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Tuning

anupaum

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I'm not entirely convinced my new O2 sensor is working. Sometimes it'll come on, but the moment I put my foot into the throttle it begins reading dead rich. Now, fuel economy is terrible, and this has me scratching my head a little bit.

Since I went to BIGGER tubing and a BIGGER throttle body, shouldn't that bump my volumetric efficiency UP, and therefore LEAN my fuel table? It seems to have had the opposite effect, though.

If I run autotune, the tuning utility that comes with the Megatune software I'm using, it puts ridiculous spikes into my fuel table that make the truck run terribly. I've always had better luck tuning it by "feel," and then running a separate analysis based on a datalog, using a program called Megalog Viewer, which has its own VE analysis.

My datalogs, however, are showing the intermittent O2 signal to which I referred earlier, and without that feedback, the computer can't correct the fuel table. So, this morning I leaned out a significant portion of the fuel table by hand. To my surprise, the truck began running much better!

This seems counterintuitive. Worse, the table I'm using had been initially set up with my stock sensor, and when I went to the wideband I found that it didn't need much tweaking. Now, however, it seems like the entire table is too rich. This seems to be confirmed by my dismal fuel economy.

There has to be a way of checking the O2 sensor for proper function . . .
 


anupaum

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This evening I did a "forensic analysis" of my fuel tables. Even with the leaning out I did, the fuel map I'm currently using is quite a bit fatter than the one I tuned earlier. I'm not sure what's happened, but I think that running autotune once or twice REALLY screwed things up.

In my mind, that confirms that I've got a problem somewhere. I've been looking for a ratio vs. voltage utility that will help me understand how Megasquirt is interpreting input from the O2 sensor. Tomorrow morning I'm going to input the older fuel map values in by hand, then shut off O2 correction entirely and see how it runs.

Very strange!
 

anupaum

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I swapped my O2 sensor this afternoon. I'd put a brand new one in after installing the new tubing and discovering that my LC-1 had burnt out. When I pulled the replacement sensor out, it was completely coated with carbon.

You think it wasn't working??? (Sheesh!)

With the new one installed, the O2 feedback works. So now I've run a data analysis and 38 of my cells have been adjusted. It's getting a little late to be messing with things, so I'll upload the new tables on Sunday and see how everything works now.
 

dieselboy740

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ah man i had the same problem i couldnt get my o2 to work one day and after dicking with the settings in megatune it still didnt want to work. Finally i gave up and bought a new lc-1 and it worked perfect.. Ive ran auto tuna a few times and i couldnt get it right but im still learning.
 

anupaum

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ah man i had the same problem i couldnt get my o2 to work one day and after dicking with the settings in megatune it still didnt want to work. Finally i gave up and bought a new lc-1 and it worked perfect.. Ive ran auto tuna a few times and i couldnt get it right but im still learning.
I was NOT impressed with the reliability and performance of the LC-1. I know there are some people who think it's great and pontificate eloquently concerning its virtues, but there is a whole category of people like ME who have found it unreliable.

Also, the marginal performance gained by the wideband sensor was simply not worth the money, as far as I am concerned. The fact that I'd managed to tune the truck so well with the factory sensor confirmed the claim in the Mega Manual that it's reasonable to generate a very good tune with a narrowband sensor.

Autotune is a mixed bag . . . I've found that driving the truck to generate datalogs, then running those through Megalog Viewer and doing a VE analysis yields far quicker and more accurate result when creating VE bins.
 
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anupaum

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Having a functional O2 sensor really makes a difference when it comes to tuning! My eldest son likes to fiddle with my VE tables while I drive, making sure that the gauges in Megatune read as they should "on the fly," and he's pretty quick at making adjustments, too.

Over the weekend, I had a conversation with a friend of mine who is a mechanic. When I mentioned that my stupid battery light is on, and that my LC-1 grounded out against the exhaust pipe, he wondered if I'd either burned one of the diodes in my alternator out, or perhaps, damaged a plate in my battery during the time I spent cranking the engine after putting on the new throttle body. (I DID have to put the battery on my charger because it started getting weak at one point.)

Now the system voltage fluctuates between 12.6 and 14.7. He wondered whether this fluctuation in voltage would ALSO create fluctuations in the sensor signals my computer needs to make its adjustments. I thought this was a good question.

So I thought I'd post the remark here and see if any of you have any feedback. The basic advice my friend gave me was this: "Fix the obvious stuff first." I've got to get rid of that pesky leak (air has ALWAYS been a problem with this project) and the altenator clearly needs to be checked.

At least I'm taking care of the issues one at a time.
 

fixizin

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Wow, anupaum, I've looked over your webpage, and you've REALLY done some extensive PLUMBING!... you're a man of great patience... you probably swear a lot too, lol.


Anyway, in its original 3.8 SC application, didn't the Eaton output DIRECTLY into the V8 intake manifold, no plumbing, no intercooler? If so, what did the 3.8 do for MAP/MAF sensing, anti-knock, etc? Just trying to learn.

