TDCO / Carcode

[Shikaroka]

I know these questions get asked a lot.
I have read many threads on the subject, but it never sank in.
I knew it probably wouldn't stick, until I tried it myself. So.....

Carcode has several different listings for 6.5s, does it matter which one you pick?

I hooked up my laptop, picked a 6.5 under enhance, and read the TDCO.

It showed -.1
Factory is -.5, so mine is retarded, right? Slop in the chain, maybe?
I've read that -1.94 is optimal, so anywhere between -.5 and -1.94 is acceptable, right?

So, I tried the Key on/Key off routine to reset the TDCO.
I tried several times, but it stayed at -.1
Are there any tricks to the routine?

Once I get it reset to 0.0 what is likely to happen next? Will it reset it -.1 once it warms up? Then, I will need to physically adjust the pump, right?

Any advice???

[gmctd]

-1.0deg TDCO is about half way between good and best - just leave it while you familiarize yourself with the pcware scantool - that is advanced a little from oem stock.

You'll want to select "S" for EGR turbo engines in 1500-2500 series, "F" for non-EGR turbo engines in 2500-3500-3500HD series - the other options are NV4500 manual trans and 4L80E auto trans.

"P" may be the non-turbo normally-aspirated series reference, which should all be EGR-equipped.

The main difference in the turbo-engine selection is EGR control, not available or needed in the "F" series.

[Shikaroka]

Mine is reading a TDCO of: -0.1 , not -1.0

The options I saw listed did not include a "S" or "F".

[gmctd]

Ok - my bad - numbers ain't my friends - what is Desired and Measured timing in degrees at ~180degF ECT?

[Shikaroka]

- what is Desired and Measured timing in degrees at ~180degF ECT?

Where do I find that?

[gmctd]

Look down thru the displayed data points till you find injection pump timing - Desired is value of advance which PCM is demanding, Measured is number read from the actual position of the Optic Sensor - Measured should be within half degree of Desired.

180deg ECT is important as PCM should not be demanding any advance at that temperature - TDCO LEARN should not function below ~170degF, altho some scantools appear to ignore that limitation.

The ko-ko routine doesn't function below 170degF - if you've done that several times and result is -0.1deg, then ECT was low, or that is where the Inj Pump is set.

Loosen and rotate it 3mm (in your case, if at -0.1deg) towards driver's-side, tighten two upper nuts, start engine, let it warm up over 180degF, shut it down, do the ko-ko routine, restart, do a scan for the new value - should then be somewhere between -1.5 to -1.94deg.

When you do the ko-ko routine, PCM is hoisting itself up by it's own petards, so the LEARNED TDCO value will be correct for the current IP position - then if necessary you can readjust the IP from there, do ko-ko again.

If the ko-ko value is not to your liking after adjusting and locking the IP down, increase engine rpm between idle and 1700rpm, use scantool TDCO LEARN command to select value up to -1.94deg - TDCO must be around -1.5deg to use this method - exit when you see the value you want.

[Shikaroka]

Thanks man! I appreciate it!

I gave up last night, but I will try again tonight.

I'm still not sure what Carcode calls the Desired and Measured pump timing values. I didn't see anything that listed those, but there are some abreviations that I don't know what they mean.

[joed]

I don't have my laptop with me, so I'll go from memory...

You'll find that most things appicable to the 6.5 are under the 'Enhanced' pulldown.

Data, for example - Click the data tab, click send - that will list the more basic parameters such as rpm, ECT, VSS, IAT. Then click the 'Enahanced' tab, then send. It will then go thru a series of screens: click GM, then scroll down and there should be about 3 listings for the 6.5 - L56, L65 Medium Duty, L65. I usuallly use the medium duty one since I have a manual trans and don't need all the auto. trans parameters. Once they all load up, you can highlight the different listings by clicking on them or using your down arrow - it will give you a description at the bottom of the window. Timing is listed as actual and desired I think.

Once you get more used to it, you can customize what parameters you want to look at and save as a 'favorite'. This allows you to read only a few (instead of the 100+) if you desire which helps speed up the sample rate of the data.

