Running problems with Lucas L (flapper 4CU) injection system
Discussion
Hello Rob, Just been reviewing your other threads on various forums on this subject and came across your last post on the V8 forum dated 10 December. The one where you said
Was this true? Is it still true?
If so, then it suggests that the thermostat is stuck wide open and the engine is simply unable to reach an efficient running temperature and, particularly in the recent very cold weather, the temperature sensor is telling the ECU to keep the mixture artificially rich, hence giving you the impression that as you say
it is holding back like it has too much choke?
Which, if the thermostat is stuck open, is exactly what is happening.
Check the thermostat and replace if necessary with an 88 degree C item.
esprits1v8 said:
checked all pipe work, no blocks or leaks, crankcase breather was blocked so cleaned it out, made no difference.
Checked the distributor cap and rotor arm, they are poor surprised they were not changed when HT leads got changed?
Tried the other used ones I got with the spare system, no difference.
Changed the AFM, Bingo did change it, the hunting on tickover has gone and revs a little better, took it for a drive, engine is still cold and is holding back like it has too much choke?
The key point being highlighted as you see.Checked the distributor cap and rotor arm, they are poor surprised they were not changed when HT leads got changed?
Tried the other used ones I got with the spare system, no difference.
Changed the AFM, Bingo did change it, the hunting on tickover has gone and revs a little better, took it for a drive, engine is still cold and is holding back like it has too much choke?
Was this true? Is it still true?
If so, then it suggests that the thermostat is stuck wide open and the engine is simply unable to reach an efficient running temperature and, particularly in the recent very cold weather, the temperature sensor is telling the ECU to keep the mixture artificially rich, hence giving you the impression that as you say
it is holding back like it has too much choke?
Which, if the thermostat is stuck open, is exactly what is happening.
Check the thermostat and replace if necessary with an 88 degree C item.
honestjohntoo said:
Hello Rob, Just been reviewing your other threads on various forums on this subject and came across your last post on the V8 forum dated 10 December. The one where you said
Was this true? Is it still true?
If so, then it suggests that the thermostat is stuck wide open and the engine is simply unable to reach an efficient running temperature and, particularly in the recent very cold weather, the temperature sensor is telling the ECU to keep the mixture artificially rich, hence giving you the impression that as you say
it is holding back like it has too much choke?
Which, if the thermostat is stuck open, is exactly what is happening.
Check the thermostat and replace if necessary with an 88 degree C item.
but the engine is getting hot? when I take it for a run the temp is going to 90 degrees, so I dont think it can be the problem?esprits1v8 said:
checked all pipe work, no blocks or leaks, crankcase breather was blocked so cleaned it out, made no difference.
Checked the distributor cap and rotor arm, they are poor surprised they were not changed when HT leads got changed?
Tried the other used ones I got with the spare system, no difference.
Changed the AFM, Bingo did change it, the hunting on tickover has gone and revs a little better, took it for a drive, engine is still cold and is holding back like it has too much choke?
The key point being highlighted as you see.Checked the distributor cap and rotor arm, they are poor surprised they were not changed when HT leads got changed?
Tried the other used ones I got with the spare system, no difference.
Changed the AFM, Bingo did change it, the hunting on tickover has gone and revs a little better, took it for a drive, engine is still cold and is holding back like it has too much choke?
Was this true? Is it still true?
If so, then it suggests that the thermostat is stuck wide open and the engine is simply unable to reach an efficient running temperature and, particularly in the recent very cold weather, the temperature sensor is telling the ECU to keep the mixture artificially rich, hence giving you the impression that as you say
it is holding back like it has too much choke?
Which, if the thermostat is stuck open, is exactly what is happening.
Check the thermostat and replace if necessary with an 88 degree C item.
s1v8esprit said:
changed the temp sender..........yes you guessed it no difference! (looked like a brand new one I took out?)
engine would not run with this disconnected? and ran very poor if I shorted the wires? like Adam suggested?
That's very interesting!engine would not run with this disconnected? and ran very poor if I shorted the wires? like Adam suggested?
Normally you only need the enrichment when it's quite cold (you did warm it up a bit first, right?) and when you short this out then the engine runs a bit leaner, but should run fine.
The fact that it runs worse make me start to think the fuel is already on the lean side? And then the rough running at 3500+ is the same reason?
So - how about checking the AFR when driving? I dunno if you can get a lambda sensor that can work up the tailpipe? Also check the usual reasons for poor fuelling:
Hardly any fuel in tank (!)
