MISFIRING CHIMAERA
Discussion
Guys
Can you help?
I have a 96 Chimaera with 71K on the clock. I bought the car privately last May and she came with a fully stamped up service book from Ferhurst.
The car has had a misfire that has been intermittant. Initially I put her into SSCC in York and then into SFR in Stcokport on three separate times. The ignition system has been replaced in entirity (leads, plugs, heat shields, coil) and the distributor rebuilt. We had some difficulties with a failing rotor arms and the car is now on its fourth but that seems ok now. The current misfire is particualrly prevelant under power and is manifesting around 3000 to 4000 rpm. However last time the car was in SFR the fault would not replicate itself!
As I am North West based I am proposing booking the car into Tunit Performance in Chorley but really want an expert to take it in who can remedy any faults - i am a mechanical numpty! I have heard of a guy called Mark Adams but I think he is based in the south. Any ideas or advice would be greatly appreciated.
Thanks in anticipation
Ian.
Can you help?
I have a 96 Chimaera with 71K on the clock. I bought the car privately last May and she came with a fully stamped up service book from Ferhurst.
The car has had a misfire that has been intermittant. Initially I put her into SSCC in York and then into SFR in Stcokport on three separate times. The ignition system has been replaced in entirity (leads, plugs, heat shields, coil) and the distributor rebuilt. We had some difficulties with a failing rotor arms and the car is now on its fourth but that seems ok now. The current misfire is particualrly prevelant under power and is manifesting around 3000 to 4000 rpm. However last time the car was in SFR the fault would not replicate itself!
As I am North West based I am proposing booking the car into Tunit Performance in Chorley but really want an expert to take it in who can remedy any faults - i am a mechanical numpty! I have heard of a guy called Mark Adams but I think he is based in the south. Any ideas or advice would be greatly appreciated.
Thanks in anticipation
Ian.
Is it a regular misfire, Ian? Not having seen that particular problem myself, I'm told a faulty airflow meter can cause a similar symptom. It's worth having someone help you take readings off the sensors with a multimeter, as per Steve Heath's bible.
Also, I assume you've changed the distributor cap - you don't mention that you have?
Also, I assume you've changed the distributor cap - you don't mention that you have?
The fact that it is intermittant seems to rule out most mechanical failures.
You really need to work out whether it is ignition or fuel related. You also need to know whether the problem is specific to one cylinder. Does it feel as if the engine is dropping a cylinder, or does the whole engine hickup or go flat?
It sounds as if you have had most of the ignition system replaced. You don't specifically mention the ignition amplifier or pickup. Do you know if they're been replaced?
A good way I've found to trace fuelling faults is to put a diagnostic LED in parallel with each injector so that it lights up while the injector is open. You can very quickly see what the ECU is asking the injectors to do which is a quick way of working out whether you have an electrical/electronic problem with the fuel injection system. I designed mine to be used with the bonnet up so I only fitted short leads, but it would be just as easy to fit longer leads so that you can put the LEDs inside the cockpit and see what is happening as you drive along. The other tool I find useful is a passive strobe light in series with an HT lead. This shows you what the spark strength and frequency is like which is dead handy to track down heat-related problems leading to a weak spark. It just so happens that on the V8S I can strap this to the plenum so I can drive along and see it through the gap at the back of the bonnet, but on most cars this would only work with the bonnet up.
Final thought for the night, I remember Steve Heath describing a recurring problem he had with his Griffith. The car would run fine with new ignition components but they kept breaking down after a few months and the problems kept coming back. I understand that Mark Adams did eventually track the problem down. The theory was that the timing marks on the front pulley were miles out causing the spark to be miles out. As Steve described it, the spark was occuring when the rotor arm was half way between two posts so every spark was getting shared between two cylinders, it would run for a while but it quickly knackered the rotor arm and dizzy cap. To be honest I don't fully understand how this would happen unless the dizzy had been built with the pickup in the wrong place, but that was how the problem was described to me. Anyway, worth a thought maybe.
Good luck!
You really need to work out whether it is ignition or fuel related. You also need to know whether the problem is specific to one cylinder. Does it feel as if the engine is dropping a cylinder, or does the whole engine hickup or go flat?
It sounds as if you have had most of the ignition system replaced. You don't specifically mention the ignition amplifier or pickup. Do you know if they're been replaced?
A good way I've found to trace fuelling faults is to put a diagnostic LED in parallel with each injector so that it lights up while the injector is open. You can very quickly see what the ECU is asking the injectors to do which is a quick way of working out whether you have an electrical/electronic problem with the fuel injection system. I designed mine to be used with the bonnet up so I only fitted short leads, but it would be just as easy to fit longer leads so that you can put the LEDs inside the cockpit and see what is happening as you drive along. The other tool I find useful is a passive strobe light in series with an HT lead. This shows you what the spark strength and frequency is like which is dead handy to track down heat-related problems leading to a weak spark. It just so happens that on the V8S I can strap this to the plenum so I can drive along and see it through the gap at the back of the bonnet, but on most cars this would only work with the bonnet up.
Final thought for the night, I remember Steve Heath describing a recurring problem he had with his Griffith. The car would run fine with new ignition components but they kept breaking down after a few months and the problems kept coming back. I understand that Mark Adams did eventually track the problem down. The theory was that the timing marks on the front pulley were miles out causing the spark to be miles out. As Steve described it, the spark was occuring when the rotor arm was half way between two posts so every spark was getting shared between two cylinders, it would run for a while but it quickly knackered the rotor arm and dizzy cap. To be honest I don't fully understand how this would happen unless the dizzy had been built with the pickup in the wrong place, but that was how the problem was described to me. Anyway, worth a thought maybe.
Good luck!
Thank you for the detailed replies and will pick up each point.
The fault disappeared briefly when it was with SFR and then returned a couple of weekends later. Initially the fault was consistentlt below 2000 rpm. After the disributor rebuild etc it cleared but returned much higher up the rev range. The fault is present 75% ish of the time but not all the time.
The distributor cap is new but the ignition amplifier and pick up have not been replaced.
It was the Steve Heath ariticle that persuaded me that I needed to get the car to a good rolling road. I will probably go to Tunit in Chorley following the article in Sprint magazine last year. The current rotor arm seeems fine having clocked up some mileage now and we concluded that the earlier failures were faulty units.
Many thanks again
Ian
The fault disappeared briefly when it was with SFR and then returned a couple of weekends later. Initially the fault was consistentlt below 2000 rpm. After the disributor rebuild etc it cleared but returned much higher up the rev range. The fault is present 75% ish of the time but not all the time.
The distributor cap is new but the ignition amplifier and pick up have not been replaced.
It was the Steve Heath ariticle that persuaded me that I needed to get the car to a good rolling road. I will probably go to Tunit in Chorley following the article in Sprint magazine last year. The current rotor arm seeems fine having clocked up some mileage now and we concluded that the earlier failures were faulty units.
Many thanks again
Ian
Hi,
Sounds very similar to a problem i had,
If the tacho goes a bit nuts with the misfire then the problem is probably with the ignition, and if that happens try a new king lead (goes from the coil to the dizzy)
The problem was cured when i changed one brand new king lead for another manufacturers.
the cost of the King Lead was about 4 quid from Halfwits, worth a try.
Pete
Sounds very similar to a problem i had,
If the tacho goes a bit nuts with the misfire then the problem is probably with the ignition, and if that happens try a new king lead (goes from the coil to the dizzy)
The problem was cured when i changed one brand new king lead for another manufacturers.
the cost of the King Lead was about 4 quid from Halfwits, worth a try.
Pete
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