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Issue Resolved : What Gauge Should I Use?
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pede69
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Dec 9, 2012, 1:43 PM
Post #51 of 66
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Re: What Gauge Should I Use?
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After checking it myself... I was hoping no one would check :)
J
(This post was edited by pede69 on Dec 9, 2012, 1:44 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Dec 9, 2012, 2:01 PM
Post #52 of 66
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Re: What Gauge Should I Use?
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You mean that magic box doesn't diagnose it for you? .................. damn
Customers tell me all the time I shouldn't charge for diagnostic because all i have to do is plug that thing in and it tells me what to do.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
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Dec 9, 2012, 9:34 PM
Post #53 of 66
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Re: What Gauge Should I Use?
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It's a time consuming process. You look at dozens & dozens of good datastreams. You find a problem without using the datastream and then go back and see what that problem does to the stream, then after a while the oddities will just kinda stick out.
You like this stuff and want to learn so that is good...You can take some good natured ribbing & that is even better..
When you get your software the most important thing would be to learn how to take a snapshot & upload it, then someone with experience can look at it for you. Of course you want to get that snapshot when the problem is happening. Taking it when the problem isn't happening would be of no use to use, everything would look normal because it's running normal.
It would be good for you though, to take a snapshot when it running good at idle, at crusie & underload. This would give you a good baseline to compare a bad snapshot to. You just have to remember that just because you are seeing a skewed reading, doesn't mean that sensor is bad. A plugged exhaust system will play tricks with you on a lot of the readings....
Just takes time, you gotta pay you dues & take your lumps with a smile......
Now run down to Napa & pick me up a case of longterm fuel trim solvent so I can wash these high trims back down to 0%, not the shortterm...we got plenty of that....
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pede69
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Dec 16, 2012, 2:49 PM
Post #54 of 66
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Re: What Gauge Should I Use?
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Hi guys...
What do you think it means if I spray carb cleaner on the coil pack and engine changes (studders and loses rpm) but If I spray water mist on it, there is no change whatsoever? No arcing or change in engine.
Thanks,
J
(This post was edited by pede69 on Dec 16, 2012, 2:52 PM)
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Sidom
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Dec 16, 2012, 2:57 PM
Post #55 of 66
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Re: What Gauge Should I Use?
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Carb cleaner is flammable so I wouldn't recommend spraying it on a coil pack.
That's not really a valid test so I can't say why the difference other than you may be momentarily shorting out the coil pack due to a weak seal?
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pede69
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Dec 16, 2012, 2:59 PM
Post #56 of 66
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Re: What Gauge Should I Use?
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It was an accident, I was trying to spray the vac line underneath it.
J
(This post was edited by pede69 on Dec 16, 2012, 3:02 PM)
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Sidom
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Dec 16, 2012, 3:04 PM
Post #58 of 66
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Re: What Gauge Should I Use?
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Using that to find vacuum leaks is one good way to do it.......It's best to keep it away from electronics, I know things get tight so you just gotta do the best you can.......
Once you get your software if you study up on fuel trims, you can look at trims as see the change in them when you hit the spot......propane actually works better with trims but once again you need to make sure there are no obvious shorts anywhere & use caution
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pede69
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Dec 16, 2012, 3:06 PM
Post #59 of 66
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Re: What Gauge Should I Use?
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Thank you for your concern Hammer but "no can do" :)
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pede69
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Dec 16, 2012, 3:12 PM
Post #60 of 66
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Re: What Gauge Should I Use?
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Thanks Sidom...
I already received the unit and software. Problem to me is that the free software that came with it is very basic.
It did have some trim tab info but I am confused because the data on the screen keeps fluctuating so I am not sure how to read it.
Should I take some screen shots about 15 seconds apart and show it to you?
Thanks,
J
(This post was edited by pede69 on Dec 16, 2012, 3:41 PM)
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Sidom
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Dec 16, 2012, 4:07 PM
Post #61 of 66
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Re: What Gauge Should I Use?
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Sure go ahead & up load a snap shot, one @ idle & one @ cruise...
The data learning is just a slow process.....Just look at the main stuff.....MAF, O2, ECT, TPS, etc..... See what they look like when the engine is running good they when there is a problem you will see it...
Fuel trims are important, it lets you see what the PCM is doing. How it's trying to keep the engine in fuel control. Fuel control is an air/fuel ratio of 14.7 to 1.
The O2 moniters the exhaust gases. The voltage varies from .100mv to .900mv, lean is low, rich is high with 14.7 being in the middle. It's impossible for the PCM to maintain a 14.7 ratio so it's always switch between rich & lean. This is referred to as crosscounts and where the fuel trims come in.
Short term mirrors the O2 readings and it goes fast....so when the O2 is going rich,lean,rich,lean,rich,lean the STFT is going lean,rich,lean,rich,lean,rich and as long as it stays that way the the trims are at 0% & the PCM is happy.....
Now if there is a lean or rich condition that cause the O2 voltage to stay on one side then the STFT does the same on the other side & this is where the longterm fuel trim comes in....
The Longterm Fuel trim is a slower, greater adjustment and how the PCM is trying to control the O2. If the STFT is going lean, lean, lean, lean then the LTFT will take 1 step + (adding fuel) 1% trying to get the crosscounts back & a 14.7 to 1 a/f ratio. If the STFT is still going lean, lean, lean, lean it takes another step, 2% trying to get the cross counts back an so on. Until the LTFT get to around the 25% and then the PCM throw up it's hands and as says " I can't bring this POS back into fuel control" (14.7 to1) and turns on the check engine light setting a lean code. If its just bank one then its a P0171, if it's just bank 2 then its a P0174, if it's both then you get the P0171, P0174.
