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Timing VS. TDCOffset

TDCO limits are +2.50* to -2.50*, as I stated

Also, as I stated, DTC limit is ~ -2.20* for OBD2, less for OBD1

The consensus of moderator opinion, Buddy, is that you need to

a - commit the posted DS4 timing procedure to memory - it is correct in scope and intent, performed with a new TECH2 - the details are fuzzy, but, iirc, GMTDScan Tech duplicated TECH2 function, per Stefan's corrections and updates
b - study it till you get it right - it is correct
c - the problem is you not understanding Diesel technology vs gasser (patooie!) operation, not understanding Diesel injection function, not understanding DS4 timing procedure, all while also trying to learn GMTDScan, and trying to learn that and an afermarket chip - the resulting responses are confusing to all, because you use them to cast doubt on posted information - it is your input that is differing from standard DS4 timing procedures

The 6.5 runs well if the IP is correctly timed - if we determine that GMTDScan Tech functions differently than I've already posted, we can add that to the sticky thread in a separate GMTDScan response, incl differences, if any, encountered with the ENGH chip - same can be done for any other scantool or tune, long as the data is correctly posted - you know: correct decimal placing, correct value signing (+\-), etc and etc.....................

Remember, folks: I am dyslexic, and easily confused..........
 
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Correct, as OBD1 will also relearn any IP offset change within that period - the statement was intended as humor, but with a point: while not many people are gonna take 50 tries to get the timing adjusted in TIMESET before doing TDCO LEARN, don't dawdle - if the last setting was out of spec when PCM auto-learns TDCO, the resulting DTC will prevent further progress, and could even render the engine non-startable\runnable

FYI, Buddy, it's not a bad thing that your timing observations differ from standard procedures and results - we just need to understand why they differ, then define and post the alterations resulting from your chip\scantool setup in order to help others with duplicate setups

Back when some began posting their DES\ACT timing at +10.5* at idle, it took us several months, due to the infrequent acquisition of new tunes and subsequent posting, to understand that some vendors had begun offering tunes with altered timing matrices and other stuff, rather than the quick and dirty method of just turning up the fuel and Boost - the underlying actuality was that programmers were beginning to understand the Stanadye DS4 injection system, thereby turning out more sophisticated tunes - the easy availability of equally-sophisticated bi-directional aftermarket pcware scantools was allowing 6.5 EFI retuning to flourish and prosper
 
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I've been covered up, we have a big shop certification going on at work, but quick summary to what I found out this weekend, (more details to come when I have time) idle timing is function of the program on the PCM, when I 1st plugged in scanner I did time set with my Heath PCM avg was 1.8 timing had been 10.8 out of time set, then rotated IP set to 0 avg actual, came out of time set idle timing was 10.8 still desired/actual.

Went back into time set adjusted IP for 3.5 deg avg actual, and out of time set time still 10.8,

I had a stock 96 PCM as soon as I plugged it in desired/idle went to 8.5 per factory spec, in time set the avg was 3.5. This confirmed something I had done several years ago and forgot until GMCTD reminded me we hadc looked at this before, that different programmers have established their own idle timing parameters which may be higher than factory 8.5 baseline.

Also I recall a programmer once telling me they have ability to make a displayed value be anything they wish, and that what you see on a scanner may be true or just what the programmer wants displayed so their exact tune can't be easily copied.
 
As far as the 50 cycles thing goes, IIRC it isn't 50 key on/off events, it's 50 warm up events, where engine goes from cold thru minimum operating temp >170F, I think coincides with some of the adaptive learning features of a PCM
 
Turbine Doc said:
As far as the 50 cycles thing goes, IIRC it isn't 50 key on/off events, it's 50 warm up events, where engine goes from cold thru minimum operating temp >170F, I think coincides with some of the adaptive learning features of a PCM
Click to expand...

What I wanted to confirm was that OBD1 does TDCO relearn every 50 cycles. Because when I do TDCO set, it goes all over the place and never lands on the same value if I let it do its own thing. So I'd be surprised if it is done every 50 starts and end up the same each time. Or perhaps thats disabled in the tune.
 
OBD1 TDCO self-LEARN will do the calcs at idle, not at increased rpm, in that respect like the OBD2 KOKO procedure - your observed variations may be due to your setup, which is why I suggested using the oem chip for learning and comparison - I would normally expect some slight variation due to timing chain slop, but your engine is rather low-wear, compared to most, if only 88kmi - main reason why I installed the DSG timing gearset, early on, to eliminate guessing

Long as it's on the table, PCM automatically adjusts for timing chainset wear, where IP encoder disk TDC falls behind crank TDC as the chain link-pivots and sprockets wear - the chain does not stretch, but functional length does increase as the pivot-pins and pivot-bores in the links begin to wear - link roller diameter and sprocket pitch diameter also decreases as mileage accumulates, further "enhancing" timing chainset "stretch" - overall effect is retarded camshaft and IP timing - PCM corrects for that, but when installing replacement IP, driveability results will be much less than if timing chainset (chain and both sprockets) is also replaced
 
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gmctd said:
.. - PCM corrects for that, but when installing replacement IP, driveability results will be much less than if timing chainset (chain and both sprockets) is also replaced
Click to expand...

..so, now I'm thinking that with my 244k mile timing chain set I might see some improvement if I changed it? Hmm, another project :D ..well, maybe this winter; too much horse pulling to do right now.

I suppose with a breaker bar on the crank and looking down the oil filler pipe I should be able to rotate the crank back and forth and see if the cam sprocket has any lag? (I haven't looked to see if I can actually see the timing chain through the oil filler pipe)

oops..thread hijack... ):h ..P-)
 
If you pull the oil-filler tube, the center area of the IP timing gear can be seen - you can rock the crank back'ards and for'ards and get a sense of any timing chainset wear by observing resultant movement there - you can barely see the timing chain if you remove the waterpump and it's backing plate from the timing cover - hopefully you don't have 244kmi on the waterpump, also?