Bad Fuel Pressure Regulator - check the fuel pressure
Vacuum pipe to fuel regulator split
Failing pump
Blocked fuel filter(s)
Flapper getting a bit gummed up
Air leaks
Throttle pot totally open circuit or no voltage to pot
adam quantrill said:
s1v8esprit said:
changed the temp sender..........yes you guessed it no difference! (looked like a brand new one I took out?)
engine would not run with this disconnected? and ran very poor if I shorted the wires? like Adam suggested?
That's very interesting!engine would not run with this disconnected? and ran very poor if I shorted the wires? like Adam suggested?
Normally you only need the enrichment when it's quite cold (you did warm it up a bit first, right?) and when you short this out then the engine runs a bit leaner, but should run fine.
The fact that it runs worse make me start to think the fuel is already on the lean side? And then the rough running at 3500+ is the same reason?
So - how about checking the AFR when driving? I dunno if you can get a lambda sensor that can work up the tailpipe? Also check the usual reasons for poor fuelling:
Hardly any fuel in tank (!)
Bad Fuel Pressure Regulator - check the fuel pressure
Vacuum pipe to fuel regulator split
Failing pump
Blocked fuel filter(s)
Flapper getting a bit gummed up
Air leaks
Throttle pot totally open circuit or no voltage to pot
Granny sucking eggs and all that jazz, but make sure the vaccuum reference is disconnected when getting your fuel pressure reading (or do it with the engine off).
Adam, intermotor bits dufff from the box doesn't surprise me in the slightest, strange to think that we now regard Lucas as a paragon of quality
Adam, intermotor bits dufff from the box doesn't surprise me in the slightest, strange to think that we now regard Lucas as a paragon of quality
B-Reight said:
Ramon, i don't think this could be true, from my experimentation with the L-jet ECUs it would appear that the enrichment %age is only significant under 40degrees C coolant temp. Over that value there was no discernable enrichment.
I think you are right because of placing the emphasis on the word "significant". The sensor chart bears out the change from 40 to 100 degrees accounts for only about 1000 ohms in a total resistance change from nearly 10,000 ohms very cold, down to approx 200 ohms at full temperature. Coolant Temperature Sensor Chart
-10°C......9100-9300
0°C........5700-5900
20°C.......2400-2600
40°C.......1100-1300
60°C.......500-700
80°C.......300-400
100°C......150-200
and whilst the temperature/resistance curve is non linear, the ECU enrichment circuits will be linear as far as their response to the input resistance is concerned and that final 10% change whilst being "small" does not exactly qualify as "no discernable enrichment".
Indeed continually driving with enriched mixture will feel like a choked engine. Even the reported plug colour seems to bear that out for an engine/system that normally runs a bit on the weak side with normal plug colour, in my experience, a bit lighter than reported.
Now its all academic, but before the information came in that the engine does indeed get up to temperature the sufferer actually says "took it for a drive, engine is still cold and is holding back like it has too much choke?"
Also following the progress of the reportage on three threads over two different forums is not bringing in any cohesive actions.
My own solution from the getgo would be in the simple "back to basics" test programs suggested earlier. On the other hand, sooner or later the scattergun approach to component replacement will eventually bring about an answer even if that answer is total disenchantment and moving on to a different marque.
honestjohntoo said:
B-Reight said:
Ramon, i don't think this could be true, from my experimentation with the L-jet ECUs it would appear that the enrichment %age is only significant under 40degrees C coolant temp. Over that value there was no discernable enrichment.
I think you are right because of placing the emphasis on the word "significant". The sensor chart bears out the change from 40 to 100 degrees accounts for only about 1000 ohms in a total resistance change from nearly 10,000 ohms very cold, down to approx 200 ohms at full temperature. Coolant Temperature Sensor Chart
-10°C......9100-9300
0°C........5700-5900
20°C.......2400-2600
40°C.......1100-1300
60°C.......500-700
80°C.......300-400
100°C......150-200
and whilst the temperature/resistance curve is non linear, the ECU enrichment circuits will be linear as far as their response to the input resistance is concerned and that final 10% change whilst being "small" does not exactly qualify as "no discernable enrichment".
Indeed continually driving with enriched mixture will feel like a choked engine. Even the reported plug colour seems to bear that out for an engine/system that normally runs a bit on the weak side with normal plug colour, in my experience, a bit lighter than reported.
Now its all academic, but before the information came in that the engine does indeed get up to temperature the sufferer actually says "took it for a drive, engine is still cold and is holding back like it has too much choke?"
Also following the progress of the reportage on three threads over two different forums is not bringing in any cohesive actions.
My own solution from the getgo would be in the simple "back to basics" test programs suggested earlier. On the other hand, sooner or later the scattergun approach to component replacement will eventually bring about an answer even if that answer is total disenchantment and moving on to a different marque.
today it is running real bad, will not tick over, stalls and just will not rev clean? took it for a short drive and its horrible, lumpy,flat spots and missing.
