well, I've been trying to track down this damned misfire. I was testing all the coil packs resistance and voltage. The TSRM calls for .3-.5 ohms resistance for each coil pack and mine ended up being .9 ohms on each pack. Is this causing some problems?
resistance on coil packs
- Thread starter TurboSupra7
- Start date
i don't know if that much makes a difference. it could be just the difference in calibration of the ohm meter you're using :dunno:
i need to check mine again too. i may have an ignition issue. my rpm data is very jagged, on my wideband logs, when i get into wot.
i need to check mine again too. i may have an ignition issue. my rpm data is very jagged, on my wideband logs, when i get into wot.
Pretty tough to check low ohms with the typical DMM. Use the delta function if you meter has one to zero out the test lead resistance or short them together and factor it into your mesaurement. Check your plug wires too.
Misfire can be caused by other things than ignition. That said, there is nothing like looking at a secondary ignition waveform on a scope to help with this kind of thing. You might want to buy a cheap one on ebay. Same with a four gas analyzer. Nothing beats having the right tools and knowing how to use them when messing around with cars
Misfire can be caused by other things than ignition. That said, there is nothing like looking at a secondary ignition waveform on a scope to help with this kind of thing. You might want to buy a cheap one on ebay. Same with a four gas analyzer. Nothing beats having the right tools and knowing how to use them when messing around with cars
well, it is a cheap meter that i'm using, but I've used it to test other things and it's proved to be a pretty accurate meter.
JetJock: I'm not sure I understand what you mean by shorting them together and factoring that into my measurement.
I'm pretty new to electrical stuff, could you maybe go into a bit more detail about this secondary ignition waveform deal? Thanks for the help!
JetJock: I'm not sure I understand what you mean by shorting them together and factoring that into my measurement.
I'm pretty new to electrical stuff, could you maybe go into a bit more detail about this secondary ignition waveform deal? Thanks for the help!
i was having an issue with one of my cylinders missing, but was all the time, so was easy to check, started pulling off plug wires, started with #1 listening for the change...well it didn't change when i pulled that off, so checked #2 just to be sure and just about killed the engine. So then i grabed another plug to make sure i was getting good spark, and i was, so didn't think it was that, so next i checked the injector connection, as soon as i touched it engine smoothed out...was as simple as that, the wires inside of the connector had worked loose some how and just needed to be pushed back down...
just offering something else for ya to think about
just offering something else for ya to think about
Your meter leads have resisitance of their own so short them together before you take a mesaurement and then factor that reading into what you get whenever you measure something with very low ohms. It's a good habit to get into anyway as it tests your leads and meter before beginning any work. Chasing an open circuit that turns out to be a bad meter lead just once will teach you the value of this habit
Ignition waveforms display the primary or secondary (high voltage) circuit. They're a visual window on what the electricitiy in your ignition system is doing. The interpertaion of them is part art and part science but it can be learned with a bit of study. You can tell a great deal, everything from bad plugs, wires, coils, primary circuits (the CPS), even the mixture in individual cylinders. Older ignition scopes can be found on ebay. Try to find one that does DIS as that's what the Supra has but you can also get by with a non-DIS version. Most will also do the kind of cylinder balance testing Draken is talking about but in a much nicer way.
A scope (igniton or otherwise) may seem like a luxury but good tools and the knowledge to use them are an investment in your future if you're going to mess with cars. It's amusing how some guys will spend thousands on the latest bling and performance goodies yet ignore tools and diagnostic gear. For example you should spring for a good meter as it's one of the most useful tools you can own. When it comes to cars these days I'll quote Doc Brown in Back To The Future: "This sucker's electrical!"
Good tools make life so much easier when trying to track down this kind of stuff. Frankly, it's a pity the MKIII isn't OBD-II. It'd also make life much easier.
Ignition waveforms display the primary or secondary (high voltage) circuit. They're a visual window on what the electricitiy in your ignition system is doing. The interpertaion of them is part art and part science but it can be learned with a bit of study. You can tell a great deal, everything from bad plugs, wires, coils, primary circuits (the CPS), even the mixture in individual cylinders. Older ignition scopes can be found on ebay. Try to find one that does DIS as that's what the Supra has but you can also get by with a non-DIS version. Most will also do the kind of cylinder balance testing Draken is talking about but in a much nicer way.
A scope (igniton or otherwise) may seem like a luxury but good tools and the knowledge to use them are an investment in your future if you're going to mess with cars. It's amusing how some guys will spend thousands on the latest bling and performance goodies yet ignore tools and diagnostic gear. For example you should spring for a good meter as it's one of the most useful tools you can own. When it comes to cars these days I'll quote Doc Brown in Back To The Future: "This sucker's electrical!"
Good tools make life so much easier when trying to track down this kind of stuff. Frankly, it's a pity the MKIII isn't OBD-II. It'd also make life much easier.
jetjock - you've always got good info
that's something I need to look into also.
THE SCOOP ON SCOPES - http://www.aa1car.com/library/us296.htm
that's something I need to look into also.
THE SCOOP ON SCOPES - http://www.aa1car.com/library/us296.htm
I have a little older Fluke 76 meter that has a 40 ohm scale and delta feature, it is very accurate for coils. It has a .01 ohm resolution.
