1998 Chimaera 450 Misfire after minor job
Discussion
Hi guys,
So I’m hoping for some help with my Chimaera 450 – Manufactured in 2018. The car is New Zealand New and doesn’t have Cats or lambda sensors (original).
I replaced the Timing housing gasket after it failed. The job was straightforward and whilst waiting on some parts I did a little bit of degreasing around the engine but was pretty careful not to get degreaser in any sensitive areas. Since putting the car back together I’ve been plagued with a misfire.
Apologies in advance for the long read. To pre-empt the obvious question of why not take the car to a specialist, the local TVR guy here (yes there basically is only 1 in my region) is not an expert in the ECU and I have had many chats with him. I could trailer the car to a Land Rover specialist but that’s probably my next step. I’m reluctant though, because fiberglass cars are “Different”.
So For I have;
Checked timing – also confirmed TDC and the timing mark was accurate – no change
Tried moving the distributor one notch forward and re timing – no change
Replaced Coil, Leads, and spark plugs. I removed the TVR spark plug shrouds. The new coil is designed to be used with “R” type plugs. I bought new BPR6 plugs and the leads are MSD leads with LAVA covers. – No Change.
Checked the earth wires at the front of the engine. No issues.
Took the car to local auto electrical guys (no experience with Lucas 14CUX) and they said the timing is good and the spark is good. But the car is running very rich and the smell from the exhaust is overpowering. I’m fouling plugs within 10 minutes of cleaning them when ticking over. On the road the car pulls strong but feels like it’s in limp mode and misfiring when you’re not pressing hard.
Looked up the LUCAS14 CUX manual and went through all tests.
Notably these test okay;
Battery Power, Ignition Power, Main Relay power, Engine speed sensor cable and resistor, Fuel Pump, Injectors, both banks, Fuel and water temp sensors, Bypass air valve, TPS.
However I have some test that I’m not certain about.
And I also notice a wire that has melted in the loom – OBD connector. The melted wire is the Black white wire and I have peeled the insulation right back to the blue plastic joiner. No other cables look to be damaged. Its also measuring 0 ohms to earth.
The AFM Signal wire (Blue/Green) is giving 0.09V and this should be between 0.2 and 0.7V.
All wires to the AFM test 0 Ohms end to end.
I’m confused about why I’m seeing 0.18V across the AFM Red/Black wire to earth. I though Red/Black was earth.
Anyway I have tried 3 x ECU’s and three AFM’s, all no change.
I have two wiring diagrams that have come from Pistonheads forums. One is from “Rob” and looks to be an excellent diagram and very detailed. Rob shows the Red/Black wire to the AFM as being “Common Ground” and is also joined to other sensors. This makes sense. However I have seen a couple of other RV8 drawings that suggest the Red/Black is the sensor voltage supply line.
I don’t want to start cutting into the loom without knowing for certain if this wire is earth or signal. And, I’m hoping some of our brains trust here may be able to suggest something that I’ve overlooked or misunderstood.
Thanks in advance. – Steve (in New Zealand)
So I’m hoping for some help with my Chimaera 450 – Manufactured in 2018. The car is New Zealand New and doesn’t have Cats or lambda sensors (original).
I replaced the Timing housing gasket after it failed. The job was straightforward and whilst waiting on some parts I did a little bit of degreasing around the engine but was pretty careful not to get degreaser in any sensitive areas. Since putting the car back together I’ve been plagued with a misfire.
Apologies in advance for the long read. To pre-empt the obvious question of why not take the car to a specialist, the local TVR guy here (yes there basically is only 1 in my region) is not an expert in the ECU and I have had many chats with him. I could trailer the car to a Land Rover specialist but that’s probably my next step. I’m reluctant though, because fiberglass cars are “Different”.
So For I have;
Checked timing – also confirmed TDC and the timing mark was accurate – no change
Tried moving the distributor one notch forward and re timing – no change
Replaced Coil, Leads, and spark plugs. I removed the TVR spark plug shrouds. The new coil is designed to be used with “R” type plugs. I bought new BPR6 plugs and the leads are MSD leads with LAVA covers. – No Change.
Checked the earth wires at the front of the engine. No issues.
