• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

OBDII

It is a noticeable difference in power and mileage. It is worth the effort in my opinion. Just the sound at a cold idle makes it worth it to me. I get a lot of compliments when she is just sitting there idling.
 
I'm so confuuuuused

So I have CarCode and I used Qwomack's instructions (thank you again). The truck runs fine at -1.32 but I have a question about the IPT and IPTD fields in CarCode.

This truck is a 98 and obviously OBDII. Is either one of these numbers supposed to be 3.5º/3.5º or is that for the OBDI engines? I have searched here and the other place and can't figure out the answer. There was all this talk of getting to 3.5º before setting TDCO. Is this number set by the PCM on OBDII and not adjustable?

I have included a screen shot and both are at 12.7 at this point in time when it was running. They both fluctuate between 11.x and 13.x. I know they move and they only get a few tenths apart at the most. Thanks for your insight!

rpm
 

Attachments

  • IPTD Screenshot.jpg
    IPTD Screenshot.jpg
    42.5 KB · Views: 14
I believe the 12.7 is actual and 3.5 is base if I understood correctly. Tim tried to exlain it to me a few eeks ago and If I understand right when you are in base time the Ip is fixed sort of like a DB2 in other words the ECM is not altering the timing and then you move the IP to get the desired setting and then set tdterwards but that is the part i dont quite get cause I thought in oBD2 you didn't have to set base just TDCO.
 
The 3.5 is what you see in time set, the figures you have are actual and desired as determined by the PCM. They are the same which is what you want.
 
NVW said:
The 3.5 is what you see in time set, the figures you have are actual and desired as determined by the PCM. They are the same which is what you want.
Click to expand...

Exactly. Use Timeset when you install a new pump or want to set it right.

Once you exit Timeset the PCM resumes control of the timing via the stepper motor IIRC.

Those values seem similar to mine. (I'm at -1.94).


Now Even though I reached it before with the APP, I went ahead and physically moved the pump also. Now I can get -1.94 at will, and bounce all around it.

So I actually physically advanced my Base Timing by moving the pump right?

So in each instance I had the same -1.94 TDCO.

Is there any differences in the timing between the two?


BTW, This thread should be renamed to OBDII Car-Code
 
Thanks for the info. I am new to the 6.5 diesel. I have had old Mercedes for a few years and they are much quieter running. I just wanted to make sure that I wasn't (potentially) damaging my new engine. It is loud at cold idle and really makes a nice clatter. I am just trying to get used to it.

I also have a question about IPCR in Car Code. Should I start a new thread or is this the unofficial Car Code thread now? I believe IPCR is IP cam reference missed counts. There are two of the same item listed in the advanced data section. I noticed mine a month or so ago when I got Car Code and was playing around. Does anyone know what this should read, is it allowed to miss counts or should it read "0"? I believe I read somewhere that this may be related to the optical sensor not being able to see through the fuel to the disc in the pump. Does this make sense? Would anyone with Car Code be willing to connect to their truck and see what their readings for IPCR are? I do add some 2 stroke oil to the tank and the power service that comes in the gray container. Any chance the 2 stroke oil is too dark?

Thanks

rpm

p.s. Did you know you can save your sessions and view them back later with Car Code not connected to the truck? I am collecting some baseline readings so that when some part craps out I may have be able to see a difference in the readings. Not that I know what every line of data means, but in time I may be able to figure them out.
 
I can do it tomorrow mid/late afternoon to get my data. Any specific RPM? I'll do Idle, 1k, 2k.

I love watching my datalogs. Its alot safer that way too! From watchign the datalogs you can remember where you were, what hills you climbed, what points of the test run you were on. Its quite fun. Especially when comparing a new change.
 
Matt,

Thanks for the offer, that would be fantastic! Idle would be fine. I don't notice that the number changes with speed. I have looked over on the highway and it still has the same number of missed counts at 1700-1800 rpm that it does at 575-600.

rpm
 
Might try using nd 30 wt oil instead of the 2 stroke some people have problems with 2 stroke others don't. My guess is the fuel must be the variable. If any mods want to change the title of this thread it's fine by me. I'd like to see it or a condensed version in the stickies to make it easier to find.
 
The reason you might be able to get a higher TDCO value by revving the engine and so on could be explained by the IP mod threads. You stepper motor is disabled but changing RPMs changes the IP charge pressure and the differential is what moves the advance piston. The stepper motor controls the differential normally. So when you do this its not the same as actually moving the IP. The difference may be seen if you monitor the actual pump timing, which would show you timing in reference to crank timing. When you move the IP for -1.94 TDCO the actual pump timing will be fixed at about 30.5 degrees, until your desired cam timing goes over 15.25 (which is 30.5 crank degrees). But stepper can bring it below this set timing position up to 22 degrees. When at an IP position of 0 TDCO then the actual pump timing would be like 28.9 degrees. At -0.5 TDCO its like 29.5. If you are fooling the PCM by changing the RPM at which it learns TDCO which changes the differentail IP pressure while stepper is disabled then the PCM really isnt controlling things precisely.

