1994 TVR Chimaera running poorly, and way too rich
Discussion
I hope that I am behaving appropriately by starting a new topic in the Chimaera section of this forum. I am seeking advice on a 1994 TVR Chimaera, which currently resides in my workshop stall after failing to pass a Colorado, USA emissions test.
When the vehicle arrived on the hook, it exhibited a crank, but no start condition, and came with a failed emissions test report, showing HC at 500% of the limit, CO at 125% of the limit, and NOx at 90% of the limit.
After replacing the fuel pump, replacing the fuel pressure regulator, cleaning the spark plugs, and blowing compressed air into the cylinders, the engine ran quite well, and powerfully. However, the CO reading out the pipe was approximately 5%, and the HC reading remained excessive. The oxygen sensor signals for both banks were pegged at 1.25 volts. There appears to be a mummified catalytic converter, front and center in the engine compartment.
I read on PistonHeads that the signal from the air mass meter must measure approximately 1.75 volts if there is any hope of the engine reaching closed loop operation.
I attempted to adjust the signal, which began at about 7 volts. I found the meter responsive, and was able to set the signal to approximately 1.75 volts. Unfortunately, I found that if I tapped the box on the air meter with my fingers, the signal would jump up to 7-8 volts again, and the engine would choke on fuel. Eventually the engine stalled due to rich running, and the plugs and cylinders had to be cleaned again.
I found a Land Rover air meter, (part number referred through PistonHeads discussion) and installed it. The engine ran badly, and I found the signal from the new air meter at 2.7 volts, and invariant with attempted adjustment.
I have a difficult time finding relevant technical information about this car. I hope for, and humbly ask for any help that can be offered. One thing I would like to have is an accurate wiring diagram for the air meter. (when the car arrived, the wires were soldered directly to the air meter, and I would like to verify that they reside in the correct position.)
Also, is it normal for a new Land Rover air meter to be locked on 2.7 volts, and not adjust, even though there is a screw?
Any help is valued and appreciated. Thank you.
Tim
Gunbarrel Import Motors, Niwot Colorado, USA
When the vehicle arrived on the hook, it exhibited a crank, but no start condition, and came with a failed emissions test report, showing HC at 500% of the limit, CO at 125% of the limit, and NOx at 90% of the limit.
After replacing the fuel pump, replacing the fuel pressure regulator, cleaning the spark plugs, and blowing compressed air into the cylinders, the engine ran quite well, and powerfully. However, the CO reading out the pipe was approximately 5%, and the HC reading remained excessive. The oxygen sensor signals for both banks were pegged at 1.25 volts. There appears to be a mummified catalytic converter, front and center in the engine compartment.
I read on PistonHeads that the signal from the air mass meter must measure approximately 1.75 volts if there is any hope of the engine reaching closed loop operation.
I attempted to adjust the signal, which began at about 7 volts. I found the meter responsive, and was able to set the signal to approximately 1.75 volts. Unfortunately, I found that if I tapped the box on the air meter with my fingers, the signal would jump up to 7-8 volts again, and the engine would choke on fuel. Eventually the engine stalled due to rich running, and the plugs and cylinders had to be cleaned again.
I found a Land Rover air meter, (part number referred through PistonHeads discussion) and installed it. The engine ran badly, and I found the signal from the new air meter at 2.7 volts, and invariant with attempted adjustment.
I have a difficult time finding relevant technical information about this car. I hope for, and humbly ask for any help that can be offered. One thing I would like to have is an accurate wiring diagram for the air meter. (when the car arrived, the wires were soldered directly to the air meter, and I would like to verify that they reside in the correct position.)
Also, is it normal for a new Land Rover air meter to be locked on 2.7 volts, and not adjust, even though there is a screw?
Any help is valued and appreciated. Thank you.
Tim
Gunbarrel Import Motors, Niwot Colorado, USA
Whilst I'm of no use to help with your question(s), there are folk on here who can help.
The AFM is a tricky topic, finding a decent one is not simple, and people have found new replacements that make the car worse.
The tricky thing for you is your location, it is a lot easier to find Jaguar and Rover parts in the UK.
I, amongst others, would be willing to help locate and re-post things to you. Even the specialists here would probably do that same (then it's more direct for you). For AFMs, I would look up Kits n Classics - the website looks basic but they are a respected outfit (http://www.kitsandclassics.co.uk/)
The other thing is to get hold of a RoverGauge - the only supplier I know of is on eBay - and they may be willing to post direct to you
https://www.ebay.co.uk/itm/315830169187?mkcid=16&a...