Took the car to local auto electrical guys (no experience with Lucas 14CUX) and they said the timing is good and the spark is good. But the car is running very rich and the smell from the exhaust is overpowering. I’m fouling plugs within 10 minutes of cleaning them when ticking over. On the road the car pulls strong but feels like it’s in limp mode and misfiring when you’re not pressing hard.
Looked up the LUCAS14 CUX manual and went through all tests.
Notably these test okay;
Battery Power, Ignition Power, Main Relay power, Engine speed sensor cable and resistor, Fuel Pump, Injectors, both banks, Fuel and water temp sensors, Bypass air valve, TPS.
However I have some test that I’m not certain about.
And I also notice a wire that has melted in the loom – OBD connector. The melted wire is the Black white wire and I have peeled the insulation right back to the blue plastic joiner. No other cables look to be damaged. Its also measuring 0 ohms to earth.
The AFM Signal wire (Blue/Green) is giving 0.09V and this should be between 0.2 and 0.7V.
All wires to the AFM test 0 Ohms end to end.
I’m confused about why I’m seeing 0.18V across the AFM Red/Black wire to earth. I though Red/Black was earth.
Anyway I have tried 3 x ECU’s and three AFM’s, all no change.
I have two wiring diagrams that have come from Pistonheads forums. One is from “Rob” and looks to be an excellent diagram and very detailed. Rob shows the Red/Black wire to the AFM as being “Common Ground” and is also joined to other sensors. This makes sense. However I have seen a couple of other RV8 drawings that suggest the Red/Black is the sensor voltage supply line.
I don’t want to start cutting into the loom without knowing for certain if this wire is earth or signal. And, I’m hoping some of our brains trust here may be able to suggest something that I’ve overlooked or misunderstood.
Thanks in advance. – Steve (in New Zealand)
just to clarify, the car ran ok before the work was carried out?
Some useful info regarding testing here.
http://g33.co.uk/pages/technical-fuel-injection.ht...
Some useful info regarding testing here.
http://g33.co.uk/pages/technical-fuel-injection.ht...
Edited by Belle427 on Saturday 1st April 07:50
i cant help much as its such a strange one, i would be careful about replacing parts such as the coil though as some aftermarket stuff is complete junk.
i would only retrace my steps at this point checking all wiring is where it should be etc and hasnt been trapped anywhere.
Tvrs dont like being started and sat ticking over from cold which may not be helping the plug fouling situation.
Any ideas what tune resistor it is running?
i would only retrace my steps at this point checking all wiring is where it should be etc and hasnt been trapped anywhere.
Tvrs dont like being started and sat ticking over from cold which may not be helping the plug fouling situation.
Any ideas what tune resistor it is running?
SteveSNZ said:
And I also notice a wire that has melted in the loom – OBD connector. The melted wire is the Black white wire
Melted wire could well be from the past, someone else burnt it out, you can't miss the smell of burnt wiring if it recently went up in smokeProblem you're now faced with is that there's burnt wiring that hasn't been replaced, even though the burnt wiring might not be causing the problem you now face there is a chance that it's caused it
A burnt wire in the loom often damages other wires and they do often short out within the loom at a later date once damp kicks off corrosion
Have you traced through the loom from one end to the other of the Black/White wire?
You might not want to be reading the following but it's fact, no vehicle is fit for purpose with burnt wiring as more and more problems arise over time due to it, there's a chance that you disturbed the loom when replacing the gasket or all the other parts that were replaced later when trying to solve the problem
Anyway.....do what must be done. Over-fueling problem does point to an injector being stuck open due to a short on its wiring or mechanical failure (doubtful as ok before work done)
Just had a look at my 14CUX main build diagram and there are no black/whites in the engine harness. There are some black/slates . A couple are in the blue header by the main ECU . Cavity 27(ECU) to blue header then to tune resistor. The other is Cavity 33(ECU) to the compressor clutch relay (aircon).
Belle427 said:
i cant help much as its such a strange one, i would be careful about replacing parts such as the coil though as some aftermarket stuff is complete junk.
i would only retrace my steps at this point checking all wiring is where it should be etc and hasnt been trapped anywhere.
Tvrs dont like being started and sat ticking over from cold which may not be helping the plug fouling situation.
Any ideas what tune resistor it is running?
