Help With My Idle, Not Sure if Mechanical or Tune?

[Supercharged111]

A little background: back in March I swapped my stock cam (190/196 .414/.428 111LSA 106ICL) for a ramjet cam (196/206 .460/.480 with 1.6s 109LSA 106.5ICL) along with some 1.6:1 Comp roller rockers. Since then, on a cold start, the motor sits there and stumbles most days until warm. One little poke of the gas and everything is back to normal, nice and responsive, but the idle is bad enough to affect TCC operation. The exhaust also stinks noticeably more which surprised me for such a small cam, but it's supposed to have more duration at .050" and less at .006". I did end up cleaning my lifters, they were all badly gunked up and stuck in their spots. The plungers wouldn't return to the top of their travel so I had to disassemble and clean them to free them up. I then ran the engine to get it warm and changed the oil and filter and refilled with dino oil and a bottle of Marvel Mystery oil to ensure the lifters were good to go. This fixed my intermittent cold start lifter tick that the truck had had for years. Since this cam isn't much bigger than stock and my LTFTs were within 2% so I never bothered with the fuel, though I will because I still need to from the initial 411 swap (I believe the MAF table is off). With all that said I'm not sure where to begin. I've sprayed for vacuum leaks and didn't find any. I figure the data can point me in the right direction but I'm not sure what all I need to capture or what it's going to mean.

[Supercharged111]

Took a stab and logged a bunch of idle parameters. . . and the truck fired and idled beautifully. That said, there is a little spark fluctuation after the truck fires.

18691

Not sure if there's anything to be had here. It idles with 13-16 AC off and around 20 with AC on. Thinking I can probably bump timing around 5 degrees but doubting that's the solution to my problem that didn't show this time. Yesterday it fired and stalled (after sitting 3 weeks and then the battery died) and I had to keep my foot in it for 30 seconds or so before it would barely idle at 400 RPM. Seemed to run fine otherwise.

[joecar]

Connect a vacuum gauge and study it to see it shows any ticks or sweeps.

[Supercharged111]

Those indicate leaking valves, right? I'll dig one out tomorrow and capture data and shoot video. Chances are the damn thing will run perfect again though now that I have time to deal with it.

[Supercharged111]

Finally rigged up a tee to do this. There was only 1 vacuum line on the whole truck! Anyway the gauge was perfectly steady, only fluctuating as the engine initially hunted for idle and then stayed put when the engine settled down.

[Supercharged111]

I've gotten nowhere on this and now that the weather is beginning to cool off, it's going to do it more. I took another short log, of course it only ran rough for the first few seconds. This time though I tried to capture misfires, not sure if GM.MFCSTAT was the way to go there or not? It was all over the place initially as was the spark, desipte the fact that MAP and MAF look smooth and consstant. After the idle smoothed out I took it for a drive to see if the TCC would lock and initially, no. Should have logged trans temp too to be certain the misfire was the cause and not the temperature. It seemed warm enough outside for it to lock right away.

18943

http://i198.photobucket.com/albums/aa70/supercharged111/GMC/Cropped%20Idle%20Screen%20Shot_zpssu8srqli.jpg (http://s198.photobucket.com/user/supercharged111/media/GMC/Cropped%20Idle%20Screen%20Shot_zpssu8srqli.jpg.htm l)

And here's a log with the individual cylinders, though the truck was already warm and acting OK. Still got some rogue misfire counts though.

[joecar]

Log the pid GM.MFTOTAL instead of GM.MFCSTAT.

From Log 3:
Looks like #5 logged 20 misfire events over 1.5 minutes... if this did not cause the MIL to flash then it may not be a problem given that ECT had not yet reached warm up temp (i.e. not yet closed loop).

[Supercharged111]

No flashing of the MIL, hell the TCC locked right up too. I am logging the TSTATEs that'll tell me when it doesn't lock, if it's due to trans temp or misfires. Didn't have time to grab the laptop on the way to work this morning, hoping to do it tomorrow on my way in and hoping to capture some good data too. I've added GM.MFTOTAL to the lineup, is MFCSTAT of any use at all?

[joecar]

MFCSTAT is supposed to indicate how far into the misfire determining cycle it has gone, I don't know that it is useful (...or I don't know how to use it yet).

[joecar]

If the MIL is not flashing and the TCC stays locked, then the PCM does not think that the misfire counts are significant...

from what I have seen, 20 counts in a minute or two is quite low, especially since it clears up as the engine heats up and runs more.

