My 96' pump is set to the factory spec's so is it safe to move it the 2.5mm toward driver side.What are the real benifit's too this?
Thank's

Timing is advanced ~5 degs (retarded 6* for emmissions). This means the fuel is injected at ~8.5*'s before the piston hits top dead center. By the time the cam rotates around to ~13*'s after TDC and opens the exhaust valve, the fuel has had ~22*'s to completle combustion. Egt's will run lower, torque is improved.

Timing is advanced ~5 degsIts electronic, it doesn't work like that.
Advancing or Retarding the pump simply put, just changes the operational advance range the pump will function in which will ALWAYS be in the same range relative to the crank, and if you go out of that specified operating range you get a TDC Offset, Pump Rotor Cam Problem, or Stepper Motor code.

Can you elaborate on that. I was thinking once tdc offset was relearded the range was reset.

Timing is advanced ~5 degs (retarded 6* for emmissions). This means the fuel is injected at ~8.5*'s before the piston hits top dead center. By the time the cam rotates around to ~13*'s after TDC and opens the exhaust valve, the fuel has had ~22*'s to completle combustion. Egt's will run lower, torque is improved.
So then is this just for 4911's?

As QM said,i to thought it would relearn after you moved the pump 2.5mm from what i have read on some of the forum's.

Can you elaborate on that. I was thinking once tdc offset was relearded the range was reset.Yes, if you move the pump you change your TDC Offset. If you go too far you will not be able to relearn a new Offset and you will get a code.

TDC Offset does not denote a change in injection timing, its not a value thats added into your injection timing, its just a number that tells the ECM that pump is or isn't physically in a place where it should be able to operate the advance mechanism to meet its demands.

There are only 2 ways to actually change your injection timing, either by changing the pump (optic bump) or the ECM (reflash).

Rotating the IP +5deg rotates the distributor, advancing the mechanical timing relative to crank TDC.

At resulted +8.5deg base timing (DESIRED), TDCO relearns to -1.5deg, which is the electronics version of TDG's 'bump' - alters the point on the ramp where injection pressure starts building, which is required to fit the narrower 'window' required at upper rpm by the advanced distributor timing.

Because the 'bump' is electronic, and recognized -'learned' - by the PCM, it does not cause any problems at lower rpm, including idle.

OEM timing is +3.5deg, max adv to approx +12.5deg - new timing is +8.5deg with max adv of approx +17.5deg - can go to +19deg, cruise, no load, with the 3.73 and 4.10 gearing.

At 3500rpm, injection pressure must be reached much quicker than at 700 idle rpm - advancing mech and elect timing requires that injection pressure be reached even quicker - TDCO accomplishes that function.

-0.5deg TDCO works at 3500rpm with +3.5deg base timing; +8.5deg base timing requires -1.5deg TDCO at 3500rpm.

If you want a little more advantage at 3500 rpm, TDCO can be manipulated to -2.4deg in the OBD-II PCM's, -2.0deg in the OBD-I PCM's without causing DTC's, while maintaining the +8.5deg base timing setting.

As that ball-pein hammer sound in the 6.5's is the hammering in the pre-cups, the harsh rattle associated with that much TDCO is rather scary, particularly on a cold morning, so, wuss that I am, I chose -1.5deg TDCO as safe mode with 22.5:1cr.

The hammers are not quite as busy in the 18:1cr motors, but I think that level of TDCO is not safe for towing\hauling, or any other continuous away-from-home use.

...Changing TDC Offset does NOT CHANGE running advance of the pump relative to the crank, it ONLY changes the operating advance range the pump will function in internally. It will not affect your TIMING, if you go far enough that it does you will set a code.

The PCM will calculate your DESired advance movement, and it will move the stepper motor to get the ACTual advance. DES and ACT are both relative to the crank, not relative to the position of the pump.

Re-read it a hundred times, or more, till it soaks in, TDG - contrariness is often a sign of misunderstanding.:cool:

BTW, FYI, IIRC, and a BUNCH MORE abbreviations, QM - exhaust valve opens ABDC following the combustion\power stroke, not ATDC

my bad I didn't look it up just off the top of my head.
BTW, FYI, IIRC, and a BUNCH MORE abbreviations, QM - exhaust valve opens ABDC following the combustion\power stroke, not ATDC Actually I did look it up and we're both wrong. The exhaust opens ~39*'s BBDC

By the sound's of it,i will leave the timing alone:badidea: .I'am not up on working's of the pump like u guy's.So i will live with the factory spec's..