Hi, first an apology. I did go and look at the g33 page and its changed quite a bit since the last time I looked at it. This link is very helpful as it confirms that the Red/Black wire is Earth. i would only retrace my steps at this point checking all wiring is where it should be etc and hasnt been trapped anywhere.
Tvrs dont like being started and sat ticking over from cold which may not be helping the plug fouling situation.
Any ideas what tune resistor it is running?
As the car doesn't idle properly , plugs fouling and ok on hard acceleration but not on light throttle IMO it’s a fuel issue. Have you checked that the temperature sender has been reconnected as this enriches the fuel if not reading correctly. Also worth mentioning to try Rover Gauge to see if any fault codes have been tripped and to pull a plug from each bank to see if they are the same colour. One side black the other grey may indicate an injector based problem. Rover Gauge will also confirm the temperature sender is reading correctly. If you don’t have Rover Gauge ask on the NZ TVR Facebook page for a loan of a RG connector and download it. My car is parked up in another part of NZ from where I am currently living so I can’t send you mine. If you can spare to wait a couple of weeks maybe have one sent out from the UK. (Mark- Blitzracing - the g33 site you were looking at used to sell them or maybe on eBay) failing all that the other area to investigate would be the MAF sensor plug itself as a few years ago I used to have intermittent issues with overfueling before repairing the plug.
Belle427 said:
i cant help much as its such a strange one, i would be careful about replacing parts such as the coil though as some aftermarket stuff is complete junk.
i would only retrace my steps at this point checking all wiring is where it should be etc and hasnt been trapped anywhere.
Tvrs dont like being started and sat ticking over from cold which may not be helping the plug fouling situation.
Any ideas what tune resistor it is running?
I believe its a green tune resistor and will update my answer here if its something other than greeni would only retrace my steps at this point checking all wiring is where it should be etc and hasnt been trapped anywhere.
Tvrs dont like being started and sat ticking over from cold which may not be helping the plug fouling situation.
Any ideas what tune resistor it is running?
ITVRI said:
As the car doesn't idle properly , plugs fouling and ok on hard acceleration but not on light throttle IMO it’s a fuel issue. Have you checked that the temperature sender has been reconnected as this enriches the fuel if not reading correctly. Also worth mentioning to try Rover Gauge to see if any fault codes have been tripped and to pull a plug from each bank to see if they are the same colour. One side black the other grey may indicate an injector based problem. Rover Gauge will also confirm the temperature sender is reading correctly. If you don’t have Rover Gauge ask on the NZ TVR Facebook page for a loan of a RG connector and download it. My car is parked up in another part of NZ from where I am currently living so I can’t send you mine. If you can spare to wait a couple of weeks maybe have one sent out from the UK. (Mark- Blitzracing - the g33 site you were looking at used to sell them or maybe on eBay) failing all that the other area to investigate would be the MAF sensor plug itself as a few years ago I used to have intermittent issues with overfueling before repairing the plug.
Thanks, the CUX14 manual described how to test the fuel temperature and the coolant temperature sensors and these both test okay (2,500 Ohms at 20 degrees). From that I'm confident the cables are connected as they should. I was aware that its easy to plug the sensors into the incorrect plugs so never unplugged any two at the same time. All plugs have been disconnected, cleaned with electrical contact cleaner, dried and reconnected, then tested again. I have made up a Roverguage cable using the FTDI board (for my first Chimaera), however I couldn't get it to connect in the time I had. I'm not certain if the laptop was properly configure for the USB so will definitely revisit that. I agree re the MAF plug, I will look at it more closely as its possible one of the connectors has recessed into the plug. Thanks, again. DVR V8 said:
Just had a look at my 14CUX main build diagram and there are no black/whites in the engine harness. There are some black/slates . A couple are in the blue header by the main ECU . Cavity 27(ECU) to blue header then to tune resistor. The other is Cavity 33(ECU) to the compressor clutch relay (aircon).
Yes I am concerned about the wire. It is Black/Slate after all, I thought it was just grubby as I'd unraveled the electrical tape and its not easy to get good light in there. The internal copper conductor does look compromised but is reading 0 Ohms to earth. The wire has fused itself to the insulation of other wires but they all checked out okay with no insulation breakdown.I traced the wire from what is shown on my wiring diagram as the OBD connector (but see that the correct name for the plug is a TTL connector) all the way to the blue header.
