feel like Too rich mixture

[pastr]

Hello
When I'm driving up hill (on road, to work), I'm losing power very quick.
If I'll press the pedal a little bit the rev will fall down, so I'm shifting from "D" to "3" and keeping rev close to 3K for short time, then losing more power and shifting to "2" to keep rev close to 3K.
The feeling is of rich mixture.
What to do?

3.9 V8 Auto with Cat 1996 disco (green with white roof)
Thanks.

[pastr]

44 viewers and no reply, too technical question?

[bee utey]

What makes you think its too rich mixture? Can you see rolling clouds of black smoke in your rear vision mirror? Are your spark plugs all carboned up? Have you checked the air filter element?

Too lean from a nearly failed fuel pump or blocked fuel filter is more likely.

[libertyts]

My first thought would also have been too rich. I had an old Audi with similar symptoms a while back. Turned out to be the injectors were stuffed, they were just chucking at much fuel as possible in whenever it felt like it!!

On that though, checking your spark plugs should give you a pretty good indication of what is going on, Black and stuffed up with carbon = rich, brown = lean, well put simply anyway. The rich condition could be caused by a number of things, though the first thing I would be looking into would be how it is breathing, things like the air filter, etc.

From there it becomes more complicated and more expensive usually. I try to start "optimistically" first with the cheap stuff and work my way in. Have you tried anything to fix the issue yet or investigated it in any way? If we know what you have done so far, people can give you some more things to look at.

As for the lack of response, no it's not too technical question, there has been a little less activity on AULRO lately I think as every seems to be pretty busy at the moment. I know I'm pretty busy at the moment, but I need my AULRO fix! :p

Chris

[pastr]

a friend came with his 3.9,so:
crossed: AFM,TPS,ECU,STEPPER MOTOR, O2 SENSORS
new:spark plugs and air filter.
nothing!!
thinking of replacing the injectors and if it will not help,i'll replace the timing chain.
i have the ECUmate and there is no code.
TPS - 0.3
AFM - 1.6 (should be 1.8 but i don't think this is the problem)
am i missing some things?

[rangy01]

I agree with be utey, sounds more like low fuel pressure or supply. Did you checked the colour of the spark plugs while swapping over? Possibly fuel pump failing or blocked fuel filter.
Andy

[pastr]

the color was very pale brown.
fuel filter i have change a year and a half ago but if you say so, i'll replace it.
how i'm checking fuel pressure? can i do that with a vacuum gauge?
i'll buy one for better timing adjustment.

[libertyts]

After hearing all that, would have to agree it's likely a fuel pressure issue now. I don't know what the recommendation is for the V8, but for the TDI's LR say you should replace the fuel filler every 10k km's. They must say that for a reason, it could be that it is all clogged up on yours.

Either way its the cheaper of the fixes. Can't help too much testing pressure though. Any time I have had a pump go it just died outright, no real warning, fairly simple issue to diagnose. No fuel coming from tank, hmmmm, what could it be? :p

Chris

[pastr]

I have replaced the spark plugs, but there wasn't any improvement, the engine still rev up and dawn almost from start, when trans. gear is at "P" "N" or in "D".
I think it's not electrical problem, maybe it's timing chain or worn camshaft.
I know timing chain can be checked by the distributor.
how much should the distributor rotate in order of determine if the timing chain is O.K or not?
how i'll check if the camshaft is worn without taking it off ?
i'll check the fuel pressure like recommended before.
what pressure should i'll expect for?
another thing from reading here, if the camshaft is worn, i should feel it not just when the trans. gear in "N", "P" or "D" while standing, but i should feel it working bed even in acceleration and high rev, don't i?
the problem is just when the car is standing no matter what the gear.

[libertyts]

No offence mate, but your English is atrocious! I'm sorry, but I can barely make out what you are trying to say. Any chance of reading over your post before you hit submit? I realise you may not be a native English speaker, but in the end, that is the language we speak on this forum. If you could proof-read your post, you may be able to get some responses and suggestions on what to do next.

Regards,

Chris

[pastr]

I took it to my attention, is it better and more understandable now?

[Blknight.aus]

check the air filter, and air intake ducting.

check the throttle position sensor, if the ECU isnt reading a more pedal position then you get no more fuel and no more power, just a leaner run.

[libertyts]

Much better mate. Thanks.

As for your issue. I'm not sure if I can be much help, as I don't know the V8's and the auto's all that well.

What I would suggest, in an older Audi I used to have, there were two things unplugged. Who the hell knows why, crazy previous owner!?!?! The idle control valve had an electrical component to it, the plug for this was detached. There was also a plug from the ECU that sent some basic sensor information to the auto (engine speed, temperatures, throttle position, etc), this was also detached.

Those two items being unplugged didn't stop the car from working, but it did make it a little sluggish in gear changes and it would rev up and down when standing still like yours is. So possibly this is an issue for you, though as I said I'm not entirely familiar with the LR V8's and autos so it might not apply.

One other thing that may present your symptoms is overheating. It is possible some mild overheating (slowly occurring head issues, etc) may cause the engine to "surge" momentarily as some "simpler" ECU's get a little confused and inject a little more fuel to bring the temperature down (in a N/A petrol) as it assumes that it is running too lean because it is only slightly over temperature. This is from experience on previous vehicles as well and again may or may not apply to the Disco V8 auto.

Hope they give you something to look at. At some stage soon someone else should jump in with a, quite likely, better suggestion.

Chris



Edit: Hahaha, see, someone else waaaay more knowledgeable beat me to it!

[Stumpy1]

Hi Pastr,

I noticed that you haven't mentioned the coil in your investigation?

After replacing the fuel filter like the others suggested, if there is no improvement I would definitely get your friends Disco back over and swap out the coil.

My Disco had poor performance similar to what you have mentioned. I too tried nearly everything in the book and it drove me mad!

A bad coil can trick you into thinking its ok as most will still offer a spark. Until you see the spark from a healthy one you will not realise just how average yours maybe.

Good luck with it all.