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PMD Resistor "Re-Learn" Needed?

D

DennisG01

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Location
Allentown, PA
With OBDII:

I recently installed a new PMD (I guess it's actually called an FSD, now). Originally, there was a #5 resistor in there. Now there is a #9. Truck runs fine, but I wonder if the ECM still thinks there is a #5 in there?

So, I searched for the answer... I found some answers saying "No, you need a Tech2 (or similar) to do a TDC Offset Learn". I found other answers saying you can do some type of KO-KO procedure.

Then I found this one by Turbine Doc:

"warm engine to >170F, then shut down truck, put APP to floor, then with ignition key in run, not start; hold APP to floor for 1 minute, this will initiate the learn after 1 minute on then turn ingition off for 1 minute and APP in normal position, start truck and the new resistor code will be learned, also this will let the PCM learn the current TDCO setting."

So, can I do a re-learn without a Tech2?
 
Yes, that is the KOKO procedure that TD described. Now that will also update the TDCO, so if your IP isnt timed it could set a fault. Although if it isnt timed it could help you by running the procedure, if its in tolerance.
 
Thanks, Buddy. Could please expand on your last sentence? I'm not following what you're saying. While my truck was in the shop, they noted that the IP Timing was at -2.29. The pulse width is 2.20ms -- just in case that helps explain anything. They said that 2.20 is a little high, but weren't worried as the truck started and ran fine.
 
If the TDCO is at -2.29 then you should have set a DTC for timing and it needs to be timed. The IP is too far to the drivers side. Do you not have an SES light or any codes?

The pulse width is way high, could be because the timing is so far out, or the IP is not healthy, it should be around 1.6 to 1.9ms. Thats the time it takes the fuel solenoid metering valve to reseat after being extended to close the valve to allow fuel pressure to the injectors. The PMD sends a square wave power signal to the Fuel Solenoid, which moved this plunger in and out. So when power goes to 0, the plunger is supposed to come back to the solenoid in a certain amount of time.

The KOKO will run the procedure which relearns the timing, so that it could change that TDCO value that is currently -2.29. Of course I would ask which scanner they are using, because if its a Snap-On it could be displaying it incorrect.
 
Thanks for that explanation about pulse width - I never really understood it until you explained it the way you did! :D

I have no codes, at all. What's interesting about the IP timing is that the shop where I took it to (to do the repair) is the ONLY shop I've ever had do timing for me (don't know what scanner they have, but at least it's the same one). The last time I had it there, they put it to -1.94. No one has touched the IP, since. I don't know why it would be -2.29, now.

Could the Kennedy tune I have be allowing the -2.29 w/o setting a code?
 
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Did you add the Kenedy PCM after the IP was installed and timed? If so, you are supposed to run the TDCO learn procedure when you get any new PCM. That is because the PCM stores a TDCO value, from last time it was run. If you didnt then it just had -2.29 stored. According to a 1996 manual, the OBDII PCM only codes after 2.5, which I wonder why people only set it to -1.94. The OBD1 PCM codes anything past -1.94. It is possible they reran the TDCO when checking it, and it ended up at -2.29, which it bounces around during the procedure so that is possible.

I would also check what the idle fuel rate is, it should be around 8mm3. If its much lower could be an issue.

If youre not using a fuel lubricant then you should start with those high pulse width values its getting close to coding.

I would say youre good to run the KOKO procedure, since timing was set before.
 
I've had the Kennedy Tune for about 3 or 4 years - I had the IP timed after putting the tune in (at -1.94). I use FPPF Total power religiously, at the double dose rate. The -2.29 reading was taken when I first brought the truck in to them to diagnose the problem I was having. They did not check it again after the new FSD got hooked up.

I'll do the KOKO thing tomorrow night. I'll make an appointment over the next few days to stop by and have them do a quick check for timing - including idle fuel rate.

Aside from coding, what sort of problems could happen with the high pulse width readings. The shop didn't think it was anything to worry about - said "they're high, but everything seems to be fine".
 
Well, sorry to say that FPPF stuff may not be helping you at all, part of the issue. Check out this study
http://www.thetruckstop.us/forum/sh...el-additive(s)&p=103971&viewfull=1#post103971

FPPF had a good product, but it appears that when the add in the anti-gel the lubricity suffered, actually worse than baseline fuel. So dump the Total Power and use the FPPF RV, Bus, SUV Diesel/Gas fuel treatment, or just use a quart of plain old TCW3 2-cycle oil. And I wouldn't use a detergent or anti-gel regularly, the anti-gel only when you really need it.

This could resolve some of your issues, as the guys in your PMD thread figured you had "other" issues. The long pulse width could cause extra smoke on startup or when hitting the accelerator. Lubrication may bring the pulse width down.

Changing the FSD wouldnt change the TDCO, I imagine they just ran it again to make sure it hadnt moved. when you set it, it jumps around and just sets whatever it is when it times out. I would not be worried about the timing, except I usually just set it lower for less engine noise.

Also, would be good to check lift pump pressure at idle and under load, a lot of them dont last 5 years and even if they provide some pressure when off or even at idle, they can fail under load. That can add additional strain on the IP.
 
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Hmmm... That's both interesting and saddening at the same time. I wonder if there are any biodiesel retailers near me - I'm going to look for that.

The shop put in a new lift pump as the one of the truck fried while they were testing. I was just about ready to buy a Walbro, too. Now, I just put money into a new "normal" LP :mad2:

I'll still check the new LP - just for the heck of it - it's easy enough to do, anyways.

Thanks for that link!!!
 
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