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M. Recke (Disco_Obsession)
| | Posted on Friday, December 20, 2002 - 04:35 am: | 
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Help appreciated please.
My '96 V* Disco manual has the following sympton. I can't check the diagnostics as I have no access to OBD.
At startup it takes acouple of attempts. when it starts the idle is low till I give the pedal some gas then the idle reaches normal RPMS. Whilst driving the idle can vary when the aircon is operating, usually it dives.
I don't believe this is fuel related, ie Fuel pressure or fuel starving from a blocked fuel filter as it happens on LPG which bypasses the injectors etc.
When starting off from staionary on a hill, there is significant power loos, and the same applies when cruising at 35mph and an incline occurs, it seems to lack power.
I have checked the timing and the stepper motor appears clean and functioning.
my temperature guage reads normal.
When running the Airconditioning, Aircon will intermitantly switch off automatically.
when switching the engine off the thermatic fans will somtimes run for 10 mins to cool the system down.
I thought it could be the Coolant Temp sensor, but a workshop had a brief look at it and said it tested ok.
I have replaced the ignition leads and no difference.
plugs are only 3 months old.
ignition timing is set to specs.
This is an Australian spec Disco and uses a distibutor.
Dizzy cap appears serviceable, ditto for the rotor button.
New airfilter installed.
the workshop mechanic who briefly looked at it (who can't do anything till newyear) said it could be carbon build up on the valves. ( Wouldn't I find this carbon also on my plugs?) Can carbon be removed by running injector cleaner through the fuel system?
Ot it could be a ECU going?
Airflow sensor faulty?
Or it is need of a tuneup?
Correct me if I'm wrong, but tune ups on EFI vechicle basicaly are spark wires and plugs, filter etc, ECU and engine management take care of most and are un ajustable?
I thought it was a coolant sensor as for the sympton I had, but have been told otherwise.
Any suggestions as to what to check and in what order, and info on how to test them.
I rerad on another post the Earth/grounding can cause problems?
Soory for the long post, but it's geeting frustrating, especially when I would like to hit a trail over the Christmas/ Newyear break.
Thanks in advance. |
M. Recke (Disco_Obsession)
| | Posted on Friday, December 20, 2002 - 07:13 am: |
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Further to my above post.
I just checked out a few things and I noticed that with ignition switch in the "ON" position when I switch the Aircon button ON the thermatic fans start, switch the aircon off and they turn off. Is this Normal or is there a fault?
Thanks |
Randall Smith
| | Posted on Friday, December 20, 2002 - 08:47 am: |
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Mr Recke
The aux fans should blow on whenever the ignition is on, and the AC is on.
If the ECU detects that the fuel temp and the coolant temp are both high after you have turned the engine off...then a timer will run the aux fans for ten minutes.
Problems related to hot starting of the engine can often be traced to a faulty fuel temp sensor. (cold starting problems are often the coolant temp sensor) So now we have two clues pointing to the fuel temp sensor.
Also I would get a new stepper motor. This is quick and easy way to diagnose idling problems.
Final advise, take advantage of the OBD system!
Randall |
Paul T. Schram (Paulschram)
| | Posted on Friday, December 20, 2002 - 12:31 pm: |
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Mr. Recke:
I'm assuming that your truck is similar to mine, late MY'95 with distributor (I think I dislike Dizzy almost as much as Kyle dislikes ••••••).
As a result, you may have limited OBD capabilities. Is there a diagnostic readout beneath the passenger seat? If so, you may have some clues there. Also, the control the ECU has over ignition is limited if you have the distributor. If you have the GEMS with coil packs, then yes, you have complete computer control over ignition.
While Randall and I disagree on OEM vs. aftermarket Idle Air Control Valves, I believe this could be a contributing factor to this condition. You could also be suffering from leaking fuel injectors as an additional contributor.
As for removing carbon from the valves, it is unlikely that anything you could add to the fuel would help much as I believe it is typically the exhaust valves that carbon up and they would have limited utility for compounds introduced through the intake system. My truck has recently rebuilt heads and even as a 3.9, it had significant carbon buildup on the valves and seats. I suggest the use of additives for injector cleaning, not valve cleaning.
Again, adding further credence to my suspicion it is the IAC valve is the correlation between air conditioning use and the problem. Might also be bad Tee-piece restrictor (vacuum leak), fuel pump, and pressure regulator (hard starting requiring go pedal). Have you checked the fuel pressure with key on and off?
WHOAH cowboys and girls. You state you think it might need a tune-up... Start with the basics-plugs, wires, rotor, cap, fuel filter. Until you get back to a baseline, we are stabbing in the dark.
