Please for the love of god can someone help me?

I hate intermiten faults and i have a stonker of one on my Tin top RV8.

Its a long post as its been going on for some time.

Range rover 4.6 (stroked 3.9) with a upgraded cam, air filter and exhaust. All was running fine on this engine for 2 years.

Ploblems started about 6 months ago, just hesitant on part throttle in the lower part of the rev range. I serviced it but it didnt solve the hesitancy. It would also be intermitent which did my nut in.

It got worse and also developed into the odd stall at junctions. I checked the timing and this seemed within book figueres. However, it got worse to the point of my having to keep the throttle down a small amount to stop it stalling, again it was intermitent.

I replaced the dizzy cap and rotor arm (the cheapest parts) but it made no difference. I put up with it for a few months, but it then degraded again with the new problem of not starting, it would spin fine, but smelt like it was overfueling. It would chugg to start and then missfire when i reved it up, this seemed to 'clear it' but would still hunt.

I took off the air bypass valve/solinoid and cleaned it out and this did improve it but not solve the intermitent problems.

The starting problem got worse and has now being intermitent for about 4 months, so i took it to a range rover place where they fitted a new water temp sensor and tuned the engine. This did nothing as a few days later it came back.

So off i popped to a spares place and bought all the cheapest parts i could think of with the intention to replace one at a time when it was playing up, air bypas valve, coil, spark plugs and leads.

I thought it was sorted when i replaced the air bypass valve, but after leaving it over the weekend it wouldnt start this morning, just spun over without even a stutter. it has a spark but wont fine up.

I HATE being in the position of not knowing what to do next, if i take it to a car place to get it fixed they are just going to have the same problems i will have and the chances of it 'playing up' when it gets booked in is 50/50.

I have really had enought and i think my neighbours have too, 7 am and 30 minutes of me cranking it over abd now a flat battery.

Please suggest something.

Have you checked the air flow meter is giving a good signal and varying the fuelling to suit the engines operating conditions?

I have had similar symptoms with my MX5 engine and found it was due to the air flow meter.

All of your symptoms sound like poor fuelling.

In my case it's a flap type meter but your hot wire AFM could be just as bust.

Is it carb or injection?

If injection, does it have an air flow meter, one of the older flap type ones? The sysmptoms you describe sound similar to problems I had when the air flow meter was failing on a Pug 205. The reisitive position element of the meter starts to disintegrate and gives the ECU a real hard time trying to compensate for it.

Of course i it's carb based then that's no use to you at all


Edit to say...
Beaten to it & Great minds

[Edited on 24/9/07 by nick205]

I had a very similar problem with my 3.9, although it would start fine, it would buck under accel, be hesitant and junctions, wouldn't accelerate past 2500rpm. Drove me nuts for ages. As I was using MS I put it down to my lack of knowledge on tuning, but it eventually did my crust in too much.

Faulty distributor was the cause of all the problems. I had originally eliminated this by changing rotor arm, dizzy, cap, new leads etc. Vacuum advance working ok. It seems that there was enough play in it to cause timing scatter.

I changed over to wasted spark system (direct coil on plug vitually). Even when the dizzy was good, it was never as good as it is now, response is instantaneous, tickover is miles smoother, even with the square CAM fitted. Not saying yours is the same, but It may be worth trying another dizzy to eliminate it. I also (I think) have a spare airflow meter in the garage if you want to try that.

Cheers

you would be better off posting this on land rover forums.

my v8 is carbed so unfortuantely for you, I don;t pay much attention to fuel innjected engine woes. A lot of the time it is some component that needs cleaning.replacing - stepper motor for the air control valve? ( sorry, can't remember the exact part).

Ahhh the good old Hotwire system.

From your description I would say its the Dizzie that at fault - But that a gut feeling.

Have a look on here and let us know which one you have ( 1/2 way down the page ) it also has a lot of usfull info on the 'Shortcummings of either unit'.

RV8 Dizzi info - RPI.

I would suspect you have the middle one ( with the control unit on the side of the dizzie ). IF you have ( You can buy the control unit seperatly for £20 / 30 ) I have detals somewhere.

Check this first .

Regarding the Hotwire operations I have the full Range Rover Hotwire Test manual in PDF. This will enable you to test all the relevant parts of the system with a decent Multimeter. U2U me your email address and I will forward it to you ( though may take some finding ).

PS I have just upgraded my Hotwire to VEMS so have a garage of Hotwire bits including ammases spares.

Kind regards

Agriv8

thanks for the replys. Mine is the middle dizzy.

some things i forgot to mention, i replaced the advance unit as it was broke. but it didnt change the problems.

Aslo it has been 'chipped' by the last owner. i have the original chip but im unsure if its a diy job??

Having replaced alot of items im left with, ecu, afm, dizzy unit and fuel items.

I would love to borrow/buy a spare AFM and throttle position sensor if one is available from you guys. Please give us a U2U with the price and i will sort it out.

This is not the answer you want to hear.

However, If you are using Std Rover injection, what was it from? 3.5, 3.9, 4.2, 4.6???

Each ECU will be programmed for that sort of engine capacity / fueling, Cam, ignition etc etc ie the Maps.

If yours is a 3.9 stroked to 4.6, then you can guarantee that the mapping is not 100% correct, and you could expect some issues.

Why not throw away the Rover injection, and just fit a Megasquirt? OK it will cost to get it mapped properly. But you will then get the full benefit of the other modifications to the engine. Its got to be a better solution to what you have.

As I said, its not the answer you want to hear.

Other than the above, cant help with the problem. I'm all carbed up.
but hoping to do a Megasquirt conversion to throttle bodies on my RV8

Oh and throw away the Dizzy and use the Ford Coils driven directly from the MSquirt.



[Edited on 24/9/2007 by wilkingj]

Hi Moorron,

U2U and email sent.

Ahh so you have swapped the Dizzie unit so possibly count that out ( unless that dodgy as well) I have spare control module somewhere.

Did you check to see if you had a spark when she wont start ?

let us know if you have a spark or not regards

Agriv8

quote:

---

Originally posted by wilkingj
This is not the answer you want to hear.

However, If you are using Std Rover injection, what was it from? 3.5, 3.9, 4.2, 4.6???

Each ECU will be programmed for that sort of engine capacity / fueling, Cam, ignition etc etc ie the Maps.

If yours is a 3.9 stroked to 4.6, then you can guarantee that the mapping is not 100% correct, and you could expect some issues.

Why not throw away the Rover injection, and just fit a Megasquirt? OK it will cost to get it mapped properly. But you will then get the full benefit of the other modifications to the engine. Its got to be a better solution to what you have.

As I said, its not the answer you want to hear.

Other than the above, cant help with the problem. I'm all carbed up.
but hoping to do a Megasquirt conversion to throttle bodies on my RV8

Oh and throw away the Dizzy and use the Ford Coils driven directly from the MSquirt.



[Edited on 24/9/2007 by wilkingj]

---

im charging the battery as we speak, but its hoofing it down outside so it maybe later today or tommorrow when i get back on it.

Knowing my luck, when i put the battery back on it will start straight up!

Ive looked on the RPI link and seen how to check the throttle pot. Will do this too if its still playing silly buger.

Moorron.

That 6mb PDF got through Yet ?

Regards


Agriv8

does it have a k&n or any type of oiled filter
clamped onto the airflow meter as these can often cause problems as the oil can get drawn over the wire and causes problems

Update.

After refitting the charged battery i tried a few other things,

Disconected the TPS, still no change.
Changed king lead. no change
Took off dizzy cap and sprayed WD40. Started first time but with a misfire, after a few minutes it cleared.

The culprit looks like the cap, arm or dizzy unit it self. Ive noticed looking on a few forums that they say non OEM part cap and arm cause troubles. Im unsure when i replaced mine 6 months ago if it was a replica job or not. So of to but a real set.

I moved the arm by hand while the cap was off and noticed some rotational play, is this normal?

MMMmmm must say I dont know on that one.

Regards

Agriv8

Yes, some rotational play is normal.
The top of the distributor shaft (the bit where the rotor arm fits) is not directly connected to the lower part of the shaft; The lower part of the shaft turns a plate with the bob-weights attached. The bob-weights spin out under centrifugal force when the revs increase (they return at low revs because they are spring loaded). The bob-weights are linked to the top part of the shaft, so that when the bob-weights "expand", they move the top shaft relative to the bottom shaft, and advance / retard the timing.
The profile of the bob-weights, and the strength of the return springs are what control the advance curve. Basically, they perform the engine speed part of old skool ignition mapping.

HTH,

quote:

---

Originally posted by Agriv8
Moorron.

That 6mb PDF got through Yet ?

Regards


Agriv8

---

Update, getting urgent now.

Well, just took it for its mot. All was fine except it failed its emissions. Too rich i was told.

So i replaced the dizzy cap and rotor arm (again) and it didnt help. I'm a little stuffed now as the law is going to catch me out in a week or so. What would cause a hotwire system to run rich??

I have checked the throttle pot and Co trim on the air flow meter and all seems fine. So that only leaves Ecu, fuel pressire regulator and fuel temp sensors!

Any help?????

Lucas Hot wire systems are generally very reliable although the Hitachi made hotwire air flow sensors dirfts off with age (idle gets richer over years of use) when they do cause problem like most other MPi systems it is usually the coolant tempewrature sensor.

However if your engine has a dizzie -- if it is the type with the vac advance and the hall effect sensor built in to the dizzie the most likely cause of trouble is the ribbion cable inside the dizzie this was a constant source of trouble on Rover SD1s.

[Edited on 9/10/07 by britishtrident]

Yepee! its past it MOT!

Now the explaination. After a member here gave me a PDF on the Range rover ECU ( u r a star!), it explained some of its functions. After searching the net for more info i came across some setting up help regarding the various pot sensors on the engine like the throttle pot and air flow meter. What i gathered is the ECU reverts to the cat fuel map if it detects a fault on any of these sensors and therefore runs rich (limp home mode). I found the air flow meter co2 trim value was way off, actualy reading 0.01V instead of the estimated 1.5V. Now i was confused as it said that the lower the volt reading here the leaner the engine ran. But i still set it 'richer' to 1.5V.

After a few days driving it felt much better. Went to the MOT station today hoping it was ok and it was...just. What i think was happening is the co2 trim value was so low that the ECU thought it was faulty and set the cat map to run and so meant i was running rich (above 6% co2!).

just need to reset the timing and base idle and im done. 6 months of bad running, £250+ on parts, 14mpg instead of 16 lol, constant worry of it not starting when i was out and about and 1 expert tuning sension with a local range rover garage! (they have lost a customer they could never have tuned it or touched the co2 trim).

Thanks for the advice, ive learnt alot about EFI AND my range rover in the process.