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In reviewing and researching the information I'm getting from the live data on my OBD2 I think I may have a vacuum leak somewhere on Bank 2.
The upstream O2 sensor is giving me readings of -111 to +126 mA. The Bank 2 readings are between -.54 to +.15 mA.
The downstream sensors are reading between .14 V and .63 V (Bank 1) and .335 V and .74 V (Bank 2). From my research these readings indicate functioning Catalytic converters.
Both LTFT levels are -2.3% which, from what I'm reading is withing the normal levels.
The STFT at the downstream sensors are steady at -1.6% (Bank 1) and -.8% (Bank 2). The upstream sensors fluctuate between -1.6% and -.8% (Bank 1) and 2.3% and 4.7% (Bank 2). My understanding is these should be between -10% and -10% for normal ranges.
I should have mentioned in the above post I am not getting any codes indicating anything is wrong with the sensors, converters or injectors.
That might be due to unset (aka incomplete aka not ready) monitors. Each unset one means a lot of codes can't flag (because the car does not know enough to figure what to flag).
See, this gets me back my comment above about what I guess is the terminology being used. To me a "monitor", in the context of a system like an engine, is a device that measures the input or output of components and tells you what is going on with those components. I think of them like the alarm on my iPhone. When I set the alarm it keeps track of the time the phone is telling the alarm it is. When a particular level is reached, the time the alarm is set for, the alarm tell me it's been reached by playing a lovely tune. If I want it to "monitor" the time of day again I have to reset it. To do this I simply go to the monitor, the alarm, and turn it back on. I don't have to hold the phone level with the floor, move it clockwise 3.6 times, set it on a table for 24 seconds for it to reset.
The O2 sensors on the car are supposed to be telling me (and the car's computer) what the levels of oxygen are coming out of the engine and coming out of the catalytic converter. (I know they are not actually measuring the "oxygen" levels but their effect of the electrical current in the sensors). Supposedly, when this information reaches a certain point the car (the car's computer) tells me there is a problem by sending a code to another computer (the OBD2) that I plug into the car's brain (the OBD2 port). So, my question is if that's the case what is this magical "monitor" that is referred to? Where is it located and what information is it "monitoring"? How is it's operation different from that of the combination of O2 sensors and the ECM? And, if it somehow is performing the same function as the O2 monitors are supposed to perform, why is it needed? And, most of all, why do I have to perform what appears to be some highly secretive procedure to get it to "reset"? A procedure for which there appears to be no less than 4 opinions as to the how it is to be done.
These are the kinds of things that drive old skool, really old skool, wrench turners like me absolutely crazy. I completely understand that it's a good idea for our cars not to throw out all kinds of thing that can make people sick, however, making a system to do that so complicated and convoluted makes no sense. If these "monitors" do what everyone is saying they are supposed to do, why can't I just do a hard reset and have them reset? After 25+ years of law enforcement and another 10 after that of dealing with criminal law I like to think I have a pretty logical mind. This whole "monitor" thing is in no way logical. To me it sounds like it was specifically put there to cause consumers to spend more money to have their cars fixed. Now, whether it was put in the car because of some government's order, or by the car companies, I don't know. All I know is the measurements that I am getting from the above live data seems to be telling me that my catalytic converter is ok, but this CAT monitor, where ever it is located in the car, is not going to "reset" until I do some special dance of speed, acceleration, deceleration and time. GRRRRRRRRRRRRRRRRRRRR!!!!!
See, this gets me back my comment above about what I guess is the terminology being used. To me a "monitor", in the context of a system like an engine, is a device that measures the input or output of components and tells you what is going on with those components. I think of them like the alarm on my iPhone. When I set the alarm it keeps track of the time the phone is telling the alarm it is. When a particular level is reached, the time the alarm is set for, the alarm tell me it's been reached by playing a lovely tune. If I want it to "monitor" the time of day again I have to reset it. To do this I simply go to the monitor, the alarm, and turn it back on. I don't have to hold the phone level with the floor, move it clockwise 3.6 times, set it on a table for 24 seconds for it to reset.