I was hoping to drain the fuel tank and check the filters and pump today but its raining. Now because its running at its worst today and because its wet would that make it more likely to be a wiring loom connection fault?
I was hoping to drain the fuel tank and check the filters and pump today but its raining. Now because its running at its worst today and because its wet would that make it more likely to be a wiring loom connection fault?
s1v8esprit said:
so could I not try bypassing the temp sensor with a resistor at the ECU end of the loom? just in case I have a faulty connection or wiring?
Yes indeed, 200 ohms will make the fuelling correct for normal running temperature, if you have access to the wiring at the ECU, or you could simply carry out the test process for the CTS as detailed here: http://www.vintagemodelairplane.com/pages/Rover_Te...
and in the manu of course.
Apologies if I'm wrong but you seem to be reluctant to do any suggested testing - just wanna replace components randomly and in hope?
s1v8esprit said:
today it is running real bad, will not tick over, stalls and just will not rev clean? took it for a short drive and its horrible, lumpy,flat spots and missing.
I was hoping to drain the fuel tank and check the filters and pump today but its raining. Now because its running at its worst today and because its wet would that make it more likely to be a wiring loom connection fault?
Internal combustion engines normally run a little better in cold damp conditions,and yes its possible that your wiring loom is fickle.I was hoping to drain the fuel tank and check the filters and pump today but its raining. Now because its running at its worst today and because its wet would that make it more likely to be a wiring loom connection fault?
For diagnosis it helps to know if its fuelling or ignition, so to test the fuelling status, what are the plug conditions after such a bout of running. One plug from each bank is a good viewpoin to report on
Regarding the symptoms reported it may very well be crudded fuel delivery so that needs to be checked.
My personal feeling it you have a seriously sick motor with more than one problem and as such, one needs to address the issues "back to basics", testing each component and its loom connections as per the individual component testing schedules previously mentioned.
Guessing what might be wrong will lead absolutely nowhere, unfortunately.
You'll recall also the advice about air leaks? Such symptoms as you describe are quite typical of that problem so, not to put too fine a point on the subject, do yourself a favour and do some testing as suggested.
honestjohntoo said:
s1v8esprit said:
so could I not try bypassing the temp sensor with a resistor at the ECU end of the loom? just in case I have a faulty connection or wiring?
Yes indeed, 200 ohms will make the fuelling correct for normal running temperature, if you have access to the wiring at the ECU, or you could simply carry out the test process for the CTS as detailed here: http://www.vintagemodelairplane.com/pages/Rover_Te...
and in the manu of course.
Apologies if I'm wrong but you seem to be reluctant to do any suggested testing - just wanna replace components randomly and in hope?
These have been changed, and it made no difference? I have not been randomly changing parts? I have a complete system for spares, its quicker just to change the parts as to test them again just in case the parts have intermittent faults? I have been changing parts in order of what is most likely at fault.
I have a fuel pressure gauge on order and will be going back to basics starting with the fuel, I had hoped to have fixed it by changing the parts that I had, but this has been a tricky problem as the results have changed and not been consistent......other than it drives real crappy.
What is the history of the spare parts system you are robbing bits from? Was it from a good runner? For it is quite possible that you have replaced your ECU with another one, with a different fault.
Damp and running worse suggests the ignition isn't pukka, but as HJ2 says, there may be more than one fault present.
Now it is dark go outside and run it, in the dark, and check for arcing.
What is the spark like at the end of the king lead, and then at the end of each lead in turn, weak, or nice and fat? (You'll need to poke a well-grounded screwdriver up the shrouds for the last test)
Then, are all the leads connected up in the correct firing order?
Damp and running worse suggests the ignition isn't pukka, but as HJ2 says, there may be more than one fault present.
Now it is dark go outside and run it, in the dark, and check for arcing.
What is the spark like at the end of the king lead, and then at the end of each lead in turn, weak, or nice and fat? (You'll need to poke a well-grounded screwdriver up the shrouds for the last test)
Then, are all the leads connected up in the correct firing order?
adam quantrill said:
What is the history of the spare parts system you are robbing bits from? Was it from a good runner? For it is quite possible that you have replaced your ECU with another one, with a different fault.
Damp and running worse suggests the ignition isn't pukka, but as HJ2 says, there may be more than one fault present.
Now it is dark go outside and run it, in the dark, and check for arcing.
