Injector monitoring
Discussion
Hi
I would like to measure the injector pulses on a rover V8 engine, so just 2 signals on a PWM control, obviously a multimeter won’t measure this properly, any recommendations on a lowish cost piece of kit to either monitor live or record and view later, any idea of what voltages might be required ??
I would like to measure the injector pulses on a rover V8 engine, so just 2 signals on a PWM control, obviously a multimeter won’t measure this properly, any recommendations on a lowish cost piece of kit to either monitor live or record and view later, any idea of what voltages might be required ??
A multimeter with a pw setting will of course measure it properly.
Recording it other than say on a scope or similar logging device....is another matter.
Some meters can record to some degree, or there are various logger devices out there that will require some hardware and then log on a PC.
Depends how much you need to log..
Although do you really need to log it in the first place ?
Recording it other than say on a scope or similar logging device....is another matter.
Some meters can record to some degree, or there are various logger devices out there that will require some hardware and then log on a PC.
Depends how much you need to log..
Although do you really need to log it in the first place ?
I have an intermittent misfire and could go a few hundred miles inbetween problems, it only lasts about 2 min and then slowly corrects itself, people behind me have reported a strong petrol smell and maybe one bank of 4 is way over fuelling and flooding that bank, my DVM a fluke 77 will show a voltage and it does vary with revs but not sure how close this relates to a real signal so I was thinking that ideally I could record or monitor both banks of injectors and see the difference when the misfire occurs, so something to record or display would be ideal, I have spent a lot of time trying to try and track this fault, so far without any luck
An oscilloscope would be one option.
But really...I'd be wanting lambda sensor data to see if one bank or the other is actually running rich or not whenever you are having this problem.
Even a narrow band sensor would be viable here.
Any decent automotive multimeter will give you pulsewidth or duty...but I doubt it would be of any use on a simple display like that, it would need to be viewed as a graph to see any anomalies.
But start properly...find out if it is actually rich etc.
After that, I'd be more concerned with main sensor data into the ecu, rather than controlling actions out, and if you feel it is only one bank, that'd make it even more pointless, as the ecu is not going to be deliberately doing different things on either bank.
But really...I'd be wanting lambda sensor data to see if one bank or the other is actually running rich or not whenever you are having this problem.
Even a narrow band sensor would be viable here.
Any decent automotive multimeter will give you pulsewidth or duty...but I doubt it would be of any use on a simple display like that, it would need to be viewed as a graph to see any anomalies.
But start properly...find out if it is actually rich etc.
After that, I'd be more concerned with main sensor data into the ecu, rather than controlling actions out, and if you feel it is only one bank, that'd make it even more pointless, as the ecu is not going to be deliberately doing different things on either bank.
For a quick sanity check you could just wire up a remote NOID light across one of the injectors so that you get a crude visual indication of the duty cycle and see whether that changes significantly when the problem happens.
There are various ways to log that signal but they're all going to involve some pretty tedious analysis to track down the few seconds worth of data covering the problem.
What engine management system are you using?
There are various ways to log that signal but they're all going to involve some pretty tedious analysis to track down the few seconds worth of data covering the problem.
What engine management system are you using?
Paulprior said:
I have an intermittent misfire and could go a few hundred miles inbetween problems, it only lasts about 2 min and then slowly corrects itself, people behind me have reported a strong petrol smell and maybe one bank of 4 is way over fuelling and flooding that bank, my DVM a fluke 77 will show a voltage and it does vary with revs but not sure how close this relates to a real signal so I was thinking that ideally I could record or monitor both banks of injectors and see the difference when the misfire occurs, so something to record or display would be ideal, I have spent a lot of time trying to try and track this fault, so far without any luck
Normally the coil driver ime! Does it mostly happen when the engine is fully warmed up?A cheapish meter with pulse width.
Although odd how many meters out there for sale claiming automotive....that dont have it !
https://www.ebay.co.uk/itm/Automotive-Multimeter-H...