Doesn't require looking up, QM - requires a basic understanding of 4-stroke engine function.

That's a part of what I meant by - thinking outside the box requires an understanding of what's IN the box.

IMO, you're doin' all-around better - hang in there...........

Also been noticing TDG's posts indicate someone up in the great white north is much more knowledgeable on the several 6.5 EFI systems, as well as how they work together..

Don't think Stanadyne is relaxing their stance, so must be them crazy canucks up there don't care much for American moratoriums - cain't say as I blame'em, any.........

There you go again GMCTD, using big words and confusing us Canucks again.

American moratoriums? I think i need a dictionary...:confused:

Sub5 - positive results of this are dependent on conditon of your engine, Inj Pump, and timing chain set.
Also requires improved exhaust system, which often results in performance increase by itself.

Moving the IP 2.5mm to driver's side will get you +5deg advance - the PCM will relearn the required parameters with a simple manual 'learn' routine involving the Ign Seitch and the accelerator pedal.

Doing the OS 'bump' will give you similar, using the same 'learn' routine.

Not sure how the two - 2.5mm mechanical advance AND 1mm OS 'bump' - will work together, as each separately results in -1.5deg TDCO.

Your OBD-II system will DTC at -2.4deg TDCO, so you might axe TDG fer some input on that.

Means EPA, and C.A.F.E., and such, CR, vs MORE POWER............
;)

What about the measured or actual timing moving relative to the crank? Doesn't the injection event come earlier at 8.5*s and advance from there? The advance rate/curve dependent on ECM program charts?

Making sure where all looking in the same box.

Yes - advancing the Inj Pump increases minimum DES\ACT injection timing, and the PCM can call for increase from there.

I have not observed DES\ACT go below +8.5deg after the adustment.

Most OS bumps have been done with stock oem +3.5deg timing - but not doing the mechanical 2.5mm distributor advance.

A few weeks back, TDG stated reading -1.5deg TDCO after the 'bump', but did not indicate any DESIRED, or base, timing increase

OK GMCTD...

I have been following the 'Timing Two-Step' saga on this and other threads on this and other boards, and I finally gots ta ask the burning question...

When I take my truck in to a dealer to set the timing, what EXACTLY do I tell them I want to do?

Do I tell them "I want the base timing set to +8.5* and the TDC Offset set to 1.5"* or what? I just don't know how to word it for them (Assuming of course I can get them to do it outside of their 'factory specified' values)

Tim

Good question, the other Tim\Cr -

Just tell him to give you -1.5deg TDCO, and observe what he does - post the procedure here.......

Or -

First, you'll need an initial scan to see from where you're starting.

If starting from +3.5deg DES\ACT with -0.5deg TDCO, (they are displayed real-time when the scanner is connected) which is factory stock setting, have him move the Inj Pump 2.5mm to driver's-side.

Do TIme Set command (don't worry about any displayed readings in this mode)- when finished, DES\ACT timing will display +8.5deg
Time Set appears to be a required function in OBD-I, but not OBD-II

Do TDC Offset Learn, will display around -1.5deg TDCO
TDCO Learn is commanded in OBD-I, can be initiated in OBD-II by key\accel pedal procedure, but 'command' function response is erratic

To get greater TDCO value, do TDCO Learn, rev engine some rpm below 2000, end TDCO Learn when the desired value displays.

Do not go greater than -1.94, to prevent DTC's on OBD-I

At some point above 1500rpm in TDCO Learn command, PCM will DTC for TDCO - use Tech-X to clear DTC, then start TDCO Learn again.

+3.5deg\-0.5deg factory setting gives economy and power within emissions specs

+8.5deg\-1.Xdeg increases\flattens torque curve to 2500rpm, raises HP curve to 3500rpm with hot-chip, charge-air cooler, larger exhaust- check rj's dyno charts to see.........

Oh..you guys are KILLING ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!

Too many things getting lumped together and facts are getting smudged over.