[Supercharged111]

It only clears up when you don't idle. Sometimes. Others it'll purr like a kitten. This morning on the way to work it wouldn't act up, but tonight with 8 minutes left on the laptop battery I got it to act up pretty good. Now the MIL didn't flash, but the TCC wouldn't lock either. You can see from the data that I fired it up warm, drove down the road to a spot I could sit which was very close to a stretch of road fast enough to induce 4th TCC lockup which it did not do. I haven't verified in the TCC state yet that this is why, but I do see that cylinder #2 was missing like crazy the whole time. About every 100 frames or so, the counter would reset so it's clear that the PCM must see X amount of misfires in Y amount of time and when it doesn't, it allows TCC lockup. So how accurate is my 4X crank reluctor at calling out what cylinder is acting up? Because the other day's log had cylinder #2 going ever-so-slightly rogue, but I needed more data to confirm. In fact, it appears that the whole right bank had some misfire activity, but then again 5 briefly joined the party when I fired up too. Either way, #2 is the biggest offender from what I can see so far. The right bank is the one that shit an O2 sensor earlier this year so I replaced both with AC Delco parts.

Idle Log 4 is from this morning and is uneventful (until 30 seconds after I shut the laptop right in front of the gate :wallbash:

Idle Log 5 is the short log I grabbed this evening with some good data showing how it's a turd at an idle then clears up at speed.

[joecar]

You mean there is a definite stumble when this happens...?

[joecar]

Hmmm, I see...

[joecar]

Also, while #2 is misfiring I see LTFT1 (the other bank from cyl #2) climbing which is odd (is there a slow air leak...?)


and LTFT2 starts climbing down and then hovers at -3.9% to -4.7%... PCM thinks there's a little too much fuel in bank2... I wonder if the #2 injector has a small leak... what happens if you swap #2 injector with #1 say...?

[Supercharged111]

The truck doesn't idle smoothly when it does this but the RPM, airflow, and MAP values seem to remain steady. Even when it's idling like crap, throttle response is as if nothing's wrong and acceleration/cruising effort remains unchanged per the butt dyno. I've been thinking injector, so I ran a bunch of fuel system cleaner through but no change in the idle. I can't physically swap injectors around as it's the illustrious spider setup. That said, it fires up instantly when cold or warm and cranking times are unchanged from before.

[Supercharged111]

OK made another log and watched #2's counter increment much farther and more quickly when in gear than in park/neutral. I'll check the plug and wire for #2 against the rest and really give it a once over for vacuum leaks. Maybe even see what the compression's like, but isn't the one thing the motor should be the most sensitive to during a low idle be fuel? I mean at such low RPM, a little change goes a long way right? All cylinders ought to have the same advance, so assuming it's getting the same firepower it seems like it has to be fuel (or a vacuum leak that's intermittent) doesn't it? If it is an injector, it just seems odd because it didn't do this at all before I had the spider out of the vehicle. While it was out, I cleaned it up real nice too. Should've left it covered in EGR gunk.

[joecar]

Maybe swap coils around.

[Supercharged111]

I only have 1, truck has a distributor. 5.7 Vortec. I suppose it's clear now that it's mechanical. Going to try open loop tomorrow and monitor O2 voltages too.

[joecar]

( lol, I'm not as familiar with Vortec's )

Check distributor cap and plug wires.

[Supercharged111]

Cap and rotor were new last fall. Made no difference then on performance. Then I found this.

http://i198.photobucket.com/albums/aa70/supercharged111/GMC/8%20Non%20Misfire%20Wire_zpszhaswbwt.jpg (http://s198.photobucket.com/user/supercharged111/media/GMC/8%20Non%20Misfire%20Wire_zpszhaswbwt.jpg.html)

Wasn't fully seated, there's arcing and corrosion in there. Put a new wire on, no change. Reminded me of the cap and rotor. So then I pulled #2 and #4 for reference. Here's #2.

http://i198.photobucket.com/albums/aa70/supercharged111/GMC/2%20Misfire%20Plug_zpsg5hu1z0a.jpg (http://s198.photobucket.com/user/supercharged111/media/GMC/2%20Misfire%20Plug_zpsg5hu1z0a.jpg.html)

Not sure what to make of the brown. #4 looked normal, but all the ground straps have a greenish hue to them. Must be the fuel?

http://i198.photobucket.com/albums/aa70/supercharged111/GMC/3%20Green%20Ground%20Lug%20Plug_zpsb5rb0huu.jpg (http://s198.photobucket.com/user/supercharged111/media/GMC/3%20Green%20Ground%20Lug%20Plug_zpsb5rb0huu.jpg.ht ml)

Forgot to ohm out the plug wires, I got all excited when I found #8 all nasty and figured the truck was calling out the wrong cylinder. Guess not.

Just ran out and slapped in another wire for #2 and no change. I guess tomorrow I'll verify that it is still #2 and try turning off its injector with the bidirectional controls and see what that does.

[Supercharged111]

Monkeyed around quite a bit on this. Polished the distributor posts and that seemed to help a little, I assume now because it's more difficult to light off a less homogenous or lean mixture. I swapped the fuel filter today and it helped a lot. Shame on me. So if it was just the same couple of cylinders missing, those poppers must be borderline because there still a hint of a miss. I then redid my cmpret and got it down from 3.5-4 to .25-.5 and then I did a CASE relearn. Going to drive it for a bit now and see how it does.

[joecar]

Greenish color on ground strap: what fuel are you running...?

