fuel problems on new 4L

[suzidisco]

i have recently put in a new 4l engine into my 93 3.5l disco the 4l is set up with all the 3.5 sensors these have been checked or replaced, including the air flow sensor and computer and all are within the required peremiters
The problem is that my fuel figures are around 28-30/100kms has anyone done this transplant and had this problem if so how did you fix it

otherwise what do people think about running a after market computer so that i can run a fuel map but what type are people using.

[TuffRR]

I assume you are still running the 3.5 computer and flapper style AFM? If so, its most likely that the efi system is just not up to the job. Does the motor feel less responsive above say 4000rpm?
If you want to go aftermarket ecu's then a megasquirt is worth considering. Cheap and effective solution if you are prepared to learn a bit about efi.

Also, have you checked your timing?

[RaginRover]

Also, have you checked your timing?

and try and borrow/use a vacuum gauge to set it, that way you can largely ignore the timing marks that might be wrong/slipped anyway

Tom

[Philip A]

A 93 3.5 Disco has a 14CUX with MAF.

I would suggest that your best bet is to fit a unichip to trim the fuel as the requirements for a 4.0 litre would be different from a 3.5 and it is probably rich.

BUT first I would check your MAF. A dirty MAF can give wrong readings. Clean it with electronic cleaner, and check the resistance. it should be if I recall 160 Ohms, but check the manual.

If you want a trouble free engine that starts every time, every expert I have talked to or read in Autospeed etc says that you cannot beat the standard ECU.
Megasquirts sound great to me, and I may fit one , but I am prepared for a long frustrating time setting it up. AFAIK NO dyno tuner in Australia has experience with a megasquirt.

You will gain much more from a unichip than you gained from the capacity change. My engine with heads, unichip and a "Thor" manifold now makes 50% !!!!!! more power at 1,000 to 2600 RPM than a standard 3.9 and the unichip and dyno tuning are the greatest contributors. You can imagine what this means in an auto.

Regards Philip A

[TRobbo]

off topic

Phil - I'm interested in what you did to your heads and where u can get a unichip from. Now for the really dumb Q, is this different to an ecu such as wolf 3d or motec?
cheers

[Philip A]

The unichip is a 'piggyback' ECU which has two functions
1 to intercept the MAF and temp sensor signals to the ECU and therefore adjust the air/fuel ratio
2 to have a rudimentary computer advance curve(or two so that you can have a petrol and gas setting) , that enable s the unichip to supplement the centrifigul advance. The vacuum advance is disconnected.
see
http://www.airpowersystems.com.au/unich ... tions.html

You go to an agent and they load up the motor on a 4WD dyno and trim the fuel to the correct A/F ratio and manipulate the ign advance to get the most power without pinging.

This has a dramatic effect, with mine picking up almost 20% at the bottom and top ends and 11% at 3000. Graeme Cooper is an agent in Sydney. It costs about $1500 including the dyno time and a new ignition module,( which can run a Bosch 717 transformer coil)

The advantage over an afternmarket computer is that you keep all the nice things about the 14CUX ( which is a Bosch LE Jetronic under licence)like flawless starting in any temp, the stepper etc etc. Now the proponents of megasquirt etc will say that you can do this with it but it is not glitch free as far as I can read on the Megasquirt site . a Haltech looks a good unit, and I find Ted Lehmann's interesting, but still you have to be quite conversant with interpretation of the computer program to get it right. Ted has a wide band o2 sensor also but still has to have it dynod to be right.

With regard to the heads, I spent about 30 hours or so on port blending around the inlet and exhaust valves, mainly on the exhausts as the castings are very poor. I shortened the inlet guides, and opened the combustion chambers around the inlet valves, and then took 50 thou off, and fitted composite gaskets. This gave me 7% power across the board.
However really I got the most benefit from the unichip and the inlet manifold.
Give me your email address and I will send you a composite dyno sheet standard 3.9 to unichip , then heads, then "Thor " manifold and the ultimate 50% more from idle to 2500RPM.. Its messy but you will get the idea. I never seem to be able to post here as it is always full of photos

regards Philip A

[RaginRover]

Phil,

email it to me and I will post it for you

Tom

[Philip A]

Tom, see above I got it to work. Often the host space on the board is full of photos I believe and there is no allocation left .
regards Philip A