Over Fuelling, Miss Fire ---Help
Discussion
Well after ten years of ownership my 1998 450 Chimaera has a problem and I’m gutted. Need to sort this as daughter wants to use the car for her wedding. Its not that it’s not had problems before though these have been of a simple nature which have been resolved etc.
During its life so far nearly all the major components have been replaced or upgraded suspension, bushes, suspension arms, big disc conversion etc. etc. including the ignition leads, coil, rotor arm distributor cap, plugs, plug extensions etc. however the problem started a few months ago.
Start-up is fine with tick over steady at 900 rpm. On acceleration around 3000 rpm the car seemed to blip but then carries on accelerating to its limit.
Then on a steady run between 50 mph and 80 mph it seemed she would blip for a second then carry on possibly for the rest of the day fine.
The other day she started to miss on start-up with a strong smell of petrol after a few seconds this would clear and all seemed fine.
This last week end I took a run of to see Sportmotive in Stoke and all seemed fine, just before getting there she did this blip again, but again carried on fine.
Returning home later that day she ran like a dream across the A50, then after arriving at Melton Mowbray she started to miss but this time it didn’t clear. Tried blipping the throttle while out of gear and seemed fine, but then try to accelerate and missing again. Also at the same time you could actually see the fuel gauge dropping at a dramatic rate and the ambient air filled with the scent of super unleaded.
Finally I had to pull over, switch off and start checking all the usual culprits the leads, connections to the coil etc. but all seemed fine and no indication of a fuel leak which was good as all the fuel lines had been replaced last year.
Having left it for 10 mins I tried to start her but this time it just spun on the starter with wisps of tell tale white smoke or un burnt fuel. Kept her spinning on the starter for a short while after which a lumpy V8 kicked into life and they cleared and run up ok finally getting home with a few coughs and splutters then tucked up in the garage.
So any idea where to start? Could she be over fuelling, fueul pump, ECU any idea where to start would be welcome and a bottle of fine wine to whoever helps me to resolve it otherwise Ian at Sportmotive will be getting another LS conversion….
During its life so far nearly all the major components have been replaced or upgraded suspension, bushes, suspension arms, big disc conversion etc. etc. including the ignition leads, coil, rotor arm distributor cap, plugs, plug extensions etc. however the problem started a few months ago.
Start-up is fine with tick over steady at 900 rpm. On acceleration around 3000 rpm the car seemed to blip but then carries on accelerating to its limit.
Then on a steady run between 50 mph and 80 mph it seemed she would blip for a second then carry on possibly for the rest of the day fine.
The other day she started to miss on start-up with a strong smell of petrol after a few seconds this would clear and all seemed fine.
This last week end I took a run of to see Sportmotive in Stoke and all seemed fine, just before getting there she did this blip again, but again carried on fine.
Returning home later that day she ran like a dream across the A50, then after arriving at Melton Mowbray she started to miss but this time it didn’t clear. Tried blipping the throttle while out of gear and seemed fine, but then try to accelerate and missing again. Also at the same time you could actually see the fuel gauge dropping at a dramatic rate and the ambient air filled with the scent of super unleaded.
Finally I had to pull over, switch off and start checking all the usual culprits the leads, connections to the coil etc. but all seemed fine and no indication of a fuel leak which was good as all the fuel lines had been replaced last year.
Having left it for 10 mins I tried to start her but this time it just spun on the starter with wisps of tell tale white smoke or un burnt fuel. Kept her spinning on the starter for a short while after which a lumpy V8 kicked into life and they cleared and run up ok finally getting home with a few coughs and splutters then tucked up in the garage.
So any idea where to start? Could she be over fuelling, fueul pump, ECU any idea where to start would be welcome and a bottle of fine wine to whoever helps me to resolve it otherwise Ian at Sportmotive will be getting another LS conversion….
Are you saying you could actually see the fuel gauge moving?
Surely if the gauge was visibly going down, that must indicate a major leak? If it were over-fuelling badly enough to make the fuel gauge move, then it would be far too rich for the engine to run at all.
Just mulling over some numbers in my mind, for the gauge to move quickly enough for you to be able to see the movement, I reckon you'd need to use (or lose!) several litres per minute. Consider this: even if you're losing a gallon per minute it's going to take more than 10 minutes for the gauge to move across its full deflection, and I'm not sure that would necessarily be fast enough for you to perceive the movement. In normal operation you'd expect the engine to use only half a pint per minute at the maximum.
I may have misunderstood, but if you could see the gauge moving before your very eyes then it simply has to be a leak, I would think. I don't think I'd be driving it again until you've got to the bottom of this.
Surely if the gauge was visibly going down, that must indicate a major leak? If it were over-fuelling badly enough to make the fuel gauge move, then it would be far too rich for the engine to run at all.
Just mulling over some numbers in my mind, for the gauge to move quickly enough for you to be able to see the movement, I reckon you'd need to use (or lose!) several litres per minute. Consider this: even if you're losing a gallon per minute it's going to take more than 10 minutes for the gauge to move across its full deflection, and I'm not sure that would necessarily be fast enough for you to perceive the movement. In normal operation you'd expect the engine to use only half a pint per minute at the maximum.
I may have misunderstood, but if you could see the gauge moving before your very eyes then it simply has to be a leak, I would think. I don't think I'd be driving it again until you've got to the bottom of this.
Edited by Dr Mike Oxgreen on Tuesday 30th August 10:14
Edited by Dr Mike Oxgreen on Tuesday 30th August 10:19
Dont grasp at straws, get a fault code reader plugged in, you should get an error code if its that bad. If you dont then the normal culprit for severe overfueling is the AFM, or AFM connection. The AFM voltage floats high enough to make the ECU throw in loads of fuel, but not always enough for a fault code. Its worth dropping a plug out from each side and see if they are both sooted up. An electrical missfire will also cause the engine to overfuel, and if its one one side of the V8 then only the plugs on that side will soot as the fueling is independently controlled on each side.
