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See Ignition for idling problems caused by faulty HT leads
Internet Mailing List Feb 97
Has anyone had experience of their 5.0 Chimaera continually stalling
on them? My 18 month old 12,000 miler has a habit of dying on
me on downshifts - going into roundabouts etc. It usually won't
start again for about 5 minutes. Sometimes the engine fires but
dies immediately, at other times it refuses to fire at all. My
dealer can't find the cause.
Philip Morland
Internet Mailing List Feb 97
Yes, I have had the problem you described on my Griff 500 when
I got the car. All or a combination of the following were done
and it solved the problem:
1. If it has been happening since you got the car, check to make sure that the chip in the ECU is the correct one for the 500HC engine. Mine was incorrect when a replacement unit was sent despite specifying the car it was for (came with Griffith 500 written on labels). ECU is stock Land Rover/Lucas part but mapping chip is TVR proprietary. We suspect someone forgot to change the chip at the factory.
2. The tune resistor value used should be 3900 ohms, and is standard Land Rover part. We found a variable resistor in my car which is not factory standard, and was probably installed by my dealer here to pass emission tests. Adjustment is for biasing ECU's fuel/air mixture, and if the engine runs too rich when engine is up to running temperatures, causes stalling at low rpm in my car. You did not mention whether your problem is related to engine temperature, but may be why you can't fire it up when warmed up. oo lean and drive train snatch is more pronounced. Suggest sticking to 3900 ohms since it offered the best driveability, and is the factory setting for good reasons. ther settings may cause damage to catalytic converter.
3. Have stepper motor and valve cleaned with wire brush. Check that stepper motor itself is functioning. There is a allen key screw on the plenum at side of air inlet which is redundant for this version but make sure someone has not inadvertently screwed it all the way in. The factory setting for it is two and a half turns starting from bottom.
4. Basic tuning such as cleaning/replacing plugs, ignition cables (these deteriorated very quickly in my car, probably due to climate and heat from manifolds), and ignition timing. Another possibility to check is the fuel pump.
Please be aware that I am sharing these as my experiences of a
problem similar to what you describe. Without a more detailed
assessment its difficult to diagnose. Hopefully, this information
would be useful in suggesting places for your dealer to look.
Kenny Heng
Oct 96
I had a minor problem with the Griff, and also previously with
the Chimaera, where when the ambient temperature was very high
e.g. 30C the engine would stall when depressing the clutch at
a junction, instead of dropping to idle speed. I had a similar
problem last year with the Golf that I was running, and it was
caused by a plunger sticking in a cylinder due to a combination
of dirt buildup, misalignment and/or and thermal expansion. I
understand that the TVR problem is very similar, and I know it
is also widespread. The main reason I would like a definitive
answer is that I am regularly communicating with a soon-to-be
owner in Singapore and the car he is buying is afflicted with
the problem due to the higher ambient temperatures. I also know
it's a simple problem to fix, as SHG cured mine in about 5 minutes.
Have you got anything on this one?
Steve Powell
Oct 96
I've asked my dealer about the stalling problem you described
and he has two suggestions.
The most likely cause is carbon build-up on the stepper-motor valve, which will make it stick shut. This can be checked by removing the stepper-motor unit (at the back of the plenum chamber on the end of the air by-pass hose) and cleaning the seat of the valve with a wire brush. I've never had this apart myself but I'm told it's pretty obvious what to do once the unit is off the car. This sounds like the problem you described with your Golf. A TVR or Range Rover dealer can check the operation of the motor by using their diagnostic equipment to trigger it in the same way that the ECU does. I don't think you can do it any other way, but a bodger might try whipping one end of the by-pass hose off and seeing if they can feel any suction on tickover. If the motor itself has to be replaced, the Lucas part number for all models is 73312.
Another possibility is that the fuel filler cap is on too tight.
The cap is supposed to allow just enough air in to prevent a partial
vaccuum developing in the tank, while not actually venting petrol
fumes to the atmosphere. I'm told that it doesn't aways work as
it should, especially in hot weather (maybe because the seals
in the cap expand). A clue is if the tank goes whoosh when you
take the cap off at a filling station. Try loosening it a fraction
and see if the problem goes away. No doubt it would be illegal
to drill a small hole in the cap . . .
Peter Beech
Internet Mailing List Dec 96
After not having the Griff for a week it now seems to be sitting
at idle at between 400 and 800 rpm. Is this normal as it has taken
to stalling in traffic unless I keep the revs up?
David Donnan
Internet Mailing List Dec 96
Around 1,000 rpm or above is the usual idle speed. Stalling in
traffic usually indicates a mis-adjustment or other problem with
the stepper motor, which prevents the engine from idling properly.
I'd have it looked at by a dealer if I were you, as it's a common
and easily rectified problem.