I realize no such intake exists off-the-shelf for your 4.0, and I think your "upside-down" solution is very innovative. :icon_thumby:
 

anupaum

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Wow, anupaum, I've looked over your webpage, and you've REALLY done some extensive PLUMBING!... you're a man of great patience... you probably swear a lot too, lol.
Patience or insanity? Sometimes I'm not sure which . . . Anyone who would take a perfectly working machine and mess with it as much as I have might qualify as mentally ill--particularly when it's taken YEARS to work out all of the problems.

Anyway, in its original 3.8 SC application, didn't the Eaton output DIRECTLY into the V8 intake manifold, no plumbing, no intercooler? If so, what did the 3.8 do for MAP/MAF sensing, anti-knock, etc? Just trying to learn.
Honestly, I don't know. I've never actually seen a Supercoupe in real life. (Wasn't the 3.8 a V6?) I tried going directly into the intake manifold when I first put the blower on, but it would ping at part throttle on a cool day and I couldn't get it to go into boost without some serious detonation happening. I could have used water injection, but after a bad experience with that method (it's in the archives, somewhere), I had to find a different way of cooling down the intake charge. That meant I needed an intercooler, which meant that the MAF system wouldn't work anymore, which meant that I needed a new computer, which meant . . .

It's been one thing after another! Trust me!

I realize no such intake exists off-the-shelf for your 4.0, and I think your "upside-down" solution is very innovative. :icon_thumby:
Thank you! (It's a 2.3, not a 4.0) I'd initially thought putting a blower on the truck would be easier than a turbo. It's not, but it DOES earn me the occasional "coolness discount" when I need the truck worked on . . .
 

drmazda94

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the reason it read rich is when you put it to the floor your computer richs the system when you let off it should start working and going rich to lean to rich the reason it does this is to put o2 in the cat to help it work best
 

anupaum

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the reason it read rich is when you put it to the floor your computer richs the system when you let off it should start working and going rich to lean to rich the reason it does this is to put o2 in the cat to help it work best
I'm not using the factory computer. I have to tune this thing myself! The entire fuel map had to be adjusted, though, and I'm not sure why it had been running rich when it HAD been in good tune with the wideband sensor. I've long suspected that there's an electrical problem lurking somewhere that's caused all manner of weird, spiky behavior with my sensors.

This afternoon I took the truck to an electrical shop to have them check my alternator and battery. Apparently, one of the stator wires had broken somehow, so the mechanic replaced both ends and now the battery idiot light is off. On a positive note, the alternator is charging nicely (even though it's only got about 30% contact on the belt) and my battery is still working well.

We've got the truck back in pretty good tune right now. There are still some spots that need a bit of adjustment, but one of the NICE things about living on top of a hill is that driving uphill gives me a load to work against. My eldest son tweaks the bins while I drive, and the occasional excursion toward 5 000 rpm allows him to get the fuel map set up in an area where I generally don't push too hard. The truck just ROARS uphill, though.

Gotta love being in boost! :icon_bounceblue:

At some point I'll have to swap out my catalytic convertor. All of this running rich has likely wrecked what had been a marginal cat to begin with. I saw a replacement on e-bay for $140 that includes the pipe. ("Bolt in" sounds really good to me!) I'm not sure how big I should go, but I want the truck to stay QUIET--so no Flowmaster for me!
 
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TireIron

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The original V6 installation in a supercoupe has the M90 sitting in the V of the motor just above the intake manifold with the output facing upwards. The output then runs to the front with solid pipe to an intercooler then back around on the other side and into the intake manifold. It's a pretty trick setup for factory. There is a MAF and a TB before the M90 and they run a pretty massive set of injectors factory also.

GM and buick used an M62 on their V6 setup and they had a downward output that entered directly into the intake manifold with no intercooling. They made aftermarket intake manifolds with air/water intercoolers in them for an upgrade when running more boost.

The lightning uses an M112 that feeds directly into the intake manifold with no intercooling also. Again there are aftermarket intake manifolds with air/water intercoolers in them.

Obviously the blocks and fuel management are designed to handle the boost, especially on the non-intercooled applications. So adding boost to a factory N/A motor like Anupaum did (and I may do eventually) takes a lot of research and planning to get working right without blowing things up.
 

anupaum

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Part of my serpentine belt shredded yesterday. I'd just picked up my son from school when the inside edge of the belt peeled away and began flailing around beneath the hood. Apparently, when the mechanic who fixed my electrical problem put the wiring back, he didn't route the wire that plugs into my alternator far away enough from the belt. It had apparently been rubbing since then, the belt got hot and the rest is history . . .

I replaced the belt this morning, but my sweetheart was NOT happy! She said: "When are you going to get this thing running reliably?"

It's running pretty well, though. I've just got a vibration and a minor air leak issue to tackle, and the truck will seem like it's completely stock--until the throttle opens up!

I've got two short radius elbows AND a blower motor from a Cadillac on the way up here now. (The local yards want nearly $400 for that stupid blower motor. I bought the same part on e-bay for $70. What were they thinking?) I'm hoping to have EVERYTHING taken care of soon!
 

turbo cat

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Tell her if she has a problem to get out there a fix it herself:icon_thumby:
 

anupaum

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Tell her if she has a problem to get out there a fix it herself:icon_thumby:
You're either not married, or won't be for long with THAT kind of an attitude!

:derisive:
 

turbo cat

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Im basically married and I stand my ground as well as she does
 

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