The software for it is a free download (and was written by an American chap), works best on a PC laptop
https://github.com/colinbourassa/rovergauge/releas...
Then there is a chap called Frank Wilson on Facebook groups such as TVR Chimaera and Griffith Technical, but also folks on here who can read the data, to help with the diagnosis of the 14CUX ECU controlled fuelling. And as you probably know, the ignition system often benefits from a good check through - and you're lucky that in the USA, the Accel 9002C leads are much easier to get hold of!
The AFM is a tricky topic, finding a decent one is not simple, and people have found new replacements that make the car worse.
The tricky thing for you is your location, it is a lot easier to find Jaguar and Rover parts in the UK.
I, amongst others, would be willing to help locate and re-post things to you. Even the specialists here would probably do that same (then it's more direct for you). For AFMs, I would look up Kits n Classics - the website looks basic but they are a respected outfit (http://www.kitsandclassics.co.uk/)
The other thing is to get hold of a RoverGauge - the only supplier I know of is on eBay - and they may be willing to post direct to you
https://www.ebay.co.uk/itm/315830169187?mkcid=16&a...
The software for it is a free download (and was written by an American chap), works best on a PC laptop
https://github.com/colinbourassa/rovergauge/releas...
Then there is a chap called Frank Wilson on Facebook groups such as TVR Chimaera and Griffith Technical, but also folks on here who can read the data, to help with the diagnosis of the 14CUX ECU controlled fuelling. And as you probably know, the ignition system often benefits from a good check through - and you're lucky that in the USA, the Accel 9002C leads are much easier to get hold of!
There are others on here that can advise about the AFM outputs but you seem to be on the right track. 
I would add though that owners were (and are) know to remove the Y piece from the exhaust system, cut it open remove the catalyst and weld it up again. Are you sure there is one present? There should also be pre-cats in the exhaust manifolds but there only help reduce emissions on a cold engine so are often removed with no problems, since emission testing is done on a warm engine.
I would add though that owners were (and are) know to remove the Y piece from the exhaust system, cut it open remove the catalyst and weld it up again. Are you sure there is one present? There should also be pre-cats in the exhaust manifolds but there only help reduce emissions on a cold engine so are often removed with no problems, since emission testing is done on a warm engine.
There is some good info on this site, you have to get the AFM right really, it certainly sounds like its an issue. Obviously if the wiring has been tampered with its worth checking that.
http://g33.co.uk/pages/technical-fuel-injection.ht...
http://g33.co.uk/pages/technical-fuel-injection.ht...
Belle427 said:
There is some good info on this site, you have to get the AFM right really, it certainly sounds like its an issue. Obviously if the wiring has been tampered with its worth checking that.
http://g33.co.uk/pages/technical-fuel-injection.ht...
I love the way that page starts with “this page is far from complete” and then goes on to give what is probably the most complete explanation of the 14CUX system ever written http://g33.co.uk/pages/technical-fuel-injection.ht...
Anyway, can’t help directly but happy to join the list of people who will help ship parts to you if needed.
Basically the AFM should give only up to 5 volts at peak airflow, so I dont know where the 7 v is coming from unless you have some short of short on the ECU input for a very faulty AFM? The other variable is the CO trim, that is simply a resistor that pulls a voltage line up or down from the ECU. The important bit here, is this setting has absolutely no affect on the catalyst engines (map 5) as the CO levels are set automatically with the long term fuel trim from the lambda feedback. Both the long term trim, and CO trim use the same memory locations in the ECU programming, so you have one or the other, but never both. So:
Map 5 Catalyst- CO trim automatic
Map 3, Non catalyst- set by hand on exhaust gas- usually in the range of 1.2 to 1.5 volts, but can be higher or lower if needed.
CO trim is measured between Blue/Red (positive) and Red /black (negative) and is set with the receded Hex screw on the side of the AFM, NON cat cars only.
On the face of the original fault if you did have 7 v on the AFM input, it should generate an error code to show and AFM / Throttle pot mismatch error, but you need RoverGauge or a code reader to access the error codes.
Without diagnostics you can do basic AFM test like this:
Peel back the rubber boot on the airflow meter connector and leave it plugged in to the airflow meter. Set up the digital multimeter to read voltage. Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal).
Turn on the ignition, but do not start the engine. The meter should immediately indicate a reading of approximately 0.3-0.34 Volts after the initial "warm up" spike. Most defective airflow meters will overshoot to 0.8 Volts or higher, and take at least 2 seconds to come down to the correct voltage.