Although odd how many meters out there for sale claiming automotive....that dont have it !
https://www.ebay.co.uk/itm/Automotive-Multimeter-H...
I’m familiar with DMMs but not automotive ones, what does the pulse display show, length / time of pulse ??, is that better than a similar priced DMM / scope ??
The car is a TVR with a rover V8 running a Lucas 14 cux
What I have observed so far, when driving say at 50 mph if the misfire happens I loose so much power that I can maintain speed but not accelerate, I have stopped a couple of times when sage to do do and checked the manifold temps, driver side 270, passenger side 170, I have seen this a couple of times, as mentioned it last about 2 mins then clears gradually over another 2 mins with a few pops and bangs, I connected 2 DMMs to the injector signal at the ECU , the injectors have a constant 12v and the return side is earthed through the ecu, so I measured from 12v to the injector return , so 13v with engine off, the display shows around 12v when running at tickover and drops as the rpm rises, on the one occasion that it went wrong and I had the meters connected it was just after start up and still in the garage, passenger side stayed at 12v but passenger side dropped to around 9v, after approx 2 min it looks like the voltage stepped up a little, it’s not perfect to see as the engine is now running rather lumpy, but it certainly looked like the voltage increased in steps over a few minutes until it reaches the 12v and then everything is fine.
I considered what could cause differences between both banks and could only see it as the Lambdas , not knowing anything about how this all works I disconnected the passenger side one while running , no change at all, engine running perfectly.
How it seems to me is that something makes the ecu run very rich on one side and then it tries gradually to correct itself??????
Any ideas on how to go forward greatly appreciated, the car is great apart from this frustrating issue, it’s difficult to find as it might be weeks or sometimes months before it occurs, several times I thought I had fixed it
The car is a TVR with a rover V8 running a Lucas 14 cux
What I have observed so far, when driving say at 50 mph if the misfire happens I loose so much power that I can maintain speed but not accelerate, I have stopped a couple of times when sage to do do and checked the manifold temps, driver side 270, passenger side 170, I have seen this a couple of times, as mentioned it last about 2 mins then clears gradually over another 2 mins with a few pops and bangs, I connected 2 DMMs to the injector signal at the ECU , the injectors have a constant 12v and the return side is earthed through the ecu, so I measured from 12v to the injector return , so 13v with engine off, the display shows around 12v when running at tickover and drops as the rpm rises, on the one occasion that it went wrong and I had the meters connected it was just after start up and still in the garage, passenger side stayed at 12v but passenger side dropped to around 9v, after approx 2 min it looks like the voltage stepped up a little, it’s not perfect to see as the engine is now running rather lumpy, but it certainly looked like the voltage increased in steps over a few minutes until it reaches the 12v and then everything is fine.
I considered what could cause differences between both banks and could only see it as the Lambdas , not knowing anything about how this all works I disconnected the passenger side one while running , no change at all, engine running perfectly.
How it seems to me is that something makes the ecu run very rich on one side and then it tries gradually to correct itself??????
Any ideas on how to go forward greatly appreciated, the car is great apart from this frustrating issue, it’s difficult to find as it might be weeks or sometimes months before it occurs, several times I thought I had fixed it
Your diagnosis steps seem reasonable but is suggesting that you've got severe overfuelling caused by the ECU. This would be a good time to get yourself a copy of Rovergauge and the ECU/USB adapter lead from blitzracing. This will show you the live fault codes, sensor inputs and fuel map outputs. If you have a picoscope or similar, you could also log the two bank's injector signals to confirm that the discrepancy your meter showed is real.
I don't know what practical issues you're facing, but if you can find a way to get the problem to happen with rovergauge connected that ought to make it clear.
Something else you could check if that is not practical is the heater supply to the lambda sensors. IIRC the heater supply also powers the probe and the probe will send a fully lean signal if the heater supply fails. That could be a consequence of a broken wire or dodgy connector. You could monitor that with a simple test lamp between the heater terminal of the lambda probe connector, and ground.