Base Timing - is the value that is displayed while you are performing the TIME SET function on ANY SCAN TOOL, Desired is 3.5 deg advance before TDC (Cam vs. Crank Pulse)

TDC Offset - A value determined by the PCM that is the difference, in deg, between full retard position of the pump (optic, cam pulse, lo res) and 3.5 deg before TDC (crank pulse)

DES timing - Determined in real time by the PCM based on sensor inputs and programming. DES timing DOES NOT change or compenstate for TDC OFFSET OR BASE TIMING. Rather, Base timing is a function to 'ball park' the pump to set the TDC Offset so the PCM knows the Pump is in a position where it can manipulate the pump to get all possible DES timings it might request.
Set your TDC offset to -.1 or -2.0 and you DES timing will not compensate, only move the pump's internal advance via the stepper motor/advance mechanism to achieve (ACT) the DESired advance.

Interesting discussion - wish I understood what is being said. However, along this line, can you (any or all of you) answer this question on timing and the hidious hammering or whatever and how to cure it. Engine is a 99 in a 3/4 sub (do not know cr) which rattles (hammers) when cold, at speed when warm, and most of the time. Friendly (not a 6.5 specialist) mechanic says it is timing. Vehicle is a spare vehicle, used sparingly (53,000 miles - now gets about 2,000 miles a year put on it), don't care about power (has 4:11 gears), and is in otherwise new condition. Has rattled since I bought it with 19,000 miles as a GM exec vehicle in 2000. All I want to do is quiet it down like the rest of my 6.5's have been. Suggestions? Thanks in advance.

Thank's for asking Cowracer,that was one of the question's in the back of my mind and Gmctd thank's for the answer's again.

garnder, start a new thread on your truck.
I suspect you won't find an easy solution though, '99 ECM is quite different than previous models and does run the engine noticeable louder.

I have been using the term 'base timing' to refer to the minimum timing the engine runs with, usually +3.5deg factory DES\ACT, some other value when performance tuned, usually +8.5deg DES\ACT with TDCO of -1.5deg.

I have observed this : in Time SET, PCM DESIRES 0deg, but Inj Pump\distributor has been physically adj at the factory to +3.5deg BTDC, so +3.5deg ACTUAL is displayed.

Physically increase advance - rotate the IP - by +5deg, to +8.5deg, Time Set indicates PCM is calling for 0deg DESIRED, and the displayed ACTUAL value then fluctuates all around the +3.5deg value, but never displaying any specific value.

Exit Time Set command, and DES\ACT displays +8.5deg - any required advance is then based on the new +8.5deg value, will display up to +18-19deg DES\ACT cruising no-load.

The distributor is now +5deg more advanced relative to rotor TDC, which is mechanically timed to crankshaft TDC.

Now, here's the big problem - the Inj Pump has been physically advanced by +5deg from factory-set +3.5deg, to a new position of +8.5deg.

How does the PCM determine that the OPTIC SENSOR is now -1.0 deg more retarded, when the IP body, distributor, and cam-ring\advance piston has been moved +5deg more positive?

And why, when your mechanical 'bump' physically retards the Optic Sensor position on the cam-ring, does TDCO reset to -1.5deg, with DES\ACT +3.5deg.

In the immortal words of Ricky Ricardo - 'splain me that, Lucy............;)

***************
Gardnerteam - the '99 PCM is the hottest of the factory programming - previous owner probably had TDCO set to -1.94deg for added performance.

Take it to a dealer, or someone with a TECH-II, for a reference timing scan - that will also check ECT and advance timing stepper motor function.

Almost fergot - poor fuel quality can givie the same result.

GMCTD, I have a lot of respect for you and your experience, but I am 110% positive on this.

If you watch the scanner, any scanner, any 6.5, your DES timing @ idle speed will change mostly with engine temp, cooler -> more advanced. Fully warm, on ALL of them, reguardless of TDC Offset, DES timing will be ~8.5 deg.

