Rough Running! CURED!!!
Discussion
THANK YOU, THANK YOU, THANK YOU to Dale who started this thread back in 2004. I too had rough running problems between 1000 to 2000 revs plus the smell of unburnt fuel. I changed the sensor today, Lucas part no SNB802,(£9.99 off eBay) and hey presto the old car is running as smooth as silk and pulling well from low speeds in 5th gear. Wonderful and such a cheap and easy fix. Thanks again Dale.
Fwiw - land rover part LETC8496 AJ10 will work and intermotor part 55128
Good reference:
http://www.parkersteve.dsl.pipex.com/chimaeraparts...
Good reference:
http://www.parkersteve.dsl.pipex.com/chimaeraparts...
Edited by Chimp871 on Wednesday 7th September 21:19
Helpful thread this. My Chimaera (5.0 Taraka) was running quite rough lately, with some intermittent popping and banging at idle, and kangarooing in the 1000-1800rpm range when at operating temperature. I've changed the sensor last night (used the intermotor part) and at least the car felt smoother at low rpm, a lot of the kangarooing taken away. Also less crackling at the overrun, which could indicate it's running quite a bit leaner now (less petrol smell as well). Indeed worth noting that the intermotor part has a larger electrical connector so might not fit your average 19mm deep socket. Managed to get the old sensor off with the deep socket, and put the new sensor in place by hand and finished it off with spanners/pliers. Not very suave but it doesn't leak, so will ask the garage to tighten it at the next service
I too followed this very helpful advice, replaced the water temp sender, and the kangarooing improved considerably. After an hour in a hot traffic jam on the way to Burghley last weekend, though, the car ran roughly and the kangarooing returned. It hadn't fully recovered by the time I got home in much cooler conditions. I'll look for air leaks after the Airflow meter and for air in the cooling system (highest point in the system just beneath the temp sender?). But no-one has mentioned replacing the temp sender in the fuel rail- is that worth a try or is it not actually a temp sender at all?
Any comments gratefully received.
Cheers Malcolm
Any comments gratefully received.
Cheers Malcolm
woodlandsale said:
I too followed this very helpful advice, replaced the water temp sender, and the kangarooing improved considerably. After an hour in a hot traffic jam on the way to Burghley last weekend, though, the car ran roughly and the kangarooing returned. It hadn't fully recovered by the time I got home in much cooler conditions. I'll look for air leaks after the Airflow meter and for air in the cooling system (highest point in the system just beneath the temp sender?). But no-one has mentioned replacing the temp sender in the fuel rail- is that worth a try or is it not actually a temp sender at all?
Any comments gratefully received.
Cheers Malcolm
Have you guys got Rovergauge and checked the output before replacement ? Just wondering if you are finding that replacing the sender, even with it showing apparently healthy output, is giving improvement.Any comments gratefully received.
Cheers Malcolm
I wonder if the hot under-bonnet temperatures is cooking the sensor, i.e. you said it got worse again after being in a traffic jam ? The air temperature wouldn't be as hot as the water temp that they are designed for though so you'd think they could cope.
My recent experience has been that certain drivability issues can be attributed to voltage drops, if you study the spec of an idle air control valve (stepper motor) you'll find it's a low voltage device making it very sensitive to small changes in supply voltage, this in turn can cause undesirable engine behaviors if it's supply is not within it's designed operating parameters.
An idle air control valve is effectively generating a managed induction leak, in nearly all cases an induction leak is a bad thing so if an engine management controlled idle air control valve system is to work correctly and not introduce drivability issues of its own it must be controlled extremely accurately indeed. Anything that minutely influences the perfect control of the idle air control valve will very likely introduce the kind of kangarooing behaviors (shunting) we so often hear these cars suffer from, keep in mind TVR wouldn't have sold many Chimaeras & Griffiths from new if the cars functioned so poorly on test drives. The Range Rover & Discovery that ran the same system didn't kangaroo up the road from new either, so something is clearly wrong with your TVR if its doing this and I would put money on it being a voltage and or current supply issue.
Its worth remembering the other sensors screwed into the engine block like the engine coolant sensor and the fuel temperature sensor are earthed through the block and they also operate on a very low voltage, so if the engine is poorly earthed you can't begin to hope the sensors will work correctly. I discovered recently eliminating a significant electrical drain made a big difference to the way my engine idles, it's throttle response and drivability, given this and the well known dubious quality of the TVR wiring I'd encourage people with issues relating to sensors and their stepper motor to test supply voltages and run some additional stout engine earth straps before they resort to buying new stepper motors and or engine sensors.
The pish poor radio reception you get with pretty much every Chimaera & Griffith is all the evidence you need to prove the engine isn't earthed as well as it should be, the fact our cars can suffer shunting may well also be a function of poor earthing so I'm in the process of adding some block to chassis earth straps..... because in the words of an experienced professional mechanic Sardonicus.....
Just to add to this Lloyd Specialist Developments make the following statement...
