I installed a replacement PMD in my 94 C2500 recently when the truck failed to start (at all). After replacing it, it starts and runs, but very poorly. I ordered the parts from SS Diesel whom preinstalled the #9 resistor I bought from them and therefore I do not have the stock #5.

Has anyone else encountered issues with the #9 ? The truck smells of fuel, cuts off at stop lights, and in general runs terrible especially under load. It's basically useless, and I have no parts to troubleshoot immediately available.

Any tips?

Thanks.

I started using the #9 resistor with my new PMD/FSD with no problems. You might want to to the Diagnostic Checklist and post your answers...

I was told if you go with the #9 you have to change the timing.

I started using the #9 resistor with my new PMD/FSD with no problems. You might want to to the Diagnostic Checklist and post your answers...

I agree - I can't see an EXTREMELY marginal increase in fuel output causing any problems. IIRC, going from a #5 to a #9 gives, at best, a 2% increase in fuel at max throttle.

Shouldn't have to change the timing. However, the OBD-I trucks (like your 94) don't automatically re-learn the new resistor value, so what's happening is your PCM thinks it still has the old resistor in. If there is significant difference between the 2, then you got issues. Funny how SSDiesel keeps telling everybody about the virtues of the #9 resistor, huh?

I think we're going to need to post a factual explanation of "What the Calibration Resistor Really Does" in the FAQ's... there are far too many people who think the calibration resistor is a poor man's reflash.

What is the value of the old one? Fish it out with a paperclip and look.

It's about 1 mm^3 at full output... but I've seen people post about IPs with #3 resistors in them, so that's 6mm^3 per 1000 strokes. 6mm/56 mm stock is enough to notice at idle .

You're probably going to need to do a re-learn, if that's the issue.

PS - you might wanna think about moving the SSDiesel PMD kit, if you put it under the hood, as instructed. Or start saving your pocket change every day, in case you have to replace it in a few years, once the warranty runs out.

Oh my, we're not gracious hosts this morning ... Belated "Welcome Aboard", lwalling!

There is a ton of information on this site. Please take the time to introduce yourself, fill out your signature with relevant information, and read the FAQs...

Completing the Diagnostic checklist helps us to help you!

Jim

The number nine resistor does not affect your timing. As a matter of fact, if you change the resistor alone, it won't change the fuel delivery either. The PCM only reads the resistor during the TDC offset learn procedure. I read this on another GM diesel site. They even had a nice table that showed how much fuel flowed when using the various resistors. Unfortunately, I didn't save it and now it would be very handy to have. I run a #9 resistor with my Heath PCM. No such thing as too much fuel or too much smoke!!!

Jake

Jake

It's in the FAQs, Jake. 'Way at the bottom of this (http://dieselplace.com/forum/showthread.php?t=39436) post

Yes, that's the chart I was referring to. I've saved it now. Of course, I already have the #9 resistor, so I've done about as much there as I could. Time for a new Heath PCM, just as soon as I get my tranny problems solved.

Jake

Rigger had problems with his #9 resistor....

The PMD resistor will be checked by the ECM every 50 key starts. Disconnect your batts for about 30 min. then reconnect and see how thr truck runs. Sometimes, but not often, there is a problem, after changing the resistor. Just dis- and reconnect the batts after 30 min and see.


Cu,
Sven

I encountered a similar issue after replacing my old PMD with a new one. After a though system check I found the issue to be the OPS unit. After replacing the OPS the new PMD and #9 resistor perform well.

Frank

I vaguely seem to remember (through a beer-induced haze) a discussion about the differences between OBD-I and OBD-II, and how they react when the resistor is changed.

IIRC, OBD-I will NOT automatically assume the new value once it discovers it, and will have problems with that, either going into limp mode or not running.

The OBD-II computers can assume new values without a tech-II.

Is this wrong?

Turbine Doc, gmctd, one of the other gurus want to chime in on this one?

iirc - obd 1 cheks every 50 starts, obd 2 checks every start....TD or jd will know better...

I know that; what I don't know is if OBD-I adapts... I seem to recall stories that people have put in a PMD with no resistor and things are fine, then one day it notices the missing resistor and dies. An OBD-II would default to 5. With a new resistor, an OND-II would learn the new one.

So... does the OBD-I learn the new one, or go to limp mode?