I'm pretty sure I know exactly what screen your looking at, and where the misinterpretation is coming from. When you first enter 'Time Set' mode, the DES timing is displayed, and since the engine is warm and you havent hit the button to start 'Time Set', your DES says ~3.5 and ACT reads ~8.5. When you hit the button, your ACT drops to ~3.5 give or take what ever your TDC Offset is approx and fluxuates a little.
All in the world this means, is the scanner is telling you it WILL command the pump to full retard position which should be ~3.5 BTDC (DES), but until you hit the button, the PCM is still controlling advance movement.

If you revisit your scanner, maybe play with someone elses truck a while too, I honestly think you will see what I mean, you can't cheat it, if you could go in and advance the pump 5 deg across the board, it would be unbearably loud, and prone to overheating and eventually crack something in the engine.

Now, about the optic 'bump'. The PCM has no idea that you've gone in and moved your optic sensor, because again its referencing cam movement inside the pump by reading the Lo Res pulse and comparing it to Crank Pulses.
The 'bump' uses this to our advantage. The PCM is programmed to operate a pump specifically calibrated to deliver Xcc of fuel @ X pulse width.
What the bump does, is make the pump put out (X+1)cc of fuel with the same pulse width.[/QUOTE]

Fair enough - guess I'll do some 'splainin', then, because when the IP is rotated 2.5mm to the driver's-side, the pump assembly IS advanced by +5deg, and the rattle is considerably noisier at the newly 'learned' -1.5deg TDCO.

The advance includes everything but the rotor, which is tied to the camshaft by the gears, thence to the crank by the timing chain set - immoveable, fapp.

The 6.5 does begin to sound more like a Cummins if TDCO is further 'learned' to -1.94deg, which is easily done with Tech-II, my choice of weaponry.
Not shaken, but stirring.

When the +5deg mechanical advance results in +8.5deg DES and ACT, which it does, TDCO always 'learns' to -1.5deg.

Next, factory setup procedures.

to be continued..............

A new engine is placed in the Test Stand, primed, loaded, started, run up to operating temperature.

The Inj Pump is then physically timed, using a microwave setup, to +3.5deg while the engine is running.

Advance is then checked for +\- 11deg, for 22deg total movement, referenced to the crankshaft.

Engine is placed in target vehicle, connected, started, and new PCM 'learns' TDC Offset of -0.5deg.
Des\Act is checked at +3.5deg.

This is how new owners get their truck - injection timing is +3.5deg BTDC, TDCO is -0.5deg.

So - let's hook up the Tech-II to see what has changed after being on the street for awhile.

Enter DATA DISPLAY

ECT........................177deg
IAT.........................105deg
Inj pulse width..........1.88ms
Des Inj Pump...........+3.5deg
Measured Inj Pump...+3.5deg
TDC Offset..............-0.5deg
Des Idle....................694rpm

Looks good, let's tweak it - DSG gearset, TDCO of -1.94.

Rotate the Inj Pump 2.5mm to driver's-side, lock it down.
Crank it up, Des\Act still at +3.5deg, TDCO at -0.5.

Select SPECIAL FUNCTIONS, enter.
Select F0 ENGINE OUTPUT CONTROLS, enter
Select F0 INJECTION PUMP, enter
Select F0 TIME SET, enter

Command State: None
Desired injection pump........+3.5deg
Measured inj pump.............+3.5deg

Press 'ON'
Command State: On
Diesel rattle quietens
Desired inj pump.................0deg
Measured inj pump............+3.0deg to +5deg, varying all around, no specific number

Press 'OFF'
Command State: None
Desired inj pump = 0deg
Measured inj pump...............varying between +3deg and +5deg

EXIT TIME SET, re-enter TIME SET
Diesel rattle comes back, little louder
Command State: None
Desired inj pump..................+8.5deg
Measured inj pump...............+8.4deg

Exit TIME SET
Enter DATA DISPLAY
Des\Act....+8.5deg
TDCO........-0.5deg

Back to SPECIAL FUNCTIONS
Enter F3 TDC OFFSET
Command State: None
TDC Offset.....................-0.5deg
Desired inj pump..............+8.5deg
Measured inj pump............+8.5deg

Press 'ON'
Command state: On
Rattle quietens
Engine idle drops, skips, returns
Desired inj pump..................0deg
Measured inj pump.............+3 to +5deg,varying
TDC Offset........................-1.5deg
Rev engine slightly, TDCO starts varying
Press 'OFF' when -1.94 value is displayed.
Engine skips, hesitates, rattle becomes very loud, harsh

Exit SPECIAL FUNCTIONS
Enter DATA DISPLAY
ECT.......................180deg
IAT........................104deg
Inj pulse width..........1.88ms
Des inj pump............+8.5deg
Meas inj pump..........+8.5deg
TDC Offset..............-1.94deg

Later, with cooler weather in the Fall, reduced TDCO to -1.5deg because the rattle was very scary, Harry - not my cup of tea, as it were.