What is the spark like at the end of the king lead, and then at the end of each lead in turn, weak, or nice and fat? (You'll need to poke a well-grounded screwdriver up the shrouds for the last test)
Then, are all the leads connected up in the correct firing order?
was told it was all good, bottom end went in water (off roading) and knackered the bottom end so the bloke sold all the bits off the car and scrapped it.Damp and running worse suggests the ignition isn't pukka, but as HJ2 says, there may be more than one fault present.
Now it is dark go outside and run it, in the dark, and check for arcing.
What is the spark like at the end of the king lead, and then at the end of each lead in turn, weak, or nice and fat? (You'll need to poke a well-grounded screwdriver up the shrouds for the last test)
Then, are all the leads connected up in the correct firing order?
right just ran it in the dark, no arcing and still running crap! have now got a 3rd ECU and has made no change. Tried the bypass of the temp sender with a 320 ohms resistor (all I could find) engine very hard to start and will not run, really does not like it at all? is this not a clue?
will check condition of spark tomorrow, too cold and wet now, and double check firing order but can not see that being wrong as at times it has run ok?
Yes it should be running leaner with the 320 ohm resistor in - if cold the engine temp sensor will be in the 1k ohm + value with the weather we've been having lately.
If all the components have been replaced with good ones then the wiring loom needs checking. If (for example) the air meter isn't feeding back a good value via the wiring, then you could end up running lean.
Maybe if you take off the ECU multiplug and check each wire one at a time for continuity all the way to the corresponding pin on the other end, e.g. air meter, throttle pot, etc.
Then (with all the engine bits disconnected) check for shorts between the various wires at the ECU multiplug. Some are grounds so should be shorted.
If all the components have been replaced with good ones then the wiring loom needs checking. If (for example) the air meter isn't feeding back a good value via the wiring, then you could end up running lean.
Maybe if you take off the ECU multiplug and check each wire one at a time for continuity all the way to the corresponding pin on the other end, e.g. air meter, throttle pot, etc.
Then (with all the engine bits disconnected) check for shorts between the various wires at the ECU multiplug. Some are grounds so should be shorted.
adam quantrill said:
Yes it should be running leaner with the 320 ohm resistor in - if cold the engine temp sensor will be in the 1k ohm + value with the weather we've been having lately.
If all the components have been replaced with good ones then the wiring loom needs checking. If (for example) the air meter isn't feeding back a good value via the wiring, then you could end up running lean.
Maybe if you take off the ECU multiplug and check each wire one at a time for continuity all the way to the corresponding pin on the other end, e.g. air meter, throttle pot, etc.
Then (with all the engine bits disconnected) check for shorts between the various wires at the ECU multiplug. Some are grounds so should be shorted.
yes good idea, the whole injection loom could be dodgy! the auto electrician who done the checks could have been lazy and not checked the loom properly?If all the components have been replaced with good ones then the wiring loom needs checking. If (for example) the air meter isn't feeding back a good value via the wiring, then you could end up running lean.
Maybe if you take off the ECU multiplug and check each wire one at a time for continuity all the way to the corresponding pin on the other end, e.g. air meter, throttle pot, etc.
Then (with all the engine bits disconnected) check for shorts between the various wires at the ECU multiplug. Some are grounds so should be shorted.
I have a complete loom so I will check this as its easy to do than on the car, and if it checks out ok will swap it over, (I have swapped every thing else!) still going to check the fuel setup first. Hopefully have it sussed soon.
TVRleigh_BBWR said:
once you get it sorted, let me know if you want to sell one of the ECU,
Looking for a broken one or One I can brake to make adaptor so I can connect a DL1 logger so you can get real time diagnostic's on a laptop, or recorded data for later analysis
There's an ECU on Ebay at the mo (relisted as no bids last time) complete with various other injection bits, spare injectors etc... well worth the £25 start bid IMHO. I'd have it myself but I have more injection spares than I know what to do with (5 ECUs at the last count including one fom a Sprintex'd Range Rover that was used in the Paris-Dakar in '89 IIRC!).Looking for a broken one or One I can brake to make adaptor so I can connect a DL1 logger so you can get real time diagnostic's on a laptop, or recorded data for later analysis
I sacrificed an ECU to make a diagnostics splitter box and planned to use the insides as spares for faulty ones, but invariably it isn't an ECU fault or else is just the old dry joints problem - the components themselves rarely fail, disproving the myth that 30 year old electronics are unreliable.
To the OP: it will almost definitely be something very simple, the whole system isn't that complicated and if you can prove any of your ECUs and airflow meters on another V8 (preferably a boggo 3.5L rather than a tuned or large-capacity variant) that will shorten the diagnostics considerably. I'd be tempted to go with the theory that the fault lies in the loom; could even be high-resistance crimp/solder to the main loom earth terminal. If you were 250 miles closer I'd have fixed it by now
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