Interestingly, the diagram I have also suggest this is connected to the tune resistor and earthed at E2. E2 being engine timing cover! THATS INTERESTING!!
DVR V8 said:
The connector you mentioned with the melted wire is called a header , just a way of connecting multiple wires together. The blue header is a group of grounds. The 14 CUX ignition system does not have OBD. Regards. Edited by DVR V8 on Saturday 1st April 20:02
Yes the headers come apart. Just give the top section that links all the terminals together a good tug with a pair of pliers. With that section removed it makes it easier to check the integrity of individual wires. Also from memory many years ago I forgot to refit the plug on the AFM, started it up and the fuel smell was horrendous and the plugs went black. So I would start with the AFM wires and check everyone from end to end . The negative is in the header and the positive comes from one of the relays with a stripe on it. Brown/orange cable which also feeds injectors on one bank.
If you consider it’s an injector signal issue then it’s worth checking each side for temp on the manifold, all 4 injectors each side fire at the same time, there is a constant 12v and the negative is switched via the 14 cux to give more or less fuel, I seem to think that at tickover the manifold should be around 270 deg C, any easy test is to see if you can melt a cable toe if you don’t have a temp monitor, if one bank had a short to earth from its negative you would get far too much fuel and thst bank won’t run so it will be cooler
Thanks everyone for their comments and suggestions so far. It may take me a while to get anymore checks done as I have a few things on the go at the same time, including a trip home to Scotland on the 12th May. I'll 100% feed back with any progress or ask for more help as I go. Hopefully I can get time on the car this weekend coming.
Steve
Steve
If "Rob" is the Rob we all know, he is one of the main TVR engine builders and V8 Developments is his company.
When my car wouldn't idle (it just died at junctions when warm) I called him for advice (he had supplied the engine) and he said "bring it over and I will have a look".
He then spent a good hour running through everything before muttering "it MUST be the stepper motor".
Off to his spare parts shed and came out with a good original used one.
Problem solved.
TVRs are small enough to go in your hand luggage when you fly back to Scotland?
When my car wouldn't idle (it just died at junctions when warm) I called him for advice (he had supplied the engine) and he said "bring it over and I will have a look".
He then spent a good hour running through everything before muttering "it MUST be the stepper motor".
Off to his spare parts shed and came out with a good original used one.
Problem solved.
TVRs are small enough to go in your hand luggage when you fly back to Scotland?
Rob is the name of my car. Those wiring diagrams are mine (and available to anyone who wants them).
Rovergauge is a must as it can answer many questions like, is the ECU seeing the correct temperatures for both fuel and coolant temperatures i.e. with the engine cold both readings should be about the same and read ambient temp. It will also show if the ECU is using the right fuel map. The map is set by a 'Tune Resistor' so any poor connection could cause the ECU to use the wrong map.
The blue 'Loopback Connector' or header is a way of joining together wires of a like function. There are 4 'functions' passing through this connector being...
Ignition switched 12 volt. mainly white/green wires with 1 black going to the coil.
+12V from the main ECU relay. 4 Brown/orange wires.
Earths. Possibly 6 wires black or Black/Slate.
Sensor earths. Possibly 6 wires all Black/Red. These are sensor earths connecting back to the ECU so should only be tested for resistance with all the sensors and the ECU disconnected otherwise false readings can occur such as Steve has already mentioned.
This connector lives in the footwell so (for a UK car) could be a rather damp environment and I have seen a number of cars with corrosion in this area (and in ECUs).
If corrosion is present then each group of wires should be cut from the connector, stripped back to clean copper and soldered together as a group and finally sealed.
Were all the plugs fouling or just one bank? Have seen a situation where the number 1 injector wire (that connects to the ECU) had chaffed through on the coil mounting bracket and earthed so all the injectors were wide open on that bank.
Steve
Rovergauge is a must as it can answer many questions like, is the ECU seeing the correct temperatures for both fuel and coolant temperatures i.e. with the engine cold both readings should be about the same and read ambient temp. It will also show if the ECU is using the right fuel map. The map is set by a 'Tune Resistor' so any poor connection could cause the ECU to use the wrong map.
