Discussion
I'm still having running problems with my Chimaera after several trips back and forth to the local specialist.
My question is about the way the ECU reprograms itself after a battery disconnect. It seems that every time I see this mentioned in a thread it describes what is happening to my car every time I start it.
Would somebody explain how this mechanism works or at least point me in some direction as to where I can find out. I've looked at Peter Beech's pages and poked my multimeter into the appropriate places, but the problem refuses to explain itself.
My question is about the way the ECU reprograms itself after a battery disconnect. It seems that every time I see this mentioned in a thread it describes what is happening to my car every time I start it.
Would somebody explain how this mechanism works or at least point me in some direction as to where I can find out. I've looked at Peter Beech's pages and poked my multimeter into the appropriate places, but the problem refuses to explain itself.
Sorry if you've mentioned this previously, but why do you need to reset the ECU?
From what I understand, which isn't much, an ECU reset is done to clear fault codes or after a tune.
When you take the car to your local specialist do they check the ECU for fault codes? and if so do you know what they are?
From what I understand, which isn't much, an ECU reset is done to clear fault codes or after a tune.
When you take the car to your local specialist do they check the ECU for fault codes? and if so do you know what they are?
Don't understand the question. When it resets it looses all the liottle adaptions it has made and goes back to its default settings. All done in software on the microprocessor. Nothing to see or do or probe with a multimeter...
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
Sorry, bad explaination. I'll try again.
My car suffers from a problem which has symptoms which seem very much like the ECU is resetting itself everytime the car is switched off.
I was using the multimeter to check that the various voltages and resistances on the ECU multiplug were correct. In particular, I was looking to see if the permanent live feed was present to the ECU.
To try to explain further, the symptoms of the problem are that the car runs roughly when cold. If the car is left to run until warm, the engine performs a short routine of a) revs dropping to around 200rpm, then b) very rough running at around 800rpm for 15-ish seconds, then c) engine revs to about 1800rpm for 5 seconds before settling to a normal idle. After this has happened the car runs perfectly until it is switched off.
The car will only perform this routine if the temperature is between about 60 and 75 degrees while the car is stationary.
I borrowed an ECU from another car for a week, but this had no effect on the problem. The car has also had new lambda sensors and airflow meter. The people trying to fix the car are at their wits end, so I was just trying to do some independent research.
I had seen mentioned in various threads that the ECU does some kind of adaptive fuelling, but did not know how this works. It just seems to me that this information may be lost from the ECU eveytime I turn off the ignition.
Any help is greatly appreciated.
My car suffers from a problem which has symptoms which seem very much like the ECU is resetting itself everytime the car is switched off.
I was using the multimeter to check that the various voltages and resistances on the ECU multiplug were correct. In particular, I was looking to see if the permanent live feed was present to the ECU.
To try to explain further, the symptoms of the problem are that the car runs roughly when cold. If the car is left to run until warm, the engine performs a short routine of a) revs dropping to around 200rpm, then b) very rough running at around 800rpm for 15-ish seconds, then c) engine revs to about 1800rpm for 5 seconds before settling to a normal idle. After this has happened the car runs perfectly until it is switched off.
The car will only perform this routine if the temperature is between about 60 and 75 degrees while the car is stationary.
I borrowed an ECU from another car for a week, but this had no effect on the problem. The car has also had new lambda sensors and airflow meter. The people trying to fix the car are at their wits end, so I was just trying to do some independent research.
I had seen mentioned in various threads that the ECU does some kind of adaptive fuelling, but did not know how this works. It just seems to me that this information may be lost from the ECU eveytime I turn off the ignition.
Any help is greatly appreciated.
quote:
Ok, time to go back to basics.
Have you had your battery load tested? Has it been replaced ?
Yes.
The car has actually spent around 2 weeks in the local specialist and has them stumped.
I know that the real answer is to let somebody else have a look at it, but finding the time to take it to somewhere 40+ miles away is difficult at the moment. I'm in the process of selling/buying houses at the moment so people at work have already almost forgotten who I am.
quote:
Sorry, bad explaination. I'll try again.
My car suffers from a problem which has symptoms which seem very much like the ECU is resetting itself everytime the car is switched off.
I was using the multimeter to check that the various voltages and resistances on the ECU multiplug were correct. In particular, I was looking to see if the permanent live feed was present to the ECU.
To try to explain further, the symptoms of the problem are that the car runs roughly when cold. If the car is left to run until warm, the engine performs a short routine of a) revs dropping to around 200rpm, then b) very rough running at around 800rpm for 15-ish seconds, then c) engine revs to about 1800rpm for 5 seconds before settling to a normal idle. After this has happened the car runs perfectly until it is switched off.
The car will only perform this routine if the temperature is between about 60 and 75 degrees while the car is stationary.
I borrowed an ECU from another car for a week, but this had no effect on the problem. The car has also had new lambda sensors and airflow meter. The people trying to fix the car are at their wits end, so I was just trying to do some independent research.
I had seen mentioned in various threads that the ECU does some kind of adaptive fuelling, but did not know how this works. It just seems to me that this information may be lost from the ECU eveytime I turn off the ignition.
Any help is greatly appreciated.
That is not the ECU resetiing itself. The default settings should not cause any real fault with the engine running. It doesn't go into anything other than normal operation but without tweeking. The adaption happens when the car is idling and when the water temp is around 90 degrees.
Changes in idle speed are often related to the stepper motor (it has been cleaned hasn't it!) and even the temp sensor. These can fail but do not necessarily show up any fault code. Some advocate changing the temp sensor with any injection problem.