BTW, if you're indicating that your injectors pop at 2700psi, you can expect way increased mechanical wear inside the IP - Stanadyne spec'ed ~1850psi to extract maximum mileage from the DS4 camring and pump-plunger rollers - while 2050psi or 2250psi gives better spray pattern than 1850psi, resultant increased mechanical wear pushes increased metal contamination thru the rotor\distributor and even more thru the injectors as the rotor\distributor deteriorates - the greater the increase, the greater the wear - increased hydraulic pressure also increases loading on timing chainset
 
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Ah-ha, new information! I've been wondering what the practical limits are on pop pressure. Bill Heath agreed that I was playing roulette with my IP and suggested I put them back to 2050. Also interesting is the Stanadyne web site talks about the DS peaking at 7250# (I realize peak is not pop pressure). The shop I'm working with said there are applications where the DS was pushing injectors at 3k so I thought I'd be reasonably safe. Nevertheless, after a year with these I'm putting a set together at the 2050 spec. Loosing my nerve I guess :rolleyes5: and it sounds like I've got one that is a bit off, particularly when it's cold. The MPG didn't improve as much as I would have liked for the added risk/wear. The IP was new before I got the truck in '07 and only has about 30k on it now.

..and the water pump was new in '05...PO had some great service records.

Mike
 
gmctd said:
BTW, if you're indicating that your injectors pop at 2700psi, you can expect way increased mechanical wear inside the IP - Stanadyne spec'ed ~1850psi to extract maximum mileage from the DS4 camring and pump-plunger rollers - increased wear pushes increased metal contamination thru the rotor\distributor and even more thru the injectors - increased hydraulic pressure also increases loading on timing chainset
Click to expand...

I have been asking that question on every Marine Injector thread i've seen.... I thought it may. I'll never think twice about getting them again........

Thanks again for all your recent activity. DTR should be paying you :)
 
pressure and volume again, but if the pump runs 3000psi regardless it wouldnt matter if they pop at 1800 or 2700. What is the pumps range? and what pressure does it hit if the injectors pop at 1800? They could pop at 1800 and the pump still reach 6000psi, hypothetically. The nozzle size would change how much it works, if the nozzle is larger then the pump would have to pump more volume to maintain 6000psi. But thats how you would get more fuel too.
 
Untrue again, Buddy, and equally confusing to those with inquiring minds - the injectors set injection pressure in it's entirety, no if's, and's, or but's about it

- the system will have 1850psi press if the injector springs are calibrated to 1850psi

- the system will have 2275psi press if the injector springs are calibrated to 2275psi

- the system will have 2700psi press if the injector springs are calibrated to 2700psi

- the system will have 6950psi press if the injector springs are calibrated to 6950psi

- etc, limited only by IP pumping pressure - CRD's for instance run at ~5000psi at idle to ~22000psi at traffic speeds (see my CP3 threads in the DMax and Cummins sections for more info\comparison) ..........

At the risk of repeating myself (ad infinitum:rolleyes:), injector calibration sets system injection pressure - nozzle size determines the rate of injection, how fast the fuel passes thru the injector and into the cylinder - fe, marine injectors usually also advance injection timing because it takes less time for 69mm3 to get thru large marine nozzles than thru the smaller oem nozzles - those are sometimes also referred to as hi-flow injectors - hi-pop injectors are usually those selected to be at the high end of their calibration, ~2075-2250psi - hi-pop hi-flow injectors are selected for both of those qualities

As stated earlier, the DS4 could go as hi as ~7000psi, maybe on the flowbench, but that may be part of the final calibration to check for leaks in the pumping plungers to bores dimension, and the rotor to bore dimension, and is certainly not intended for end-use

Again, Buddy, it would really help matters if you would ask, rather than making erroneous statements intended to indicate expertise
 
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That could happen if there happens to be a chunk of some foreign material in the fuel stuck in the injector
Otherwise, as the pumping plunger roller rides down the camring ramp from outermost plunger position to innermost plunger position, PCM closes the Fuel Solenoid valve, allowing fuel pressure to build in the injector pipe connected to the injector until calibrated injector spring pressure is reached, which at that time passes fuel thru the injector into the cylinder - PCM opens the Fuel Solenoid upon reaching the required metered volume (idle to fwot), releasing excess fuel and pressure back into the IP reservoir\accumulator, ending the injection event - residual fuel pressure in the injector pipe is prevented from dropping to 0psi by a one-way valve at each port on the fuel distributor, thereby reducing pumping time during subsequent injection events for each cylinder

So, no, the DS4 IP does not build up 2000psi in order for fuel to breach the 1850psi spring-loaded "valve" in the injector - remember: when the injector "pops", the pumping plunger rollers on the ramps stop building pressure and start producing volume at that pressure - the FSol controls that volume
 
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The sticky version is in final revision(s):eek:lcoot: - read it and weep - if any further questions or clarifications, state them here and I'll respond here :soapbox and append any pertinent significance in that thread for posteriority's sake...............
 
Gmctd, I've read over your sticky on setting the timing/TDCO on the electronic 6.5's. I am left with some confusion though on the Base, Actual, and Desired. I have GMTDScan Tech, and all it lists is actual injection pump timing, measured injection timing, and desired injection timing. I was wondering how these align with base, actual, and desired? I was thinking actual=base, measured=actual, and desired=desired, since my actual is around 27*, my measured around 6 and desired around 5, with TDCO being at -.79. Sorry if I missed it somewhere in your post. Any help is appriciated. Thank you.
 
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
 
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