The blue 'Loopback Connector' or header is a way of joining together wires of a like function. There are 4 'functions' passing through this connector being...
Ignition switched 12 volt. mainly white/green wires with 1 black going to the coil.
+12V from the main ECU relay. 4 Brown/orange wires.
Earths. Possibly 6 wires black or Black/Slate.
Sensor earths. Possibly 6 wires all Black/Red. These are sensor earths connecting back to the ECU so should only be tested for resistance with all the sensors and the ECU disconnected otherwise false readings can occur such as Steve has already mentioned.
This connector lives in the footwell so (for a UK car) could be a rather damp environment and I have seen a number of cars with corrosion in this area (and in ECUs).
If corrosion is present then each group of wires should be cut from the connector, stripped back to clean copper and soldered together as a group and finally sealed.
Were all the plugs fouling or just one bank? Have seen a situation where the number 1 injector wire (that connects to the ECU) had chaffed through on the coil mounting bracket and earthed so all the injectors were wide open on that bank.
Steve
Steve_D said:
Rob is the name of my car. Those wiring diagrams are mine (and available to anyone who wants them).
Rovergauge is a must as it can answer many questions like, is the ECU seeing the correct temperatures for both fuel and coolant temperatures i.e. with the engine cold both readings should be about the same and read ambient temp. It will also show if the ECU is using the right fuel map. The map is set by a 'Tune Resistor' so any poor connection could cause the ECU to use the wrong map.
The blue 'Loopback Connector' or header is a way of joining together wires of a like function. There are 4 'functions' passing through this connector being...
Ignition switched 12 volt. mainly white/green wires with 1 black going to the coil.
+12V from the main ECU relay. 4 Brown/orange wires.
Earths. Possibly 6 wires black or Black/Slate.
Sensor earths. Possibly 6 wires all Black/Red. These are sensor earths connecting back to the ECU so should only be tested for resistance with all the sensors and the ECU disconnected otherwise false readings can occur such as Steve has already mentioned.
This connector lives in the footwell so (for a UK car) could be a rather damp environment and I have seen a number of cars with corrosion in this area (and in ECUs).
If corrosion is present then each group of wires should be cut from the connector, stripped back to clean copper and soldered together as a group and finally sealed.
Were all the plugs fouling or just one bank? Have seen a situation where the number 1 injector wire (that connects to the ECU) had chaffed through on the coil mounting bracket and earthed so all the injectors were wide open on that bank.
Steve
Hi Steve-D,Rovergauge is a must as it can answer many questions like, is the ECU seeing the correct temperatures for both fuel and coolant temperatures i.e. with the engine cold both readings should be about the same and read ambient temp. It will also show if the ECU is using the right fuel map. The map is set by a 'Tune Resistor' so any poor connection could cause the ECU to use the wrong map.
The blue 'Loopback Connector' or header is a way of joining together wires of a like function. There are 4 'functions' passing through this connector being...
Ignition switched 12 volt. mainly white/green wires with 1 black going to the coil.
+12V from the main ECU relay. 4 Brown/orange wires.
Earths. Possibly 6 wires black or Black/Slate.
Sensor earths. Possibly 6 wires all Black/Red. These are sensor earths connecting back to the ECU so should only be tested for resistance with all the sensors and the ECU disconnected otherwise false readings can occur such as Steve has already mentioned.
This connector lives in the footwell so (for a UK car) could be a rather damp environment and I have seen a number of cars with corrosion in this area (and in ECUs).
If corrosion is present then each group of wires should be cut from the connector, stripped back to clean copper and soldered together as a group and finally sealed.
Were all the plugs fouling or just one bank? Have seen a situation where the number 1 injector wire (that connects to the ECU) had chaffed through on the coil mounting bracket and earthed so all the injectors were wide open on that bank.
Steve
Your diagrams are amazing and have been very useful. I will follow your suggestions when I get a chance to get back to the car, with other commitments it may be some time before I get back to it. Its both banks that are fouling and the car has been kept very dry since new. We have hot summers here and I'm told by previous owners that the car has never been on a wet road (I certainly changed that). I'd be very surprised if this is related to corrosion.
Steve
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