Steve Powell
Internet Mailing List Dec 96
Mine did that when I first got it and I have yet to completely
cure it. I cleaned the stepper motor valve which improved matters
a little. This requires its removal from the back of the plenum
but is relatively simple to do. I have been told that replacing
the motor itself may be necessary, and I have just received the
part and will try this out soon. Another adjustment is the allen
bolt at the side of the plenum on the passenger side nearest to
air hose. I am told by the factory to have this set 2.5 turns
starting from fully screwed in. Mine stalled too and this was
cured by removing the variable tune resistor (installed by dealer
and running too rich) and replacing it with a fixed resistor (Land
Rover part, 3900ohms for Griff 500). This is found in your harness
leading to the ECU in the passenger footwell. I doubt however
that this would be your problem, but is simple to check.
Kenny Heng
Internet Mailing List Dec 96
So how does this thing effect idle speed?
Paul (engine Illiterate)
Internet Mailing List Dec 96
It doesn't... but the jet it controls does. The V8 engine sets
the idle speed by bleeding a small amount of air from the air
intake into the plenum chamber. It's the equivalent of opening
the throttle slightly without having to touch the accelerator.
This is controlled by a jet which is controlled by the stepper
motor which in turn is controlled by the engine mangement system.
If the jet gets stuck or the stepper fails, the idle speed goes
out of the window. This used to be done by adjusting a metal screw
- which is still there but does very little now its function is
done by the stepper motor.
Steve Heath
Internet Mailing List Dec 96
. . . Apart from for keeping the engine idling, I understand it
is also used to keep revs up during gear changes (the moment when
throttle is closed) so that they are smoother. The ECU controls
the stepper motor based on inputs such as engine temperature,
engine speed, and vehicle speed.
Kenny Heng
Internet Mailing List May 96
. . . My Chimaera initially idles at just over 2000 rpm for no
apparent reason. If you start it from cold or warm it either jumps
to 2000 revs or shoots up and down between 1-2000 revs. Strange
thing is when you let it idle for about 2 minutes it settles down
to a much more reasonable 98Oish revs but if you should restart
the engine for any reason its straight back up to 2000.
Tony Orr
Internet Mailing List May 96
My S3C has the same 'feature' in normal use and also a very similar
problem relating to a faulty component. My solution is the following:
1. Start the car using no throttle
2. Let engine settle down to it's start-up revs (usually 1,500-2,000)
3. The battery light is still on.
4. Rev the engine to turn off the battery light.
5. Immediately let the engine revs settle down.
Simple as that! . . . obvious really?!
A very similar problem also occurs when there is a faulty throttle
regulator. This gets steadily worse especially in summer when
it is hot. What happens is that when you are braking (!) or when
stopping at lights the car can inadvertently go to 2,000 (or more)
revs - which is obviously dangerous. The solution is to get a
new one.
Mark Gee
Apr 97
In my experience, if the idle speed is searching between say 1500
and 2000 rpm it is usually a stepper motor problem.
Steve Beresford
Internet Mailing List Jun 97
The stepper motor is a black plastic unit about 1.5 inches across
with an electrical lead plugged into the back. It screws into
the rear of the plenum chamber at the back of the engine on the
driver's (RHD) side. To remove it, disconnect the lead and gently
with a large spanner unscrew the unti. If it is gummed up, clean
it and put it back. Do not over torque it or it will break. Some
people recommend using some ptfe tape - as used by plumbers -
around the thread to ensure a good seal. If it not gummed up,
then it could still be faulty in which case it will need testing
and replacing i.e. a trip to your friendly dealer. This is best
done when the engine is cold. Not only is there no hot metal work
waiting to burn you, but the stepper is often easier to remove.
Steve Heath
In the Summer/Autumn of last year the car developed an intermittent problem where it would stall and prove impossible to re-start unless left for several hours. The problem seemed to occur mostly when damp, and after many hours at the TVR Centre was traced to a badly soldered transistor in the ECU. This was re-soldered and the car ran trouble free for about six months.
Then at the beginning of the summer the car, on occasion, would seem to lose a considerable amount of power. If the car was idling, it would stall. If moving, there would be a momentary loss of power. These were the same symptoms as described in the above problem, except this time the car would always re-start. Again, the problem occured sporadically. I assumed that there was yet another issue with the ECU, and insisted that it be sent away to be checked (the TVR Centre computer had failed to pick up the earlier fault).
The TVR Centre says that the ECU is fine and that the problem is carbon build up in the cylinder head valves. Their solution is a de-coking of the cylinders for £1,300. Now I admittedly do most of my driving in London, but after only 9,500 miles in total there is no way that this can be ordinary wear and tear. If a carbon build up is the problem then surely there must be something else wrong. I haven't heard of anyone de-coking a car (although my father has, but twenty years ago and then only after about 50,000 miles).
