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Discussion Starter #1
My saga continues 4.6 gems issues started after she nearly ran out of fuel, she was literally running on vapour . After refuelling idle was ,2k. Did an adaptive reset which sorted that, replaced maf, throttle position sensor ( don’t ask why in hindsight neither do I) down on power won’t kick down and hunting/almost dying and this continues.. collected 2 tons of hay today and managed t coax her the 5 miles there and back but it has to be something relatively obvious. She will sometimes drop 2 gears Rev to 3-4K rpm and do this 3 or4 times ( I’ve seen another post with the same symptoms but there as n resolution posted). before going back to the hunting . I’m now convinced (no faults on faultmate) that it’s fuelling or possibly coil pack but leaning. To fuel due to her being run virtually dry just before this whole saga started. In line fuel filter has also been changed. I’m thinking it may be debris in the fuel line that is blocking the line and tending to think blowing the tank to fuel filter and filter to injector rail is the next thing to try... any helpful thoughts/ ideas are most welcome
 

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Have you put a pressure gauge on the fuel rail? At least that will show if the pressure is right at idle and when you rev it at standstill. Blowing through the fuel lines isn't going to do any harm and might just do it if it is clogged lines.
 

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Discussion Starter #4
Well no progress had it to specialist who has ruled out fuel and checked everything I’ve done ie maf, TPS, lambdas, adaptive resets and his professional test gear cannot bring up ant faults so I’m back to square 1. The only other thing I had done as to install a mobi4 immobiliser bypass which I can’t see could be the issue but all I can think of is to deinstall it. The garage can only surmise that as shell rev cleanly over 1500rpm in the garage but as soon as it’s out on the road plays up dropping revs to 1000 then recovers ad infinitum something is instructing the ecu or TPS to run weirdly... come on team, chuck any and all thoughts and suggestions at me.
 

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When I was down on power, I wasn't actually getting any codes until it got really bad. For me, it ended up being one of the coil packs going bad and not being able to provide a strong enough spark (worn out spark plugs made it all the more obvious). The way I was able to determine this was by hooking an inductive capacitance sensor on the spark plug wire near the plug and looked at the secondary ignition waveform.

How are your short/long term fuel trims? Is your IAC in good working order? are your HT leads in good condition?
 

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Discussion Starter #6
Right, firstly thanks for your reply. Plugs and leads are newish, but I’m being a bit thick in understanding what you mean about fuel trims and IAC. are you able to tell me what to look for/test lease. I have a Faultmate extreme
 

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You would read those values in the "live data" part of a code reader. Just trying to get a sense of how it's running. Fuel trims will usually help you see if it's running rich or lean.
 

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Discussion Starter #9
RIGHT. did a further check and got a tps fault which is new from Rimmers see attached file.cleared ok. also took some data from the fueliing and idle also attached.. its so weird - all started when running on petrol fumes to get home.. on idle shes fine up to 1200rpm and will hold stable revs to 4500 no probs in Park but in Drive either low or high ratios above 1200rpm she drops to |<1000 then recovers and repeats = I have found i can power through this to something akin to normal running without kickdown. but unless i can fi this v.soon it will be consigned to being an offroad car use only
 

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Discussion Starter #12
well, none of my saved data seems to be showing on line possibly because of the format. had another look this morning and now think the brand new replacement TPS may be faulty. I unplugged it went for a short 2 mile run and no hesitation or dropped revs, she would suddenly rev up and drop 2 gears then chnage back up which I think is the gearbox ecu being confused about the throttle position sensor. about 1/2 mile from home replugged in the tps and no hesitation - plugged in my Faultmate and got:-

THE GEMS FAULT CODE MEMORY CONTAINS CODES FOR THE FOLLOWING FAULTS -:


P0122, THROTTLE/PEDAL POSITION SENSOR/SWITCH A CIRCUIT LOW INPUT.

P0121, THROTTLE/PEDAL POSITION SENSOR/SWITCH A CIRCUIT RANGE/PERFORMANCE PROBLEM.

THERE IS NO FREEZE FRAME DATA STORED.



cleared ok.
Also, got the handbook symbol on the hvac screen and fault codes

THE HEVAC CONTROL UNITS FAULT CODE MEMORY LOG CONTAINS CODES FOR THE FOLLOWING FAULTS -:

(33) COMPRESSOR CLUTCH CIRCUIT OPEN.