Did same function when replacing orig 5288 with 5521 inj pump, same results, still at +8.5deg Des\Act and -1.5deg TDCO, even as we type.

Essentially same results with OBD-II, but OBD-II doesn't like TIME SET function - just requires manual TDCO 'learn' routine, and can be further Offset with Tech-II.

OBD-I and OBD-II learn -1.5deg TDCO with +2.5mm inj pump rotation to +8.5deg Des\Act timing.

2.5mm inj pump movement does rotate the distributor to a point +5deg more advanced wrt TDC, for +8.5deg total BTDC.

Diesel rattle is louder.

Oh..you guys are KILLING ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!

Too many things getting lumped together and facts are getting smudged over.

Base Timing - is the value that is displayed while you are performing the TIME SET function on ANY SCAN TOOL, Desired is 3.5 deg advance before TDC (Cam vs. Crank Pulse)

TDC Offset - A value determined by the PCM that is the difference, in deg, between full retard position of the pump (optic, cam pulse, lo res) and 3.5 deg before TDC (crank pulse)

DES timing - Determined in real time by the PCM based on sensor inputs and programming. DES timing DOES NOT change or compenstate for TDC OFFSET OR BASE TIMING. Rather, Base timing is a function to 'ball park' the pump to set the TDC Offset so the PCM knows the Pump is in a position where it can manipulate the pump to get all possible DES timings it might request.
Set your TDC offset to -.1 or -2.0 and you DES timing will not compensate, only move the pump's internal advance via the stepper motor/advance mechanism to achieve (ACT) the DESired advance.

Thanks for elaborating once again. Evertime I think I understand the timing on this truck I have to rethink it but it does seem clearer to me):h

What about the relationship between the Fsol,PMD and timing and the bump. Is it possible to set DTC 36 from too much optical advance or a faulty FS driver? or is the Fsol just showing it's wear? On DavidW's truck it'd DTC36 and everytime you let off the pedal after WOT and Fuel delivery went to 0 mm for ~5-8 seconds them back to 5mm but no surging or anything erratic other than DTC 35 as well a few times. Other than that it ran like it should.

When the IP is rotated 2.5mm to the driver's-side, the pump assembly IS advanced by +5deg, and the rattle is considerably noisier at the newly 'learned' -1.5deg TDCO.

The advance includes everything but the rotor, which is tied to the camshaft by the gears, thence to the crank by the timing chain set - immoveable, fapp.


Let's go a little further with this and I think I can explain it better. This is an ELECTRONIC pump. The Optic sensor is bolted to and moves with the Cam Ring and reads the data disc that turns with the driveshaft that turns the rotor.

Start of injection is not dependent on rotor position at all, the trailing port in the rotor is open to the delivery port in the head over a LONG duration so fuel delivery can start/end at any time in that window as dictated by the poppet valve which is controlled by the Fuel Solenoid, powered by the PMD, controlled by the PCM.

The cam pulse the Optic sensor gets from the data disc is the signal to the PCM to start injection and energize the poppet valve, when the rollers hit the ramp and push fuel through the rotor, THAT is your SOI. Thats how the 'bump' works, what your actually doing is moving the start of the cam ramp closer to the optic sensor pickup and means your SOI is now earlier (advanced timing) and because the duration is controlled by the PCM and is unchanged the fuel delivery quantity is increased. Basically, whatever the PCM decides it wants for fuel, it gets that + the change in optic sensor position.

So let's say the PCM is commanding 50cc of fuel from the pump and you bumped the optic 2cc, your really getting 52.
Let's say before the bump, at L.I. your fuel rate showed ~9cc, and after the bump it shows ~7cc. The engine doesn't magically need less fue to maintain idle, the bump has offset your fuel quantity by 2cc, the PCM thinks its delivering 7, but its getting (7+2) 9, which is the original value.
Its an offset is all it is, the increase is higher % at lower end than at the top, which is the main limiting factor.

