3.9 EFI poor starting and high idle "roverguage"

[bigalcoles]

Hi there I've got a 3.9 EFI from a 1990 Range Rover with no cats or speed transducer. Fitted in to my LR I am having trouble with cold starting it requires a lot of cranking and the throttle to be held wide open. It does not seem to have the auto "choke" working. It also after running for a while occasionally high idles at about 900 to 1100 rpm. I've bought the Rovergauge software and cable and all seems to be ok with no fault codes. I've checked around the engine for air leaks by spraying brake cleaner and listening for a change in engine note but have not found anything. I've fitted a new idle control valve. The coolant temp sensor starts at 15'c and rises to about 75-80 and the fuel temp starts about the same 16'c and rises to about 25-30. Thanks in advance.

[Steve_D]

So what readings is RG giving for all the parameters?
Does the idle light come on?
What revs does it say it is trying to achive?
What was the idle valve reading
Etc Etc

Steve

[v8250]

OP, you'd be better off posting this Q? on the V8forum.co.uk here

http://www.v8forum.co.uk/forum/viewforum.php?f=12&...

Your problem could, logically, come from a number of areas...even a poor signal ground connection. Have you checked both engine and gearbox earthing points/measured cable resistance?

The occasional higher idle is most likely due to standard default cold idle settings. Is this transplant a recent one or was the transplant complete some while ago, with the LR running perfectly, and this fault just recently arisen?

Also, although not running Cats, do you have lambda probes installed and running correctly? If not, the 14CUX ECU is expecting to see lambda signal returns which will throw out correct engine fueling.

[shoehorn]

v8250 said:

OP, you'd be better off posting this Q? on the V8forum.co.uk here

http://www.v8forum.co.uk/forum/viewforum.php?f=12&...


Also, although not running Cats, do you have lambda probes installed and running correctly? If not, the 14CUX ECU is expecting to see lambda signal returns which will throw out correct engine fueling.

Not all 14 CUX use/have lambda input,the one in my Capri has none.

[v8250]

shoehorn said:

ot all 14 CUX use/have lambda input,the one in my Capri has none.

You are quite correct, BUT re-read the OP's message. It's from a 1990 RR and the majority, with or without catalytic converters, used lambda sensors. We can assume the OP's unit is not from the 1983-1989 RR's which used the non lambda 4CU unit. Conventionally, the ECU signals were static via a fixed resistor. This was/is not the ideal as unless re-mapped the ECU will often over rich or or lean. If you have a perfectly working 3.9/4.0 14CUX with no lambda input, you're very lucky. Has the ECU been re-mapped?

OP, I have a digital copy of the 14CUX manual if you'd like one. PM me and I'll forward to you.

[paintman]

Any use?
http://www.britishv8.org/Articles/Rover-14CUX-EFI....
http://www.actproducts.co.uk/2011/lucas-14cux-fuel...

[shoehorn]

v8250 said:

You are quite correct,If you have a perfectly working 3.9/4.0 14CUX with no lambda input, you're very lucky.

Is that so? I have 2,ones an oddball and just thought that it was luck of the draw until 93.
My ecu came from a 92 RR with no lambda inputs straight off the bat,I bought it from the exchange and Mart.
I sent this to JE motors who changed the chip,supplied a modified loom for it,removed the RR top speed limiter and supplied a road speed sender.
I was supplied sensor bosses with bungs for the down-pipes which were used by them for mapping and then bunged afterwards.
The guy from JE told me at the time that it was an unusual ecu,it was 1994 at the time and I just assumed it was because of it relative young age.
Being a dyed in the wool Ford man and knowing little of about the `hot wire` injection system,it was still quite new tech back then and there was no internet worth talking about
I remember it was bloody hard work at the time finding someone who was conversant with the system.
With varying advice right across the board(including sawing off the idle control plunger from one clown)some suggesting it was too complex and to use the flapper system, until I stumbled upon JE motors I was even tempted at one point to stick on a four barrel Holley.


I fitted a 3.9 into an `89` manual 3.5 RR for a pal a couple of years later and the new engine turned up on a plant trailer complete with gearbox,loom,ecu,airbox,rads,the lot!
I re-used the flapper injection system and kept the ecu my self.
This engine and box came from South America,Brazil I believe and the ecu is clearly marked 1994 and again has no inputs for lambda,although this ecu is an unknown quantity.
next year the V8 is coming out to be replaced by a FI V6 Duratec,so the ecu and associated bits will be up for grabs at some time.

Edited by shoehorn on Thursday 23 October 02:50

[v8250]

Now that is a mish-mash of V8 parts, though not unheard of as so many folk have mixed parts where they complete engine transplants and conversions. Was the JE Motors the RR people or John Eales of JE Developments? It does sound like a 'rare' ECU and I guess few from Brazil found there way back home...though one would expect this to be a US spec'd ECU. I'm in the process of dropping a 4.0 TVR V8 + all the electrical gubbins' into my MGB Roadster. As with these projects there's so much more to do than ever planned...

[shoehorn]

v8250 said:

Was the JE Motors the RR people or John Eales of JE Developments?

JE motors of RR fame.