Something else you could check if that is not practical is the heater supply to the lambda sensors. IIRC the heater supply also powers the probe and the probe will send a fully lean signal if the heater supply fails. That could be a consequence of a broken wire or dodgy connector. You could monitor that with a simple test lamp between the heater terminal of the lambda probe connector, and ground.
Using a voltmeter here ( at the injector ) is utterly useless. And no multimeter will be a match for an oscilloscope....of course the price reflects that.
You can buy cheap scopes, ( low hundreds ) but they just arent that user friendly and some of them do not record data, which is annoying.
At the top end is the Picoscope, but it starts at 4 figures heading wayyyy up there.
But at least say a 4 channel scope will allow you to view various signals and voltages etc at the same time. Not much good if you're trying to drive too though.
You have now said there are lambda sensors....so do what I said and see what they are telling you regarding mixtures. Potentially feedback or issues with one side, could cause different fueling on one side. So the obvious first step is to see what they're doing.
A scope trace would be nice, but a good DMM is also usable.
And pulse width is just that. It will be measured in one way....which is a time period, most sensible here is milliseconds.
Whilst the book is a little basic, it'd probably be a good place for you to start
https://www.amazon.co.uk/Electrical-Electronic-Sys...
and likewise if you had a scope, this book gives some nice pictures and explanations at a basic level...but the visuals will also help you understand what is happening
https://www.amazon.co.uk/Automotive-Oscilloscopes-...
Of course, for almost anything you'd want to try and diagnose, youtube has people doing videos, one excellent guy is Paul Danner, ScannerDanner.
https://www.youtube.com/watch?v=uYMGnvtgi8w&
You can buy cheap scopes, ( low hundreds ) but they just arent that user friendly and some of them do not record data, which is annoying.
At the top end is the Picoscope, but it starts at 4 figures heading wayyyy up there.
But at least say a 4 channel scope will allow you to view various signals and voltages etc at the same time. Not much good if you're trying to drive too though.
You have now said there are lambda sensors....so do what I said and see what they are telling you regarding mixtures. Potentially feedback or issues with one side, could cause different fueling on one side. So the obvious first step is to see what they're doing.
A scope trace would be nice, but a good DMM is also usable.
And pulse width is just that. It will be measured in one way....which is a time period, most sensible here is milliseconds.
Whilst the book is a little basic, it'd probably be a good place for you to start
https://www.amazon.co.uk/Electrical-Electronic-Sys...
and likewise if you had a scope, this book gives some nice pictures and explanations at a basic level...but the visuals will also help you understand what is happening
https://www.amazon.co.uk/Automotive-Oscilloscopes-...
Of course, for almost anything you'd want to try and diagnose, youtube has people doing videos, one excellent guy is Paul Danner, ScannerDanner.
https://www.youtube.com/watch?v=uYMGnvtgi8w&
Paulprior,
Ocilloscopes get to be pricey, but a 'Picoscope' that will display your injector pulses can be about £100. They link to a laptop that provides the display, via the software that comes with the device
See: https://www.picoauto.com/library/automotive-guided...
https://www.picoauto.com/images/uploads/screenshot...
John
No connection except as a very satisfied user of a Picoscope 2204 (2 channel)
Ocilloscopes get to be pricey, but a 'Picoscope' that will display your injector pulses can be about £100. They link to a laptop that provides the display, via the software that comes with the device
See: https://www.picoauto.com/library/automotive-guided...
https://www.picoauto.com/images/uploads/screenshot...
John
No connection except as a very satisfied user of a Picoscope 2204 (2 channel)
Already been through this with you, you asked for advice and I posted you good advice
You are wasting your time measuring any circuit voltages if using Battery Negative when taking readings with the multimeter
The only way of testing the circuit voltages is to measure those voltages at the circuits own negatives and positives
Also previously mentioned that there is no point in you measuring ECU outputs at the ECU, ECU outputs need to be first measured at the components and then at the ECU if incorrect, this method will prove if a wiring loom fault exists
https://www.pistonheads.com/gassing/topic.asp?h=0&...
All components cables need to be proven good when the fault is on the system
Perhaps you've now proven the above
Throwing cash at test equipment is a waste of time if the above hasn't been proven
Do you know that all components including the ECU can be disconnected and then a load test on the cables including terminals can be carried out to their maximum current carrying capacity?
The above test often shows what's causing an intermittent fault as the load applied to the cables is higher than that applied by the components
Previously mentioned other possibles such as short on loom or injector internal short
You are wasting your time measuring any circuit voltages if using Battery Negative when taking readings with the multimeter
The only way of testing the circuit voltages is to measure those voltages at the circuits own negatives and positives
Also previously mentioned that there is no point in you measuring ECU outputs at the ECU, ECU outputs need to be first measured at the components and then at the ECU if incorrect, this method will prove if a wiring loom fault exists
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Penelope Stopit said:
Due to the fault being Intermittent
If the Inputs (Positives and Negatives) at the components (Lambda Sensors) haven't been proven good, it is a total waste of time checking the outputs
If the Inputs (Positives) at the components (Fuel Injectors) haven't been proven good, it is a total waste of time checking the Lambda Sensor outputs
If the cables from ECU to Injectors (Negative Switching) haven't been proven good, it is a total waste of time checking the Lambda Sensor outputs
I hope for your benefit that it isn't unfortunate for you to disagree with my methods of testing
Have you now proven that the cables to the components are working as should be?If the Inputs (Positives and Negatives) at the components (Lambda Sensors) haven't been proven good, it is a total waste of time checking the outputs
If the Inputs (Positives) at the components (Fuel Injectors) haven't been proven good, it is a total waste of time checking the Lambda Sensor outputs
If the cables from ECU to Injectors (Negative Switching) haven't been proven good, it is a total waste of time checking the Lambda Sensor outputs
I hope for your benefit that it isn't unfortunate for you to disagree with my methods of testing
All components cables need to be proven good when the fault is on the system
Perhaps you've now proven the above
Throwing cash at test equipment is a waste of time if the above hasn't been proven
Do you know that all components including the ECU can be disconnected and then a load test on the cables including terminals can be carried out to their maximum current carrying capacity?
The above test often shows what's causing an intermittent fault as the load applied to the cables is higher than that applied by the components
Previously mentioned other possibles such as short on loom or injector internal short
Paulprior said:
on the one occasion that it went wrong and I had the meters connected it was just after start up and still in the garage, passenger side stayed at 12v but passenger side dropped to around 9v, after approx 2 min it looks like the voltage stepped up a little, it’s not perfect to see as the engine is now running rather lumpy, but it certainly looked like the voltage increased in steps over a few minutes until it reaches the 12v and then everything is fine.
Lets assume that what you measured is fact."the injector supply voltage dropped to 9v on one bank"
This has two possible causes:
1) A poor connection or contact upstream of the injectors increases the resistance of the power supply to that bank. As the injectors open, they pull current, and as a result of the higher upstream resistance, the voltage measured at the injectors falls - this would result in less fuel being delivered
2) The injectors, instead of being driven (pulled low by the driver in the ecu) with an appropriate duty cycle, have somehow become continuously energised (full and continuously on) this causes much more current to be drawn by the injectors on that bank, that extra current results in a lower measured injector supply voltage (due to the normal upstream resistance in the supply wiring) - this would result in more fuel being delivered
The good news is that it's really easy to check which of those cases is occuring!
either
1) Refit your voltage meaurement, find the wire at the ecu plug that comes from that bank of injectors, and with the fuel pump disconnected (no fuel pressure) short that wire to ground. This will turn on continuously that banks injectors. If the injector supply voltage drops to 9V, then bingo, we know what's happening
or
2) Move the voltage measurement point to downstream of the injectors (after the injector coils). Try to recreate the fault. If it occurs, and that voltage falls to zero volts (or very close) then indeed, that banks injectors are being eroneously turned on by some fault or short.
Once you have determined which of those cases is valid, then you can consider the next steps to find the precise fault !
Olas said:
Im not intimately familiar with CUX - are you intimating that they are not present?
What objection do people have to Weber/Dellorto? Or Haltech/Jenvey?
I am not familiar with the old system myself...but the point is, it is an extremely old system. Someone, somewhere may be able to interrogate the ecu and get some data from it...but it is a far cry from any even "old" modern ecu's in terms of data and OBD type info.What objection do people have to Weber/Dellorto? Or Haltech/Jenvey?
As for the latter question....is this a new query, or other ? as it doesnt relate to the thread, and it seems a very open ended vague question ? Given they all make different things.
Max_Torque said:
Lets assume that what you measured is fact.
"the injector supply voltage dropped to 9v on one bank"
This has two possible causes:
1) A poor connection or contact upstream of the injectors increases the resistance of the power supply to that bank. As the injectors open, they pull current, and as a result of the higher upstream resistance, the voltage measured at the injectors falls - this would result in less fuel being delivered
2) The injectors, instead of being driven (pulled low by the driver in the ecu) with an appropriate duty cycle, have somehow become continuously energised (full and continuously on) this causes much more current to be drawn by the injectors on that bank, that extra current results in a lower measured injector supply voltage (due to the normal upstream resistance in the supply wiring) - this would result in more fuel being delivered
The good news is that it's really easy to check which of those cases is occuring!
either
1) Refit your voltage meaurement, find the wire at the ecu plug that comes from that bank of injectors, and with the fuel pump disconnected (no fuel pressure) short that wire to ground. This will turn on continuously that banks injectors. If the injector supply voltage drops to 9V, then bingo, we know what's happening
or
2) Move the voltage measurement point to downstream of the injectors (after the injector coils). Try to recreate the fault. If it occurs, and that voltage falls to zero volts (or very close) then indeed, that banks injectors are being eroneously turned on by some fault or short.
Once you have determined which of those cases is valid, then you can consider the next steps to find the precise fault !
It may be fact to him, but it is an incorrect and unusable measurement IMO."the injector supply voltage dropped to 9v on one bank"
This has two possible causes:
1) A poor connection or contact upstream of the injectors increases the resistance of the power supply to that bank. As the injectors open, they pull current, and as a result of the higher upstream resistance, the voltage measured at the injectors falls - this would result in less fuel being delivered
2) The injectors, instead of being driven (pulled low by the driver in the ecu) with an appropriate duty cycle, have somehow become continuously energised (full and continuously on) this causes much more current to be drawn by the injectors on that bank, that extra current results in a lower measured injector supply voltage (due to the normal upstream resistance in the supply wiring) - this would result in more fuel being delivered
The good news is that it's really easy to check which of those cases is occuring!
either
1) Refit your voltage meaurement, find the wire at the ecu plug that comes from that bank of injectors, and with the fuel pump disconnected (no fuel pressure) short that wire to ground. This will turn on continuously that banks injectors. If the injector supply voltage drops to 9V, then bingo, we know what's happening
or
2) Move the voltage measurement point to downstream of the injectors (after the injector coils). Try to recreate the fault. If it occurs, and that voltage falls to zero volts (or very close) then indeed, that banks injectors are being eroneously turned on by some fault or short.
Once you have determined which of those cases is valid, then you can consider the next steps to find the precise fault !
As I read that he simply placed his multimeter across the 12v and injector trigger. So depending on the meter, lag with readings etc....at low duties it might appear like a low voltage, and at 100% duty it should probably appear as nominal running voltage...circa 14v or so.
IMO a useless test method.
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