What about the relationship between the Fsol,PMD and timing and the bump. Is it possible to set DTC 36 from too much optical advance or a faulty FS driver? or is the Fsol just showing it's wear? On DavidW's truck it'd DTC36 and everytime you let off the pedal after WOT and Fuel delivery went to 0 mm for ~5-8 seconds them back to 5mm but no surging or anything erratic other than DTC 35 as well a few times. Other than that it ran like it should.

Fuel Solenoid and PMD operate completely normally, 'bump' has no effect on them.

Timing changes in 2 ways. (DES/ACT are unnaffected, still PCM controlled)
Actual injection is a hair advanced, a degree give or take depending on how far you go.
TDC Offset moves to a lower value (more neg) than before, again, correspondant to the change in optic position.

I'm done 'splainin', TDG - check it out, edited above to maintain continuity............

....I think your scanner's broke ;)
I just did a PMD in a '97 and a pump in a '98 today and played with the scanner/TDC Offset some more today.
TDC Offset on both trucks was ~-4.0 deg, still hot when I scanned them, DES/ACT timing on both showed in the 8.5 deg range.
After I finished working on them, they cooled, retarded the pumps on both a hair to get the TDC Offset more where I like it, and both trucks showed a DES/ACT timing of about 12.5 deg while cold, why??? because DES/ACT have nothing in the world to do with TDC Offset, the PCM called for advanced timing because the engines were cold.
Took them for a test drive to warm them up and check TDC Offset, one -1.5, one -2.0, and both showed the same DES/ACT timing as when they came in warm, about 8.5 deg.

The advance mechanism is completely PCM controlled, and is calculated cam pulse vs. crank pulse and adjusted via the stepper motor.
Adjusting TDC Offset within specifications will not change DES/ACT timing on the scanner or in reality. The pump was designed to meet emissions specs, thus, the PCM controlled advance that cannot be cheated by adjusting the pump.
THe pump has an advance range that is much greater than the PCM will demand, thus, the large window of allowable TDC Offsets which the pump can function normally within.

So, you're saying both trucks were hard into the DTC for excessive TDCO?
As you may know - OBD-II will DTC at -2.4deg TDCO, where OBD-I will DTC at -2.0deg.
Observed, in person.......

What you're talking is cold advance - and, as you know, once TDCO is 'learned', it does not vary for any level of PCM-demanded advance.

If TDCO is wrong for any adjusted positional Actual timing, for whatever reason, PCM will relearn a correct value over a number of re-starts - OBD-I is within 50 re-starts.

As you can see, my ECT was always above minimum required for TDCO 'learn', which means no 'cold advance' was in effect at any point in each selected procedure.

As you can see, my ECT was always above minimum required for TDCO 'learn', which means no 'cold advance' was in effect at any point in each selected procedure.
I know, thats why you always got ~8.5 deg DES/ACT timing, you were at operating temp, put a scanner on your truck while its cold, it will say ~12 deg, they all will.

About the other trucks...
NO codes tripped, but I agree with you, by all rights they 'should' both have tripped a TDCO code, but they seemed perfectly content...?
TDCO is TDCO, hot cold, doesn't matter, its the Offset between the pump and crank, nothing else.

Were you using a Tech-X, or other scanner-type?

MT2500, and no, I don't like it either, much prefer the Tech-series, I have a considerable amount of experience using them and I miss it.

Aha! I sorta suspected that, when you posted reading -4 deg on both trucks.

Iirc, Turbine Doc's MT2500 read -4.3deg for -0.5deg on the Tech-II

Yes for TDC offset of -.5 on a T2 equivalent reading on my Snap display is -4.2 I'm busy this morning but Il do the check of my time with cold engine later & post result both cold & hot. 12 deg is what I sort of remember also on mine, which is what I was referring to in the other post where member was having hard starting and was only seeing 5.3 for time request and wound up at 7.2 actual after rotating IP to drivers side with 5.3 request still.

