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Changed PMD still not right

GMMomma74

GMMomma74

Mother of Trucks and Mopar Minivans
Messages
63
Reaction score
89
Location
Texas
So my first post was my intro and I said about Beast and her black smoke/runaway throttle issue. Changed out the PMD (my sis bought me 1 off Amazon that came with a heat sink and relocator line) added a #9 little green piece (šŸ˜„) and she is a bit better. Doesn't immediately run away but now takes a second to hit 4,000rpm's instead of buried. Is it a bad PMD or is it the IP? Hopefully getting a scanner on it this weekend. No check engine light unless we pushed it hard when it would still go. She hasn't stalled out except in Jan when we had a cold spell and she wouldn't stay started one day until it warmed up (started plugging it in when at home) but that may have been gelled fuel.

Now it has had problems in the last few months (since Nov/Dec) with gas pedal issues (sorry not a mechanic. I just pretend I'm one). Above 50mph the throttle is either on full as soon as I hit the gas (is it still a gas pedal on a diesel?) or when I let off it starts "dying". No sweet spot. And black exhaust. And reving at 2,000ish until warmed up and dropped into gear.
Wondering if maybe its worth it to get a pmd from AutoZone with at least a 3 month warranty and try that. Or just jump to letting it sit til I can get an Ip.. Finances suck in my house. Or is it maybe air filter? Can one needing changed (also black) cause some of this? Could it still be the pmd? And we just got a bad one? It's now mounted inside the front bumper behind the licence plate. Texas (70 miles east of Dallas) requires front plates.
I should have become a mechanic 25 years ago... But girls didn't take shop class.
Most of what I know is Google or learning from my step dad as a kid. I'd ask him but he's 84 with Parkinson's and age induced dementia...


Thanks for listening
 
Air filter can cause black smoke, weak power, and slooowww acceleration. It can always be checked by remove for quick test drive. I doubt this is your issue.

Gas pedal for all vehicles is properly ā€œaccelerator pedalā€, but just say what you can and we will get it- no final exam here to study for. Just be careful saying ā€œput gas in the truckā€- that means bad day. You will read about faulty APP that is the accelerator pedal for your rig which is all electrical. So it could be bad, but unlikely by description.

Leroydiesel.com sells lifetime warranty pmd on or off heatsink. Long term my suggestion is have 2 mounted on heatsinks next to each other. Use a dummy plug in one to keep connection clean and operate off the other. Then when any problem occurs you just swap the dummy plug and extension lead. Really nice in bad weather or along side a freeway... Then just remove and send in the bad one under warranty later that week when you have time at home.

Unfortunately there is no testing a pmd- only ā€œreplace with known good unitā€. Hence needing one not just for when it actually dies, but for testing purposes.

It is sounding like bad pmd or bad ip.

There is possible bad grounds on engine, bent pins at pmd extension cable ends, or something similar.

Also Is your engine burning oil? You could be burning the oil as fuel causing it. Check for blow by & excess getting pulled in through the cdr.
 
Ok... I know it uses oil.. I put a quart every 2 weeks or so. Right now I'm afraid to run it because of the rpm's to get it hot.
What is a cdr?
It's used oil the entire 2 years I've had it and problems only cropped up now.
So I guess trying another pmd and replacing air filter and see where we stand.. (I can replace a pmd but not an ip) If that doesn't work I'll guess it's the IP (hoping not those things are expensive).
Thanks... I'm sure I'll be back...
 
Only thing every 6.2/6.5 owners frets more than a new ip is a new block, I get it- we all do.

Long term, fuel pressure gauge with the T or sensor at the ip inlet- low pressure/ volume causee the ip to wear out quickly. Water free fuel and fuel lube additive is the next things to do for long term life of ip, but these 2 also extend injector life. So for now a gauge is a great thing to do, as you will want it regardless of if this ip is toast or not.

1 qt in 2 weeks is a descent amount. Idk if that is enough to feed the rpm though.

CDR is relatable to a pcv valve for a gas engine- kind of.
As the air gets pulled into the intake plenum, it pulls the excess crankcase pressure out of the block& heads, and into the intake manifold so that it burns the oil fumes i stead of puking oil onto the ground.

If the oil burning was new,You could try just removing the cdr (big tuna can) on top of the passenger valve cover, and have a long hose just vent to open air along the oilpan for now. See if that eases oil burning and more importantly if it stops the high rpm. I doubt it will stop the rpm issue, but worth a try. Long term, invest in a catch can. I am going to a provent 200.
You could diy one cheap enough, that it will pay for itself in you not buying so much oil.
Provent is the Cadillac, and priced accordingly. But for now, just do the open vent to test (like the first demo in video with open hose to oil pan area). NEVER just plug it off, it will blow out all oil seals in minutes.
Unfortunately, this is probably not going to solve your issue, but will help costs later.

Remove and cleaning grounds, new pmd, check pins on both ends of pmd extension cable, is about it.
There is a written test procedure for ip testing on e all the basics are done. I believe it is in the stickies.
 