The O2 sensors on the car are supposed to be telling me (and the car's computer) what the levels of oxygen are coming out of the engine and coming out of the catalytic converter. (I know they are not actually measuring the "oxygen" levels but their effect of the electrical current in the sensors). Supposedly, when this information reaches a certain point the car (the car's computer) tells me there is a problem by sending a code to another computer (the OBD2) that I plug into the car's brain (the OBD2 port). So, my question is if that's the case what is this magical "monitor" that is referred to? Where is it located and what information is it "monitoring"? How is it's operation different from that of the combination of O2 sensors and the ECM? And, if it somehow is performing the same function as the O2 monitors are supposed to perform, why is it needed? And, most of all, why do I have to perform what appears to be some highly secretive procedure to get it to "reset"? A procedure for which there appears to be no less than 4 opinions as to the how it is to be done.
These are the kinds of things that drive old skool, really old skool, wrench turners like me absolutely crazy. I completely understand that it's a good idea for our cars not to throw out all kinds of thing that can make people sick, however, making a system to do that so complicated and convoluted makes no sense. If these "monitors" do what everyone is saying they are supposed to do, why can't I just do a hard reset and have them reset? After 25+ years of law enforcement and another 10 after that of dealing with criminal law I like to think I have a pretty logical mind. This whole "monitor" thing is in no way logical. To me it sounds like it was specifically put there to cause consumers to spend more money to have their cars fixed. Now, whether it was put in the car because of some government's order, or by the car companies, I don't know. All I know is the measurements that I am getting from the above live data seems to be telling me that my catalytic converter is ok, but this CAT monitor, where ever it is located in the car, is not going to "reset" until I do some special dance of speed, acceleration, deceleration and time. GRRRRRRRRRRRRRRRRRRRR!!!!!
The OBD II system is from your government. (The car makers mostly hated it.) My understanding is that OBD was put in place to reduce deaths due to pollution from cars.
It may be an unusual meaning of "monitor" but it is what they use.
Naturally it's from the government, who else would design something requiring such a complicated system that doesn't work but will cost lots of money.
Is there anyone out there who knows exactly what the CAT monitor does and how it does it? If it is actually "monitoring" if the catalytic converter is working how does it do that? If it is using the information from the O2 sensors why is it not resetting, since the data that I'm getting from the sensors is, I'm told, within the normal range. What it sounds like it is measuring is if the car has been driven at some randomly selected speed, for some randomly selected amount of time in order to "reset". If it is supposed to be "monitoring" the information coming from the catalytic converter why does it require me to drive through some series of made up engine speeds, for some made up periods of time to "reset". Shouldn't it just reset each time I start the car so it can then monitor what the converter is doing?
After speaking with a state certified smog station employee, and scheduling an appointment, he told me that the issue may be with the MAF sensor. Last month I had read something about that and purchased specific MAF cleaner and removed the MAF sensor and sprayed it clean. After reading here and on other forums that it may take a few cleanings to allow the MAF to read correctly I took it out and sprayed it a couple more times. There does not appear to be any contaminants on the sensor. I've been looking for information on what the MAF sensor readings should be and so far the only thread I found indicated what they should be at red line. I've not had my car to red line yet. However, when I did the live data I got the following readings for 700, 1500 and 2500 rpm respectively, .8 lb/min; 1.3 lb/min; 1.8-2.0 lb/min. The idle rate seems ok, but it is my understanding that the rates at 2,500 rpm should be 1.9-3.3 lb/min. Is my 1.8-2.0 sufficient?
I also used the flammable carb cleaner to check for vacuum leaks and couldn't find any. I sprayed starting at the air box, along the duct to the throttle body and didn't notice any increase in RPMs. I sprayed all the hoses I could find with the same result. All the hoses seemed very flexible and not dried out. Any other suggestions as to where to check for vacuum leaks?