A standard el chepo meter has a .1 ohm resolution, and a stated basic accuracy plus X digits. Usually it is 1 up to 7 digits on most meters.
That means if you try to measure .1 ohm on the 200 or 400 ohm scale of a cheap meter, it could display anything from 0 ohms to .8 ohms. I sold test equipment for a while so I just thought I would share.
If you are looking into a o-scope, get analog. You can find a basic one for under $400. You might be tempted to get digital, but trust me, to get a digital that will display the waveform as fast as a analog you are going to have to spend several thousand dollars. We sold several low priced digital scopes and they were fairly useless for this type of testing.
A standard el chepo meter has a .1 ohm resolution, and a stated basic accuracy plus X digits. Usually it is 1 up to 7 digits on most meters.
That means if you try to measure .1 ohm on the 200 or 400 ohm scale of a cheap meter, it could display anything from 0 ohms to .8 ohms. I sold test equipment for a while so I just thought I would share.
If you are looking into a o-scope, get analog. You can find a basic one for under $400. You might be tempted to get digital, but trust me, to get a digital that will display the waveform as fast as a analog you are going to have to spend several thousand dollars. We sold several low priced digital scopes and they were fairly useless for this type of testing.
Pretty tough to beat Fluke gear. It's all I've ever used. I currently have two Model 89s since I do other types of electronics but all the better if you can snagged one made for automotive use. The model 88 comes to mind.
A bit more about scopes. One thing about the computer revolution is it's made formerly expensive gear "obsolete". You can get good deals on these things if you know what you're looking for. They're gonna be bigger than todays handheld stuff but also a lot cheaper. You don't need too fancy. After all, you're not running a shop or doing this stuff every day so investing too much is crazy. On the other hand, you can't do serious car work with tools from Ace Hardware and Radio Shack. Anytime you feel you're spending too much money for tools or too much time learning I suggest you review shop rates. Doing your own not only saves you big money but you also get to take the knowledge all the way to the grave.
Understand I'm not talking about the old engine anaylzers, the so called "big box" units. Yeah, they work well and you can get them for peanuts these days but the things are huge and can be fussy. Pass them by and look for something smaller, something 10 years old or so. The Snap On MT1665 is a good example and all the better if you can get the DIS attachment with it. I see them on ebay all the time. That said, interperting igniton waveforms requires a bit of study and thought.
Be sure to research what you're buying and understand that, as with all test equipment, owning it is worthless until you know how to use it. This goes double for things like scopes and gas anaylzers. Even a DMM has more uses then what many people realize so get yourself one of the many book on the subject or search the Net. A PowerProbe or Powerprobe II is also a nice item to have when dealing with body electrical issues.
I agree ignition scopes should be analog but for other car work (like what isnms was alluding to) I feel a DSO is the only way to go. The DSO's ability to capture waveforms makes it very valuable when chasing sensor, injection, ignition primary, or any kind of intermittent circuit problem. You can make do with an analog scope in these cases but you'll give up some capabilities. Of course, if you spend more you can get a scope to do both jobs or even a box that can turn your laptop into one.
Lastly, none of this stuff is useful if you don't fathom what you're working on. The TCCS has it's roots (as do all electronic engine management systems) in the Bosch D and L Jetronic systems of old. Bosch pioneered the technology so those systems are a good place to start understanding the finer points of EFI. There is lots of info out there about them.
A bit more about scopes. One thing about the computer revolution is it's made formerly expensive gear "obsolete". You can get good deals on these things if you know what you're looking for. They're gonna be bigger than todays handheld stuff but also a lot cheaper. You don't need too fancy. After all, you're not running a shop or doing this stuff every day so investing too much is crazy. On the other hand, you can't do serious car work with tools from Ace Hardware and Radio Shack. Anytime you feel you're spending too much money for tools or too much time learning I suggest you review shop rates. Doing your own not only saves you big money but you also get to take the knowledge all the way to the grave.
Understand I'm not talking about the old engine anaylzers, the so called "big box" units. Yeah, they work well and you can get them for peanuts these days but the things are huge and can be fussy. Pass them by and look for something smaller, something 10 years old or so. The Snap On MT1665 is a good example and all the better if you can get the DIS attachment with it. I see them on ebay all the time. That said, interperting igniton waveforms requires a bit of study and thought.
Be sure to research what you're buying and understand that, as with all test equipment, owning it is worthless until you know how to use it. This goes double for things like scopes and gas anaylzers. Even a DMM has more uses then what many people realize so get yourself one of the many book on the subject or search the Net. A PowerProbe or Powerprobe II is also a nice item to have when dealing with body electrical issues.
I agree ignition scopes should be analog but for other car work (like what isnms was alluding to) I feel a DSO is the only way to go. The DSO's ability to capture waveforms makes it very valuable when chasing sensor, injection, ignition primary, or any kind of intermittent circuit problem. You can make do with an analog scope in these cases but you'll give up some capabilities. Of course, if you spend more you can get a scope to do both jobs or even a box that can turn your laptop into one.
Lastly, none of this stuff is useful if you don't fathom what you're working on. The TCCS has it's roots (as do all electronic engine management systems) in the Bosch D and L Jetronic systems of old. Bosch pioneered the technology so those systems are a good place to start understanding the finer points of EFI. There is lots of info out there about them.
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