OBD2 data

turtlevette

turtlevette

The Turdle
Joined
Mar 24, 2008
Messages
1,492
Location
Marshfield, MA
My suburban check engine light came on the other day. I went to Autozone and got a reader to get the codes but it also gets real time data.

I have 0171, 0174 and 0300 codes

0171 bank1 lean
0174 bank2 lean
0300 random misfire

One of the oxygen sensors was stuck at .830 volts. They're supposed to fluctuate between .1 and .8 volts constantly. I did go for a drive this afternoon and the sensor that was "stuck" started working normally. I'll check again in the morning to see if its acting up again.

The codes suggest a vacuum leak but the MAP was steady at 10.6 and i sprayed lubricant all around the manifold with no change in rpm.

Long term fuel trim was +7% on both banks. So whatever is happening is a balanced condition.

I'd like to get a OBD2 to USB cable and gather data on a laptop using one of the many softwares available.

Has anyone else played around with this?
 
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PM Doug Mariani. He does this crap all the time, and excells at it.:devil:
 
aldlcable.com and download tts datamaster, make sure you dowload the correct one for your car. It is by far the best software out there.

Since both your banks show lean, clamp off the air feed to the manifolds w/ some vice grips and see what that does
 
The zone has the actron scanner reader. Is that the one that you have? They have the PC download software. I believe it is 50MB and doesn't work with windows 7(if I remember correctly). You can also see real time data in a graph on the unit.

I can only get about 8 or 10 PID's from my ECU for real time data which includes the O2 sensors before and after the cats. The ones before fluctuate as your's do while the the computer adjusts for the ideal mixture. The ones after have a steady reading.

The one PID that I am trying to figure out is the timing.......it fluctuates at idle quite a bit...probably adjusting for best burn of the mixture along with the O2 readings. At cruise, it is steady with a healthy advance reading. I get a little stumble at idle and I am trying to figure out if it is timing related or mixture related.....So far, I have the scanner info, just not the intelligence to figure it all out:confused2:
 
SmokinBBC said:
The zone has the actron scanner reader. Is that the one that you have? They have the PC download software. I believe it is 50MB and doesn't work with windows 7(if I remember correctly). You can also see real time data in a graph on the unit.

I can only get about 8 or 10 PID's from my ECU for real time data which includes the O2 sensors before and after the cats. The ones before fluctuate as your's do while the the computer adjusts for the ideal mixture. The ones after have a steady reading.

The one PID that I am trying to figure out is the timing.......it fluctuates at idle quite a bit...probably adjusting for best burn of the mixture along with the O2 readings. At cruise, it is steady with a healthy advance reading. I get a little stumble at idle and I am trying to figure out if it is timing related or mixture related.....So far, I have the scanner info, just not the intelligence to figure it all out:confused2:
Click to expand...

I have the actron cp9575. My 02 suburban gives about 20 points. The oxygen sensors after the cats fluctuate so i'm worried they're shot. My idle timing is all over the place too. I think that's the way the computer fires it.

I was getting a steady rich reading out of one of the pre cat oxy sensors but after driving for a while it got hot enough? to work correctly. They say oxygen sensors should be replaced after 100k miles anyway and mine is at 90k. I've seen some crap that you put in your gas that's supposed to clean out the cats. Might give that a try.

I'm also going to clean the MAF sensor, change the plugs and wires. The check engine light nanny makes you do maintenance which is something i'm not used to doing.
 
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turtlevette said:
The check engine light nanny makes you do maintenance which is something i'm not used to doing.
Click to expand...

I've seen guys put a little black tape over the light, take out the bulb or even cut the wire. Makes that CE light nanny graveyard dead.
 
TimAT said:
turtlevette said:
The check engine light nanny makes you do maintenance which is something i'm not used to doing.
Click to expand...

I've seen guys put a little black tape over the light, take out the bulb or even cut the wire. Makes that CE light nanny graveyard dead.
Click to expand...

That ain't gonna work. At inspection tech plugs in scanner and it says light is supposed to be on provides codes and lets him know if the system is ready ie, has been driven long enough for the computer to determine everything is OK.

So disconnecting the battery right before inspection or cutting the wire to the light ain't gonna fool anyone.
 
THIS is a prime example of why I have a '72 vette, modified and antique tagged....hell with the .gov forever.....

Simply said, there is almost no reasonable, quick SOLVENT way to fix modern cars on this off the wall shit.....

best of luck, you going to need it...and I curious to what you find....

:surrender:
 
turtlevette said:
SmokinBBC said:
The zone has the actron scanner reader. Is that the one that you have? They have the PC download software. I believe it is 50MB and doesn't work with windows 7(if I remember correctly). You can also see real time data in a graph on the unit.

I can only get about 8 or 10 PID's from my ECU for real time data which includes the O2 sensors before and after the cats. The ones before fluctuate as your's do while the the computer adjusts for the ideal mixture. The ones after have a steady reading.

The one PID that I am trying to figure out is the timing.......it fluctuates at idle quite a bit...probably adjusting for best burn of the mixture along with the O2 readings. At cruise, it is steady with a healthy advance reading. I get a little stumble at idle and I am trying to figure out if it is timing related or mixture related.....So far, I have the scanner info, just not the intelligence to figure it all out:confused2:
Click to expand...

I have the actron cp9575. My 02 suburban gives about 20 points. The oxygen sensors after the cats fluctuate so i'm worried they're shot. My idle timing is all over the place too. I think that's the way the computer fires it.

I was getting a steady rich reading out of one of the pre cat oxy sensors but after driving for a while it got hot enough? to work correctly. They say oxygen sensors should be replaced after 100k miles anyway and mine is at 90k. I've seen some crap that you put in your gas that's supposed to clean out the cats. Might give that a try.