Also what type of multimeter as in my experience the only real thing they can be used for is continuity and testing temp sensors as thye do not show any electrical noise that can cause problems. Electrical noise on the throttle pot can throw the ECU out but unless you have an oscilloscope you will not see the fault with a meter.
It could also be a combination of problems that combine. Nothing serious on their own but can come together. Took a rolling road session to find these out on my Griff.
Steve
>> Edited by shpub on Thursday 1st August 07:41
The coolant temperature sensor hasn't been changed to the best of my knowledge. I'll make that next on the list.
I'm pretty sure the stepper motor is OK, since after the car has performed it's little routine, it runs perfectly. Also, apart from when the car is going through its 30 second routine I never have any idle speed problems. However, I'll get the garage to have a look at that too.
As for the throttle pot, I was told that they had tried a new throttle pot on the car to no avail last time it was in the garage.
I use the car as my daily transport and the problem is so repeatable that I now have places on all of my regular journeys where I can pull over to let it 'cure' itself.
As for the multimeter - I was using it to check for sensible resistances and voltages from the various sensors. I know that noise can also cause problems, but I was just doing some low level diagnostics.
I'm pretty sure the stepper motor is OK, since after the car has performed it's little routine, it runs perfectly. Also, apart from when the car is going through its 30 second routine I never have any idle speed problems. However, I'll get the garage to have a look at that too.
As for the throttle pot, I was told that they had tried a new throttle pot on the car to no avail last time it was in the garage.
I use the car as my daily transport and the problem is so repeatable that I now have places on all of my regular journeys where I can pull over to let it 'cure' itself.
As for the multimeter - I was using it to check for sensible resistances and voltages from the various sensors. I know that noise can also cause problems, but I was just doing some low level diagnostics.
I am always amazed by this ECU thing. Just had my battery out (yes, again - my fault this time - forgot to turn the radio off..!) and with this post in mind I had cause to look at the ECU. It didn't have any advice for me so I put it back on the passenger seat (it spends more time there than in the footwell!!!).
Anyway - my battery has been in and out many a time over the past few months. But each time the thing goes neatly back (with the requisite amount of swearing to ease it in) and the ECU is dutifully stuffed back in amongst the other assorted wiring. Never give it a second thought. Car always powers up, and runs like it would straight out the box. No coughing, burbling, funny revs, nothing. It hunts a little, but it is 9 years old! After its warmed through it idles so nicely that even the wife (who knows more about sewing machines than cars) feels compelled to comment.
I've had batteries out many cars in the past, and with the exception of a particularly nasty Rover 800, I've never had any symptoms or trouble of a 'resetting ECU'. Is my engine just perfectly in line with an ECU standard programming or, as I thought was the case, these things work fast, on line, and don't really posses a 'memory' as such?
Anyway - my battery has been in and out many a time over the past few months. But each time the thing goes neatly back (with the requisite amount of swearing to ease it in) and the ECU is dutifully stuffed back in amongst the other assorted wiring. Never give it a second thought. Car always powers up, and runs like it would straight out the box. No coughing, burbling, funny revs, nothing. It hunts a little, but it is 9 years old! After its warmed through it idles so nicely that even the wife (who knows more about sewing machines than cars) feels compelled to comment.
I've had batteries out many cars in the past, and with the exception of a particularly nasty Rover 800, I've never had any symptoms or trouble of a 'resetting ECU'. Is my engine just perfectly in line with an ECU standard programming or, as I thought was the case, these things work fast, on line, and don't really posses a 'memory' as such?
The resetting really only comes into play where there is a fault elsewhere in the system and this has caused the ECU to get its knickers in a twist. Disconnecting the ECU will reset it and can cure (on a tempororary basis) many a strange fault. With normal cars it does as you say make little or no difference.
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
Can anybody explain the :
that I've seen in a few other threads. It would appear that this does something, but I'm not sure exactly what.
I still can't get my head around the fact that the engine will run perfectly after it has done whatever it does to reset (best word I can think of at the moment) itself. This suggests to me that there is nothing physically 'wrong' with the engine, but something awry with the control of the engine.
Can anybody suggest a garage North of Birmingham who might be able to help me with this? I'm having no joy with my current place and they have stopped returning my calls now!
- 'start the engine and leave it until the fans come on'
that I've seen in a few other threads. It would appear that this does something, but I'm not sure exactly what.
I still can't get my head around the fact that the engine will run perfectly after it has done whatever it does to reset (best word I can think of at the moment) itself. This suggests to me that there is nothing physically 'wrong' with the engine, but something awry with the control of the engine.
Can anybody suggest a garage North of Birmingham who might be able to help me with this? I'm having no joy with my current place and they have stopped returning my calls now!
Bizarre. Sounds like a case of crap data in, crap data out. Given that it happens as the engine is coming up to temp, it sounds sensible to replace the coolant temp sensor ... cheap part too.
What kind of diagnostic equipment is available? Is there such a thing as an "ECU emulator" in the same way that you can buy microcontroller emulators? I'd assume it would be an important bit of kit to have when chipping a car.
What kind of diagnostic equipment is available? Is there such a thing as an "ECU emulator" in the same way that you can buy microcontroller emulators? I'd assume it would be an important bit of kit to have when chipping a car.
It means that the engine starts gets warm and at some point the fans come on. Normal state of affairs.
Call Mark Adams and arrange a rolling road session where he can duplicate the effect and see what is happening. May cost a couple of hundred but that will be cheaper than the replacing the fuel injection by stealth that you are on at the moment. His number is in the archives and in Sprint.
Call Mark Adams and arrange a rolling road session where he can duplicate the effect and see what is happening. May cost a couple of hundred but that will be cheaper than the replacing the fuel injection by stealth that you are on at the moment. His number is in the archives and in Sprint.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff