Range Rover Engine

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J

JASPER6BEARS

New Member
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4
Hello

Just joined the forum - Hello All.

We have just acquired a 1995 Range Rover 4.6. (P38)

I have put on new plugs,leads,air and fuel filters but it ticks over a bit lumpy! Also had a new stainless exhaust and cats fitted.

Any ideas how to narrow the problem down?

Do I need kit to diagnose this? I am based in Surrey so any help appreciated - or local workshops to plug it in would be great.

I am willing to buy the code reader ir reasoably priced.

Thanks Tim
 
I had the same problem a few years back, sorted it by ensuring the high tension leads were keptl apart. Preferably at night, lift the bonnet while engine running to see if any blue glowing colour visable along the leads, if so then this is the problem.

Regards,

Stephen.
 
you could do with getting it on a obd2 scanner, the elm 327 off ebay is fine for this and around 30 quid a useful bit of kit!

fuel trims, maf reading etc in the ecu could tell you what is going on, i would check the maf sensor, sounds like classic maf sensor failing or mebbe just neads a clean out,

also lambda probe reading would tell you if they are functioning correctly.

you dont say if its lpg, if it is and runs well on lpg it could be that the lpg kit is way out and giving the ecu readings it isnt expecting causeing it to fuel the car incorrectly when back on petrol!
 
Hello All

Thanks for all your help.

Heres an update on Range Rover Rough running problem.

Local independent garage on autologic says O2 sensor faulty - changed it - But No Difference to lumpy running?

Does the ECU need time to adapt? Or does it need resetting?

Just as a reminder I have put on new plugs,leads,air and fuel filters,new exhaust and cats - now new coils and o2 sensor.

MAF shows ok on OBD and the Autologic - have used carb spray up inlet as well.

Any more clues to rough running and lumpy tickover would be great - it is useable as is but - it should be better?

Thanks
 
Its very important to know if its got LPG on it.Did the indy do an adaptive reset of the engine ecu when the Oxygen sensor was changed ? Are there any inlet/exhaust manifold leaks.Are all the vac hoses around the inlet manifold in good nick - esp the breather hoses off the rocker covers,are they split/collapsed ?
 
Hello again

It has a Prins Multipoint LPG system.

The ECU has not been reset after O2 sensor Installed?

I cannot see any inlet or vacuum leaks.

Which breathers should I check?

Thanks
 
Hello

Good idea - Selling it that is!!!

Local gas man does not want to set up until its running ok on Petrol.

If I switch between gas and Petrol still runs the same?

Thanks
 
Have you got an idea of the way the plug leads are to be arranged?? and I'm not talking firing order. they're not touch each other in places and upset the firing by shorting against one-n-other, doesn't matter if their the best leads money can buy they have to be apart it is CRITICAL with these engines.
 
Anyone using an Autologic system doing diagnostics on a RR like this should know that if its been running with a faulty oxy sensor for more than a couple of hundred miles,the long term fuel trims will be way out.As a result the new oxy sensor will be giving feedback that the short term trims cant possibly meet.
Take it back and ask for a reset before you do anything else.And dont run it on LPG till its sorted on petrol or more harm will occur.
 
i could tell and i was using a cheapo obd2 scanner off fleebay, 24% on fuel trim and reading rich with lambda sat still at 0.8 (or could have been 0.08, but the number is irrelevant, the fact it was still signals dead lambda)

this reset buisness after a lambda change, how important is it? fuel trims are fine and reading flicking up and down as they s'posed to!
 
Can be very important,esp if the car has LPG and the LPG feeds the engine differently than the petrol ecu would.When an oxy sensor fails and its output stays the same or there is an exhaust leak/vac leak/failed plug etc - the engine runs differently than it would when in good health.The Gems ecu will try its best to adapt to it by shifting the trims to suit,so if its say trying to lean off a bank to cope with a misfire.It will narrow right down the available pulse width to get the oxy sensor cycling again.
When the misfire is repaired,the unburnt fuel in the exhaust is massively reduced so Gems trys to richen it up to get it cycling.Trouble is the range of injector pulse width due to the long term trim is too narrow and it cant get rich enough.With a reset to base values it can start over.
Your car sounds fine if the trims are both cycling,its when they go fully positive or negative and sit there,but the engine still cant run right.
Simples :D
 
to be honest its running sweet again, i will have a look at trims but they wer fine yesterday, as far as i can tell, i did tweek the lpg settings slightly but again i use the lambda display on the lpg software to get it flicking as it does on petrol. never can get it perfectly matching on tickover but at 3k revs it perfoms almost exactly as on petrol. it does bias to rich on lpg tickover but flicks slowly to lean then back for a second or two then flicks. this i prefer as we all know lean can be harmful and create too much heat!

as for the op's setup, mine also seems to have a slight miss but its not a miss as ive had it on occiliascope. probably poor quality leads or the proximity to eachother, its fine when running and revving etc.

another thing i have done is block the breather inlets to the plenum and put the breathers pipes to the back of the heads, this saves alot of messing about as the breathers change the mixture, the petrol side is able to cope but the lpg side doesnt like em in thier factory way!!
 
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