You can also use the program to set TDCO - this is under 'Tests - Enhanced'. This is a little involved and I can explain more if want to try it.

For now, you may want to try to KOKO routine first and see what you get.

Hope this helps.

Joe.

[Shikaroka]

Right on Joe, thanks!

I hope to play around with it more this evening.

Is there anything I can do, that would screw it up, and not get me home?

[joed]

Not really. It may be better to try and set the TDC at home in case you need to bump the IP. I probably wouldn't mess with the 'tests' either, until you get more familiar with how it operates.

Joe.

[Shikaroka]

Yeh, that's what I was thinking.

Thanks again, Joe!

[lifer]

The first screen shot shows what I select for my 96 K2500 Suburban 6.5TD. Depends on the eighth digit of your VIN. if "F" you have the L65 engine and use the one pictured, if "S" you have the L57 so use the one two below.

Next screen shot shows what you should see at idle. If not, follow gmctd's advice to fix it.

Note that Carcode presently doesn't display enough digits to see -1.94. I've asked the developer to increase the number of displayed digits and he agreed to do it in the next release.

[gmctd]

Excellent post, lifer - show 'n' tell rules...............

Highlight each entry and the definition will display at bottom of chart(s), as illustrated.

ECT is Engine Coolant Temp
IAT is Intake Air Temp
RPM is idle speed
BPS is MAP, or Boost - should be local Baro at idle
WGS is Waste Gate dutycycle in % - 78% indicates the wg rod will be difficult to move
FR is fuel Flow Rate - 8.1mm3 is correct for 560rpm idle
IPS is Inj Pulsewidth - 2.08 is high, or long - should be ~1.84
IPTD is Inj Pump Desired Timing
IPT is Inj Pump Measured Timing
TDCO is, of course, TDCO as indicated at the bottom of the chart

[Shikaroka]

Awesome! Thanks guys!!!
I didn't get a chance to fool with it tonight, but I hope to tomorrow evening.

It would be nice if I could get it running a little better, although I don't think it runs bad now I just don't have anything to compare it to.

[lifer]

Thanks gm - just trying to pay forward all the help you and others have given me.:)

[lifer]

"IPS is Inj Pulsewidth - 2.08 is high, or long - should be ~1.84"

Is there anything I can do to correct this?

[gmctd]

Maybe - backprobe the ESO solenoid to measure same voltage as on either battery post while idling - about 14v - ESO is on same circuit as FSD\PMD so if ESO is low, FSD\PMD is low, one of the causes for long inj pulsewidth.

[Shikaroka]

What "should" the desired and actual be?

[gmctd]

I see +8.5deg on mine at operating temperature, -1.5deg TDCO - some have posted +12deg as normal on the various scantools - I'd see +12 on the hiway at 65mph, drop back to +8.5 if I nailed it, then go back up as rpm\power increased - 'course, my TC wasn't constantly locking and unlocking and the trans wasn't downshifting , either - my T400\aux o.d. setup functioned more like the manual trans versions - just check yours regularly at various oper rpms to get the feel for your system, post your results for comparo

[Shikaroka]

I think mine was in the 10 range at idle.

I tired moving the pump, but couldn't budge it.
There are 3 nuts, right? I loosed all of those.
I have the special tool made for rotating the pump, but I couldn't move it towards the driver's side at all. (I didn't try to move it the other way.)
One of the nuts was already pretty loose.

I believe my IP is the original one.

[gmctd]

You're attempting to rotate it against the tension of 8 hi-carbon steel 1/4"dia pipes - may require some effort to do so, also holding new position while you lock it down - be sure to scribe a line across the flange in the original position, for reference - don't wanna move it more than ~2-2.5mm, hold it there till you get one of the two upper nuts cinched down

[Shikaroka]

OIC, I didn't expect it to be so difficult, but I didn't look at it that way.
I'll try again. Thanks!!

[lifer]

I use a 2 to 2 1/2 foot long pry bar to turn the pump. Try not to destroy anything you are prying against.:(