Other items that can make it overfuel are temperature sensors out of range or open circuit, a faulty fuel pressure requlator (unlikely), or a blocked fuel return pipe. Its unlikely to be the pump or control relays.
Other items that can make it overfuel are temperature sensors out of range or open circuit, a faulty fuel pressure requlator (unlikely), or a blocked fuel return pipe. Its unlikely to be the pump or control relays.
Hi,
similar problem on my Chim, we have done a little Tvr meeting this week end near St Malo, around 60 liter of fuel to do 150 miles !!!!
black smoke, non starting when hot, fuel smell, very rich.
some weeks ago, I had also some cutting off at junction, but have not use the car since this WE.Also some misfire!!
Perhaps AFM or the connector 6 way or another part, difficult without code reader .
similar problem on my Chim, we have done a little Tvr meeting this week end near St Malo, around 60 liter of fuel to do 150 miles !!!!
black smoke, non starting when hot, fuel smell, very rich.
some weeks ago, I had also some cutting off at junction, but have not use the car since this WE.Also some misfire!!
Perhaps AFM or the connector 6 way or another part, difficult without code reader .
Your problems sound very similar to problem i had that took me three years to finally
Track down. The car would run fine for weeks then mess me about for a week with one bank not running and stinking of fuel. It would then clear and produce clouds of smoke amd be fine for another couple of months.
I had the dash and engine loom in bits, looked at ECU internally, replaced ignition amp on recommendation of a TVR specialist.
The problem persisted, i got a noid light to find out that the left bank injectors were full on when fault occured, even with engine stopped and ignition on.
Eventually the fault became permanent then i found out what it was.
Number 7 injector was shorting to ground through the body.
New set of injectors later never had the problem since.
The very fact that your using so much fuel suggest to me you have something similar going on.
I used half a tank in about 20 miles when my fault first occured.
Good luck finding it. Let us know the outcome.
Paul
Track down. The car would run fine for weeks then mess me about for a week with one bank not running and stinking of fuel. It would then clear and produce clouds of smoke amd be fine for another couple of months.
I had the dash and engine loom in bits, looked at ECU internally, replaced ignition amp on recommendation of a TVR specialist.
The problem persisted, i got a noid light to find out that the left bank injectors were full on when fault occured, even with engine stopped and ignition on.
Eventually the fault became permanent then i found out what it was.
Number 7 injector was shorting to ground through the body.
New set of injectors later never had the problem since.
The very fact that your using so much fuel suggest to me you have something similar going on.
I used half a tank in about 20 miles when my fault first occured.
Good luck finding it. Let us know the outcome.
Paul
Sorry S4CJO, I know it's your post but just tested my AFM( 2 years old!!)and the readings on my multimeter are :
Turning switch on without starting
connected to Red/black (ground) and Blue/green 0.015v must be normally 0.3V I think
" " Red/black and Brown/orange 11.9V correct
" " Red/black and Blue/red 0.018V
starting the car give me similar results
Could I adjust something, or is the AFM out??
Chris
Turning switch on without starting
connected to Red/black (ground) and Blue/green 0.015v must be normally 0.3V I think
" " Red/black and Brown/orange 11.9V correct
" " Red/black and Blue/red 0.018V
starting the car give me similar results
Could I adjust something, or is the AFM out??
Chris
Edited by brittanytvr on Wednesday 31st August 21:03
That 88 code wont be the reason for the overfuelling. It may simply be the first code stored, as the ecu can store more than one.
Higher priority faults need to be "cleared" before lower priority faults will be displayed. A "blank" (dark) display usually indicates there are no faults.
Use this procedure to clear faults:
1. Switch "on" the ignition.
2. Disconnect the serial link mating plug, wait five seconds, and reconnect.
3. Switch "off" the ignition, and wait several seconds.
4. Switch "on" the ignition. The display should now reset.
Note: It should either show a lower priority fault code or appear dark.
Heres the correct AFM voltages:
Most airflow meter faults will cause the engine to run excessively rich. However if the airflow meter remains connected whilst defective then the vehicle will probably not run. In most cases the output from a defective airflow meter will be in the range 2.0-2.5 Volts, which is a viable value. This represents a moderate load and will cause heavy over-fuelling without setting a fault code.
Testing is performed in the following manner. 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 next test is full load, and as with the fuel pressure test it will require use of a rolling road or a steep hill in the same manner. Under full load the voltage should rise to 4.45 Volts (3.5 Litre engine) to 4.95 Volts (5.0 Litre engine).
Higher priority faults need to be "cleared" before lower priority faults will be displayed. A "blank" (dark) display usually indicates there are no faults.
Use this procedure to clear faults:
1. Switch "on" the ignition.
2. Disconnect the serial link mating plug, wait five seconds, and reconnect.
3. Switch "off" the ignition, and wait several seconds.
4. Switch "on" the ignition. The display should now reset.
Note: It should either show a lower priority fault code or appear dark.
Heres the correct AFM voltages:
Most airflow meter faults will cause the engine to run excessively rich. However if the airflow meter remains connected whilst defective then the vehicle will probably not run. In most cases the output from a defective airflow meter will be in the range 2.0-2.5 Volts, which is a viable value. This represents a moderate load and will cause heavy over-fuelling without setting a fault code.
Testing is performed in the following manner. 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 next test is full load, and as with the fuel pressure test it will require use of a rolling road or a steep hill in the same manner. Under full load the voltage should rise to 4.45 Volts (3.5 Litre engine) to 4.95 Volts (5.0 Litre engine).
Edited by blitzracing on Friday 2nd September 12:18
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