(55) DISTRIBUTION DOOR MOTOR STALLED DURING SELF CALIBRATION.

IT IS ALSO SHOWING THE FOLLOWING CODES AS BEING CURRENTLY PRESENT -:

(33) COMPRESSOR CLUTCH CIRCUIT OPEN.

So, before I go back to Rimmer Bros re the TPS what do you all think / suggest about that fault code and where should I start on the a/c / hvac issue??????????????????????
 

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Discussion Starter #13
add in from a previous fault on the tps with freeze frame data :-

THE GEMS FAULT CODE MEMORY CONTAINS CODES FOR THE FOLLOWING FAULTS -:


P0121, THROTTLE/PEDAL POSITION SENSOR/SWITCH A CIRCUIT RANGE/PERFORMANCE PROBLEM.

FREEZE FRAME DATA STORED WAS:

48,6B,E8,42,02,00,01,21,01
 

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Definitely sounds as though the TPS is faulty. You should be able to check it with your diagnostics by looking at the live data with the ignition on but engine not running. You should be able to see the voltage from it which will vary between around 0.6V at a closed throttle and approaching 5V at fully open. If you slowly depress the throttle pedal you should see the voltage steadily climbing with no jumps.

As for the HEVAC faults, that's a different thing entirely. A GEMS will drive the compressor clutch directly and you may find that the voltage reaching the clutch is low. The feed goes via the large multiway connector behind the RH kick panel and also via the pressure switch. Bad connections at either of those points will cause insufficient voltage at the clutch. Or it might be that you are low on refrigerant so the pressure switch is open to protect the compressor. When you first turn on the ignition, the HEVAC cycles the blend motors and logs the fault if they don't all do a full sweep from one end to the other. Distribution motor stalled may be a faulty blend motor or it could be that the distribution flap is getting a bit sticky so stalled the motor. If the latter that one will be intermittent depending on temperature or other variables.
 

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Discussion Starter #15
Thanks, can’t see how to read voltages of the TPS on faultmate , thought it would be under petrol ems/inputs/ fuel-idle but whilst I see a box with voltage it’s static at 0.16.
 

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Can't help with the Faultmate but on the Nanocom it's under GEMS/Inputs/Air and Idle rather than GEMS/Inputs/Fuelling which is where you see whether it is running Open or Closed Loop and read the lambda sensor voltages. What is the box showing 0.16V labelled as?
 

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Discussion Starter #17
Just checking a data save from a week ago the page headed gems inputs fuelling bank 1 shows loop status as open.. and gems inputs air and idle page shows current throttle position at the same as read today ie .16 v, stored brittle position the same, air flow sensor voltage 0.31v, with amongst other hints an idle air control valve position n steps st 76
 

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0.16v is way too low. If it doesn't change when you open the throttle then it could be a faulty TPS but I'd be looking at the wiring to it having a break. Idle air control steps should be between 15 and 30 at idle so 76 is too high.
 

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Discussion Starter #19
Right, thanks a lot for this guidance I really appreciate it. I’ll redo all readings again tomorrow and then get rimmers to swap the TPS. Regards . Richard
 

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I don't think it is the TPS, more likely the wiring. You can check the TPS with a multimeter on the Ohms scale. Between the outer two pins you will see a fixed resistance, while between the centre pin and one of the outer pins you will see the same as the fixed resistance with it at one end of the travel and near zero at the other. I'd be looking at checking continuity between the TPS and the ECU. At the connector there will be a Red/Black wire which should have 5V on it (when tested against ground) which is the same 5V supply that comes from pin 36 on C507 (36 way Red connector) at the ECU and also supplies the MAF, fuel temperature sensor, cam position sensor and intake air temperature sensor. The middle pin (Yellow/Light Green) goes to pin 15 on C507 while the other end pin (Red) goes to pin 4 on C509 (18 way Black connector atthe ECU, the one nearest the centre of the car). If you unplug the TPS and link the Red/Black to the Yellow/Light Green in the plug, turn on the ignition and check the TPS voltage you should see a reading of 5V. If you don't the problem is in the wiring.
 
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