Jif
Just to muddy the waters further I seem to remember TD posting that it was the OBDII ,s that would/ may not start after 50 starts if no resistor in a changed pmd. Others reported no problem. Dont know about changing the value . Thought that could be done without problem.

Actually, my truck (OBD-I) was fine with no resistor at all in it from the time I bought it until I took it to a diesel shop for a "free diagnostic check" (found a coupon on their Web site). Something they did when they were checking it out caused it to go looking for the resistor instead of just using the stored value. It threw a code when it didn't find the resistor, but it still ran just fine -- just had the SES light on constantly until I got a resistor and installed it.

My 95 had no resistor in it when I bought it....was running fine....

My 95 has been running without any resistor since I changed my PMD about 3 months ago. I drive it pretty much every day so I know it's been over 50 starts. I am wanting to put a resistor in and was thinking of going with a stock #5 because I was told that a TDC learn had to be performed when going to a #9. If I can put in a #9 and make the ECM recognize it that is what I would do if anybody can tell me for sure what I need to do.

LOL. In other words, none of us has any freaking idea what to do about this. This is just hugely amusing...

Turbine Doc, JD, where are you???

ok i give where is this resistor?

how about a pic?

ok i give where is this resistor?

how about a pic?

SSDiesel has a couple of good pics; one of the resistor by itself, and another of it installed in the PMD (or FSD :rolleyes:). Here's a link:

Staff edit hyperlink to non-site vendor SS Diesel removed

[quote=rhythm_junkie;2320885]SSDiesel has a couple of good pics; one of the resistor by itself, and another of it installed in the PMD (or FSD :rolleyes:). Here's a link:

Staff edit hyperlink to non site vendor SS Diesel removed

thanks rhythm_junkie

LOL. In other words, none of us has any freaking idea what to do about this. This is just hugely amusing...

Turbine Doc, JD, where are you???

IIRC, when I installed mine -- after it had thrown a code because it didn't have one -- I just disconnected the batteries for a few minutes to clear the codes. When I reconnected things and fired 'er up, everything seemed fine -- no more SES, and it ran just the same as it had before, as far as I could tell.

You know what's funny?

The guy who started this thread with his 1st post has not returned to clarify things, and we're all worked up about it...

Was the truck running fine before? Will it run if plugged back into the old PMD?

He says he installed the new SSDiesel PMD... we're assuming he put the remote, on-the-manifold one with the heat-sink.

Sometimes, the wires don't want to reach that far... did he pull something too hard?

Did he move the ground wire from the IP to the Heat-sink (as instructed by SSD, but which causes issues with many trucks?

Did he come back with the checklist?

I'm not gonna worry until he comes back. JD or Tim will know the specific ins-and-outs of the resistor, and I'm sure they'll laugh at us for not knowing... :)

The dude who drives our '95 swapped PMD's to cure stallin', which it did, but the truck ran like garbage. He didn't swap the resistor into the new unit. After swappin' the resistor, it came back to normal again. Kinda weird how some work ok and some don't?

I don't like weird. I have enough trouble keeping things straight when they're predictable.

Weird is too much like... female. One day, you smile, things are all good. Next day, you smile, you're in poop. Engines aren't supposed to act that way!

:)

i put a new resistor in mine,. now the fan only works on high,..:D

I don't like weird. I have enough trouble keeping things straight when they're predictable.

Weird is too much like... female. One day, you smile, things are all good. Next day, you smile, you're in poop. Engines aren't supposed to act that way!

:)

You're gettin' off easy if she changes day-to-day, mine changes by the hour!:eek:

You're gettin' off easy if she changes day-to-day, mine changes by the hour!:eek:


ROFL ... how does that song go? "If a man says something in a forest, and there's no woman around to hear him, is he still wrong?"



.

Here's another question, guys. How large a value can we put in the PMD (to get more fuel) before it throws a code? I wonder if anyone has already figured this one out?

Here's another question, guys. How large a value can we put in the PMD (to get more fuel) before it throws a code? I wonder if anyone has already figured this one out?


IIRC, the info at the ssdiesel link provided on post #22 of this thred, it says something about "aftermarket resistor #13 will throw a SES".

Hi,

I did not think to try it without the resistor at all. The prior PMD was completely failed, the truck wouldn't start with it. I chucked it - didn't think to look for a resistor in there or not (stupid!).