I'm also going to clean the MAF sensor, change the plugs and wires. The check engine light nanny makes you do maintenance which is something i'm not used to doing.
Click to expand...


I think the system operates in open loop mode until they reach about 600 degrees f.

Ford says mine should be replaced at 100k. I have 154k on them. The dealer tech said no need to replace them unless out of whack(ie: they can last a long time). The exp. has the COP which are about 90 bucks each to replace. When I had a cylinder misfire code, I pulled that COP and tested it...it was out of range so I replaced it. Back to normal. I cleaned my MAF. with electric spray cleaner. I also pulled IAC to clean it and saw that it was COMPLETELY gummed up. Cleaned that up as well. Maybe run something like seafoam through the system....there might be a lot of build-up in there.
 
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I just downloaded EFIlive. All I need now is a cable. Looks to me like it'll work on just about any OBDII system. It'll even do injector balance rates and injector shutoff on my diesel..
 
turtlevette said:
sounds like a fuel pressure gauge is in my future.
Click to expand...

I have always used the LO side of my HVAC gauges...and never a issue for doing it, either....done it for years...and maybe 3 cheep hoses that dry out sometimes....

:thumbs:
 
turtlevette said:
My suburban check engine light came on the other day. I went to Autozone and got a reader to get the codes but it also gets real time data.

I have 0171, 0174 and 0300 codes

0171 bank1 lean
0174 bank2 lean
0300 random misfire

One of the oxygen sensors was stuck at .830 volts. They're supposed to fluctuate between .1 and .8 volts constantly. I did go for a drive this afternoon and the sensor that was "stuck" started working normally. I'll check again in the morning to see if its acting up again.

The codes suggest a vacuum leak but the MAP was steady at 10.6 and i sprayed lubricant all around the manifold with no change in rpm.

Long term fuel trim was +7% on both banks. So whatever is happening is a balanced condition.

I'd like to get a OBD2 to USB cable and gather data on a laptop using one of the many softwares available.

Has anyone else played around with this?
Click to expand...

You must address P0300 first. Then if you still have P0171 or P0174 you can address them.

The reason for this is the O2 sensor measures the amount of oxygen in the exhaust, but does not look at the amount of fuel. So if you have a misfire you have unburned fuel and oxygen in the exhaust, but the O2 sensor will only see a higher amount of oxygen and think that you are running lean when your really not.

So if you figure out and fix your misfire then your lean codes will probably go away.

Also how about some info on the Suburban. Like year, engine, miles...
 
Getting close to needing plugs at that mileage.

Can you see the misfire data? That will tell the whole story. Show what cylinders are missing and when.

I would check them out. Also check the intake for a vacuum leak. That is very common on those engines.

I would also pull the maff and see if it is dirty. If so clean it.
 
Fuelie74 said:
Getting close to needing plugs at that mileage.

Can you see the misfire data? That will tell the whole story. Show what cylinders are missing and when.

I would check them out. Also check the intake for a vacuum leak. That is very common on those engines.

I would also pull the maff and see if it is dirty. If so clean it.
Click to expand...

Yep, I'm planning to do all of the above. The misfire would read a 0301 for cylinder 1, 0302 for cylinder 2 etc. A 0300 is random and does not indicate any paticular cylinder.

I did spray the manifold with no change in engine rpm. The manifold pressure is steady at 10.6mm so i don't think its a vacuum leak.

I am starting to think it's the fuel pump or fuel filter. I'm going to take it out next time and accelerate hard and look at the short term and long term fuel trim. And also purchase a fuel pressure gauge. Will check the fuel pressure regulator for leakage.
 
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turtlevette said:
The misfire would read a 0301 for cylinder 1, 0302 for cylinder 2 etc. A 0300 is random and does not indicate any paticular cylinder.
Click to expand...

You are right in theory on this, but many times you will only get a P0300 code even if the problem is related to one cylinder. That is why a person needs to look at the misfire data not just look at the code. Trust me on this on, it's what I do for a living.
 
Fuelie74 said:
turtlevette said:
The misfire would read a 0301 for cylinder 1, 0302 for cylinder 2 etc. A 0300 is random and does not indicate any paticular cylinder.
Click to expand...

You are right in theory on this, but many times you will only get a P0300 code even if the problem is related to one cylinder. That is why a person needs to look at the misfire data not just look at the code. Trust me on this on, it's what I do for a living.
Click to expand...

The freeze data?

I'll have to wait until it sets the codes again. They were cleared when i changed the battery. Right now everything shows good and there are no pending codes.
 
turtlevette said:
Fuelie74 said:
turtlevette said:
The misfire would read a 0301 for cylinder 1, 0302 for cylinder 2 etc. A 0300 is random and does not indicate any paticular cylinder.
Click to expand...

You are right in theory on this, but many times you will only get a P0300 code even if the problem is related to one cylinder. That is why a person needs to look at the misfire data not just look at the code. Trust me on this on, it's what I do for a living.
Click to expand...

The freeze data?

I'll have to wait until it sets the codes again. They were cleared when i changed the battery. Right now everything shows good and there are no pending codes.
Click to expand...
No the freeze data is a snap shot of what is going on when the code sets. I would look at that if say it had a P0300, but wasn't missing. That would show me when it is happening. Like on cold start up, possibly pointing to a leaking injector.

The misfire data is live data showing the misfire count for each cylinder in real time. If you only have a code reader or possibly a lower end scan tool you will not be able to see it.

I would guess that you have felt it misfire if it has missed bad enough to set a code. If so when does it miss?

You may also be right on a low fuel pressure problem. Not because of the lean codes, but because the lean codes are showing up for both banks. Meaning that its not related to one bank and a fuel is your common point. I would check it with key on engine off, running, and while under load.
 
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