Now this is just a basic explantion of how trims work. there are narrow band O2 sensors, wide band air/fuel sensors, different fuel strategies for different manufacturers all with slight differences but thats generally how it works...
What you can do is fire up your scanner and see where the trims are at idle. Now pull off a vacuum line & give it a vacuum leak and you should see your LTFT go positive trying to control the problem.....Then, still with the leak, take the rpms up to 2500-3000 and you should see the trims come back down close to 0% because a vacuum leak won't have much of an effect at high rpms. You have greater air intake, more fuel and the vacuum leak is constant so it won't delute the a\f mixture as much as it does at idle. The problem with vacuum leaks are they are past the MAF sensor so the comp doesn't see it on the front end and compensate for it, it just sees leaner exhaust gases then what it expected to see so it will richen it up according.....It doesn't know there is a vacuum, just it made perfect adjustment via all the data input to get a 14.7 a/f (this is also referred to as a stochiometric air/fuel ratio but we don't have to get into that)and for some reason it's lean...
(This post was edited by Sidom on Dec 16, 2012, 4:07 PM)
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pede69
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Dec 16, 2012, 6:29 PM
Post #62 of 66
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Re: What Gauge Should I Use?
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Have the snaps...
Be a bit until I have them ready.
Thank you Sidom :)
J
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pede69
User
Dec 16, 2012, 7:32 PM
Post #63 of 66
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Re: What Gauge Should I Use?
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Well Sidom, (and others) the images are a bit large but here ya go. I hope this is enough data.
Thank you again for your kind help.
http://jaxehost.com/sidom
J
PS - I did multiple images because of the way the data kept changing. They are 10 to 15 seconds apart, I think.
(This post was edited by Hammer Time on Dec 17, 2012, 5:11 AM)
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Sidom
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Dec 16, 2012, 9:06 PM
Post #64 of 66
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Re: What Gauge Should I Use?
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Well it might be basic but there will be some very useful information there if you are having a problem.
With a datastream some of the info is always changing. This is a live stream of what the comp is seeing. This is where graphing comes in handy so that is a very nice feature.
Take the O2 voltage, when you were looking at on the data screen it probably just looked like numbers bouncing all over the place. It will do that as it goes from rich to lean, those are the crosscounts you need see. If you are looking at O2 voltage its really easier to see that in graphing mode (unless you have a really good memory & quick eye). You have the sweep (time division) set a little to fast. The screen says 1 sec so that should be 100ms divisions but by looking at voltage change on the O2s it really looks like 10ms divisions
If you can, slow the graphing mode way down the O2 and trims will make more sense..
With the LTFT at idle they all seemed to be on the rich (-)side but those you really need to see as movie rather than snapshots, for seeing what a normal pattern is. With a hard failure a snapshot can give you some clues....With the trims as long as you are in the single digits you are good. Don't get hung up on trying to be at 0% all the time because that isn't going to happen.... Once you are staying at 13 14 15% then there is something starting to go on...Most systems won't code until around 25%.
It looked like it might of been a small vacuum line you took off. The LTFT was on the rich side and then went to 0% with the leak.....Try pulling the brk booster hose off & give it a big leak and see what the trims do. You can spray some carb clean in a vacuum line & then hook it back up quickly and give a rich conditions and see what it does...
Some data I look at differently like throttle position. I use voltage as opposed to % but its what every you prefer to look at and more importantly what you can reconize as a good reading compared to a bad one..
But coolant temp & load all seemed normal...
But once you slow it down you can look at the trims, O2 voltage, throttle position, engine load and see how they all work together.
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pede69
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Dec 16, 2012, 9:39 PM
Post #65 of 66
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Re: What Gauge Should I Use?
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You are awesome...
Thank you :)
As far as the % v volts goes, I could not find anywhere to change it from %.
I will have another look tomorrow and also change the sampling rate.
The image at the link below shows my choices. what do you think?
Sorry, I do not know how to put images here.
Thank you again for your concern and help.
Catch you tomorrow,
John
PS - I took off the vac line at the throttle body :)
(This post was edited by Hammer Time on Dec 17, 2012, 5:09 AM)
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Sidom
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Dec 17, 2012, 10:48 PM
Post #66 of 66
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Re: What Gauge Should I Use?
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You do want to slow it down. Try the 100ms & then maybe 250ms as see what it looks like. I'm not familar with the other 2 options so try them out...
With the PIDs, you should be able to control the time and if there is a metric or standard scale, change that, but tkhe valve is what that PID shows. There is one for voltage but that one may not be available.
Like I said before it's just a matter of putting in the time and getting use to what normal data looks like....Also having a good understanding of how the other systems work, like the ignition, the mechanical end and a good background in electrical....All computers assumes the car has a good battery, has compression & is mechanical in time, etc...It has no way to check this stuff so will just set codes to the systems that are effect by these failures...And you can get some strange readings some times off mechanical problems and wouldn't believe what a bad battery can make these systems do, I guess one of my strangest problems was having a bad battery cause an a/c system not to work(and yes it took me way too long to find that bad battery)......The newer systems are a little more forgiving but with the OBD I systems if you jumped right into the computer problems with out checking the timing, battery & some other basics, you could waste an awful lot of time & money
I'm sure you are already doing this but I will throw it out there anyway but on tests drives you should really have a helper do the driving so you can focus on the info, saving snapshots, movies & so on.......I can't say for sure but I would have to imagine that scanners now fall under a states cell phone & texting laws.....
I'll have to admit I still do that BUT I've been using this equipment for years, if I'm in any kind of traffic at all I don't look at the scanner & I can save a snapshot or start a movie with out looking at the scanner....If I can catch a movie during a failure I actually preferring looking at it on my comp vs the scanner screen anyway (screens bigger & it's easier on tired eyes)...
I'm guessing your software has some type of computer based program you can look at your data on?
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