I installed the new PMD, truck started right up in 30 degree weather. I noticed it missing while it was sitting there idling though. When I drive it, it chugs and misses worse, cutting off, etc.

The truck ran fine a few weeks prior to the total PMD failure. The remote location is.. yes.. the intake manifold. I figured? How bad can it be? I barely use the truck. Well.. 5 years and only 10,000 miles and it failed again sitting up there. The prior failure was the unit attached to the IP. When I first received the "kit" I thought that it made no sense - and it doesn't. Fins that don't follow the airflow path, and no phenolic spacer or anything to keep it away from the heat being transmitted over by the direct contact with the intake.

I will relocate it one day. The harness has been cleanly cut & spliced with connections soldered 5 years ago, however, when I relocate the PMD I will likely replace the whole harness and use a nice premade extension. I figure theres a fair chance my problem is actually the fuel flow sensor in the pump at this point, so it may be time to do that soon.

I didn't think to run the PMD without the resistor, it look a little time with a small pick to get it out - I will try it later today and see if the truck runs. I'll then repeat with the #9 after killing the power to the ECM for a bit.

These 6.5's are wild.. I've had two.. Injection pump failures seem regular, I went through 2 PMD's in the factory location in 2 years on a 96 Suburban - Dealer replaced them free under the 120k warranty, 1 lift pump, and one whole replacement IP. This truck has had a lift pump and a handful of PMDs during my limited use.

I like my old truck, just hate the PMD/Lift Pump/Injection Pump problems - seems just totally silly. GM should be ashamed.

Here's another question, guys. How large a value can we put in the PMD (to get more fuel) before it throws a code? I wonder if anyone has already figured this one out?


Everything above the factory #9 will throw a code/SES light.

Cu,
Sven

Thanks for checking back in, lwalling. fill out your signature and let us know how you make out.

As you can tell, we're interested in this issue.

Replacing the PMD with a Heath PMD isolator solves the problem for 7 years; lots of people have moved their SSDiesel unit out of the engine bay and gotten much better life, and there are lots of home-built units that work OK...

This whole thing with the resistor is goofy, as you can tell from the posts on this thread.

Lots of people think that the resistor is a poor man's "chip" and try to put bigger ones in, hoping for lots more power. Wrong.

More often than not, the only real difference you notice is when things go wonky, like you describe.

Rigger had problems with his #9 resistor....
Good memory, mine was an issue of not running correctly, rough idle almost as if it was a gasser all cammed up. But my situation wouldn't apply to anyone since i was running a 5068 IP in OBDII. Oh and it recognised the different resistor immediately on fire up.

I've gone between a #5 and #9 resistor in my truck. The only difference I've noticed is slightly better mileage around town with the #5. (stop and go)

I went back to the #5 lately.

No such thing as too much fuel or too much smoke!!!
Amen to that!

Amen to that!

:eek::(:eek::( ever hear of melted pistons, I'm more impressed with a truck that makes more power & no smoke, that is healthy power, not just wasted fuel and reduced engine life

:eek::(:eek::( ever hear of melted pistons, I'm more impressed with a truck that makes more power & no smoke, that is healthy power, not just wasted fuel and reduced engine life

Oh, TD, there you go, trying to make sense again.

Didn't anybody tell you, this ain't about facts?

ROFL
Jim

If you weren't a "moderator" the gloves would be off, but since you are one, then you are always right.

Not always

but I do tend to get it rite more than I do wrong so my averages are good

I don't understand gloves off comment, I'm more than willing to discuss opposing viewpoints, emphasis on discuss

I don't understand gloves off comment, I'm more than willing to discuss opposing viewpoints, emphasis on discuss
Probably the same reason you did not understand the humor in my original post. Obviously, excessive black smoke can be a cause of damage, etc., but it is also a humorous aspect of owning a diesel - especially when romping on he accelerator. I used to love to watch the excess fuel blow by as smoke as my obnoxious F350 would blow by the cell phone idiot on the freeway.

Understood the humor, but lots of newbies want black smoke not knowing it isn't a good or desired thing; as mod, I feel it is incumbent on me to discourage that which can be misunderstood, maybe I'm wrong with taking that position and if you think I was singling you out my apology that wasn't my intention.

I agree. Simply dumping more fuel without the "other" proper upgrades is not the optimal way to achieve HP and engine performance. Besides, it is the blue smoke that causes me concern.