Running a 4.2ECU on a 3.9 engine..?

Great if somebody can give me a good answer on this one.....

I've EFI'd the 3.9 engine I was running in my 101 on carbs. The kit is all 3.9 except the ECU with is out if a 1995 4.2 Range Rover LSE.

Seems okay but can anyone confirm this going to work? My understanding is that the mixtures etc are controlled by airflow and the lambdas - am I about to come unstuck with this?

Jock

should be ok as the ecu is the same 14 cux unit. the tune select between the cat and non cat engine is done by the resistor in the loom which can be swapped for a beige non cat one if its not on one already

Yepo....

Seems to be running okay - timing is set for gas (now removed) and there's a wee bit of flutter when accelerating. Idle is rubbish - runs badly for a few seconds then dies. Think it's got an air leak tho.

Will fettle and report back.

Exhaust smells okay....

jockscotland said:

Yepo....

Seems to be running okay - timing is set for gas (now removed) and there's a wee bit of flutter when accelerating. Idle is rubbish - runs badly for a few seconds then dies. Think it's got an air leak tho.

Will fettle and report back.

Exhaust smells okay....

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A bit late I know but sounds like an air leak so while you're sorting that, take the opportunity to clean the ram housing and plenum, check/set the throttle disc and then re-assemble. (Hopefully it will start again) Run up to temp, check/set ignition timing then set base idle - hopefully all will then be well (maybe!). HTH

Right. 500 miles last week weekend, fuel economy not as good as I would like so swapped the 3.5 ecu into it (don't have a 3.9!)' made no difference.

It's running rich, black exhaust, high idle and stinking. Checked MAF - 300 ohms, cleaned the wires etc then cleaned the stepper motor.

No better. Gonna swap the EFI temp sender as it seems a bit like its running on choke all the time.

Got lambdas in the exhausts but it seems to be ignoring these....any ideas?

Try bridging the temp thermistor plug with a paperclip, ECU will think engine is hot.

if you need a coolant temp thermistor I have a genuine one (non genuine a waste of time with these)

fett said:

if you need a coolant temp thermistor I have a genuine one (non genuine a waste of time with these)

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Oh bugger, the usual story then? Ordered a Allmakes one from 252 Spares today - ill phone and change that for a genuine' unless you east to sell yours? 252 quoted £18 odd for genuine and £6 ish for Allmakes.

yeah you want a genuine one, I would want a tenner for mine but it been in the car for diagnostic and then out again. Its at work so i couldnt get it till monday anyway.

As you ahve already started the process with your place I would just change the order with them to genuine

Right, new sender fitted but not fully tested. Also found that the crankcase ventilation restrictor which feeds into the plenum at the front was blocked up solid. Cleaned that too.

Still smells a bit rich at idle after a short run.....

It'll get a couple hundred miles this weekend so we'll see if it's any better then.

Jock

let us know

Right,

200 odd miles again yesterday, still stinking rich at idle - exhaust is sooty black and fuel economy not as good as I would like.

The temp sender has been swapped but has made no difference.

Just a thought.....when I put this EFI kit on it was running MUCH too rich, to the point it wouldn't start. I did some diagnostics and found the fuel return to the tank was blocked up and a tyre pressure gauge connected to the tyre valve on the fuel rail showed nearly 7 Bar of pressure(!)

Soooo.....sorted that and its running like it is now...better but not great. I'm thinking now that all that pressure may have damaged the diaphragm in the fuel pressure regulator and it may be leaking fuel back into the plenum through the vacuum hose.

Maybe I'm clutching at straws? Need a replacement regulator.....

could be that, also you need to have the fault codes read as it may be in linp home mode

Shifted the thread to here:

http://www.landyzone.co.uk/lz/f42/3-9-v8-running-rich-186291.html#post1942987