86 troubleshooting with datamaster
Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
86 troubleshooting with datamaster
I am new to using the scan functions, and after my first data collection on my 86 I'd like to ask a few questions. My car recently failed NYS emmision test, my CO was high( running rich). I adjusted my timing, checked my plugs. I added Seafoam to my gas. and after a few attempts to get my Datamaster & cable going I was able to collect about 20 mins of data.
after the PCM went into closed loop, the reading for the O2 volts is 71 which is lean, but will momentarily jump to 533 but go back to 70 or so.
does this sound like my car is actually running lean now or is this a false reading, making the PCM richen the mixture, giving me a failure on the emission test.
any ides would be appreciated,
Tom
after the PCM went into closed loop, the reading for the O2 volts is 71 which is lean, but will momentarily jump to 533 but go back to 70 or so.
does this sound like my car is actually running lean now or is this a false reading, making the PCM richen the mixture, giving me a failure on the emission test.
any ides would be appreciated,
Tom
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The O2 sensor voltage will change very quickly. It should fluctuate every fraction of a second. It ranges from .1-.9v with .45v being a perfect A/F ratio. .1v is on the lean side and .9v is on the rich side. What is the BLM?
Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
the L-term BLM is 150, the S - term is 128, which from the datamaster manual says that this is a lean condition. my readings were taken at idle 750 rpm in the shop, closed loop, temp - 215.2 deg.
one other item, i get a DTC 42 -EST monitor error( I do not have this error whe I am not connected to the scanner) I do not know if this is a result of the "10K mode" the 10k resistor across aldl connector A&B.
Thanks, Tom
one other item, i get a DTC 42 -EST monitor error( I do not have this error whe I am not connected to the scanner) I do not know if this is a result of the "10K mode" the 10k resistor across aldl connector A&B.
Thanks, Tom
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The long term is showing lean and the short term is right on the money as far as A/F ratio. Not sure about the EST code, but I don't get any codes when scanning.
Do you get it when the scanner is not connected?
Have you checked the EST connector between the brake booster and distrubitor?
I would check for vacuum leaks and check for air leaks (pre O2 sensor) around the left (driverside) exhaust manifold. This would be for starters, but need to rule things out.
EST connector
Do you get it when the scanner is not connected?
Have you checked the EST connector between the brake booster and distrubitor?
I would check for vacuum leaks and check for air leaks (pre O2 sensor) around the left (driverside) exhaust manifold. This would be for starters, but need to rule things out.
EST connector
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Your CO is high because it's too rich and that's shown by the BLM's you captured. Air is getting into the exhaust stream, the O2 reads that as lean, and the ECM fattens up the mix with a bunch of fuel it doesn't need. Check for vacuum, intake, and/or exhaust leaks and if you don't find any, clamp off the air pump hoses to the Headers and with your equipment hooked up, see if the BLM's drop (or you can do that first - it's a hell of lot easier than looking for the other stuff). Anyway, once you find and fix it, your BLM'S will be more tolerable (I don't like to see more than 122 to 132) and your CO will be 0.
Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
RRT, the EST connector is good, and I do not get the error 42 without the scanner hooked up.
as for my vacuum, it is rock steady and well within spec.
I will set up my laptop and try to clamp off the air hoses and see what I get, it's just been so damn cold out there!
what if my reading changes with the hoses clamped, what is that telling me?
Thanks,
Tom
as for my vacuum, it is rock steady and well within spec.
I will set up my laptop and try to clamp off the air hoses and see what I get, it's just been so damn cold out there!
what if my reading changes with the hoses clamped, what is that telling me?
Thanks,
Tom
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
By clamping or capping of the AIR ports to the exhaust manifolds your will not allow air/oxygen to enter the manifolds to help lite up the Cat...this is mainly at warm up. Once closed loop the diverters direct the air via the pipe to the Cat. If the AIR is not diverting the air/oxygen, it will continue to enter the exhaust manifolds after closed loop and the O2 sensors picks up a lot of oxygen that it shouldn't thus sending a false signal to the ECM and dumping more fuel.
http://forums.corvetteforum.com/show...&highlight=air
http://forums.corvetteforum.com/show...&highlight=air
Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
Your CO is high because it's too rich and that's shown by the BLM's you captured. Air is getting into the exhaust stream, the O2 reads that as lean, and the ECM fattens up the mix with a bunch of fuel it doesn't need. Check for vacuum, intake, and/or exhaust leaks and if you don't find any, clamp off the air pump hoses to the Headers and with your equipment hooked up, see if the BLM's drop (or you can do that first - it's a hell of lot easier than looking for the other stuff). Anyway, once you find and fix it, your BLM'S will be more tolerable (I don't like to see more than 122 to 132) and your CO will be 0.
the BLM long term dropped to 138 (from 150 -160) and my vacuum improved to 21".
SunCr, I have a question - I get a DTC error 42 on the scanner (10k mode) but I do not see this error without the scanner, is this from the scanner? I tested the spark advanced (EST) and the circuit appears to work correctly.
Thanks,
Tom
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Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
I was reading the shop manual this AM, and if I understand correctly,
when you are retrieving data from the ALDL connector, and there is a jumper to fom A to B the system will report an DTC 42 error,
maybe the 10k resistor across A&B is enough to cause the error 42
Tom
when you are retrieving data from the ALDL connector, and there is a jumper to fom A to B the system will report an DTC 42 error,
maybe the 10k resistor across A&B is enough to cause the error 42
Tom
Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
After failing my inspection for the second time I went back to the shop manual. I still believe my problem lies in the AIR system, and after further reading found I can see if the air switching solenoid is switching by checking the voltage on pin c of the ALDL connector. It was never activating. I noticed I was getting a code 42 flashing on the service engine soon light in diagnostic mode. This error did not display during normal operation.
I disconnected the battery & cleared the error, went back and checked pin c the switching solenoid is now operating.
Tom
I disconnected the battery & cleared the error, went back and checked pin c the switching solenoid is now operating.
Tom
Thread Starter
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
By clamping or capping of the AIR ports to the exhaust manifolds your will not allow air/oxygen to enter the manifolds to help lite up the Cat...this is mainly at warm up. Once closed loop the diverters direct the air via the pipe to the Cat. If the AIR is not diverting the air/oxygen, it will continue to enter the exhaust manifolds after closed loop and the O2 sensors picks up a lot of oxygen that it shouldn't thus sending a false signal to the ECM and dumping more fuel.
http://forums.corvetteforum.com/show...&highlight=air
http://forums.corvetteforum.com/show...&highlight=air
The AIR switching solenoid is all frozen up, air is constantly going into the exhaust manifold, The check valve to the catalytic converter was full of rust, I cleaned it out but it allows air to pass in both directions,
I need to find a new solenoid valve (or fix it if I can).
I will then run another scan and see if the BLMS go down.
Tom