TurbineDoc,you say that advancing the pump drivers side can help a hard start problem?I have a hard start problem cold or hot and have checked every thing from compression to injectors and every thing in between and all good but still a hard starter.Electrical/batteries,starter/ground's all good,OPS/lift pump,etc,etc,etc.My timing was checked by 2 different Stealer's and a diesel shop and they all told me it is with-in factory specs .SOOOOOOOOO is it safe for me to move the pump driver side and see what happens??You guy's are way over my head on the IP workings and understanding of it's operation.


ThankYou
Peter

Hard-start problem could be low glow heat, incl failing Glow relay, which is electronic-driven, but still a mechanical connection - same results as a bad starter solenoid.
Scan would indicate low Glow voltage.
Solution = new AC Glow Controller

Could be AC60G glow plugs - require extended glow time to get same heat as 11G's.
Solution = SLM quick-heats, from Heath, Kennedy, SS, etc. A-1 - NOT!!!!

Could also be failing Timing Stepper Motor, but scan would have indicated that, also.

Hard start all the time though? I'm leaning away from GP/relay problem.
Worn transfer pump (inside the IP) will make very low transfer pressure, which will keep you from getting sufficient fuel delivery for startup and slow advance piston operation.
Worn Fuel Solenoid will exhibit LONG CTimes during cranking as well.

Basically, if it were only a problem with a cold engine, I'd definitely start with plugs, if it is still hard start hot, and supply pressure is good, I suspect the problem is inside the IP.

Setting TDC Offset to lower end of spec (-1.5 to -2) may help, may not, need to see where you are at now, but I don't expect it will make a noticeable difference.

Gmctd i do have the ac60g plugs and Tdguy i have noticed that if you only give it a few cranks and turn off and back on it usually starts right away.After first glow cycle (10 or 11 sec.)if you turn off and back on the glow light only flashes on then off.To me it feels like it is not getting fuel right off the bat,because when it does start it smokes black that is why i wondering about the timing.

black smoke is a good sign, means theres plenty of fuel, but why does it take so long to get there? If it were glowplugs/compression/timing or other heat related problem you'd get white smoke. I think your right on the money, your not getting cranking delivery right away, but as soon as you do it fires up and you get a puff of black.

Hi mileage Inj Pump and injectors wil give black smoke with poor spray pattern, incl low atomization.

Loose timing chain, also.

injectors could very well be the problem too, easy to pull 4 driver's side and have them tested.

Diesel shop tested a few on the driver side----all were very good.Truck has 131 k or about 80thou miles.

So, you've ruled out everything but the injection pump itself then right?

Is the cranking speed good to slow you get black smoke.

...[I] have checked every thing from compression to injectors and every thing in between and all good but still a hard starter. Electrical, batteries, starter, grounds, OPS, lift pump, etc,etc,etc.

I don't think cranking speed is his problem

I don't remember the exact number but i think the crank speed was 120 rpm?Maybe i should try a longer glow cycle or those fast glow plugs.

120RPM???? thats about half the speed you want! 150 is minimum, you want 200+.
The IP is tested on the stand at 150 crank (75 pump) for cranking, if you can't get that fast, you will have tons of problems.

Nice shooting Fis Teck.

Thank's again TDGuy,checked the work order and it say's 155 rpm.Can you get a starter that crank's faster than that or is that O.K.They said 155 is acceptable.Has new batteries but i think i should make-up some decent cables,i have lots of 1/0 welding cable.Checked the ground and cable end's all clean.

What about the starter itself? Does it sound like its dragging? You don't need a 'faster' or gear reduction starter, just one that works good.

150 is bare minimum, at that speed, the pump should be able to deliver fuel, but you won't be able to get up to combustion temps at that speed unless you have 100% compression.

No the starter doen't sound like it dragging.*what rpm does the perfect system deliver*Compression not 100% all in the 380 range except for#4 he is close to 360.At the start of this that cylinder was at 300 so i added Marvel Mystery Oil a few times and drained the oil after 4-500 miles about 3 times and then checked the compression again.Have also been adding it to the fuel and it does run much better.this was done because the diesel tech said with such low milage it could be carbon and he was right as the compression did come up.I also removed the glow plug and filled the cylinder with some MM Oil and let it sit for a few days.