Just because you got a new PMD doesn't mean it's any good especially if you got it from Amazon... I know somebody's going to yell at me for this LOL.. I just got one from AutoZone because it's got a lifetime warranty..so if I take it back every 6 months I don't care LOL.. but they're brand new so they work( usually).. and I've actually only burned up one since I relocated it.. I agree with Will and a k it does possibly sound like a IP problem..BUT I thought the same thing at one time with my truck and it turned out to be a bad sensor so yeah check all your grounds and there are a ton of them. Clean them really good..
 
One of the guys I go to church with who works on the big rigs swears it's the pmd. There's only 180,000ish miles on my Beast. I got a hold of the guy we traded for it and he said the IP was changed out at about 130,000. Since AutoZone is here in town I'm gonna try a new pmd and go from there. The one I got helped but not enough. Then if it needs the ip I need to decide if I want to get that now or shell out about the same amount for a 2nd crappy vehicle.
I need to get a video of my truck. Or at least pictures.
Should have gotten one the other night. I had to climb up on top of the radiator/fan to reach the bolts to get the plastic turbo cover off. My husband was laughing at me and said not to fall. I'm an almost 45 (next week) year old very chubby short thing. But he couldn't get it and was ready to throw things.
Thanks again folks... Now I just need money. Gotta start a go fund me for repairs... Hahaha..
 
GMMomma74 said:
One of the guys I go to church with who works on the big rigs swears it's the pmd. There's only 180,000ish miles on my Beast. I got a hold of the guy we traded for it and he said the IP was changed out at about 130,000. Since AutoZone is here in town I'm gonna try a new pmd and go from there. The one I got helped but not enough. Then if it needs the ip I need to decide if I want to get that now or shell out about the same amount for a 2nd crappy vehicle.
I need to get a video of my truck. Or at least pictures.
Should have gotten one the other night. I had to climb up on top of the radiator/fan to reach the bolts to get the plastic turbo cover off. My husband was laughing at me and said not to fall. I'm an almost 45 (next week) year old very chubby short thing. But he couldn't get it and was ready to throw things.
Thanks again folks... Now I just need money. Gotta start a go fund me for repairs... Hahaha..
Click to expand...

Go ahead and leave that plastic cover off. It just traps heat anyway
 
Yup...

Ok I had a mechanic friend (the one from church who works on the BIG rigs) show up and started the beast up. She started right up and her exhaust has changed to a variety of grey. His feelings are bad pmd. He said it's getting fuel so the injectors and pump are ok. But it's not being regulated (pmd/fsd). Tore me a new one for buying a cheap chinese part (I didn't... My sister did). He did say I did a good job installing it in the bumper nose.
So a new warrantied pmd should (cross fingers and knock on wood) do the trick.

Picture attached is the Chinese paperweight that was ordered. Of course the heatsink and wiring are probably good... And the resistor is from AutoZone.Screenshot_2019-06-02-18-37-21.png
 
I think I paid right around $200 for a PMD from AutoZone.. might have been less.. tell them you want dorman brand.. they are fairly reliable as long as they're mounted up in the bumper like you already have.. and they are lifetime warranty.. and plan on buying a second one to have on hand down the road aways when finances allow..
 
He actually makes a good point.. you have a brand-new PMD.. unplug your extension cable.. plug your new PMD right into the original plug.. and just leave it sit on top don't put it down in anywhere.. and start the truck and see if you can feel or hear any difference.. there won't be enough heat under there with the hood up to damage the PMD by any means.... It's just a quick way to eliminate the cable possibility
 
Nope. Gotta disagree with Stoney on that one. If the ip is worn, it can put a high heat load on the drivers in the pmd in seconds. I have seen quality pmd burn up in a few seconds. Never run one not on a heat sink imo.

Make sure your mechanic knows this is a NO STARTING FLUID engine. A little shot of it can destroy this engine.
 
PMD will generate heat fast when operational.

It has 2 TO transistor.
From this:

Bad PMDs Anyone? I know, the horse is dead already!!!?

Hi, everyone. I've been away for a couple of years obtaining a mechanical engineering degree and working full time, which didn't leave much time for fun things (as in zero). Well, that's all over with now, and I have time to play. I have learned tons of stuff from this forum over the years...
www.thetruckstop.us
We got the spec of the transistors:
www.mouser.com

2N6287G ON Semiconductor | Mouser

2N6287G ON Semiconductor Darlington Transistors 20A 100V Bipolar Power PNP datasheet, inventory, & pricing.
www.mouser.com www.mouser.com

That is 160W of heat dissipation with Max temp of 150C.
There are 2 of them.

The IP is supposed to be a heatsink.

Challenge with IP location is the heat cycling after engine is shut down.
I measured the engine temp after shut down during summer with IR Thermometer, it went up to 200F - 225F with the hood open.
So, the ambient temp with the self generated temp, the PMD itself can go up to 300F - 350F inside the hood.
That is way above the threshold.
Then the temperature swing back to the ambient outside, which can be freezing or hot.
The problem is when it is freezing outside, from 300F to less than 32F swing.

TurbineDoc, one of the OG in 6.5L diesel forum did a thread documenting his study on the PMD.
You can check it out in the Technical Library in this forum or the FAQ in the DP forum.

FWIW, my suggestion is to get PMD from Leroy Diesel instead of ebay or amazon or AZ or part store.
He knows what he is doing.
I know it takes time to ship but it should be within 2-3 days with priority mail.
 
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