[Supercharged111]

91 octane E10.

[joecar]

The green color might be a sign of too much timing.

[Supercharged111]

I've been suspicious of that. Another plug had white speckles too. It came from the trouble hole, so I attributed that to the cause of the miss more than anything. Can you clarify on how the green color is indicative of too much timing?

[Supercharged111]

Assuming the below is factual:

http://brianesser.com/technical-information/the-ultimate-guide-to-spark-plugs/



Reading For Ignition Timing

Ignition timing is directly responsible for the heat in the combustion chamber and therefore the color of the plug’s ground strap and the color of the first few threads on the outside of the plug. The ignition timing can be checked by looking at the color of the plug’s ground strap and the position of the “blue line” on the strap. The blue line really indicates the point at which the strap has reached annealing temperature of the metal. To help to understand this think of a bar of steel (ground strap) on a table that is being super heated with a acetylene torch at one of the tip ends. As the end heats up and the heat starts moving down the bar you will see a blue line across the bar at some point down the bar away from tip with the torch. This blue line reflects the temperature that is the annealing point of the metal. As the temperature increases the blue line moves further down the bar away from the torch. Similarly, the blue line moves down the spark plug ground strap as you put more heat in the engine.

If you are using a gold colored ground strap like with an NGK spark plug then not enough timing will show the ground strap as still gold or going light gray maybe with a few bubbles on it after a run. As you advance the ignition and put heat in the engine the plug ground strap will turn darker gray as well as the metal at the end of the threaded area. As the metal turns medium to dark gray you should start looking for the blue line (band) around the ground strap. Ideally, you want this blue line to be just below where the ground strap makes the sharp bend and above the weld. If you advance the ignition too far the blue will disappear off the strap and the strap will pick up rainbow colors (blues and greens). The next step beyond that is to start melting the strap from the tip end and detonation. When you are close to the correct timing then only change the timing by one degree at a time. If you ignition system has the capability of adjusting the timing of each cylinder independently (ICT) then you can use that feature to have the blue line in the same position on all the plugs. First, adjust the basic timing to get as many of the plugs to have the blue line just at the sharp bend in the strap. Now adjust the ICT to move the blue line to the same point on the remaining plugs. Once all the plugs read the same you can advance the ignition a little at a time to put the blue line just above the weld on the strap or whatever point gives you the best performance.

It looks like that blue line, or dark line, stops just before the weld on the original pic zoomed in on my computer.

http://i198.photobucket.com/albums/aa70/supercharged111/GMC/4%20Green%20Plug%20Zoomed%20In_zpsonupvryx.png (http://s198.photobucket.com/user/supercharged111/media/GMC/4%20Green%20Plug%20Zoomed%20In_zpsonupvryx.png.htm l)

So not sure what to make of it. Is it green from E10 like some people claim? Others claim coolant will turn it green, pretty sure that's a load of BS so maybe the whole E10 thing is too. The other thing that strikes me as odd is the fact that advancing the timing decreases EGT, it doesn't increase EGT. And isn't EGT indicative of combustion temps?

[joecar]

From what I've read about reading plugs, that blue line should be further along the ground strap...

when the blue line moves closer to the body of the spark plug, the wake it leaves on the ground strap can have various colors, including green, purple (or deep red), and gold... (I think the colors are the "heat treatment" left behind on the ground strap by combustion chamber temperature... too much timing = too much temperature);

when the blue line is completely at the bottom of the strap, people have found signs of melting on the spark plug.

[Supercharged111]

Does it look close? I.E. only a smidge too aggressive? I'll admit I tried maybe a little too hard to recoup lost torque after the cam. After a couple weeks of driving though, it seemed to improve itself. I just never went and backed it down. I was trying to get knock threshold everywhere, but really only found it in a couple spots. From there I was going to drop the whole thing globally, but never reached that point.

[joecar]

What is timing, MAP and AFR at WOT...?

[Supercharged111]

MAP 79-74, timing 34-36, AFR 12.5ish and zero knock. I think it's the midrange where I'm most aggressive.

[joecar]

MAP is 79 kPa at WOT...? What elevation are you at...? At key-on-engine-off what does MAP read...?

Timing 34 degrees at WOT: What engine is this...? What heads...? Might be too much timing.

AFR 12.5: this is good.

[Supercharged111]

6000' elevation and I run 91 octane. Never seen it above 79kpa, it tapers down to 74 at WOT with the stock intake and new Wix air filter. Timing is around 34 at midrange then bumps up to 36 at 5000 RPM, I assume because it's dropping to a lower load cell? These motors (GenI 5.7 Vortec 9.4:1 comp) like about 30 at sea level. Mine has a marine cam, 1.6:1 roller rockers, headers, and an underdrive pulley. Same powerband as stock, just more of it. I think I guesstimated the extra 4 degrees based on a stock tune and it didn't knock with it. My issue may be that I'm bringing it in too quickly, I'll post a tune when I get home.