can be seen from disconnecting the IAC (idle air control).
However, doing this when engine is cold makes it die when it tries to idle..

--------

I will start installing the Wideband today.

I will also check the injectors.

Thanks for all the great advice so far, keep em coming! :)

[joecar]

Some links here may be of help: showthread.php?t=7867 (http://forum.efilive.com/showthread.php?t=7867)