Is there anyone out there who knows exactly what the CAT monitor does and how it does it? If it is actually "monitoring" if the catalytic converter is working how does it do that? If it is using the information from the O2 sensors why is it not resetting, since the data that I'm getting from the sensors is, I'm told, within the normal range. What it sounds like it is measuring is if the car has been driven at some randomly selected speed, for some randomly selected amount of time in order to "reset". If it is supposed to be "monitoring" the information coming from the catalytic converter why does it require me to drive through some series of made up engine speeds, for some made up periods of time to "reset". Shouldn't it just reset each time I start the car so it can then monitor what the converter is doing?
Instead of Cat Monitor, let's call it "Cat efficiency monitor" because that's more accurate. And we're only dealing with the downstream O2 sensor. The "monitor" is part of the programming of the ECU, the part that checks to see if the catalytic converter is "working" or not. It's not a separate device.
Let's not forget we're dealing with 25 year old technology and Jag's wasn't all that great to begin with. OK. The ECU (the computer) only knows whether or not there is a sensor connected to the end of the wire. It has no idea whether that sensor is attached to the end of a catalytic converter, or if it's just flapping in the breeze. How can it find out? It finds out when the cat temperature rises to a point where it causes the sensor to generate a specific range of voltage. But that process is not instantaneous. It takes some time for the cat to warm up. So, in layman's terms, the computer checks from time to time to see if the cat is hot. If it is, it runs it's little checks and "sets" the monitor. At that point the computer knows that the downstream sensor is plugged into a functioning cat. From that point on, until the codes are cleared, the monitor remains "set." And now the cat efficiency can be monitored.
If the cat never reaches the temperature that causes the correct voltage in the O2 sensor, the "monitor" will never set. It won't set because the computer thinks the cat is still warming up, or that it's absent altogether. If you have a bad cat, it will never "warm up" enough to cause the correct voltage in the downstream sensor. Faulty downstream sensors can also mimic this problem, that's why we replace downstream sensors first, as that's a more common failure than a failed cat.
All of these drive cycles are simply prescribed methods of bringing the cats up to temp and causing the computer to take a look, to oversimplify a bit. But if the cats are bad they won't come to a steady temp regardless of how far you drive.
Once the "monitor" is set, i.e. the computer is convinced that functional cats are, indeed, attached to the engine, then it monitors that same voltage of the downstream sensors. If that voltage drops too much, or there is too much variation, then the computer throws a 0420 code for cat efficiency. To state it another way, the computer needs a good baseline from which to begin its monitoring operations. The monitor "setting" is the computer establishing its baseline. It now has "known good" cats and we can continuously monitor them to see if they go bad or fail, i.e. become inefficient.
After speaking with a state certified smog station employee, and scheduling an appointment, he told me that the issue may be with the MAF sensor. Last month I had read something about that and purchased specific MAF cleaner and removed the MAF sensor and sprayed it clean. After reading here and on other forums that it may take a few cleanings to allow the MAF to read correctly I took it out and sprayed it a couple more times. There does not appear to be any contaminants on the sensor.
The hot wire in the MAFS is down inside the plastic case and not readily visible. What you are probably looking at that appears clean is the Intake Air Temperature Sensor thermistor, which is a small bulb-shaped component. It is very easy to clean the IATS thermistor. It is not nearly as easy to clean the hot wire. I do the best I can by filling the housing with CRC Mass Air Flow Sensor spray cleaner, agitating the sensor housing for a few minutes, dumping out the fluid, then repeating two or three times. This will sometimes improve sensor performance, but not always. Sometimes a new Denso MAFS is the only solution. I have not had any luck with other brands.
Originally Posted by OCJoeR
I also used the flammable carb cleaner to check for vacuum leaks and couldn't find any. I sprayed starting at the air box, along the duct to the throttle body and didn't notice any increase in RPMs. I sprayed all the hoses I could find with the same result. All the hoses seemed very flexible and not dried out. Any other suggestions as to where to check for vacuum leaks?
