Timing VS. TDCOffset

[Brooklyn Tow]

Maybe add KOKO proceedure to the "Timing the DS4 Injection Pump" sticky/thread.....I mean if you feel like it.

 

[NVW]

No prob, and good question(s) - they will need clarification for all users of GMTDScan Tech

- BASE timing is my descriptor for the mechanical IP position wrt crank TDC, but you won't see that in any scantool

- we don't actually know (pun intended!) what that "actual" IP timing number represents, but it may be the count on the hi-res 512-slot or low-res 64-slot timing section of the optic encoder disk - iirc the parameter value just turned up in Stefan's scantool, so we discussed it and decided he should label it and leave it in there for future - it is not in the TECH2 heirarchy - I haven't tho't about this stuff in a long while, so for now just ignore "actual" ip timing in GMTDScan - 'measured' and 'desired' are the parameters of note

- GMTDScan measured is our ACTUAL, his desired is our DESIRED - some other scantools also refer to actual as measured IP timing

And, remember: TECH2 prevents any timing adjustments if ECT is below ~172*F - very few of the aftermarket copies, incl GMTDScan Tech, have that safety limit, so always do a scan to verify ECT is above that minimum before proceeding with any timing adjustments

jd

My GMTDScan displays timing as Desired and Actual in the timeset screenshot.

Leo

 

[gmctd]

Will do , louis

Welp, Leo, guess I'm gonna have ta bite the ole bullit, crack out the laptop and fire up the GMC and GMTDScan Tech - come to think of it, mine is one of the original versions, v1.0.1.0, several years old, so prolly best if you guys post up your versions, so we can all start on the same page

Lessee, I've got so many serial\ALDL\USB\DLC cables that I can't remember which is which - I've got one here that resembles a Swedish personal feminine vibrator toy - iirc, that's the one for GMTDScan Tech, but seems like there was one for GMTDScan Basic, both with 12-pin OBD1 connectors - yeah, 12-pins - I've only got 6 of those, so that oughtta make it easy, right?

I tell ya, folks - old age ain't all it's cracked up to be..............

Almost fergot: anybody wanna post up that OBD2 koko fingersy\footsie thingy, so I can at least get that right?

 

[RCpullerdude]

My GMTDScan displays timing as Desired and Actual in the timeset screenshot.

Leo

That is how mine displays in timeset, but only in timeset. In the dashboard, snapshots, everything else, it reads measured and desired. Since I'm trying to diagnose what my searches have indicated as a possible timing problem, I am using dashboard and snapshots to get all parameters during the condition, and that is where my confusion is (well, was).

Thank you for the explination, gmctd.

 

[NVW]

Will do , louis

Welp, Leo, guess I'm gonna have ta bite the ole bullit, crack out the laptop and fire up the GMC and GMTDScan Tech - come to think of it, mine is one of the original versions, v1.0.1.0, several years old, so prolly best if you guys post up your versions, so we can all start on the same page

Lessee, I've got so many serial\ALDL\USB\DLC cables that I can't remember which is which - I've got one here that resembles a Swedish personal feminine vibrator toy - iirc, that's the one for GMTDScan Tech, but seems like there was one for GMTDScan Basic, both with 12-pin OBD1 connectors - yeah, 12-pins - I've only got 6 of those, so that oughtta make it easy, right?

I tell ya, folks - old age ain't all it's cracked up to be..............

Almost fergot: anybody wanna post up that OBD2 koko fingersy\footsie thingy, so I can at least get that right?

That's the right one JD, with the toggle switch for low, medium and high
I have version 1.0.1.0 and 1.2.0.0 on my laptop. My key # is 50 for comparison sake.

Leo

 

[NVW]

That is how mine displays in timeset, but only in timeset. In the dashboard, snapshots, everything else, it reads measured and desired. Since I'm trying to diagnose what my searches have indicated as a possible timing problem, I am using dashboard and snapshots to get all parameters during the condition, and that is where my confusion is (well, was).

Thank you for the explination, gmctd.

Correct RC. There is also an Actual timing value in the screenshot, it's a much higher # than the measured and desired values.

Leo

 

[Diesel -T]

Have noticed on screen shots posted on the site that "actual " seems to be always 22degrees difference to Desired/Measured .

 

[gmctd]

BTT - anybody down and pat on the koko fingersy\footsie thingy? Need to post it up for reference - iirc, it's key on-key off several times while mashing the loud pedal for umpteen seconds or so

 

[buddy]

TD has a write up on how to do KOKO somewhere

 

[OregonHorseTug]

BTT - anybody down and pat on the koko fingersy\footsie thingy? Need to post it up for reference - iirc, it's key on-key off several times while mashing the loud pedal for umpteen seconds or so

1. Mash pedal to floor then
2. Key ON 45 seconds (I give it a minute)
3. Key OFF and release pedal for 30 seconds ( I give it 45 seconds)
4. Start sequence as normal (glow plug time) and should get a stumble as PCM learns timing

 

[gmctd]

Thanks - to be clear, is sequence 3 'release pedal for 30 seconds' or 'release pedal after 30 secs'?

 

[NVW]

Thanks - to be clear, is sequence 3 'release pedal for 30 seconds' or 'release pedal after 30 secs'?

Release for 30 sec.

Leo

 

[OregonHorseTug]

Thanks - to be clear, is sequence 3 'release pedal for 30 seconds' or 'release pedal after 30 secs'?

I meant to say: (KEY OFF and release pedal) for 30 seconds.

Probably should have written it like this:

1. Mash pedal to floor and hold it there
2. Key ON 45 seconds
3. Key OFF
4. Release pedal
5. Wait 30 seconds
6. Turn key and start engine after glow cycle

The KEY OFF is the (ahem) "key". You can probably release the pedal at any time as long as you don't have the pedal down when you turn the key to start the engine. My programming experience tells me the PCM doesn't see the pedal position unless/until the key is on. Sort of like the CTRL key on your computer keyboard. Holding the pedal down then turning key on for 45 sec = set the relearn bit. Then key off for 30 seconds latches or completes the relearn bit set. I don't know if you released the pedal after turning on the key would have any affect on the sequence, but maybe.
Of course all this "I think", "probably", and "maybe" us useless for your sticky..:sleep:...but someone could try it out ..:crazy::conehead:
The sequence above works for my truck

 

[gmctd]

Don't forget: key off is just IGNITON off, meaning engine won't run - PCM still has several keep-alive circuits connected to fused battery supply, so it's watching even when you think it's asleep - the procedure initializes TDCO LEARN, and precludes some accidental combination resulting in unwanted initialization

 

[OregonHorseTug]

Good point.
Man, I wish I had the time and equipment to root through the code on one of these PCMs.

 

[gmctd]

Ok, thanks, lookin' good - I'll copy and addend that as-is