Now start the engine, and the reading should rise to 1.6 Volts (3.5 Litre engine) to 1.75 Volts (5.0 Litre engine).
The .3 to .34 volts is critical as it sets the airflow scaling across the whole range, so any voltage above this will generate over fuelling.
YOU CANNOT MANUALLY SET THE AFM AIRFLOW OUTPUT IN ANY WAY BY HAND, as its simply a voltage against airflow, factory calibrated.
If you want decent full diagnostics to remove the guesswork, get RoverGauge:
https://www.ebay.co.uk/itm/315830169187
Map 5 Catalyst- CO trim automatic
Map 3, Non catalyst- set by hand on exhaust gas- usually in the range of 1.2 to 1.5 volts, but can be higher or lower if needed.
CO trim is measured between Blue/Red (positive) and Red /black (negative) and is set with the receded Hex screw on the side of the AFM, NON cat cars only.
On the face of the original fault if you did have 7 v on the AFM input, it should generate an error code to show and AFM / Throttle pot mismatch error, but you need RoverGauge or a code reader to access the error codes.
Without diagnostics you can do basic AFM test like this:
Peel back the rubber boot on the airflow meter connector and leave it plugged in to the airflow meter. Set up the digital multimeter to read voltage. Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal).
Turn on the ignition, but do not start the engine. The meter should immediately indicate a reading of approximately 0.3-0.34 Volts after the initial "warm up" spike. Most defective airflow meters will overshoot to 0.8 Volts or higher, and take at least 2 seconds to come down to the correct voltage.
Now start the engine, and the reading should rise to 1.6 Volts (3.5 Litre engine) to 1.75 Volts (5.0 Litre engine).
The .3 to .34 volts is critical as it sets the airflow scaling across the whole range, so any voltage above this will generate over fuelling.
YOU CANNOT MANUALLY SET THE AFM AIRFLOW OUTPUT IN ANY WAY BY HAND, as its simply a voltage against airflow, factory calibrated.
If you want decent full diagnostics to remove the guesswork, get RoverGauge:
https://www.ebay.co.uk/itm/315830169187
Edited by blitzracing on Thursday 23 January 13:38
Thank you all for your help. I had to hang the Chimaera on the back burner for a few days, but I am back on it this morning. So, at key on, my air flow sensor signal wire does measure 0.3 volts, and it is closer to 2 volts, rather than 1.75 volts, after engine runs,
this being the 5.0 liter version. I have scoped the ignition system, and found all cylinders firing in the 7 kilovolt range, and fairly equal. (approximately correct, according to another PistonHeads thread)
I have abother question regarding setting idle speed. Idle speed adjustment is attainable through the screw on the intake plenum on top of the throttle plate? I just want to be sure I am not changing some inviolate setting.
I have downloaded the Rover Gauge software, and I will begin looking for a cable immediately.
Thank you gain for the help. Oops... one more question. Where and how does the Rover Gauge cable interface with the car?
this being the 5.0 liter version. I have scoped the ignition system, and found all cylinders firing in the 7 kilovolt range, and fairly equal. (approximately correct, according to another PistonHeads thread)
I have abother question regarding setting idle speed. Idle speed adjustment is attainable through the screw on the intake plenum on top of the throttle plate? I just want to be sure I am not changing some inviolate setting.
I have downloaded the Rover Gauge software, and I will begin looking for a cable immediately.
Thank you gain for the help. Oops... one more question. Where and how does the Rover Gauge cable interface with the car?
punyetasterminator said:
Thank you all for your help. I had to hang the Chimaera on the back burner for a few days, but I am back on it this morning. So, at key on, my air flow sensor signal wire does measure 0.3 volts, and it is closer to 2 volts, rather than 1.75 volts, after engine runs,
this being the 5.0 liter version. I have scoped the ignition system, and found all cylinders firing in the 7 kilovolt range, and fairly equal. (approximately correct, according to another PistonHeads thread)
I have abother question regarding setting idle speed. Idle speed adjustment is attainable through the screw on the intake plenum on top of the throttle plate? I just want to be sure I am not changing some inviolate setting.
I have downloaded the Rover Gauge software, and I will begin looking for a cable immediately.
Thank you gain for the help. Oops... one more question. Where and how does the Rover Gauge cable interface with the car?
