Outer Limits 4x4 Board

About a year ago i fitted a 97 Disco 3.9EFI motor to my Range Rover. It has allways had a rough Idle and it seamed nothing i did improved it. Changed Plugs,leads ETC and couldnt get it to Idle right. It allways popped out the exhast and was fairly iratic in the idle speed. It allso uses more fuel than i beleive it should.

Tonight i was doing some work under the bonnet and i had the engine running and unplugged the Airflow meter. It didnt stall or change note?? And then i pulled the entire Airflow Meter out and it still ran. It still reved fine as well. So i took it for a drive and left the Airflow Meter at home. It ran exactly as normal. There was no noticable difference.

Now does this mean i have been driving this around for the last year or so in Limp Home mode? And my Airflow Meter is stuffed?

I borrowed another Airflow meter and with this fitted it Idled Perfectly but i didnt take it for a drive to see if this was any different.

Im just surprised that if it is in Limp Home Mode that it runs so well other than at idle.

Most factory injected things have preset settings for when things shite themselves, but generally only good enough to "limp home" e.g. coolant temp sensor will run rich but still be driveable, the puta still has presets for timing and fuel for when things pack up, but its unusual to thing it would be quite as driveable as you say

I have -90 RRC with 3.9 efi, and it has had problematic idle, and it was quite thirsty, but the car worked fine, I drove several thousand kilometers and towed a heavy trailer, too. The AFM connector was loose, now it idles OK and the fuel consumption has come down a lot. Funny, but the engine feels weaker now.

Yeah, same thing happened to me - although I didn't actually drive car without AFM. No differance at idle with or without good AFM but bad with faulty one.

I think all the sensors combined merely enhance the engines effciency and performance, not stop it from running altogether. But you'd think AFM would be the exception.
I have a busted RHS knock sensor - been like that for about 3 years, engine management doesn't seem to care. A particular LR workshop on the Southside hasn't picked up on it either even there is a fault code for that sort of thing.


Hardy

My 96 disco has had idle probs aswell, mainly surging, stalling and high idle. Fuel consumpsion is 18ltrs/100kms. On the weekend it used 116ltrs of fuel and 60ltrs of gas for 900kms 650kms on fuel 250kms on gas, is that bad?
It has had 2 second hand idle speed solanoids put in and still playing up.
So i took it to a LR dealer who ajusted the AFM and cleaned out the idle speed solanoid and said there were no major fault codes on the computer. Ran well for a day and it now has high idle again....
It woulnt start a couple of months ago either, just kept cranking over untill batery was nealy dead. Has done this about 4 times.
Could my problems be the AFM or would it have shown as a fault code?

Can the computer compensate for no airflow meter - by using throttle position or something like that instead?

That would explain why it could run fine with a bugered airflow meter.

I am going out the check mine,

further to the story - aparently it goes heaps better with a good AFM in it
time will tell as to whether it uses more or less fuel

Tom

so what happened RaginRover?
i believe i might have the same problem on a 3.5 classic i just bought, its pretty gutless imo, and uses a fair bit of fuel but idles great and starts first time everytime(hot/cold)

Sorry about that,

The car was running in limp or default mode - so was mine,

The air flow meter will probably be out of range and causing the ECU to default to limp mode.

For how to fix the AFM see this thread http://www.outerlimits4x4.com/PHP_Modul ... hlight=afm

since then mine has gone back to limp mode so I have other sensors out of range too - I just have to check them and fix/replace them in turn till I have them all working within specification

Hope that helps
Tom

RaginRover wrote:since then mine has gone back to limp mode so I have other sensors out of range too - I just have to check them and fix/replace them in turn till I have them all working within specification

Hmmm mine is also doing this

awesum will be interesting to see which ONES it is :)
i'll be doing a few i imagine.

Ive heard about ECU thingys that plug in and tell ya whats doing what, but only for 3.9 or later models, nothing for a 3.5 late 80s classic which is a shame. :(

Simple fix, 4BD1T it

Interesting thread.
My 3.9 with unichip, heads , Thor manifold etc has been going really well, but fuel economy has been awful at 22 l/100km.
I was going to return it to Cooper for a dyno analysis on fuelling but decided to clean the terminals on the MAF and temp sensor first.
All of a sudden my economy has gone to 15-17 l/100 on mixed urban and motorway.
So I think mine has been in limp home. I suspect that it was in limp home when Cooper dynod it as Ward commented that it was rich down low and he had to take fuel out. The only thing I could se was that the MAF terminals were a bit dirty with oil.
Now I notice it hunts on cold start which implies lean. BUt the economy is great now and performance same. It did this straight after the dyno about a year ago but stopped doing it later.
Regards Philip A

Maggot4x4 wrote:Simple fix, 4BD1T it

I second that!!!

MORE torque than the V8

MORE fuel economy than the V8

MORE fun listening to the turbo whistle in the 3"drain and the intake hiss at acceleration...

MORE fun blasting past most other 4bees up hills at 2200rpm....

I don't miss the 4.6 one bit.....

JC