"Although there is a certain degree of built-in compensation, electronic engine management is adversely affected by poor vehicle electrics and excessively low voltages - as you have noticed. At least 25% of our Canems installations highlight existing issues with TVR electrics (alternator issues, old cables, etc) during the installation and set-up phase."
These are the professionals speaking, professionals with lots of experience with engine management & TVR electrics
An idle air control valve is effectively generating a managed induction leak, in nearly all cases an induction leak is a bad thing so if an engine management controlled idle air control valve system is to work correctly and not introduce drivability issues of its own it must be controlled extremely accurately indeed. Anything that minutely influences the perfect control of the idle air control valve will very likely introduce the kind of kangarooing behaviors (shunting) we so often hear these cars suffer from, keep in mind TVR wouldn't have sold many Chimaeras & Griffiths from new if the cars functioned so poorly on test drives. The Range Rover & Discovery that ran the same system didn't kangaroo up the road from new either, so something is clearly wrong with your TVR if its doing this and I would put money on it being a voltage and or current supply issue.
Its worth remembering the other sensors screwed into the engine block like the engine coolant sensor and the fuel temperature sensor are earthed through the block and they also operate on a very low voltage, so if the engine is poorly earthed you can't begin to hope the sensors will work correctly. I discovered recently eliminating a significant electrical drain made a big difference to the way my engine idles, it's throttle response and drivability, given this and the well known dubious quality of the TVR wiring I'd encourage people with issues relating to sensors and their stepper motor to test supply voltages and run some additional stout engine earth straps before they resort to buying new stepper motors and or engine sensors.
The pish poor radio reception you get with pretty much every Chimaera & Griffith is all the evidence you need to prove the engine isn't earthed as well as it should be, the fact our cars can suffer shunting may well also be a function of poor earthing so I'm in the process of adding some block to chassis earth straps..... because in the words of an experienced professional mechanic Sardonicus.....
Sardonicus said:
TwinKam said:
The starter isn't fussy which earth it uses, whichever path has the least resistance. In the absence of anything more substantial, it would be quite happy to use the (choke or) accelerator cable... 
Now theres a man that knows, I have seen a few fried control cables in my time due to this, Twistgit they are your ECU grounds/earths on the N/S head, and like Dave said the more earth/ground returns the better this includes all cars IMO not just seperate chassis versions Just to add to this Lloyd Specialist Developments make the following statement...
"Although there is a certain degree of built-in compensation, electronic engine management is adversely affected by poor vehicle electrics and excessively low voltages - as you have noticed. At least 25% of our Canems installations highlight existing issues with TVR electrics (alternator issues, old cables, etc) during the installation and set-up phase."
These are the professionals speaking, professionals with lots of experience with engine management & TVR electrics
Edited by ChimpOnGas on Wednesday 19th April 11:22
I think you will find its not so much "low voltages" at source- i.e. from the battery or alternator, but bad earthing. When you have a high resistance earth joint, the voltage across it will depend on how much current is flowing through it, and this will depend on what the sensor or ecu electronics unit is doing. This has the effect of lifting the ground point of the sensor / electronics above the ground plane by whatever the voltage drop is- so the total supply voltage presented is now minus the voltage drop on the earth. A few "variable" volts dropped this way will have a far greater effect than the odd voltage wobble on the supply rail, especially if you have high current spikes through the same earth point.
ChimpOnGas
Poor radio reception in Griffith and Chimeras in fact any fibre glass vehicle has little to do with engine earthing as you said.
Where do you get these ideas from?
It is because a steel vehicle shell acts as an effective ground plane for the aerial, fibre glass being non conductive cannot do this thus the result is poor reception needing aerial amplifiers etc.
Poor radio reception in Griffith and Chimeras in fact any fibre glass vehicle has little to do with engine earthing as you said.
Where do you get these ideas from?
It is because a steel vehicle shell acts as an effective ground plane for the aerial, fibre glass being non conductive cannot do this thus the result is poor reception needing aerial amplifiers etc.
It's extra resistance (rather than voltage) as blitz says that could mess sensors about - a temp sender won't know whether it's coming or going with a dodgy earth strap to the engine as the overall resistance back to ground zero (the battery) will vary over time, temperature, vibration, wet weather etc.
I think I've already said this somewhere else but my car had it's single crappy earth cable from the battery terminal, through the bulkhead, via an old battery isolating switch next to the wiper motor, then onto a 13mm bolt on the pressed steel throttle bracket next to the plenum. No chassis earth other than the strap down at the base of the engine. Ran consistently, both with lucas and emerald, but I did always get a sudden dip in idle speed when the fans kicked in
I think I've already said this somewhere else but my car had it's single crappy earth cable from the battery terminal, through the bulkhead, via an old battery isolating switch next to the wiper motor, then onto a 13mm bolt on the pressed steel throttle bracket next to the plenum. No chassis earth other than the strap down at the base of the engine. Ran consistently, both with lucas and emerald, but I did always get a sudden dip in idle speed when the fans kicked in
Loubaruch said:
ChimpOnGas
Poor radio reception in Griffith and Chimeras in fact any fibre glass vehicle has little to do with engine earthing as you said.
Where do you get these ideas from?
