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Discussion Starter #1
Poor lubricity fuel can cause dtc 35 ? the truck runs great ,perfectly!!!!:help2:
 

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More info please. Is this a question?
 

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Add lubricity to ease DTC36 - DTC35 sez it''s already too fast...........
 

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Add lubricity to ease DTC36 - DTC35 sez it''s already too fast...........
Sooooo add talcum powder to your fuel???:joke:
 

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According to his scanner, his CTIMES are in the 1.9-1.95 range.
I don't understand how he's getting a code 35(short) instead of 36(long).
 

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Exactly........

??????
 

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To be clear - Closure Time and Pulse Width are not the same animal.

CT is how long it takes the FS armature to move 0.005" to close the valve.

PW is the duration which the PCM commands the FS valve to stay closed to set required Fuel Rate.

CT is measured in microseconds, PW is measured in milliseconds.

DTC35 is less than 1.5milliseconds.

DTC36 is more than 2.5milliseconds.

Now - how do the various Fill-Spill modes come into play at various rpm\advance\fuel rate events?

Which results in Pulse Width reducing from 1.9ms to 1.6ms at high-rpm high fuel rate\ high advance?

Injection window is less than 4.2ms at 3600rpm.............
 

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Discussion Starter #8
The truck is hard to start now , dtc 35 keeps showing up ,runs perfectly...the only unusual symptom is the hard start!
Might be the PMD?
 

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Now to be even clearer, but not to step on any toes...

CT and PW are definitely NOT the same thing, but nearly all scanners display CTime as Pulsewidth.

You hit the nail on the head about CTime, no need to add anything there.

But with a DS4, Pulse Width is actually measured in arc angles by the Hi Res signal from the optic sensor. All other electronic diesel fuel injection systems will actually use Pulse Width in ms as determined by the PCM, and thus display the actual Pulse Width in ms. The closest thing to seeing the actual pulse width of a DS on the scanner is the Fuel Rate.

Also, 94-95 6.5s will set code 36 with CTime >1.9ms.
96+ will set code P1217 with CTime >2.1ms.
 

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Unplug the extended FSD, try the one on the Inj Pump for comparo.

Also try removing the the OS filter.

Do one or the other separately, not both together.
 

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No toes crunched here, TDG. :cool:

I should have expressed it as - 'IMO the two terms should be defined so as to distinguish the seperate functions'

I have seen it expressed as 'Ctime pulse width in ms'.

Closure ain't a done deal - it is on it's way to being closed, but not there yet...............

Seems to be a very concerted technical effort to confuse everyone - no wonder Mr. Goodwrench would rather work on a dozen Geo Metro's than one 6.5.

Here, again, is another difference - my '95 with 5521IP regularly runs between 1.92 - 1.98ms, no sign of DTC.

It ran 1.88ms with the 5288 on QM's truck.

Further, when revving into the upper rpm's, PW decreases to 1.68 - 1.72ms, no DTC, from either IP.

As you may remember, I use a Tech-II for all testing. with +8.5deg BT and -1.50deg TDCO.

What it has taught me is - do not depend on or rely on the info in the GM Training and\or Service manuals.

!!!!!!!!Es no bueno por caca. dude :muahaha:

Anything else you - or anyone else - would like to bring up or state alternate view on, let's post it out - may be we can forum this thing into some kinda mutually acceptable technical understanding
 

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The actual PCM limits for when to actually trip FSOL Long/Short Response is not cut and dry, that much I definitely agree with you on.

Since your truck normally operates ~1.7ms and only idles a touch over 1.9 and doesn't trip a code, then this must be with PCM tolerances.

Stanadyne spec is between 1.5 and 1.9ms at any RPM/Fuel Rate/Advance.
 

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Pulse Width is directly related to arc angles - degrees - of crankshaft revolution.

Anytime engine is running the crank is rotating thru 360deg.

At 600rpm the crank is spinning 10 revolutions per second - 10 X 60 = 600

Thus, the crank spins 360deg once per 100ms - 10 x 100ms = 1sec

8cyl four stroke engine, four Combustion Events happen each rotation, or 40\sec at 600rpm.

Four CE, one each 90deg, in 360deg\100ms means each CE must occur within 25ms.

At 360deg in 100ms, crank will move one degree in 277 microseconds (0.277ms) - 0.000277sec\degree

1.95ms PW would then equate to 7deg of crankshaft arc angle at 600rpm idle speed.

You say potato, I say potahto
You say tomato, I say tomahto

Eh? ;)

Each combustion event, in my engine, starts at +8.5deg BTDC at idle, and around +18deg BTDC at 1700-2000rpm, hopefully giving peak cylinder pressure at around 15deg ATDC for max power output - torque.

Anyone care to extrapolate this out to 2000rpm and 3600rpm - just for grins?

For TDCO's sake?

(Check my math, KN - you know what them rascally numbers do to me............);) :cool:
 

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As you remember I posted a DTC 35, with my scanner(MT-2500) I now have a 35 and a 36, the Ctime mostly is 1.64 and when it hit 1.99 the SES tripped. it went to 1.99 when I blinked, prior to that the highest I saw was 1.68
my TDCO is -1.50 (is this right with a snap-on scanner??)
also act timming and desired timing always seem off from each other, edventually if load/RPM stabilises they match (I assume this is normal?)
Will these Ctime numbers change if I try a different PMD??
Do I need to worry about the pump or just unplug the SES??
 

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Turbine Doc posted MT2500 particulars in FAQ's - me, I don' kno' nottingk.....;)
 

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1800rpm = 30rps = 120 CE = 360deg crank rotation in 33.34ms =
1 CE\90deg\8.35ms = 0000926sec or 92.6us per deg

3600rpm = 60rps = 240 CE = 360deg crank rotation in 16.67ms =
1 CE\90deg\4.16ms = 47us per deg so 1.95ms PW = 42deg rotation
 
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