In front of the passenger footwell, where the battery is. Sticking out of the loom you’ll find a 3-pin socket. this being the 5.0 liter version. I have scoped the ignition system, and found all cylinders firing in the 7 kilovolt range, and fairly equal. (approximately correct, according to another PistonHeads thread)
I have abother question regarding setting idle speed. Idle speed adjustment is attainable through the screw on the intake plenum on top of the throttle plate? I just want to be sure I am not changing some inviolate setting.
I have downloaded the Rover Gauge software, and I will begin looking for a cable immediately.
Thank you gain for the help. Oops... one more question. Where and how does the Rover Gauge cable interface with the car?
Thank you again for the help. Belle427's reference to the Ginetta fuel injection page was amazing. blitzracing's description of the voltage behavior of the AFM is spot on. I removed the screw from the intake plenum, cleaned what I believe to be the idle air flow passage, then adjusted the screw with the engine running until my AFM signal read 1.75 volts. Lo and behold, the oxygen sensors began to cycle, and my CO emissions fell below 1 percent. The HC emissions were still high, but I have not had the chance to really put it under load to fire the catalytic converter yet.
Thank you again, and I will try to keep you posted.
Tim
Thank you again, and I will try to keep you posted.
Tim
Once you have your Cable and RoverGaige is up and running I can help you with analysis of the the data it gives you. (PS I have done this for many owners on here over last 5 or so years).
To get data I can process you'll need to create a logfile as follows.
Logging data for assessing 14CUX
1. Plug the 14CUX cable into the loom connector on the car
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed -mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get
varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO
NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
To get data I can process you'll need to create a logfile as follows.
Logging data for assessing 14CUX
1. Plug the 14CUX cable into the loom connector on the car
2. Start RoverGauge software
3. Setup RG options settings as follows
a. COM - COMx (use whatever COM port works for you)
b. Speed -mph
c. Temperature – Celsius
d. Parameters to log – all but not road speed or gear selection
4. Set RoverGauge main screen as follows:
a. MAF – Direct
b. Throttle – Absolute
c. Trim – Short Term
5. Turn on the ignition switch and press ‘connect’ to link 14CUX with your laptop.
6. Preferably start the car from cold.
7. Start logging the data (Start Log F5) and drive the car for 15 minutes on a local roads (eg A or B class to get
varying running conditions) then stop the car and allow the engine to idle for a further 5 to 10 minutes. (DO
NOT TOUCH ANY OF THE CONTROLSAT THIS STAGE)
8. You can now stop logging data by pressing “Stop Log F7”
9. Send the logfiles (held in a sub folder where RoverGauge is) to me (I will msg you my email address)
punyetasterminator said:
Thank you all for your help. I had to hang the Chimaera on the back burner for a few days, but I am back on it this morning. So, at key on, my air flow sensor signal wire does measure 0.3 volts, and it is closer to 2 volts, rather than 1.75 volts, after engine runs,
this being the 5.0 liter version. I have scoped the ignition system, and found all cylinders firing in the 7 kilovolt range, and fairly equal. (approximately correct, according to another PistonHeads thread)
I have abother question regarding setting idle speed. Idle speed adjustment is attainable through the screw on the intake plenum on top of the throttle plate? I just want to be sure I am not changing some inviolate setting.
I have downloaded the Rover Gauge software, and I will begin looking for a cable immediately.
Thank you gain for the help. Oops... one more question. Where and how does the Rover Gauge cable interface with the car?
You can get a cable here:this being the 5.0 liter version. I have scoped the ignition system, and found all cylinders firing in the 7 kilovolt range, and fairly equal. (approximately correct, according to another PistonHeads thread)
I have abother question regarding setting idle speed. Idle speed adjustment is attainable through the screw on the intake plenum on top of the throttle plate? I just want to be sure I am not changing some inviolate setting.
I have downloaded the Rover Gauge software, and I will begin looking for a cable immediately.
Thank you gain for the help. Oops... one more question. Where and how does the Rover Gauge cable interface with the car?
https://www.ebay.co.uk/itm/316163978912
Basically the ECU has to learn it's basic mixture settings depending on the lambda feedback. It does this with a long term fuel trim setting, and it needs a few minutes on a hot engine and a steady idle to set this value. The learning process stops if you drive the car as conditions are not static enough. You can get the situation if the long term trim is wrong or the ECU reset, that the short term won't cycle correctly for a while until the learning process is complete. Any engine or ignition faults also produce bad trim results. Once you get RoverGauge you can see the trim values on its display.
Edited by blitzracing on Thursday 30th January 17:24
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