Instead of Cat Monitor, let's call it "Cat efficiency monitor" because that's more accurate. And we're only dealing with the downstream O2 sensor. The "monitor" is part of the programming of the ECU, the part that checks to see if the catalytic converter is "working" or not. It's not a separate device.
Let's not forget we're dealing with 25 year old technology and Jag's wasn't all that great to begin with. OK. The ECU (the computer) only knows whether or not there is a sensor connected to the end of the wire. It has no idea whether that sensor is attached to the end of a catalytic converter, or if it's just flapping in the breeze. How can it find out? It finds out when the cat temperature rises to a point where it causes the sensor to generate a specific range of voltage. So the readings I'm getting, between .12 and .63 (at idle) on Bank 1 and .2 and .75 (at idle) on Bank 2 tell me what? But that process is not instantaneous. It takes some time for the cat to warm up. So, in layman's terms, the computer checks from time to time to see if the cat is hot. If it is, it runs it's little checks and "sets" the monitor. At that point the computer knows that the downstream sensor is plugged into a functioning cat. From that point on, until the codes are cleared, the monitor remains "set." And now the cat efficiency can be monitored. If my OBD2 is giving me voltage of a high enough range does that mean those same numbers are going to the ECU? If so that should mean the cats are working, yes?
If the cat never reaches the temperature that causes the correct voltage in the O2 sensor, the "monitor" will never set. It won't set because the computer thinks the cat is still warming up, or that it's absent altogether. If you have a bad cat, it will never "warm up" enough to cause the correct voltage in the downstream sensor. From everything I've read/watched it's looking for around .45 V, mine are showing that (although fluctuating) on both O2 sensors Faulty downstream sensors Mine are both new can also mimic this problem, that's why we replace downstream sensors first, as that's a more common failure than a failed cat.
All of these drive cycles are simply prescribed methods of bringing the cats up to temp and causing the computer to take a look, to oversimplify a bit. But if the cats are bad they won't come to a steady temp regardless of how far you drive.
Once the "monitor" is set, i.e. the computer is convinced that functional cats are, indeed, attached to the engine, then it monitors that same voltage of the downstream sensors. If that voltage drops too much, or there is too much variation, then the computer throws a 0420 code for cat efficiency. Mine is not giving me any codes, does this mean the cats are ok? To state it another way, the computer needs a good baseline from which to begin its monitoring operations. The monitor "setting" is the computer establishing its baseline. It now has "known good" cats and we can continuously monitor them to see if they go bad or fail, i.e. become inefficient.
I am going to go for a long drive today since there are no 2 year olds to chase around the house and as far as I know nothing else to stop me. Hopefully that "warms up" the cats enough to do something.
The hot wire in the MAFS is down inside the plastic case and not readily visible. What you are probably looking at that appears clean is the Intake Air Temperature Sensor thermistor, which is a small bulb-shaped component. It is very easy to clean the IATS thermistor. It is not nearly as easy to clean the hot wire. I do the best I can by filling the housing with CRC Mass Air Flow Sensor spray cleaner, agitating the sensor housing for a few minutes, dumping out the fluid, then repeating two or three times. This will sometimes improve sensor performance, but not always. Sometimes a new Denso MAFS is the only solution. I have not had any luck with other brands.
Hey Don,
This is what I'm seeing in the MAF and what I've been spraying with the CRC stuff.
The first picture then is the Air Temp Sensor you mentioned, correct? Is the second and third photo the actual wires you're referring to? I'm going to go pull it again and spray the way you suggest and see what I get. Do the numbers I'm getting for the MAF air flow rate at the different engine speeds look ok? I'm getting .8 lbs/min at idle; 1.3-1.4 lbs/min at 1,500 rpm and 1.9-2.1 at 2,500 rpm.
That's why I need a 12 year old to hack into the system
The processor used in the ECM was introduced back in the early 90s, so you probably need a 62 year old who can remember working on them when they were fresh out of university.
