disco 2 v8 4.0 loss of power not gems

[plrobo]

for starters i am a bit of a landrover nut and have worked on loads of discos v8s etc this disco i have at the min has a real problem and i was wondering if anyone had any idears or similar probs
the disco is part way through a lpg conversion and has had the injector wiring cut into as per instructions and i believe this has not caused the probs and she has had no other faults in its history here is how the fault presents its self
1. no manegment warning light iluminated
2.starts fine runs sweet
3. as soon as you rev it up it hesitates and feels like fuel stavasion
4 if you rev the nuts out it it will rev but seems to be slugish and this is the strange one

5 no yes no co2 at the tail pipe and no hydrocarbons
this would indicate lack of fuel or to much air there is no leeks in the plemim chamber and no burs pipes fuel rail preasuer is fine to
please please help
it will drive but wont go over 45 mph and is blo+dy slow

[nzoliver]

:eek:Howdy, screams out air flow meter to me. Has it been replaced? Can you try another?

[plrobo]

Thanks For That I Have Tried Another One And It Seemed To Make Little Diferance Any Other Thoughts
Please

[jetfiremuck]

Check fuel filter. Check fuel pressure.

[plrobo]

i will try that today and let you no the results
that would be so good
thanks

[plrobo]

these discos dont have a filter just found out also the fuel rail preasue is fine
thanks
anyway

[Jon v8]

A couple of things,the air flow meter you tried - was it a known good unit from another car or a cheapo off E-Bay ? Poor performance and hesitation are 99% caused by airflow metering faults on Motronic injected Thor V8's.
Beyond that I would look at oxygen sensor activity after checking all their connections etc,some LPG systems hijack the sensor output and feed a false one to the Motronic ecu - this does not help matters.The lack of gases out the back could mean the exhaust/cats are partially blocked.
What LPG system are you fitting ?

[jetfiremuck]

paper fuel filter is around the pump in the tank. However if fuel pressure and delivery is good it may eliminate the pump . Next is Mass air flow/ Inlet air temp.sensor, then TP sensor. Does the engine missfire or buck under load?

[plrobo]

thanks for the messages the air flow mtr was from a crashed disco so i can only asume that it is ok and as for the o2 sensor it now shows as faulty on bank one and ? bank 2 and the most strange thing is that the snapon diagnostic machine says that the bloody truck is runing at 17degrees (thats why its so slugish) it also says that there is no rpm no the engine (my only thought with this is if the crankcase posision sensor is faulty it would show as no rpm and i am not sure if the ecu would advance the timing to componsate for this) the lpg only hijacks a signal from pin d17 (rpm sensor)and is still not fully conected so would have no affect on the engine
thanks
paul

[Jon v8]

Failure of the crank sensor will stop the engine,there is no back up for it - simple as that.Using a Snap on diagnostic tool may lead to false/misleading readings.LR,MG and Rover cars are well known for being awkward to communicate with.You really need to use Testbook or Autologic to get the right info.The airflow meter needs to be a known good one,as even on live data displays they can still seem ok but not read a high enough value - and they dont log faults because the readings arent far enough out.

[plrobo]

i think the best thing to try would be a new air flow sensor and get a test book for a day a (any ideas abour the timing):)

[Jon v8]

Good idea with the AFM, I wouldnt worry about the timing,the Motronic ECU will set the timing as it wants too.Dont expect the timing to advance right up till the engine is hot and running fast - max advance wont happen till 2500-3000 rpm and should get up to 32-34 degrees at a guess.
When you get it on Testbook you will be able to see more clearly whats going on.

[TEMPL4R]

As Jon says, a reading of O2 sensor Bank 1 sensor 2 ( after the cat no 1 cylinder) often means people change the Lambda sensor and it makes no difference. It is the MAF most times, plus some copys are faulty. We've had a few in that run rough even though someone has fitted a new MAF, change it for a genuine part and away they go.
The Lambda goes out of it's values and so reads a code.

Recently I had a Chrysler PT with a stuck air bypass valve, kept drastically over revving ( not funny on an Auto) and other times stalling. It didn't come up with any faults, so it was down to old mechanics diagnostics. ( sticking my fingers in various holes and seeing what happened...)

Chris