So this TDCO is actually only changing timing from 29.5 to 30.5 crank degrees, which is a difference of 0.5 cam degrees from -0.5 to -1.94 TDCO. In timeset where about 3.5 degrees average is what you will see in the measured/actual timing when set at factory to -0.5 TDCO. But shooting for -1.94 TDCO you move IP and want to get a timeset of 3.8 to 4.0 average.

Also you will never see a screen with a measured/actual timing and a desired timing of 3.5 degrees. You want to see about 3.5 degrees when desired is 0 degrees in timeset. It may also show this in TDCO relearn. The PCM controls timing when operating, and at idle most OBD1 L65 programs I have seen are set at about 9 degrees during normal warm idle. If yours are 12 degrees thats pretty high or has anyone compared what Carcode shows compared to a Tech 2?

So do you get the same benefit from playing with the TDCO value as when moving the IP? I dont know for sure, but Im beginning to think it has nothing to do with timing, but a pressure offset. The timing is the timing according to the crank sensor which has to agree with the cam reference from Optical sensor. When turning the pump it may alter the differential pressures so that it actually alters the fuel metering. And the PCM is probably mapped with the TDCO as a certain modifier to pulse width. If you are just changing the number and not actually moving the pump, you may get some different metering of the fuel, but not the actual pressure change in the IP.

Nothing has really fully explained what the TDCO is, but by looking at the PCM programming and taking into account internal IP pressures incease with RPM, and how things like Optic Bump affect the PCM readings and engine operation the cloud begins to clear on the mystery.

It also seems like a bad practice to shut a computer off in the middle of a procedure like this. I guess that it works with no consequences, but with the scanner its not necessary, and with GMTDScanTech on OBD1 vehicles the software does it.
 
Last edited:
Mine are around 12 too. I'll get exact later on as I have to hook it up for the other thread too.

Its not shutting it off in the middle of a command, the 'command' if you even want to call it that, finishes, but with fear of accidently 'commanding' it to change again, shutting off is easiest.

Carcode isn't that friendly, its very odd. Simply clicking on the open window in the middle of nothing changes the TDCO value.

So no issue there. Its the same as turning off the truck normally.

Thats what made me think of this. How can it be the same? So the only gain is physical advancement of the pump, and checking TDCO seems to just verify that you are as far advanced as possible without coding.
 
I dont think it is advancing anything really, since the PCM controls the timing with external feedback. I believe what the TDCO value does is tell it how far it is off and GM mapped how pressure differentials changed at this advanced position of the IP, and made it a modifier for pulse widths/fuel rates. I suspect the increased peppiness is actually a little more fuel getting metered. But if you didnt actually move the IP then you didnt really change the pressure at every RPM.
 
My Desired and actual timing from cardone is between 13-14 at least warming up, once warm its at 11.9 Desired 12.1 actual.


IPRC - Injection pump reference counts missed was at 111 when cold and now is at 70 or so 180 ECT. Lowered 1 or 2 everytime Coolant went up.\

Odd, now that its all warmed up at 192 ECT, my IPRC is at 170/

The first reading always read 0. The 2nd one started at 111 cold, went down to 70, and then went to 170 FWIW.
 
If someone else could put up their IPCR numbers please. Truck off is 196, now mines idling at 195. Its all over the place it seems, but when watched it doesn't jump around, slowly changes.
 
Mine doesnt show any reference counts missed with GMTDScanTech. What that would usually mean is its not agreeing with the Crank sensor. But you should get a code if it were actually happening. The scanner may be lying to you. are you using the 02 setting now or 97?
 
02, and as mentioned, it is listed twice, same exact thing. One always reads zero. Who knows. It didn't change much when I turned the truck OFF either. FWIW.
 
I was away this weekend and missed your posts. Thanks for sharing your readings. Mine is similar to yours Matt, first reading is always 0 and the second reading moves slowly. Sometimes it has been as low as 60 something and up to as high as 166. I was just looking to see if others has similar readings. I am trying to capture some baseline readings so I know what "normal" is on my truck. So if anything ever really craps out, I may have a way of narrowing down what failed.

I don't have any codes tripping and maybe it is lying to me, but I don't really have any way of checking it unless I pay a dealer to scan it with Tech II.

Thanks,
rpm
 
rpmakrues said:
I'm using the '02 setting. That was based on Qwomack's instructions when setting TDOC.

rpm
Click to expand...

As am I. When I did the 97 the cylinder shut offs, and a few other things weren't there, or I couldn't use em.. Since I have always just used 02, assuming its the most complete and current.
 
You must log in or register to reply here.
Back
Top