It is because a steel vehicle shell acts as an effective ground plane for the aerial, fibre glass being non conductive cannot do this thus the result is poor reception needing aerial amplifiers etc.
On a fiberglass bodied car like a Chimaera the steel chassis is used as the earth return, on a steel monocoque chassis the car's entire body is the earth path, at this point its important to understand the earthing differences between a steel chassis made from steel tubes and a steel chassis made by welding a series of sheet steel panels together.Poor radio reception in Griffith and Chimeras in fact any fibre glass vehicle has little to do with engine earthing as you said.
Where do you get these ideas from?
It is because a steel vehicle shell acts as an effective ground plane for the aerial, fibre glass being non conductive cannot do this thus the result is poor reception needing aerial amplifiers etc.
The answer is of course... there is no difference!
In earthing terms both chassis' are made steel which conducts electricity extremely well, and if executed correctly both will provide a return path to the negative terminal of your power source (the battery) equally well. So one must ask what influence on earthing does putting a fiberglass body over a tubular steel chassis have? The answer is of course the same influence it would have if you put a fiberglass body over a steel monocoque chassis.... fek all!
When steel monocoque cars suffer poor radio reception (& they often do), the first port of call is always to study the earth's, often the issue can be attributed to a missing, disconnected, or lose earth strap of which you will find many on a monocoque car. Why do manufacturers of steel monocoque cars still use earth straps when they're made from a series of welded steel panels? Because welding steel panels together doesn't always achieve the perfect low resistance earth return path you think it might.
And how does this differ from a tubular steel chassis with a fiberglass body? The answers is of course there is no difference, both chassis types need those earth straps and the fiberglass body element in earthing terms is completely irrelevant...... because quite clearly it's not even in the equation.
There's a misnomer that you must accept poor radio reception from a fiberglass bodied car, this is of course complete nonsense if you think about it. Steel is steel, it doesn't matter a jot if you make your chassis from steel tubes or panels formed from sheet steel... it's all still steel! The only reason fiberglass bodied cars have such a bad reputation for poor earth's is because the low volume manufacturers of fiberglass bodied cars typically failed to provide sufficient earth straps.
Both Lotus and TVR were united in their complete inability to deliver a car with decent wiring, by coincidence both had fiberglass bodies and both had pish poor radio reception. I can see why people may link fiberglass body cars to the bad radio reception but this is like adding 2 + 2 and making 5, the truth is they have nothing to do with each other.
And good job too! Because with 90% of all watercraft being made almost entirely from fiberglass and relying on perfect radio reception for safety (Coast Guard communications ect), I for one am relieved the old wives tale that claims fiberglass bodied cars will always have bad radio reception is proven to be total BS.
Dave.
For good AM or FM radio reception you need a good ground plain. Good reception in a fibreglass boat is because of the very large ground plain it floats in - water. For tin-top cars it is the body. The ground plain doesn't have to be connected to a chassis to work, just linked capacitively.
ChimpOnGas,
As Churchill once said:
"Much better for people to wonder why you have not spoken than to wonder why you have"
There are several owners on here with proven experience and knowledge gained through working in their fields for years it is a pity that you chose to ignore their postings and continue with your lengthy but usually inaccurate diatribes.
As Churchill once said:
"Much better for people to wonder why you have not spoken than to wonder why you have"
There are several owners on here with proven experience and knowledge gained through working in their fields for years it is a pity that you chose to ignore their postings and continue with your lengthy but usually inaccurate diatribes.
My car was a bit recalcitrant at low revs, especially when cold. It was difficult to drive smoothly at low speeds.
I changed the coolent temp sender, but this made little, if any difference.
I then changed the throttle position sensor and this has made a huge difference! The car is now smooth when driving slowly in traffic.
The other symptom I had (which strongly hinted to me that I had a worn out TPS sensor) was that when cold, sometimes pressing the throttle very lightly would result in the revs dropping rather than raising.
I changed the coolent temp sender, but this made little, if any difference.
I then changed the throttle position sensor and this has made a huge difference! The car is now smooth when driving slowly in traffic.
The other symptom I had (which strongly hinted to me that I had a worn out TPS sensor) was that when cold, sometimes pressing the throttle very lightly would result in the revs dropping rather than raising.
I’m going to be the new guy to TVR who restarts all the old threads, so apologies in advance! I have the aforementioned kangaroo issues, idling rough, but also the car will decide randomly to cut out when driving and at low revs. Sounds by this thread that it could well be a mixture of the stepper motor and the coolant temp sender? Any advice greatly received! I guess best practice will be to change the coolant temp sender and see if it sorts it, if not, stepper next. It fires up again perfectly every time, so it isn’t ignition or fuel related I don’t think and seems to only be an issue when up to temperature..
FoxTVR430 said:
Also mentioned in the posts above is that the earths should be checked to and from the engine block. Maybe also adding an extra earthing cable as this would do no harm.
Cheers bud, I’m gash at electrical work, so what should one be attaching it to? From block to chassis rail?Gassing Station | Chimaera | Top of Page | What's New | My Stuff