Paul |
M. Recke (Disco_Obsession)
| | Posted on Friday, December 20, 2002 - 10:17 pm: |
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Thanks guys, I have an OBD2 system underthe dash, so I need a reader.I do not have the under the seat OBD. I Emailed OBD2. com to see if they had an Australian distributer or if they do mail order, I haven't a reply yet.
as I mentioned earlier the problem is also on my duel fuel LPG. So I think leaking injectors and fuel pressure can be discounted. The LPG has a mixer is attached to the plenum chamber air intake, thus fuel air is sucked in bypassing the gasoline fuel injection system.
It started ok this morning and drove resonably except for an odd miss here and there and then this afternoon when the ambient temperature was up ( Hot)I found it ran like a pig. I stopped on a traffic light on a hill and when I tried to accelerate it was very sloww to move and slowly gained momentum.
Would a compression test pick up carbon build up?
I'm still leaning toward the coolant sensor being suspect.
I'll install new plugs tomorrow and see if it improves. |
Paul T. Schram (Paulschram)
| | Posted on Saturday, December 21, 2002 - 01:58 pm: |
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Plug wires may be more of a culprit than plugs themselves. |
Ron
| | Posted on Saturday, December 21, 2002 - 02:37 pm: |
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Check the ignition module. Is it still on the side of the dizzy in 96 ROW discos? It may have gone bad. This is my first guess. As far as sensors or around and unplug them one by one and see if things improve. The ECu will substitute a default value when a sensor is unplugged.
Ron |
M. Recke (Disco_Obsession)
| | Posted on Saturday, December 21, 2002 - 07:00 pm: |
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Paul Iv'e tried 2 sets of plug wires and still the same.
Ron, My distributer does not have on of those ignition modules. They were dispensed with in 95 i think in Aus spec.
Cheers,
Mars |
M. Recke (Disco_Obsession)
| | Posted on Sunday, December 22, 2002 - 12:14 am: |
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This might be the Culprit.
Even though a mechanic reckons the Coolant sensor tested ok. I ran a multimeter on it and got Nothing as a reading either hot or cold.
He tested some other sensor Not the one on the theristat housing.! |
Paul T. Schram (Paulschram)
| | Posted on Sunday, December 22, 2002 - 12:45 pm: |
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I'm curious to hear the outcome as my last thought was that due to the problem being present on either LPG or Petrol, it would be less likely to be the coolant temp sensor, although, if the reading is way off, it might be confusing the ECU enough to cause these problems. I would expect that since the LPG is apparently completely independent of the PEtrol system, the coolant temp sensor wouldn't have any impact as the only control the coolant sensor would have would be to tell the fuel injectors to run more rich. As this engine has the distributor, the ECU has limitied control over ignition timing, if any at all.
I'm still confused.
Sorry I wasn't more help. |
M. Recke (Disco_Obsession)
| | Posted on Monday, December 23, 2002 - 04:58 am: |
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Paul, I installed a new Coolant sensor and the problem seems to have gone. I have easier starting and regain of power. I believe the Coolant sensor provides info to the Stepper motor via the ECU, as now the idle at start up is better and the idle is smoother. On advice of another Disco owner. I also clamped the stepper motor vacuum line to the plenum chamber to reset the Stepper motor range.
The base idle was checked during this time and the ignition timing. (I was unaware previously that Landrover workshops block this line off to time the vehicles whilst it is at base idle) .
I also at the advice of said person poured REDEX fuel system cleaner down the vacuum line from the rocker cover to the plenum chamber. Redex reccomends pooring this down carbys to clean gum and gunk off. after the smoke disappeared from the exhaust it seemed to run a lot smoother. New plugs wre gapped and fitted the old ones though onlt 1000 kms old had slight carbon coating on them. My Disco now drives like a new one.
The dealer spareparts man Told me that they run like shit if the coolant sensor is Kapput.
Thanks for all your hepl.
Have a meery Christmas.
Mars |
Paul T. Schram (Paulschram)
| | Posted on Monday, December 23, 2002 - 01:48 pm: |
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Learn something every day. I do readily admit that the Coolant sensor is critical to the operation of fuel injected engines, but I didn't realize to what extent. |
M. Recke (Disco_Obsession)
| | Posted on Monday, December 23, 2002 - 10:24 pm: |
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Paul, I was told by another on a differnt forum that there is a posiblity that the Coolant sensor is telling the ECU that the system temp is one thing and the fuel temp sensor is conflicting this info, the ECU says, what the shit is happening and throws a spasm . I remember many years ago I was at a Ford dealer spare parts and a customer came in tp purchase a coolant sensor. And he was told that cars run like shit if this sensor pays up. Anyway sensor or not, mine seems to be purring along nicely now. Thanks all you guys for you help and input.
Mars |
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