The processor used in the ECM was introduced back in the early 90s, so you probably need a 62 year old who can remember working on them when they were fresh out of university.
Well this 77 year old has no idea what this thing is doing so I keep posting and trying different things. I swear my next car is going to be one built withing 10 years of when I was!!!
Just got back from driving it around on the freeway and city streets for as close to the "drive cycles" as I could. Evap, CAT and Component monitors still read INC. This was the first time driving since I cleared the TCM codes so maybe I need a second set of drive cycles. Maybe I can do that later today.
I ran the live data (at idle) when I got back and got the following:
Just got back from driving it around on the freeway and city streets for as close to the "drive cycles" as I could. Evap, CAT and Component monitors still read INC. This was the first time driving since I cleared the TCM codes so maybe I need a second set of drive cycles. Maybe I can do that later today.
I ran the live data (at idle) when I got back and got the following:
I think I see the issue. Look at the downstream bank 2 monitor voltages. Bank 1, at 0.675 in both columns appears to be rock solid and textbook. Bank 2's voltages are through the floor. 0.2 volts isn't nearly high enough.
I'm not sure why those numbers were low this time. If you look at Post #71 the figures were substantially higher, .20 - .755 at idle. I know when I ran those numbers I ran each set for 60 seconds each so I got more data. The one just above I only ran it for about 15 seconds. I'll run them again if I get a chance.
It's going into a Star Certified Smog Repair station tomorrow morning that has 4 and 5 star reviews. I spoke to the guy yesterday and gave him all the info I had on the live data and the drive cycles that I completed. I also told him I had changed out the downstream O2 sensors so he at least knows that I'm conversant in the car's systems. I'm just too old and ornery to deal with this any more. If he comes back with the same plan I'm just going to scrap the car. I'm not going to put thousands of dollars into changing out one or both of the cats. I don't even know where I'd find them. I've been searching and can only find Non-C.A.R.B. compliant ones. I doubt they even make them any more. And to buy a "universal" C.A.R.B. compliant cat and then take the old one apart and weld the front flange and rear pipe to the universal one is going to cost a small fortune. If I was still working in the hot rod shop and had access to the lift and welding equipment I'd do it myself. But my garage is not where I want to do this.
Oh yeah, one other thing I forgot to post in the above post. One of the methods of resetting the monitors (at this point I forget which one or where it came from) was to leave the car in park and rev the engine to 2,500 rpm for 3 minutes. In the middle of that I got the dash message about power reduction and the orange light came on. I went down to idle and the light went off and message went away. Then when I was doing one of the drive cycles requiring to keep the car at about 55 mph and the revs around 2,500 I had the car in 3rd gear and was at 3,000 rpm and the power reduction light came on again. As soon as I lifted off the gas it went away. It did it again when I was on city streets trying to do 35 mph and 1,700 to 2,500 rpm in, I believe 2nd gear (could have been 3rd). Again once I lifted of the gas it went away.
Oh yeah, one other thing I forgot to post in the above post. One of the methods of resetting the monitors (at this point I forget which one or where it came from) was to leave the car in park and rev the engine to 2,500 rpm for 3 minutes. In the middle of that I got the dash message about power reduction and the orange light came on. I went down to idle and the light went off and message went away. Then when I was doing one of the drive cycles requiring to keep the car at about 55 mph and the revs around 2,500 I had the car in 3rd gear and was at 3,000 rpm and the power reduction light came on again. As soon as I lifted off the gas it went away. It did it again when I was on city streets trying to do 35 mph and 1,700 to 2,500 rpm in, I believe 2nd gear (could have been 3rd). Again once I lifted of the gas it went away.
Have you scanned for codes since this happened? It may show some pending codes. Or it may not.
I note your LTFT numbers look kind of high. In addition to cat problems, mine putters along fine for a while, and then suddenly the thing goes crazy rich, the fuel trims shoot way negative, and I'll get a CEL and a brief restricted performance message. I'm with you about scrapping this thing.