Do you have any thoughts/suggestions? If it is a carbon build
up should I try "blowing it off" e.g. driving it for
some long motorway stretches? Are there any products that one
can put through the fuel?. . .
Michael Hewett
Comment
I have a lot of respect for the people at the TVR Centre in Redhill [Redhill Ltd]
and often ask them for help with queries I get from other owners,
but I've no idea what the Barnet branch is like. So I rather mischievously
asked Redhill to comment on Michael's letter. If you are a cynic
you will ignore what follows, but it seemed to make some sense
to me so I thought it was worth passing on.
Redhill have had problems with several cars that are used a lot in London, and they believe it is because the ECU has been set up for 'sports' driving (oddly enough) and not for sitting in traffic jams. In stop-start conditions the messages going to the ECU could be so far outside its normal parameters that it starts assuming fault conditions and ignores them completely. The engine will still run under these circumstances, but not with anything like the correct mixture. If this is the only type of driving the car is used for, it is possible that it could have got as badly coked up as Barnet were suggesting. I gather from other sources that carbon build-up on the valves is much more common with unleaded fuel.
In this particular case one wonders whether the previous owner had also spent all their time chugging round London, and whether the duff ECU had made matters even worse. As for giving it a good thrashing, I would have thought the car would be ever so grateful even if it didn't cure the problem. An RAC man once told me that he regularly 'decoked' his own cars with a good dose of Red-X straight into the carbs, but I'm not too sure how modern engines (or cats) would react to this.
(There is a reference to this in a discussion about city driving under the Impressions section).
Peter Beech
| Code | Meaning | Comments |
| 02 | Live feed to ECU has been interrupted | Normal if ECU has been disconnected to clear old fault codes. Code 02 will clear if ignition turned off for 30 secs then on again. |
| 03 | Stored data corrupted since last trip | No useful information available. Test drive and try again. |
| 12 | Airflow meter out of range | Possible air leak or wiring fault. |
| 14 | Coolant thermistor out of range | Faulty sensor or wiring. |
| 15 | Fuel thermistor out of range | Faulty sensor or wiring. |
| 17 | Throttle sensor out of range | Sensor needs adjustment or is faulty or has wiring fault. This can cause low speed misfires |
| 18 | Throttle sensor output too high when air flow low | Large air leak between throttle butterfly and A/F meter or faulty throttle sensor or A/F meter. |
| 19 | Throttle sensor output too low when airflow high | Faulty A/F meter or throttle sensor. |
| 21 | Tune resistor out of range | Check tune resistor resistance. |
| 23 | Low fuel pressure | Blocked fuel filter or faulty pump or pressure regulator. Valid for cat cars only. |
| 25 | Misfire at full load | Faulty plugs, leads, electronic ignition unit, distributor or coil, low fuel pressure or valve or head gasket leak. See 40 and 50. Valid for cat cars only. |
| 28 | Air leak | Leak in A/F meter hoses, injector seals, inlet manifold gasket, plenum gasket, servo or crankcase vent hoses or Lambda sensors. Valid for cat cars only. |
| 29 | Checksum error | The ECU is f****d. |
| 34 | Fuelling fault in nearside injector bank | Injector or Lambda sensor wiring fault, faulty injectors, air leak at injector seals or inlet mainfold, blocked injectors. Valid for cat cars only. |
| 36 | Fuelling fault in offside injector bank | As above but for cylinders 2-4-6-8 only. Valid for cat cars only. |
| 40 | Misfire on nearside bank | As 25 but for cyclinders 1-3-5-7 only. Valid for cat cars only. |
| 44 | Nearside Lambda sensor out of range | Faulty or lead-poisoned sensor or sensor wiring fault. Valid for cat cars only. |
| 45 | Offside Lambda sensor out of range | As above. Valid for cat cars only. |
| 48 | Stepper motor fully open above 500 rpm or fully closed above 750 rpm | Sticking stepper valve, incorrect base idle speed adjustment, air leak on non-cat cars, incorrect stepper motor adjustment, incorrect throttle butterfly adjustment, rough running because of fuel or ignition or mechanical faults. |
| 50 | Misfire on offside bank | A 25 but for cylinders 2-4-6-8 only. Valid for cat cars only. |
| 59 | ECU unable to distinguish between faults 23 and 28 | Fault occured for insufficient time for ECU to diagnose. |
| 68 | Road speed sensor output too low at medium rpm and high air flow | Possible sensor or wiring fault (will also cause wrong speedo readings on electrical speedo cars). Valid for cat cars only. |
| 88 | Power-up check | Not a fault. Sometimes displayed on first connecting test module. |
28 29 30 31 32 33 34 35 36 37 38 39 40 27 26 25 24 23 22 21 20 19 19 17 16 15 14 01 02 03 04 05 06 07 08 09 10 11 12 13Don't blame me if tinkering about here produces a puff of smoke and a large bill! Power Supply to ECU