OBD2 scanner for diagnostics question

[JHZR2]

Hi,

I have a question about OBD2 scanners - the kind that gives LOTS of usdeful data - either the scangauge or the other ones that act as a go-between for a connection to a laptop.

While some of the radings are neat -RPM, fuel economy, etc., where I think I will get maximum utility is in the ability to actively determine PM and replacement intervals for items such as oxygen sensors, since I can see when they are getting lazy, etc.

So, given that IMO, the biggest justification and saver for buying one of these is to reduce the necessity of o2 sensor replacement from 60k to indefinite, Id liek to know, will any of these units give me 02 sensor readings? The scangauge will tell me if the sensor is in open or closed loop mode, but what good does that do for me? Do I care what mode it is in, if Idont know the voltage cycle? Do the actual laptop interface readers give the actual numbers?

Another example is potential misfires that do NOT set fof the CEL. On my truck, once in a while I get an engien shake at idle. Thouh other owners attribute similar things to a 90 degree v-6, Id like to know more. Someone once told me that you can have misfires without setting off the CEL. However, how do you know this? Will a scangauge give me an indication? What about a laptop interface OBD2 reader? What criteria would I use to determine if an engine was misfiring intermittently, but there was no CEL?

Any insight would be most appreciated.

Thanks!

JMH

 

[Bobert]

I just bought a cable that connects to my PC which plugs to the OBDII port in my VW, and use the free software available from Ross Tech. My situation was similar to yours as I was having a problem with misfires which were quite audible during cold starts. My check engine light did not light up at all, and had no codes stored either.

Depending on what the ECU is capable of, the software/scan tool most likely will have an option to show misfires. In my case the software did show misfires, but my ECU didn't support which cylinder was misfiring. So it takes a bit more detective work if it doesn't have the option to isolate each cylinder.

I ended up pulling all the plug wires off the spark plugs since I didn't know which one was misfiring, reseated them, and the car now runs a lot better. There was definitely a wire that wasn't completely seated. The factory tool to pull the wires is a flimsy plastic piece which makes if difficult to reseat the wires, so I ended up buying a high quality metal tool which makes putting the wires on waay easier.

As far as the 02 sensor, depending on the ECU capabilities there is sometimes a test you can run which will give a X value. Depending if that value is above or below a certain threshold this will tell you to replace or whether the 02 still has some life left. Again though the capabilities depend on your ECU and the scan tool.

 

[JHZR2]

great, thanks for the insight!!!

I suppose that all of the allinone type OBD2 tools allow you to gain full data sets from the ECU (so far as the ECU capabilities will allow), right?

Or do some all in one scanner type units (that connect to a computer) lack functionality or data throughput themselves?

Is some software better than others? Any reccomendations? Is it vehicle/make specific?

Thanks,

JMH

 

[Bobert]

There are so many different scanners and software I would probably be the wrong person to ask. For VW/Audi/Skoda, Ross Tech is a very popular vendor.

For domestics and Japanese cars I would be hesitant to steer you in one direction or the other since I'm unfamiliar with what scanner options are available. The best advice I can give you is ask other users of the same vehicle you have and what they recommend. You'll probably find good recommendations if you join a forum that is specific to your car (ie. Dodge forum, Toyota forum etc.).

 

[porcupine73]

For the real advanced, detailed stuff you'd probably want to check out either a manufacturer specific device (speaking of Japanese models Subaru has their own 'Select Monitor', which is basically a laptop with software and interface cable, which does all kinds of neat manuf specific things).

Or one of the big tool makers units, but these often require updates once or twice a year to keep up with all the new models, and aren't inexpensive.

 

[TexasHonda]

I have been well satisfied w/ Harrison Eng's OBDScan system. It's worked well on my cars; Subaru, Acura 2.5TL, Acura 2.2TL, Toyota Celica, and Dodge Ram 1500. I have about $250 in w/ cost of software, firmware interface, and a used IBM laptop as monitor. It allows O2 sensor and other outputs to be monitored, up to 4 at one time if you want. I think price for the software and firmware interface is now just over $100, which means you should be able to configure a system for < $200 bucks.

OBDScan

good luck